CA1189373A - Bituminous finisher - Google Patents
Bituminous finisherInfo
- Publication number
- CA1189373A CA1189373A CA000399809A CA399809A CA1189373A CA 1189373 A CA1189373 A CA 1189373A CA 000399809 A CA000399809 A CA 000399809A CA 399809 A CA399809 A CA 399809A CA 1189373 A CA1189373 A CA 1189373A
- Authority
- CA
- Canada
- Prior art keywords
- plank
- compactor bar
- levelling
- bar
- compactor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
- E01C19/00—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving
- E01C19/48—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving for laying-down the materials and consolidating them, or finishing the surface, e.g. slip forms therefor, forming kerbs or gutters in a continuous operation in situ
- E01C19/4833—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving for laying-down the materials and consolidating them, or finishing the surface, e.g. slip forms therefor, forming kerbs or gutters in a continuous operation in situ with tamping or vibrating means for consolidating or finishing, e.g. immersed vibrators, with or without non-vibratory or non-percussive pressing or smoothing means
- E01C19/4853—Apparatus designed for railless operation, e.g. crawler-mounted, provided with portable trackway arrangements
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
- E01C19/00—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving
- E01C19/22—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving for consolidating or finishing laid-down unset materials
- E01C19/30—Tamping or vibrating apparatus other than rollers ; Devices for ramming individual paving elements
- E01C19/34—Power-driven rammers or tampers, e.g. air-hammer impacted shoes for ramming stone-sett paving; Hand-actuated ramming or tamping machines, e.g. tampers with manually hoisted dropping weight
- E01C19/40—Power-driven rammers or tampers, e.g. air-hammer impacted shoes for ramming stone-sett paving; Hand-actuated ramming or tamping machines, e.g. tampers with manually hoisted dropping weight adapted to impart a smooth finish to the paving, e.g. tamping or vibrating finishers
- E01C19/407—Power-driven rammers or tampers, e.g. air-hammer impacted shoes for ramming stone-sett paving; Hand-actuated ramming or tamping machines, e.g. tampers with manually hoisted dropping weight adapted to impart a smooth finish to the paving, e.g. tamping or vibrating finishers with elements or parts partly or fully immersed in or penetrating into the material to act thereon, e.g. immersed vibrators or vibrating parts, kneading tampers, spaders
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
- E01C19/00—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving
- E01C19/48—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving for laying-down the materials and consolidating them, or finishing the surface, e.g. slip forms therefor, forming kerbs or gutters in a continuous operation in situ
- E01C19/4833—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving for laying-down the materials and consolidating them, or finishing the surface, e.g. slip forms therefor, forming kerbs or gutters in a continuous operation in situ with tamping or vibrating means for consolidating or finishing, e.g. immersed vibrators, with or without non-vibratory or non-percussive pressing or smoothing means
Abstract
Bituminous Finisher Abstract of the Disclosure The invention relates to a travelling finisher apparatus for laying down a road surfacing layer of a bituminous compound material, comprising a first precompacting and levelling plank carried by a plank frame, and optionally a second levelling plank connected to a vibratory drive arrangement, whereby a particularly high degree of compact ion is achieved so that subsequent roller compaction is not required. This is accomplished by providing a vertic-ally guided compactor bar extending transversely of the direction of travel at the rear of the first levelling plank in the direction of travel and being of substant-ially narrower width than said first levelling plank, said compactor bar being continually in contact with the surface of the precompacted surfacing layer and adapted to be acted on by linear pulsating forces acting between the plank frame and the compactor bar, and generated by a drive source the reaction forces of which are absorbed by the plank frame. As the reaction forces are taken up by the plank frame, it is possible to make use of the mass inertia of the plank frame and the components asso-ciated therewith for generating extraordinarily high force levels at the compactor bar. Together with the narrow contact surface of the compactor bar, this results in very high area unit loads enabling the required high compaction degrees to be achieved.
This is also enhanced by tuning the frequency of the compaction force pulses to the natural frequency of the system. The compactor bar and the levelling plank fol-lowing it may be divided into sections adapted to be angularly adjusted relative to one another for forming roof- or trough-shaped surface profiles.
This is also enhanced by tuning the frequency of the compaction force pulses to the natural frequency of the system. The compactor bar and the levelling plank fol-lowing it may be divided into sections adapted to be angularly adjusted relative to one another for forming roof- or trough-shaped surface profiles.
Description
1 Bituminous ~inisher D_scription ~his inv~ntion relates -to a -travelling finisher apparatus for making a road sur~ace layer of a bituminous compound material, said apparatus comprising a first precompacting and levelling plank carried by a plank fra~e, and option~
ally a second levelling plank connected to vibratory drive means.
~rom a paper read b~ Mr. M. Blumer at a symposium on modern soil andasphalt surface la~er compaction -tech-niques held on Nov. 22 and 2~ at ~iel, ~witzerlan~, ithas become ~nown that the service life of a road surface layer consisting of a bi-tuminous compund ma-terial (asphalt surface layer) depends largely on the reduction of the voids therein to the smalles-t possible volume. The determ-ining fac-tor of the void volume is the de~ree of compact-ion ~hich may be measured in drill core samples by means of a Marshall test body. The degree of compaction is the specific weigh-t of the core sample as related to the specific weight of -the ~arshall test body. According to the findings explained in this paper, modern re~uirements can only be me-t by asphalt surface layers having a degree o~ compaction of at least about 98 p.c.. In practice a compaction degree of this magnitude has been achieved b~
providing a travelling finisher apparatus employed for laying down the surface layer with a hydraulically oper-a-ted compactor bar adjacent the leading edge of the levelling planX, cooperating therewith to precompact the road surface layer to a maximum compaction degree of 93.5%. ~he compactor bar streaks the compound material to the proper level and compacts it by a ramming action as well as b~ means of its oblique leading face effective to compress the material to a reduced cross-section~ ~he sub-se~uently ac-ting levelling plank is effective to close and to smoothen the sur~ace. ~he subse~uently re~ulred 3~3 1 Linal compactio~ -to a compaction degree of at least 98%
reguire~ -the employ of road rollers i~media-tely following -the finisher appara-tus. This purpose is achieved by meaI~s of static smoo-th-walled rol.lers and/or vibratory rollers, which may have to travel as much as ten times over each surface unit o:E the road surface layer. .As the rolling opera-tion has -to be carried out s~nchronuously ~ith -the travel o~ the finisher appara-tus, the wide lanes laid down in large-capacity roadbuildi~g operations require the simultaneous employ of a plurality of rollers for enabling the re~uisi-te roller compaction to be carried out synchronously with -the finisher travel with -the road surface layer still in the plastic state. ~his final compaction is usually caried out with static pressures of about 3 to 12 kp/cm2.
In finisher appara-tus known from ~E-OS 17 8~ 633 and ~7 84 634, the second levelling planX is ~ormed as a trailing vibra-tory compactor provided with vibrator~
drive means. ~he compactor contacts the precompacted surface la~er with a skid-shaped vibrator plate e~tending in the travelling direction over a length corresponding approximately to one half of the travel path wid-th.
Mounted on the vibrator plate are rotar~ driven shafts carrying excenter weights for generating pulsating forces in all directions of planes extending perpendicular to -the shafts. ~he maximum downward directed resultant force obtainable by this vibration system corresponds to no more than twice the total weight of the compactor. A
greater resultant force would cause the compactor to s-tart aumping, ~hich would result in damage at leas-t in the surface area of the road cover layerO As the resultant force available for the compaction process is thus limited and is moreover distr~buted over the large surface of the vibrator plate, t~e specific surface unit load is ~ar to small as to permi-t a compaction degree of for example 98%
to be obtained thereb~. Although in bo-th references ci-ted above it is emphasized that the compaction degree obtained 7~
1 is so high as -to render subse~uent roller compaction unneces~ar~ has been found in practice that the actually obtainable compac-tion may just barely suf~ice in the case of poured a~phalt, ~rhereas in the case of normal compound layers subse~uent roller compac-tion is absolutel~ necessary~ It is also obvious that wi-th -thls compactor, io e. with the large area of the vibrator plate it is impossi~ble -to obtain the specific surEace unit loads achieved in the case of roller compaction by the sub-s-tantiall~ linear contac-t area of -the roller. In addit-ion it is to be noted that due to the employed drive sys-tem with rotating excentric masses, the pulsating forces transmitted from the vibrator plate to the surfac-ing layer are not restricted to vertically directed forces, but also include forces acting in the travel direction or obli~uel~ thereto, such forces being undesirable in any case.
It is thus an object of the invention to provide a finisher apparatus of the type set forth in the introduction, which permits a considerably higher compaction degree of the laid-down surface layer to be achieved than with the known solutions.
~or attaining this object the invention provides that -there is provided a ver-tically guided compactor bar extending transversely of the travelling direction at -the rear of the first levelling plank in the direction of travel and being of substantial~y narrower width than the first level--ling plank, said compactor bar being continually in contact with the surface of the precompacted surfacing layer and adapted to be acted on by linear pulsating forces acting between the plank frame and the compactor bar and gener-ated by a drive source the reaction forces of which are absorbed by the plank frame.
~he compactor bar engages -the road surface layer with a substantially smaller contact surface than for instance 3~73 L~
1 a second levelling plan~ with a vibratory drive means or the abovc described knot~ finishing compac-tors wi-th -their large-area vibrator plates. As the pulsating forces app-lied -to the compactor bar are taken up by the plank frame a~ld are linearly downwards direc-ted, the total force values achieved are substantially greater than hi-therto possible. ~he total force value may thus indeed be greater than -twice the weight of the plank frame wi-th -the elements mounted therein. ~his implies al-together that -the specific area unit load is as great or even greater than in the case of a roller ~ith its line contact. This is because also the compactor bar is in contact onl~ with a narrow, ribbon-shaped su~face area. In practical operation its has thus been surprisingl~ found that, probabl~ due to the dynamics of this specific operating manner of the compactor bar~ the specific area unit loads are consider-ably greater -than could have been expected in consider~
ation of -the mass of the plank frame wi-th the components contained therein. ~he absorption of the reac-tion forces by -the plank frame permits the inertia of the plank frame to be utilized for the application to the compactor bar of compaction forces greater than twice the weigh-t of said mass.
In an advantageous embodiment of the invention there is provided a mechanic or h~draulic pulsating force drive means for the compactor bar. Force generating drive mea~s of this type permit the reQuisite ~reat forces to be continuously and reliably applied to the compactor bar.
In a further sui-table em~odiment of the invention one or both levelling planks may be provided with vertical guide~
for the compactor bar, whereby the co~pactor bar is braced against the reaction forces resulting from the travel of ~he finisher apparatus, so that the compac-tion forces are introduced into the surface layer in a controlled manner.
In a further advantageous embodiment the leading portion 3'73 1 of the compac-tor bar may be provided with an obli~uely rising pressure surface extending from the lower surface of the co~pactor bar at a lower level than the lower surface oE the first levelling plank at least to the level of the lower surface of -the first levelling plank.
The obli~ue pressure surface compensates the level differ-ence between the precompacted and the finish-compac-ted layer surface and assis-ts in the compacting operation, while the lower surface of the compactor bar exerts com-paction forces ac-ting vertically into the surfacing la~er, and -that over a relatively small surface area, so -that the re~uisite high specific area unit loads are obtained.
In a further advan-tageous embodiment the invention provides that the compactor bar is connected through at leas-t one resilient element to a pressure beam mounted for linear upward and downward movement and coupled to a crank or cam drive arrangement mounted in the plank frame. ~he crank or cam dri~e arrangement is effective to generate an oscillating movement of the pressure beam, from where the resilient element transmitts exclusively do~mwards directed compacting force pulses to the compactor bar.
~he shape of -the compacting force pulses may be pre-detexm-ined by properly selecting the design of the dri~e arrange-ment so as to obtain an optimum compaction effect over awide range.
~etween the pressure beam and the compactor bar there is preferabl~ arranged a plurality of preferably pre-stressed compression springs. ~his prevents the compactor bar from being lifted off the surface, that is, the compactor bar is always held in pressure contact, with the contact-pressure varying in accordance with the fre~uency and the magnitude of the compacting force pulses. The compression springs are effective to transmit the compac-ting force pulses to the compactor bar only during downward movement of -the pressure beam 7 while upward movement of -the pressure beam results in the compactor bar being relieved~ although 3~3 1 only u~ to a point determined by the pre-stressed con-dition of the compression springs.
In a Pre~erred embodimen-t o~ -this kind, the compression springs are in the form o~ helical compression springs mounted on guide rods o~ the compactor bar, said guide rocls e~tending through the pressure beam in-to engage~ent with vertical guides provided on the or each levellin~
plank~ This type o~ mounting prevents -the compression springs from buckling sideways. At the same time; the guide rods brace the compactor bar against the reaction forces resul-ting from the travel o~ the ~inisher apparatus.
lhe operating stroke and the ro-tary speed of the cra~k-or cam drive arrangement are preferabl~ adjustable, so tha-t -the shape and magni-tude of the compacting force pulses may be varied in accordance with the consistency and thickness o~ the surfacing layer to be laid do~m.
In an alternative embodiment of the invention, a hydraulic compac-tion force drive means may comprise at least one hydraulic cylinder supported relative to the compactor bar b~ a levelling plank or by the plank ~rame and having a working chamber containing a work piston rigidly connected to the compactor bar. In a h~draulic drive arrangement there are no vibration-caused forces of oscilla-tions which are not directed parallel to the direction of the compact-ing ~orce pulses, while permi-tting particularly great compaction force values to be achieved. Moreover, the energy loss caused by the deformation effort in the mechan-ical drive arrangement is~substantially eliminated in the hydraulic system, as the compressible hydraulic medium column forms a spring cons-tant within the system which plays an important role for the operation of the compactor bar as related to the natural frequency of the system formed by the plank frame and the components mounted therein. The spring formed by the h~draulic medium column operates with lower loss, however, than a mechanical spring.
1 According -to a further characteristic fea-ture of the in-ven-tion said work chamber may be adapted to be applied with a pulsating pressu~e through a h~draulic control device~ These pressure pulses are converted into the actuating force pulses that are applied to the compac-tor bar.
In practice it has been found particularl~ effective if the,h~draulic con-trol device comprises a variable-speed rotarg valve the inlet pressure of which is adjustable.
~hese two variables then permit the actuating force pulses to be adjusted with regard to their shape, their frequency and their magnitude.
A further advantageous embodiment is characterized b~ -the fact that the compactor bar is suspended from a counter support by means of at least one tension spring acting opposite to the direction of the pulsating force. ~his tension spring de-te~mines the selec-ted pre-tension of the compactor bar, so that the pulsating force does not every - time have to be built up from zero to its maximum value, as -the compactor bar continuously rests on the surface with the selected pre-tension pressure. In addition the tension spring prevents the compactor bar from drooping during transport of the finisher~ -In a further preferred modification of the subject matterof the invention the plank frame may be connected to the finisher apparatus as a structural unit by means of pivot-able booms and vertical suppor-ts adapted to be actuated for transport or rearward' travel of the finisher apparatus.
This structural uni-t may also be attached to already existing finisher appara-tus of conventional type, whereby such existing ~inishers are enabled -to la~ down surfacing layers wi-th the re~uired high degree of compaction without subsequent roller compaction. ~he vertical supports fin-ally permit the plank frame and its structural components to be lifted to a non-operative position for transport.
37~3 1 In a further embodiment of the subaec-t matter of the in-vention it is of impor-tance that the pulsating force fre~uenc~ is e~ual to or higher than the na-tural fre~uency of a system including the mass represented by the plank frame and -the components carried -thereb~, and a spring component acting between -the compactor bar and the support absorbing the reaction forces. In addition to the purel~
static loads on the compac-tor bar, this feature permits -to obtain a dynamic ef~ect resulting in a ~pectacular increase of the compacting forces exerted by the compactor bar, as the inertia of the system is made use of to in-crease the pulsating force values. If the fre~uenc~ of the pulsating force is e~ual to the natural fre~uency of the s~stem, the resulting resonance phenomena lead to the forces exerted b~ the compactor bar becoming greater than the dead weight of the plallk frame and its components.
On the other hand it has been found that a pulsating force fre~uency above the natural frequency of the sys-tem also permits -to achieve substantially greater compaction forces than might be expected from the dead weight of the system. ~his desirable effect may be assumed to be due to the dynamic rela-tionships resulting ~rom the operations in the above described manner.
For the faultless compaction of the surfacing layer to the desired high degree it is of importance~ according to a further aspect of the inventionj that in diagrammatic representation the compaction force pulses for~ half-wave shaped curves of a narrower width and more poin-ted shape as compared to a sinus wave configuration. Due to this pointed and narrow shape, the compaction force pulses are enabled to penetrate the surfacing layer to the desired depth.
In a further advantageous embodiment of the subject matter of the invention it is proposed that in diagra~matical representation there is a time interval between each two compaction force pulses, -the length of such interval being ~ 3~ 3 1 greater, particularly several times greater than the half wave length of a compaction force pulse. ~his time interval ma~ be achieved in a simple manner by forming the compact-ion force pulses narrower and of more pointed shape as compared to a sinus wave configuration~ In this case the time interval be-tween each two compaction force pulses will be determined by the magni-tude by which the force pulses are narrower than corresponding sinus wave pulses.
~his time interval permits the entire sys~em to come to rest before a new compaction force pulse occursO
In accordance with a further important aspect of the invention~ the ~agnitude of the time interval between any two compaction force pulses may be adjusted to the travelling speed of the finisher apparatus in such a manner that the longitudinal section of the surface laJer compacted by the compactor bar at a single force pulse is shorter than the width of the lower surface of the compac-tor bar in the direction of travel. During the time interval between the compaction force pulses the entire system comes to rest, and the compactor bar is advanced over the surfacing layer-to be compac-ted in the direction of travel. The advancing stroke of the compactor bar up to the occurrence o~ the next compaction force pulse may not be too short, as there would otherwise be the danger of the surfacing material particles being crushed.
On the other hand, the advance stroke may not be too great, as this might result in a reduced compaction effect or i~ the formation of an elevation in front of the compactor bar which the latter woula tend to climb due to the react-ion forced created by the`advancing movement. ~he above described provisions permit the shape, the magnitude and the fre~uency of the compacting force pulses to be tuned to the natural fre~uency of the system in a simple manner, additionall~ taking into account the -type and thickness of the surfacing layer as well as the temperature and other physical parameters.
1 A further advantageous embodiment of the subject matter of the inve~tion, in which there is provided a hydraulic drive arrangement for generating the compaction ~orce pulses, is characterized in -that said spri~ componen-t is provided by the h~draulic fluid column acting in the system for ac-tuating the compactot bar. ~his spring constan-t m~ be determined b~ calculation so that, with a given mass of the ~stem, it is possible to determine its natural fre~uency itself governing the fre~uenc~ of -the compaction force pulses. Although the h~draulic fluid is in theo~ not compressibleg it does in practice show a certain degree of compressibilit~ enabling the h~draulic fluid column -to act as a spring under pressure exerted thereon.
In a fur-ther advantageous embodiment including a h~draulic drive arrangement and a h~draulic c~linder there may be provided a resilient connection between the hydraulic c~linder and the plank frame or levelling plank, respect-ively. ~his resilient connection intentionally providesfor a spring component which is predetermined with respect to the oscillation d~namics of the system and per~its the natural fre~ue~cy of the system to be influenced, In a particularl~ suitable practical embodiment the resilien-t con~ection may be formed b~ a resiliently be~dable beam cantilevered in a direction vertical to the linear pulsating forcesO ~his beam may be selectively . cantilevered or supported at both ends, It serves as a counter support for absorbing the reaction forces of the compaction force pulses and acts simultaneousl~ as a spring acting in the direction of the compaction force pulses. ~he counter support is rigid in all directions e~tending obli~uely or transversel~ with respect to the direction of the compaction force pulses, so that there cannot occur an~ undesirable relative movements, 7~
l A further suitable embodiment of the subject ma-tter of the inven-tion is charac-terized by the provision that along its working width e~tending transversely of the direction of travel, the compactor bar is divided into at least two sections in-terconnected by a hinged joint i~
such a manner that the lower surfaces of the sections con-tacting the surface oE the surfacing la~er are adap-ted to be angularly adjusted relative to one another in accord-ance to the road profile, without being adjustable to staggered levels relative to one another. With a compac-tor bar of this type it is possible to reliably and uniforml~
compact profiled road surfaces without the danger that an undesirable step or rib is formed in the finished surface la~er by adjustment of the adjacent ends of the two com-pactor bar sections to different levels.
A further advantageous embodiment of the subject matterof the invention is characterized by the provision that along its working width extending transversely of the direction of travel, the second levelling plank is divided into at least two sections i~terconnected by a hinged aoint in such a manner that their lower surfaces contact-ing the surface of the surfacing layer are adapted to be angularly adjusted relative to one another in accordance with the road profile without being adjustable to differ-ent levels relative to one another~ the separation gap between the sections being rectilinear and extending ob-li~uely to the direction of travel.In this manner it is thus possible to adjust also the trailing levelling plank to the surface profile. ~hanks to its obliquely extendi~g separa-tion gap the level]ing plank will not only level a surface rib possibly formed by the separation gap of the compac-tor bar, but will itself be unable to form such rib on the finished surface.
In this context the trailing end of -the separa-tion gap of the compactor bar is preferably sligh-tly offset relative to the leading end of the separation gap of the second ~ ~33~3 1 levelling pla~k. ~he surface rip exiting from the separ-ation gap of the compactor bar is -thus prevented from entering the obli~uely extending separation gap of the second levelling plank and ~rom moving therethrough~ but will instead be reliably levelled down b~ the levelling plan~.
According to a specific aspect of this embodimenty the trailing and of the separa-tion gap of the levelling pla~k is laterally offset with respect ~o its leading end by at least the width of the separation gap. ~his provision ensures tha-t no elevations can be formed in the surface of the finished surfacing layer at the location of the separation gap, as there is no linear passage extending through the second levelling plank in the direction of travel.
~mbodiments of the invention shall now be described with reference to -the accompanying drawings~ wherein:
fig. 1 shows a diagrammatical side elevation of a travel-ling finisher apparatus during layi~g down a bitum-inous surfacing layer, fig. 2 shows an enlarged detail of fig. 1 in cross-section3 fig. 3 shows a first embodiment of a drive arrangement for generating pulsa-ting compaction forces as employed in the finisher apparatus of fig~ 1, fig. 4 shows an enlarged cross-sectional view of the drive arrangement shown in fig. 3, 5 fig. 5 shows a cross-sectional view of a second embodi-ment of a drive arrangement for the compactor bar~
fig. 6 shows a front end view of the drive arrangement of fig. 5 together with a hydraulic control circuit, 3~3 '13 1 fig. 7 shows a detail of the embodimen-t of figo 5, fig. 8 shows a diagram of a further embodiment, fig3 ~ shows a graph represen-ting the shape and ~re~uency of the compaction force pulses transmitted from the compaction bar into the sur~`acing layer, fig~ 10 shows a detail view similar to fig~ 3 of` a fur-ther embodi~ent, figo 11 shows a detail view of components not visible in fi~. 10, and 5 fig. 12 shows a top plan view of components of the embodi-ment of fig. 10.
A travelling finisher apparatus 1 for laying down`a road surfacing layer of à bituminous compound material, e.g.
an æphalt surfacing layer, comprises a wheeled under-carriage 2 carr~ing an operator's cabin 3, and is adapted to travel in the direction of arrow F. Attached to the rear end of finisher appara-tus 1 by means of pivotal booms 6 and a lifting aggangement 7 is a plank frame 5 including components for pre-compacting and final compa~-ing of the sur~`acing layer. ~ocated within finisher appar-atus are containers (not shown) for receiving -the compound material~ from where said material is fed to a distrib-utor arrangement, eOg. a transverse auger 8 by means Of which it is spread on the subjacent ~loor surface. In this mPnner there is provided a lose layer 9 in front of a levelling blade 10. A first levelling plank 12 located to the rear of blade 10 is preceded by a vertically movable ramming bar 15. At this location the surfacing layer 9a is precompacted to a compaction degree of about 92 to 94%.
~ocated to the rear of first levelling plank 12 in the direction Of travel F is a compactor har 13 extending transversely of the direction of travel and effective to 3~
1L~
1 compac-t -the precompacted surfacing layer to a final compaction degree of abou-t 98% (9b). '~his is followed by a second levelling plank 14 provided ~or levelling sur-face irregulari-ties possibly caused b~ compac-tor bar 13.
~he construction of plank frame 5 is more clearly sho~n in fig. 2. ~amming bar 15 has an inclined leading pressure face 16 and is operativel~ connec-ted b~ means of drive transmitting members 17 to an excentric drive arrangement 18 mounted in stationar~ bearings 19 and adapted to be driven by a sui-table drive source (not shown). Ramming bar 15 is advantageousl~ guided for vertical movemen-t at the leading face of firs-t levelling plank 12. ~he lower surface of levelling plank 12 is formed by a level-ling plate 2~ contacting the surfacing layer for levellingan~ surface irregularities caused by ramming bar 15~
~evelling plank 12 ma~ optionally be provided with a vibrator device (not shown).
~ ~etween first levelling plank 12 and second levelling plank 14, compactor bar 13 is slidably guided in vertical guides 24 on said levelling planks. Coampactor bar 13 has a plane, narrow lower surface 23 and an obli~uely rising forward pressure face 22 for bridging the difference in height between the lower surface of levelling plate 21 and the lower surface of a levelling plate 29 attached to second levelling pl~nk 14. Compactor bar 13 is opera-t-ivel~ connected to a compaction force drive arrangement 25 through a number of guide rods 26.
The second levelling plank ma~ also be provided with a vibrator device 27 fed via a h~draulic line 28.
~igs. 3 and 4 show one embodiment of the drive arrangement 25 for compactor bar 13.
A crank or cam drive shaft 30 is rotatabl~ moun-ted in sta-tionar~ bearings and carries excentric drive members 31.
l ~ollower members 32 cooperating with shaft 30 are con-nected through push rods 33 to a pressure beam 34 located therebelow -through which the guide rods 26 carrying the compactor bar 13 extend. In ~ddition to being guided in vertical guides 24, compac-tor bar 13 is also guided b~
engagemen-t of gulde rods 26 with vertical guides 35 attached to plank frame 5 or to first levelling pla~k 12 by ~eans of brackets 380 Disposed between pressure beam 34 and the upper surface of compactor bar 13 is a plural-ity of preferabl~ pre tensioned helical compressionsprings 37 adap-ted to convert the oscillating movement of pressure beam 34 under the action of the drive arrange-men-t into vertically directed linear compaction force pulses without upward and downward movement of compactor bar 13. Within pressure beam 34 guide rods 26 are guided in slide bearings not shown in detail~
Compactor bar 13 is suspended by means of at least one - tension spring 39 from a stationary counter support, for instance from vertical guides 24 of forward levelling plank 12 in such a manner that compression springs 37 are slightly preco~pressed and that çompactor bar 13 is pre-vented from drooping during transport.
~igs. 5 and 6 show a second embodiment of a drive arrange-ment 25' for compactor bar 13. In this embodiment 7 compactor bar 13 is also suspended by means of ten~ion springs 39.
~he upper ends of guide rods 26' are formed as or connected to a hydraulic piston 40 sealingl~ guided i~ a working chamber 41 of a h~draulic cylinder 42, each c~linder 42 being attached to a mounting 35' on plank frame 5 or levelling plank 12, respectively. Hydraulic feed ducts 43 connect all working chambers 41 to a control element 45 containing a rotary valve 46. Rotary valve 46 is adapted to be rotated by a variable-speed hydraulic motor 47 to control the hydraulic pressure feed of working chambers 41 Hydraulic fluid is fed to control element 45 through duct 50 connected to the outlet of a tap valve 48 and '16 l leading to a pressure accumulator 49. Inlet 47 of -tap valve 48 is connected to a pressure source (not sho~m).
Ano-ther duct 53 connects the other outlet of -tap valve 48 to the inlet of hydraulic mo-tor 47, there being provided an adjus-table throttle element 44 for controlling the ro-tar~ speed of hydraulic motor 47 and rotary valve 4 and thus the fre~uency of the compaction force pulses.
A return duct 51 leads ~rom control element 45 to a re~
servoir 52, to which the outle-t of hydraulic motor 47 is also con~ected. A leak ret-urn duct 60 is also connected to control element 45.
Fig. ? shows in diagrammatic form the components of the finisher apparatus shown in detail in fig.-3. Plank frame 5, or first levelling plank 12, respectivel~, is shown as a box-shaped mass having a natural fre~uency fe ~ pre-determined height. The natural fre~uency fe of mass m of the plank frame or the levelling plank, respectively, is determined not alone by the mass itself, but also b~ an additional spring component C included in the system. In the embodiment shown, in which hydraulic cylinder 42 is connected relatively rigidly to mass m (see also fig. 5), spring component C is formed by the hydraulic fluid column within working chamber 41 and in feed duct 43 leadi~g to control element 45 shown in fig. 6. Although the hydraulic medium is in theory incompressible, it has a certain compressibility i~ practice, whereb~ it acts as a ~pring.
In addition, feed duct 43, which is a conventional high-pressure hydraulic tube, is capable of limited elastic expansion. ~ogether with the elasticall~ expandable duct, the hydraulic fluid columh thus acts as a spring capable of modifying the natural fre~uency of the system formed by mass m o~ plank frame 5, as this mass m is excited to vibrate by means of the drive arrangement 41, 42, 40 generating the compaction force pulses for compactor bar 13. In practice the natural frequency of this syste~ lies within the range of 20 to 22 Hertz.
3~73 l As seen in fig. 7 7 piston 40 and guide rod 26' are effective to impose linear compacting force pulses on compactor bar 13, whereb~ the latter compacts the pre-compacted surfacing layer 9a to a thickness 9b. ~he pres-sure face 22 at the leading side of compactor bar 13forms a -transition between -the levels of the two level-ling planks 12 and 14~ while the narrow flat lower sur-face 23 of compactor bar 13 exerts the downwards directed compaction forcesO In order that the compaction forces are sufficient to achieve -the required high degree of compaction, the frequency f1 of the pres.sure feed to working chamber 41 is selected equal to or higher than the natural frequency of the system. If the compaction force pulse frequenc~ lies within the range of the natural frequency, the resulting resonance phenomena lead to sub-stantially greater compaction forces introduced illtO the surfacing la~er than might be expected in view of the known weight of mass m. In a purely static condition, a compaction force which is only slightly greater than the weight of mass m would tend to lift the mass. Due to the dynamic condition resulting from the tuning of the frequen-cies, however, mass m is not lifted, but remains practic-all~ stationary, as does the compactor bar itself. ~he same occurs if the compaction force pulse frequenc~ is ~6 higher than the natural frequency of the syste~, as in this case the inertia of the oscillating mass m as in-flue~ced b~ spring constant C is sufficiently high, so that substantially greater compaction forces can be gener-ated and absorbed than might be expected in view of the known weight of mass m.
Fig. 8 shows a further embodiment .somewhat similar to that of figs. 7 and 5. At this instance~ however, the connection between mass m and hydraulic cylinder 42 is formed by a resilient beam 35" fixedly a-ttached to mass m and extend-ing perpendicular to the direction of -the compaction force pulses generated. Beam 35" in this embodiment act as a spring the action of which is superimposed on the spring action of the hydraulic medium column in working chamber ..
11~393'73 '18 l 41 and feed duc-t 43. Beam 35" thus provides one spring component C1, while the h~clraulic fluid column provides a second spring component C2, which together result in a natural ~re~uency fe of the system which is slightly lower than in the embodiment of fig. 7, namely, about 15 to 20 Hertz. It is obvious that this lower na-tural fre~uency permi-ts the frequency of -the compaction force pulses to be selected lower than in the e~bodiment o~
fig~ 7 for operation within a resonance range. On the other hG~nd, the fre~uency of the compaction :Eorce pulses need not in this embodiment be selected as high as in the embodiment of fig. 7 for operation above the natural fre~uency o~ the system. In operation of the embodiment of fig. 8 it is also found that due to the dynamics of the oscillating hydraulic fluid column and the reaction forces of the compac-tion force pulses the actuall~ achieved compaction forces 13 of compactor bar 13 are substantiall~
greater than would be expected under sta-tic conditions in view of the known weight o~ mass m. And it is only with compaction forces of this magnitude tha-t the desired high degree o~ compaction of the surfacing layer is achievable.
~ig. 9 shows the shape and the timed se~uence of the com-paction force pulses in the form of a diagram~ ~herein the interrelation between the magnitude of the compaction force, drawn in -the vertical direction, and the duration of the force pulses, drawn in the horizontal direction, becomes evide~t. A horizontal line at a distance p above the horizontal axis symbolizes -the pre-loading of com-pactor bar 13 as by tension spring 39 shown in fig. 4.
The dotted line shows a sinus wave configuration that would be achieved if compactor bar 13 were capable of undampened oscillation. As the surfacing layer acts, however, as a nearly ideal da~pening medium, the portions of the oscil-lation waves below the horizontal axis are eliminated.
The configuration of the compaction force pulses, two of which are shown at S1 and S2~ is considerably narrower l and more poin-ted as compared to the half waves of the sinus wave configuration above the horizon-tal axis. I~
the sinus wave configuration shown i~ dotted lines the pulse width would be ~', while the narrower configuration o~ Pulses S1 and S2 results in a reduced pulse width ~, corresponding to a shortened active period of the compact-ion force pulses. ~he actual width and thus the ~agnitude of each compaction force pulse can be calculated from a theoretical fre~uenc~ f2 determined by the -time interval between the positive and the negative reversal point of a half wave of the compaction force pulses. It is obvious that the higher this theoretical frequency f29 the narrower9 higher and more pointed are the compaction force pulses S1 and S2 In practice, however~ compaction force pulses ~1 and S2 ac-t of the surfacing layer with a fre~uency f1, whereb~
the system is caused to oscillate at this lower freQuenc~
f1 which is determined by the time interval between the fading of the one compaction force pulse S1 and the built-up of the succeeding force pulse S2. During this interval the system comes to rest, while compactor bar 13 i9 advanced a certain distance depending on the travelling speed of the finisher apparatus. This pulse characteristic is selected on purpose, in order on the one hand to avoid crushing of the surfacing material caused by a too short int~rval in relation to the travelling speed~ and on the other hand to avoid insufficient compaction of the sur-facing layer caused by too long intervals ~.
In the hydraulic drive arrangement shown in fi~. 5 and 6, the control of time interval ~ may be accomplished in a simple manner by proper design of the rotary valve 46 in control element 45. ~he outlet ports of rotary valve 46 may thus be formed in such a manner, that the flow passage is apruptly opened and closed on ro-tation of the rotar~
valvel succeeded by a rest phase corresponding to interval ~. It is thus possible to select the freQuency f2 by ., 1 properly adjusting the rotary speed of rotary valve 45, while the configuration of compaction force pulses S1, S2 is determined b~ the arrangement and shape of the outlet ports. The magnitude of the compaction force pulses may 6 be adjusted in a simple ma~ner via the inlet pressure at the rotar~ valve. '~he interval between force pulses may for instance be determined by providing the rota~ valve with one or more control ports~ It is thus possible to selectively determine the width and profile of the com-paction force pulses, and thus the theoretical frequencyf2, as well as9 independently thereof, the time interval T between successive force pulses S1, S2~ and thus the actual oscilla-tion fre~uency f1. As alread~ stated, the frequency f1 is selected in a desired relationship to the natural fre~uency of the system fe ~fig. 7 and 83.
In the mechanical drive arrangement according to figs. 3 and 4~ the configuration of the compaction force pulses may for ins-tance be determined by the employ of steep control cam faces, in which case the time interval between successive pulses may be determined by a neutral or rest cam surface. In this embodiment it is thus also possible to select the pulse configuration and the interval between pulses independentl~ of one another by proper design of the rise faces and rest surfaces of the cams, respectively.
In the case of the mechanical drive arrangement, the natural fre~uency of the system is by the wa~ lower than in the case of the hydraulic drive arrangement, l~ing at about 8 to 10 Hertz.
In all embodiments, the sèlection of the pulse configur-ation, the spring component and -the mass of the plank frame or levelling plank, respectivel~, in relation to one another permits the natural fre~uency of the system and the inertia of the mass to be made use of for gener-ating greater compaction forces b~ means of the compactor bar than would otherwise be possible in view of the weight of the mass and of the compactor bar~
1 r~he selec-ted narrow and pointed pulse configuration results in the occurrence of ver~ high accelerations within the s~stem, including the compactor bar, leading to ex*ra-ordinarily great forces at -the compactor bar due to -the iner-tia forces. ~his in-teraction permits the generation of compaction forces capable of obtaining compaction degrees of up to 100%.
~he embodiment sho~m in figso 10, 11 and 12 is partic-ularly sui-ted ~or laying down surfacing layers having a roof-shaped or trough-shaped profile~ I~ this embodiment, compactor bar 13 is divided in-to two sections 13a, 13b.
Between the adjacent end faces of sections 13ag 13b, there is a separation gap 62, the lower width o~ which depends on the angle to which sections ~3a, 13b are ad justed relative to one another in accordance with the profile to be obtained. On the upper surface, or at an intermediate hei~h-t of the compactor bar there is pro-vided a hinge 6l permitting sections 13a, 13b to be angul-arly adausted relative -to one another, but not -to dif~fer-en-t levels~
Shown particularly in fig. 10 is a drive arrangement 25 for the two sec~ions 1~a, 13b of compactor bar 13. An excen-ter or cam drive shaft 30 carrying drive members 31 is rotatably mounted in stationary bearings. ~ollower members 32 cooperating with shaft 30 are connected through push rods 33 to a pressure beam 24 therebelow. Guide rods 26 extending through pressure beam 24 each carry one of sections 13a~ 13b. ~he compactor bar sections are guided in vertical guides 24, and additionally via guide rods 26 in vertical guides 35 attached for instance to plank frame 5 ~nd/or to forward levelling plank 12. ~etween pressure beam 34 and the upper surfaces of compac-tor bar sections 13a, 13b there are arranged a number of helical compression springs 37 for converting the ~ertical oscil-lation of the pressure beam induced by the drive arrange-ment into vertical compaction force pulses without causing l upward and downward movement of the compactor bar~ ~he reac-tion forces of the compaction forces are directly absorbed by the pla~k frame or by the levelling pl ~{
itself.
Fig. 11 shows the second levelling plank 1~ following compactor bar 13. It is likewise divided in-to two sections 14a~ 14b transversely of -the direction o~ travel, and has a separation gap 64 between bottom plates 29a, 29b. Sect ions 14a and 14b are connec-ted to one another through a hinge 63.
As finall-~ sho~m in fig~ 12, separation gap 64 be-tween plank sec-tions 14a and 14b extends somewhat obliquely with respect -to -the direc-tion o~ tra~el. ~his enables an elevation caused b~ the separation gap 62 between compactor bar sections 13a, 13b -to be levelled down to the surface of the sur~acing layer. In detail it i9 shown that the rear end of separa-tion gap 62 is la-terall~ off-set with respect to the ~orward end of separation gap 6~,and that the rear end of the latter is offset with respect to the forward end b~ at least the width of the gap~ ~he axes of hinges 63 and 61 are aligned with one anotherO
~5 The sec-tions may also be interconnected by ~eans of an articulated joint instead of through hinges.
ally a second levelling plank connected to vibratory drive means.
~rom a paper read b~ Mr. M. Blumer at a symposium on modern soil andasphalt surface la~er compaction -tech-niques held on Nov. 22 and 2~ at ~iel, ~witzerlan~, ithas become ~nown that the service life of a road surface layer consisting of a bi-tuminous compund ma-terial (asphalt surface layer) depends largely on the reduction of the voids therein to the smalles-t possible volume. The determ-ining fac-tor of the void volume is the de~ree of compact-ion ~hich may be measured in drill core samples by means of a Marshall test body. The degree of compaction is the specific weigh-t of the core sample as related to the specific weight of -the ~arshall test body. According to the findings explained in this paper, modern re~uirements can only be me-t by asphalt surface layers having a degree o~ compaction of at least about 98 p.c.. In practice a compaction degree of this magnitude has been achieved b~
providing a travelling finisher apparatus employed for laying down the surface layer with a hydraulically oper-a-ted compactor bar adjacent the leading edge of the levelling planX, cooperating therewith to precompact the road surface layer to a maximum compaction degree of 93.5%. ~he compactor bar streaks the compound material to the proper level and compacts it by a ramming action as well as b~ means of its oblique leading face effective to compress the material to a reduced cross-section~ ~he sub-se~uently ac-ting levelling plank is effective to close and to smoothen the sur~ace. ~he subse~uently re~ulred 3~3 1 Linal compactio~ -to a compaction degree of at least 98%
reguire~ -the employ of road rollers i~media-tely following -the finisher appara-tus. This purpose is achieved by meaI~s of static smoo-th-walled rol.lers and/or vibratory rollers, which may have to travel as much as ten times over each surface unit o:E the road surface layer. .As the rolling opera-tion has -to be carried out s~nchronuously ~ith -the travel o~ the finisher appara-tus, the wide lanes laid down in large-capacity roadbuildi~g operations require the simultaneous employ of a plurality of rollers for enabling the re~uisi-te roller compaction to be carried out synchronously with -the finisher travel with -the road surface layer still in the plastic state. ~his final compaction is usually caried out with static pressures of about 3 to 12 kp/cm2.
In finisher appara-tus known from ~E-OS 17 8~ 633 and ~7 84 634, the second levelling planX is ~ormed as a trailing vibra-tory compactor provided with vibrator~
drive means. ~he compactor contacts the precompacted surface la~er with a skid-shaped vibrator plate e~tending in the travelling direction over a length corresponding approximately to one half of the travel path wid-th.
Mounted on the vibrator plate are rotar~ driven shafts carrying excenter weights for generating pulsating forces in all directions of planes extending perpendicular to -the shafts. ~he maximum downward directed resultant force obtainable by this vibration system corresponds to no more than twice the total weight of the compactor. A
greater resultant force would cause the compactor to s-tart aumping, ~hich would result in damage at leas-t in the surface area of the road cover layerO As the resultant force available for the compaction process is thus limited and is moreover distr~buted over the large surface of the vibrator plate, t~e specific surface unit load is ~ar to small as to permi-t a compaction degree of for example 98%
to be obtained thereb~. Although in bo-th references ci-ted above it is emphasized that the compaction degree obtained 7~
1 is so high as -to render subse~uent roller compaction unneces~ar~ has been found in practice that the actually obtainable compac-tion may just barely suf~ice in the case of poured a~phalt, ~rhereas in the case of normal compound layers subse~uent roller compac-tion is absolutel~ necessary~ It is also obvious that wi-th -thls compactor, io e. with the large area of the vibrator plate it is impossi~ble -to obtain the specific surEace unit loads achieved in the case of roller compaction by the sub-s-tantiall~ linear contac-t area of -the roller. In addit-ion it is to be noted that due to the employed drive sys-tem with rotating excentric masses, the pulsating forces transmitted from the vibrator plate to the surfac-ing layer are not restricted to vertically directed forces, but also include forces acting in the travel direction or obli~uel~ thereto, such forces being undesirable in any case.
It is thus an object of the invention to provide a finisher apparatus of the type set forth in the introduction, which permits a considerably higher compaction degree of the laid-down surface layer to be achieved than with the known solutions.
~or attaining this object the invention provides that -there is provided a ver-tically guided compactor bar extending transversely of the travelling direction at -the rear of the first levelling plank in the direction of travel and being of substantial~y narrower width than the first level--ling plank, said compactor bar being continually in contact with the surface of the precompacted surfacing layer and adapted to be acted on by linear pulsating forces acting between the plank frame and the compactor bar and gener-ated by a drive source the reaction forces of which are absorbed by the plank frame.
~he compactor bar engages -the road surface layer with a substantially smaller contact surface than for instance 3~73 L~
1 a second levelling plan~ with a vibratory drive means or the abovc described knot~ finishing compac-tors wi-th -their large-area vibrator plates. As the pulsating forces app-lied -to the compactor bar are taken up by the plank frame a~ld are linearly downwards direc-ted, the total force values achieved are substantially greater than hi-therto possible. ~he total force value may thus indeed be greater than -twice the weight of the plank frame wi-th -the elements mounted therein. ~his implies al-together that -the specific area unit load is as great or even greater than in the case of a roller ~ith its line contact. This is because also the compactor bar is in contact onl~ with a narrow, ribbon-shaped su~face area. In practical operation its has thus been surprisingl~ found that, probabl~ due to the dynamics of this specific operating manner of the compactor bar~ the specific area unit loads are consider-ably greater -than could have been expected in consider~
ation of -the mass of the plank frame wi-th the components contained therein. ~he absorption of the reac-tion forces by -the plank frame permits the inertia of the plank frame to be utilized for the application to the compactor bar of compaction forces greater than twice the weigh-t of said mass.
In an advantageous embodiment of the invention there is provided a mechanic or h~draulic pulsating force drive means for the compactor bar. Force generating drive mea~s of this type permit the reQuisite ~reat forces to be continuously and reliably applied to the compactor bar.
In a further sui-table em~odiment of the invention one or both levelling planks may be provided with vertical guide~
for the compactor bar, whereby the co~pactor bar is braced against the reaction forces resulting from the travel of ~he finisher apparatus, so that the compac-tion forces are introduced into the surface layer in a controlled manner.
In a further advantageous embodiment the leading portion 3'73 1 of the compac-tor bar may be provided with an obli~uely rising pressure surface extending from the lower surface of the co~pactor bar at a lower level than the lower surface oE the first levelling plank at least to the level of the lower surface of -the first levelling plank.
The obli~ue pressure surface compensates the level differ-ence between the precompacted and the finish-compac-ted layer surface and assis-ts in the compacting operation, while the lower surface of the compactor bar exerts com-paction forces ac-ting vertically into the surfacing la~er, and -that over a relatively small surface area, so -that the re~uisite high specific area unit loads are obtained.
In a further advan-tageous embodiment the invention provides that the compactor bar is connected through at leas-t one resilient element to a pressure beam mounted for linear upward and downward movement and coupled to a crank or cam drive arrangement mounted in the plank frame. ~he crank or cam dri~e arrangement is effective to generate an oscillating movement of the pressure beam, from where the resilient element transmitts exclusively do~mwards directed compacting force pulses to the compactor bar.
~he shape of -the compacting force pulses may be pre-detexm-ined by properly selecting the design of the dri~e arrange-ment so as to obtain an optimum compaction effect over awide range.
~etween the pressure beam and the compactor bar there is preferabl~ arranged a plurality of preferably pre-stressed compression springs. ~his prevents the compactor bar from being lifted off the surface, that is, the compactor bar is always held in pressure contact, with the contact-pressure varying in accordance with the fre~uency and the magnitude of the compacting force pulses. The compression springs are effective to transmit the compac-ting force pulses to the compactor bar only during downward movement of -the pressure beam 7 while upward movement of -the pressure beam results in the compactor bar being relieved~ although 3~3 1 only u~ to a point determined by the pre-stressed con-dition of the compression springs.
In a Pre~erred embodimen-t o~ -this kind, the compression springs are in the form o~ helical compression springs mounted on guide rods o~ the compactor bar, said guide rocls e~tending through the pressure beam in-to engage~ent with vertical guides provided on the or each levellin~
plank~ This type o~ mounting prevents -the compression springs from buckling sideways. At the same time; the guide rods brace the compactor bar against the reaction forces resul-ting from the travel o~ the ~inisher apparatus.
lhe operating stroke and the ro-tary speed of the cra~k-or cam drive arrangement are preferabl~ adjustable, so tha-t -the shape and magni-tude of the compacting force pulses may be varied in accordance with the consistency and thickness o~ the surfacing layer to be laid do~m.
In an alternative embodiment of the invention, a hydraulic compac-tion force drive means may comprise at least one hydraulic cylinder supported relative to the compactor bar b~ a levelling plank or by the plank ~rame and having a working chamber containing a work piston rigidly connected to the compactor bar. In a h~draulic drive arrangement there are no vibration-caused forces of oscilla-tions which are not directed parallel to the direction of the compact-ing ~orce pulses, while permi-tting particularly great compaction force values to be achieved. Moreover, the energy loss caused by the deformation effort in the mechan-ical drive arrangement is~substantially eliminated in the hydraulic system, as the compressible hydraulic medium column forms a spring cons-tant within the system which plays an important role for the operation of the compactor bar as related to the natural frequency of the system formed by the plank frame and the components mounted therein. The spring formed by the h~draulic medium column operates with lower loss, however, than a mechanical spring.
1 According -to a further characteristic fea-ture of the in-ven-tion said work chamber may be adapted to be applied with a pulsating pressu~e through a h~draulic control device~ These pressure pulses are converted into the actuating force pulses that are applied to the compac-tor bar.
In practice it has been found particularl~ effective if the,h~draulic con-trol device comprises a variable-speed rotarg valve the inlet pressure of which is adjustable.
~hese two variables then permit the actuating force pulses to be adjusted with regard to their shape, their frequency and their magnitude.
A further advantageous embodiment is characterized b~ -the fact that the compactor bar is suspended from a counter support by means of at least one tension spring acting opposite to the direction of the pulsating force. ~his tension spring de-te~mines the selec-ted pre-tension of the compactor bar, so that the pulsating force does not every - time have to be built up from zero to its maximum value, as -the compactor bar continuously rests on the surface with the selected pre-tension pressure. In addition the tension spring prevents the compactor bar from drooping during transport of the finisher~ -In a further preferred modification of the subject matterof the invention the plank frame may be connected to the finisher apparatus as a structural unit by means of pivot-able booms and vertical suppor-ts adapted to be actuated for transport or rearward' travel of the finisher apparatus.
This structural uni-t may also be attached to already existing finisher appara-tus of conventional type, whereby such existing ~inishers are enabled -to la~ down surfacing layers wi-th the re~uired high degree of compaction without subsequent roller compaction. ~he vertical supports fin-ally permit the plank frame and its structural components to be lifted to a non-operative position for transport.
37~3 1 In a further embodiment of the subaec-t matter of the in-vention it is of impor-tance that the pulsating force fre~uenc~ is e~ual to or higher than the na-tural fre~uency of a system including the mass represented by the plank frame and -the components carried -thereb~, and a spring component acting between -the compactor bar and the support absorbing the reaction forces. In addition to the purel~
static loads on the compac-tor bar, this feature permits -to obtain a dynamic ef~ect resulting in a ~pectacular increase of the compacting forces exerted by the compactor bar, as the inertia of the system is made use of to in-crease the pulsating force values. If the fre~uenc~ of the pulsating force is e~ual to the natural fre~uency of the s~stem, the resulting resonance phenomena lead to the forces exerted b~ the compactor bar becoming greater than the dead weight of the plallk frame and its components.
On the other hand it has been found that a pulsating force fre~uency above the natural frequency of the sys-tem also permits -to achieve substantially greater compaction forces than might be expected from the dead weight of the system. ~his desirable effect may be assumed to be due to the dynamic rela-tionships resulting ~rom the operations in the above described manner.
For the faultless compaction of the surfacing layer to the desired high degree it is of importance~ according to a further aspect of the inventionj that in diagrammatic representation the compaction force pulses for~ half-wave shaped curves of a narrower width and more poin-ted shape as compared to a sinus wave configuration. Due to this pointed and narrow shape, the compaction force pulses are enabled to penetrate the surfacing layer to the desired depth.
In a further advantageous embodiment of the subject matter of the invention it is proposed that in diagra~matical representation there is a time interval between each two compaction force pulses, -the length of such interval being ~ 3~ 3 1 greater, particularly several times greater than the half wave length of a compaction force pulse. ~his time interval ma~ be achieved in a simple manner by forming the compact-ion force pulses narrower and of more pointed shape as compared to a sinus wave configuration~ In this case the time interval be-tween each two compaction force pulses will be determined by the magni-tude by which the force pulses are narrower than corresponding sinus wave pulses.
~his time interval permits the entire sys~em to come to rest before a new compaction force pulse occursO
In accordance with a further important aspect of the invention~ the ~agnitude of the time interval between any two compaction force pulses may be adjusted to the travelling speed of the finisher apparatus in such a manner that the longitudinal section of the surface laJer compacted by the compactor bar at a single force pulse is shorter than the width of the lower surface of the compac-tor bar in the direction of travel. During the time interval between the compaction force pulses the entire system comes to rest, and the compactor bar is advanced over the surfacing layer-to be compac-ted in the direction of travel. The advancing stroke of the compactor bar up to the occurrence o~ the next compaction force pulse may not be too short, as there would otherwise be the danger of the surfacing material particles being crushed.
On the other hand, the advance stroke may not be too great, as this might result in a reduced compaction effect or i~ the formation of an elevation in front of the compactor bar which the latter woula tend to climb due to the react-ion forced created by the`advancing movement. ~he above described provisions permit the shape, the magnitude and the fre~uency of the compacting force pulses to be tuned to the natural fre~uency of the system in a simple manner, additionall~ taking into account the -type and thickness of the surfacing layer as well as the temperature and other physical parameters.
1 A further advantageous embodiment of the subject matter of the inve~tion, in which there is provided a hydraulic drive arrangement for generating the compaction ~orce pulses, is characterized in -that said spri~ componen-t is provided by the h~draulic fluid column acting in the system for ac-tuating the compactot bar. ~his spring constan-t m~ be determined b~ calculation so that, with a given mass of the ~stem, it is possible to determine its natural fre~uency itself governing the fre~uenc~ of -the compaction force pulses. Although the h~draulic fluid is in theo~ not compressibleg it does in practice show a certain degree of compressibilit~ enabling the h~draulic fluid column -to act as a spring under pressure exerted thereon.
In a fur-ther advantageous embodiment including a h~draulic drive arrangement and a h~draulic c~linder there may be provided a resilient connection between the hydraulic c~linder and the plank frame or levelling plank, respect-ively. ~his resilient connection intentionally providesfor a spring component which is predetermined with respect to the oscillation d~namics of the system and per~its the natural fre~ue~cy of the system to be influenced, In a particularl~ suitable practical embodiment the resilien-t con~ection may be formed b~ a resiliently be~dable beam cantilevered in a direction vertical to the linear pulsating forcesO ~his beam may be selectively . cantilevered or supported at both ends, It serves as a counter support for absorbing the reaction forces of the compaction force pulses and acts simultaneousl~ as a spring acting in the direction of the compaction force pulses. ~he counter support is rigid in all directions e~tending obli~uely or transversel~ with respect to the direction of the compaction force pulses, so that there cannot occur an~ undesirable relative movements, 7~
l A further suitable embodiment of the subject ma-tter of the inven-tion is charac-terized by the provision that along its working width e~tending transversely of the direction of travel, the compactor bar is divided into at least two sections in-terconnected by a hinged joint i~
such a manner that the lower surfaces of the sections con-tacting the surface oE the surfacing la~er are adap-ted to be angularly adjusted relative to one another in accord-ance to the road profile, without being adjustable to staggered levels relative to one another. With a compac-tor bar of this type it is possible to reliably and uniforml~
compact profiled road surfaces without the danger that an undesirable step or rib is formed in the finished surface la~er by adjustment of the adjacent ends of the two com-pactor bar sections to different levels.
A further advantageous embodiment of the subject matterof the invention is characterized by the provision that along its working width extending transversely of the direction of travel, the second levelling plank is divided into at least two sections i~terconnected by a hinged aoint in such a manner that their lower surfaces contact-ing the surface of the surfacing layer are adapted to be angularly adjusted relative to one another in accordance with the road profile without being adjustable to differ-ent levels relative to one another~ the separation gap between the sections being rectilinear and extending ob-li~uely to the direction of travel.In this manner it is thus possible to adjust also the trailing levelling plank to the surface profile. ~hanks to its obliquely extendi~g separa-tion gap the level]ing plank will not only level a surface rib possibly formed by the separation gap of the compac-tor bar, but will itself be unable to form such rib on the finished surface.
In this context the trailing end of -the separa-tion gap of the compactor bar is preferably sligh-tly offset relative to the leading end of the separation gap of the second ~ ~33~3 1 levelling pla~k. ~he surface rip exiting from the separ-ation gap of the compactor bar is -thus prevented from entering the obli~uely extending separation gap of the second levelling plank and ~rom moving therethrough~ but will instead be reliably levelled down b~ the levelling plan~.
According to a specific aspect of this embodimenty the trailing and of the separa-tion gap of the levelling pla~k is laterally offset with respect ~o its leading end by at least the width of the separation gap. ~his provision ensures tha-t no elevations can be formed in the surface of the finished surfacing layer at the location of the separation gap, as there is no linear passage extending through the second levelling plank in the direction of travel.
~mbodiments of the invention shall now be described with reference to -the accompanying drawings~ wherein:
fig. 1 shows a diagrammatical side elevation of a travel-ling finisher apparatus during layi~g down a bitum-inous surfacing layer, fig. 2 shows an enlarged detail of fig. 1 in cross-section3 fig. 3 shows a first embodiment of a drive arrangement for generating pulsa-ting compaction forces as employed in the finisher apparatus of fig~ 1, fig. 4 shows an enlarged cross-sectional view of the drive arrangement shown in fig. 3, 5 fig. 5 shows a cross-sectional view of a second embodi-ment of a drive arrangement for the compactor bar~
fig. 6 shows a front end view of the drive arrangement of fig. 5 together with a hydraulic control circuit, 3~3 '13 1 fig. 7 shows a detail of the embodimen-t of figo 5, fig. 8 shows a diagram of a further embodiment, fig3 ~ shows a graph represen-ting the shape and ~re~uency of the compaction force pulses transmitted from the compaction bar into the sur~`acing layer, fig~ 10 shows a detail view similar to fig~ 3 of` a fur-ther embodi~ent, figo 11 shows a detail view of components not visible in fi~. 10, and 5 fig. 12 shows a top plan view of components of the embodi-ment of fig. 10.
A travelling finisher apparatus 1 for laying down`a road surfacing layer of à bituminous compound material, e.g.
an æphalt surfacing layer, comprises a wheeled under-carriage 2 carr~ing an operator's cabin 3, and is adapted to travel in the direction of arrow F. Attached to the rear end of finisher appara-tus 1 by means of pivotal booms 6 and a lifting aggangement 7 is a plank frame 5 including components for pre-compacting and final compa~-ing of the sur~`acing layer. ~ocated within finisher appar-atus are containers (not shown) for receiving -the compound material~ from where said material is fed to a distrib-utor arrangement, eOg. a transverse auger 8 by means Of which it is spread on the subjacent ~loor surface. In this mPnner there is provided a lose layer 9 in front of a levelling blade 10. A first levelling plank 12 located to the rear of blade 10 is preceded by a vertically movable ramming bar 15. At this location the surfacing layer 9a is precompacted to a compaction degree of about 92 to 94%.
~ocated to the rear of first levelling plank 12 in the direction Of travel F is a compactor har 13 extending transversely of the direction of travel and effective to 3~
1L~
1 compac-t -the precompacted surfacing layer to a final compaction degree of abou-t 98% (9b). '~his is followed by a second levelling plank 14 provided ~or levelling sur-face irregulari-ties possibly caused b~ compac-tor bar 13.
~he construction of plank frame 5 is more clearly sho~n in fig. 2. ~amming bar 15 has an inclined leading pressure face 16 and is operativel~ connec-ted b~ means of drive transmitting members 17 to an excentric drive arrangement 18 mounted in stationar~ bearings 19 and adapted to be driven by a sui-table drive source (not shown). Ramming bar 15 is advantageousl~ guided for vertical movemen-t at the leading face of firs-t levelling plank 12. ~he lower surface of levelling plank 12 is formed by a level-ling plate 2~ contacting the surfacing layer for levellingan~ surface irregularities caused by ramming bar 15~
~evelling plank 12 ma~ optionally be provided with a vibrator device (not shown).
~ ~etween first levelling plank 12 and second levelling plank 14, compactor bar 13 is slidably guided in vertical guides 24 on said levelling planks. Coampactor bar 13 has a plane, narrow lower surface 23 and an obli~uely rising forward pressure face 22 for bridging the difference in height between the lower surface of levelling plate 21 and the lower surface of a levelling plate 29 attached to second levelling pl~nk 14. Compactor bar 13 is opera-t-ivel~ connected to a compaction force drive arrangement 25 through a number of guide rods 26.
The second levelling plank ma~ also be provided with a vibrator device 27 fed via a h~draulic line 28.
~igs. 3 and 4 show one embodiment of the drive arrangement 25 for compactor bar 13.
A crank or cam drive shaft 30 is rotatabl~ moun-ted in sta-tionar~ bearings and carries excentric drive members 31.
l ~ollower members 32 cooperating with shaft 30 are con-nected through push rods 33 to a pressure beam 34 located therebelow -through which the guide rods 26 carrying the compactor bar 13 extend. In ~ddition to being guided in vertical guides 24, compac-tor bar 13 is also guided b~
engagemen-t of gulde rods 26 with vertical guides 35 attached to plank frame 5 or to first levelling pla~k 12 by ~eans of brackets 380 Disposed between pressure beam 34 and the upper surface of compactor bar 13 is a plural-ity of preferabl~ pre tensioned helical compressionsprings 37 adap-ted to convert the oscillating movement of pressure beam 34 under the action of the drive arrange-men-t into vertically directed linear compaction force pulses without upward and downward movement of compactor bar 13. Within pressure beam 34 guide rods 26 are guided in slide bearings not shown in detail~
Compactor bar 13 is suspended by means of at least one - tension spring 39 from a stationary counter support, for instance from vertical guides 24 of forward levelling plank 12 in such a manner that compression springs 37 are slightly preco~pressed and that çompactor bar 13 is pre-vented from drooping during transport.
~igs. 5 and 6 show a second embodiment of a drive arrange-ment 25' for compactor bar 13. In this embodiment 7 compactor bar 13 is also suspended by means of ten~ion springs 39.
~he upper ends of guide rods 26' are formed as or connected to a hydraulic piston 40 sealingl~ guided i~ a working chamber 41 of a h~draulic cylinder 42, each c~linder 42 being attached to a mounting 35' on plank frame 5 or levelling plank 12, respectively. Hydraulic feed ducts 43 connect all working chambers 41 to a control element 45 containing a rotary valve 46. Rotary valve 46 is adapted to be rotated by a variable-speed hydraulic motor 47 to control the hydraulic pressure feed of working chambers 41 Hydraulic fluid is fed to control element 45 through duct 50 connected to the outlet of a tap valve 48 and '16 l leading to a pressure accumulator 49. Inlet 47 of -tap valve 48 is connected to a pressure source (not sho~m).
Ano-ther duct 53 connects the other outlet of -tap valve 48 to the inlet of hydraulic mo-tor 47, there being provided an adjus-table throttle element 44 for controlling the ro-tar~ speed of hydraulic motor 47 and rotary valve 4 and thus the fre~uency of the compaction force pulses.
A return duct 51 leads ~rom control element 45 to a re~
servoir 52, to which the outle-t of hydraulic motor 47 is also con~ected. A leak ret-urn duct 60 is also connected to control element 45.
Fig. ? shows in diagrammatic form the components of the finisher apparatus shown in detail in fig.-3. Plank frame 5, or first levelling plank 12, respectivel~, is shown as a box-shaped mass having a natural fre~uency fe ~ pre-determined height. The natural fre~uency fe of mass m of the plank frame or the levelling plank, respectively, is determined not alone by the mass itself, but also b~ an additional spring component C included in the system. In the embodiment shown, in which hydraulic cylinder 42 is connected relatively rigidly to mass m (see also fig. 5), spring component C is formed by the hydraulic fluid column within working chamber 41 and in feed duct 43 leadi~g to control element 45 shown in fig. 6. Although the hydraulic medium is in theory incompressible, it has a certain compressibility i~ practice, whereb~ it acts as a ~pring.
In addition, feed duct 43, which is a conventional high-pressure hydraulic tube, is capable of limited elastic expansion. ~ogether with the elasticall~ expandable duct, the hydraulic fluid columh thus acts as a spring capable of modifying the natural fre~uency of the system formed by mass m o~ plank frame 5, as this mass m is excited to vibrate by means of the drive arrangement 41, 42, 40 generating the compaction force pulses for compactor bar 13. In practice the natural frequency of this syste~ lies within the range of 20 to 22 Hertz.
3~73 l As seen in fig. 7 7 piston 40 and guide rod 26' are effective to impose linear compacting force pulses on compactor bar 13, whereb~ the latter compacts the pre-compacted surfacing layer 9a to a thickness 9b. ~he pres-sure face 22 at the leading side of compactor bar 13forms a -transition between -the levels of the two level-ling planks 12 and 14~ while the narrow flat lower sur-face 23 of compactor bar 13 exerts the downwards directed compaction forcesO In order that the compaction forces are sufficient to achieve -the required high degree of compaction, the frequency f1 of the pres.sure feed to working chamber 41 is selected equal to or higher than the natural frequency of the system. If the compaction force pulse frequenc~ lies within the range of the natural frequency, the resulting resonance phenomena lead to sub-stantially greater compaction forces introduced illtO the surfacing la~er than might be expected in view of the known weight of mass m. In a purely static condition, a compaction force which is only slightly greater than the weight of mass m would tend to lift the mass. Due to the dynamic condition resulting from the tuning of the frequen-cies, however, mass m is not lifted, but remains practic-all~ stationary, as does the compactor bar itself. ~he same occurs if the compaction force pulse frequenc~ is ~6 higher than the natural frequency of the syste~, as in this case the inertia of the oscillating mass m as in-flue~ced b~ spring constant C is sufficiently high, so that substantially greater compaction forces can be gener-ated and absorbed than might be expected in view of the known weight of mass m.
Fig. 8 shows a further embodiment .somewhat similar to that of figs. 7 and 5. At this instance~ however, the connection between mass m and hydraulic cylinder 42 is formed by a resilient beam 35" fixedly a-ttached to mass m and extend-ing perpendicular to the direction of -the compaction force pulses generated. Beam 35" in this embodiment act as a spring the action of which is superimposed on the spring action of the hydraulic medium column in working chamber ..
11~393'73 '18 l 41 and feed duc-t 43. Beam 35" thus provides one spring component C1, while the h~clraulic fluid column provides a second spring component C2, which together result in a natural ~re~uency fe of the system which is slightly lower than in the embodiment of fig. 7, namely, about 15 to 20 Hertz. It is obvious that this lower na-tural fre~uency permi-ts the frequency of -the compaction force pulses to be selected lower than in the e~bodiment o~
fig~ 7 for operation within a resonance range. On the other hG~nd, the fre~uency of the compaction :Eorce pulses need not in this embodiment be selected as high as in the embodiment of fig. 7 for operation above the natural fre~uency o~ the system. In operation of the embodiment of fig. 8 it is also found that due to the dynamics of the oscillating hydraulic fluid column and the reaction forces of the compac-tion force pulses the actuall~ achieved compaction forces 13 of compactor bar 13 are substantiall~
greater than would be expected under sta-tic conditions in view of the known weight o~ mass m. And it is only with compaction forces of this magnitude tha-t the desired high degree o~ compaction of the surfacing layer is achievable.
~ig. 9 shows the shape and the timed se~uence of the com-paction force pulses in the form of a diagram~ ~herein the interrelation between the magnitude of the compaction force, drawn in -the vertical direction, and the duration of the force pulses, drawn in the horizontal direction, becomes evide~t. A horizontal line at a distance p above the horizontal axis symbolizes -the pre-loading of com-pactor bar 13 as by tension spring 39 shown in fig. 4.
The dotted line shows a sinus wave configuration that would be achieved if compactor bar 13 were capable of undampened oscillation. As the surfacing layer acts, however, as a nearly ideal da~pening medium, the portions of the oscil-lation waves below the horizontal axis are eliminated.
The configuration of the compaction force pulses, two of which are shown at S1 and S2~ is considerably narrower l and more poin-ted as compared to the half waves of the sinus wave configuration above the horizon-tal axis. I~
the sinus wave configuration shown i~ dotted lines the pulse width would be ~', while the narrower configuration o~ Pulses S1 and S2 results in a reduced pulse width ~, corresponding to a shortened active period of the compact-ion force pulses. ~he actual width and thus the ~agnitude of each compaction force pulse can be calculated from a theoretical fre~uenc~ f2 determined by the -time interval between the positive and the negative reversal point of a half wave of the compaction force pulses. It is obvious that the higher this theoretical frequency f29 the narrower9 higher and more pointed are the compaction force pulses S1 and S2 In practice, however~ compaction force pulses ~1 and S2 ac-t of the surfacing layer with a fre~uency f1, whereb~
the system is caused to oscillate at this lower freQuenc~
f1 which is determined by the time interval between the fading of the one compaction force pulse S1 and the built-up of the succeeding force pulse S2. During this interval the system comes to rest, while compactor bar 13 i9 advanced a certain distance depending on the travelling speed of the finisher apparatus. This pulse characteristic is selected on purpose, in order on the one hand to avoid crushing of the surfacing material caused by a too short int~rval in relation to the travelling speed~ and on the other hand to avoid insufficient compaction of the sur-facing layer caused by too long intervals ~.
In the hydraulic drive arrangement shown in fi~. 5 and 6, the control of time interval ~ may be accomplished in a simple manner by proper design of the rotary valve 46 in control element 45. ~he outlet ports of rotary valve 46 may thus be formed in such a manner, that the flow passage is apruptly opened and closed on ro-tation of the rotar~
valvel succeeded by a rest phase corresponding to interval ~. It is thus possible to select the freQuency f2 by ., 1 properly adjusting the rotary speed of rotary valve 45, while the configuration of compaction force pulses S1, S2 is determined b~ the arrangement and shape of the outlet ports. The magnitude of the compaction force pulses may 6 be adjusted in a simple ma~ner via the inlet pressure at the rotar~ valve. '~he interval between force pulses may for instance be determined by providing the rota~ valve with one or more control ports~ It is thus possible to selectively determine the width and profile of the com-paction force pulses, and thus the theoretical frequencyf2, as well as9 independently thereof, the time interval T between successive force pulses S1, S2~ and thus the actual oscilla-tion fre~uency f1. As alread~ stated, the frequency f1 is selected in a desired relationship to the natural fre~uency of the system fe ~fig. 7 and 83.
In the mechanical drive arrangement according to figs. 3 and 4~ the configuration of the compaction force pulses may for ins-tance be determined by the employ of steep control cam faces, in which case the time interval between successive pulses may be determined by a neutral or rest cam surface. In this embodiment it is thus also possible to select the pulse configuration and the interval between pulses independentl~ of one another by proper design of the rise faces and rest surfaces of the cams, respectively.
In the case of the mechanical drive arrangement, the natural fre~uency of the system is by the wa~ lower than in the case of the hydraulic drive arrangement, l~ing at about 8 to 10 Hertz.
In all embodiments, the sèlection of the pulse configur-ation, the spring component and -the mass of the plank frame or levelling plank, respectivel~, in relation to one another permits the natural fre~uency of the system and the inertia of the mass to be made use of for gener-ating greater compaction forces b~ means of the compactor bar than would otherwise be possible in view of the weight of the mass and of the compactor bar~
1 r~he selec-ted narrow and pointed pulse configuration results in the occurrence of ver~ high accelerations within the s~stem, including the compactor bar, leading to ex*ra-ordinarily great forces at -the compactor bar due to -the iner-tia forces. ~his in-teraction permits the generation of compaction forces capable of obtaining compaction degrees of up to 100%.
~he embodiment sho~m in figso 10, 11 and 12 is partic-ularly sui-ted ~or laying down surfacing layers having a roof-shaped or trough-shaped profile~ I~ this embodiment, compactor bar 13 is divided in-to two sections 13a, 13b.
Between the adjacent end faces of sections 13ag 13b, there is a separation gap 62, the lower width o~ which depends on the angle to which sections ~3a, 13b are ad justed relative to one another in accordance with the profile to be obtained. On the upper surface, or at an intermediate hei~h-t of the compactor bar there is pro-vided a hinge 6l permitting sections 13a, 13b to be angul-arly adausted relative -to one another, but not -to dif~fer-en-t levels~
Shown particularly in fig. 10 is a drive arrangement 25 for the two sec~ions 1~a, 13b of compactor bar 13. An excen-ter or cam drive shaft 30 carrying drive members 31 is rotatably mounted in stationary bearings. ~ollower members 32 cooperating with shaft 30 are connected through push rods 33 to a pressure beam 24 therebelow. Guide rods 26 extending through pressure beam 24 each carry one of sections 13a~ 13b. ~he compactor bar sections are guided in vertical guides 24, and additionally via guide rods 26 in vertical guides 35 attached for instance to plank frame 5 ~nd/or to forward levelling plank 12. ~etween pressure beam 34 and the upper surfaces of compac-tor bar sections 13a, 13b there are arranged a number of helical compression springs 37 for converting the ~ertical oscil-lation of the pressure beam induced by the drive arrange-ment into vertical compaction force pulses without causing l upward and downward movement of the compactor bar~ ~he reac-tion forces of the compaction forces are directly absorbed by the pla~k frame or by the levelling pl ~{
itself.
Fig. 11 shows the second levelling plank 1~ following compactor bar 13. It is likewise divided in-to two sections 14a~ 14b transversely of -the direction o~ travel, and has a separation gap 64 between bottom plates 29a, 29b. Sect ions 14a and 14b are connec-ted to one another through a hinge 63.
As finall-~ sho~m in fig~ 12, separation gap 64 be-tween plank sec-tions 14a and 14b extends somewhat obliquely with respect -to -the direc-tion o~ tra~el. ~his enables an elevation caused b~ the separation gap 62 between compactor bar sections 13a, 13b -to be levelled down to the surface of the sur~acing layer. In detail it i9 shown that the rear end of separa-tion gap 62 is la-terall~ off-set with respect to the ~orward end of separation gap 6~,and that the rear end of the latter is offset with respect to the forward end b~ at least the width of the gap~ ~he axes of hinges 63 and 61 are aligned with one anotherO
~5 The sec-tions may also be interconnected by ~eans of an articulated joint instead of through hinges.
Claims (26)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A travelling finisher apparatus for making a road surface layer of a bituminous compound material, said apparatus comprising a first precompacting and levelling plank carried by a plank frame, and optionally a second levelling plank connected to vibratory drive means, characterized in that there is provided a vertically guided compactor bar extending transversely of the travelling direction at the rear of said first levelling plank in the direction of travel and being of substantially narrower width than said first levelling plank said compactor bar being continually in contact with the surface of the precompacted surface layer and adapted to be acted on by linear pulsating forces acting between said plank frame and said compactor bar generated by a drive source the reaction forces of which are absorbed by said plank frame.
2. Apparatus according to claim 1, characterized by comprising a mechanic or hydraulic pulsating force drive source for said compactor bar.
3. Apparatus according to claim 1, characterized in that one levelling plank or both levelling planks is/are provided with vertical guides for said compactor bar.
4. Apparatus according to any of claims 1, 2 or 3, characterized in that the leading portion of said com-pactor bar is formed with an obliquely upward extending pressure surface extending from the lower surface of said compactor bar at a lower level than the lower surface of said first levelling plank at least to the level of the lower surface of said first levelling plank.
5. Apparatus according to claim 1 or claim 2, characterized in that said compactor bar is connected by at least one resilient element to a pressure beam itself guided for linear upward and downward movement and coupled to a crank or cam drive means mounted in said plank frame.
6. Apparatus according to claim 1 or claim 2, character-ized in that said compactor bar is connected by at least one resilient element to a pressure beam itself guided for linear upward and downward movement and coupled to a crank or cam drive means mounted in said plank frame, a plurality of compression springs being located between said pressure beam and said compactor bar.
7. Apparatus according to claim 1 or claim 2 character-ized in that said compactor bar is connected by at least one resilient element to a pressure beam itself guided for linear upward and downward movement and coupled to a crank or cam drive means mounted in said plank frame, a plurality of compression springs being located between said pressure beam and said compactor bar, said compression springs being helical compression springs mounted on guide rods of said compactor bar, said guide rods extending through said pressure beam into engagement with vertical guides located on said levelling plank, or planks, respectively.
8. Apparatus according to claim 1 or claim 2, character-ized in that said compactor bar is connected by at least one resilient element to a pressure beam itself guided for linear upward and downward movement and coupled to a crank or cam drive means mounted in said plank frame, the operating stroke and the rotary speed of said crank drive means being adjustable.
9. Apparatus according to one of claims 1, 2 or 3, characterized in that said hydraulic pulsating force drive source comprises at least one hydraulic cylinder supported relative to said compactor bar by a levelling plank or by said plank frame and having a work chamber containing a work piston rigidly coupled to said compactor bar.
10. Apparatus according to one of claims 1, 2 or 3, characterized in that said hydraulic pulsating force drive source comprises at least one hydraulic cylinder supported relative to said compactor bar by a levelling plank or by said plank frame and having a work chamber containing a work piston rigidly coupled to said compactor bar, said work chamber being adapted to be supplied with a pulsating pressure through a hydraulic control device.
11. Apparatus according to one of claims 1, 2 or 3, characterized in that said hydraulic pulsating force drive source comprises at least one hydraulic cylinder supported relative to said compactor bar by a levelling plank or by said plank frame and having a work chamber containing a work piston rigidly coupled to said compactor bar, said work chamber being adapted to be supplied with a pulsating pressure through a hydraulic control device, including a variable-speed rotary valve the inlet pressure of which is adjustable.
12. Apparatus according to one of claims 1, 2 or 3, characterized in that said compactor bar is suspended from a counter support by means of at least one tension spring acting opposite to the direction of the pulsating force.
13. Apparatus according to one of claims 1, 2 or 3, characterized in that said plank frame is formed as a structural unit connected to the finisher apparatus by means of pivotable booms and vertical supports adapted to by actuated for transport or rearward travel of the finisher apparatus.
14. Apparatus according to one of claims 1, 2 or 3, characterized in that the pulsating force frequency is equal to or higher than the natural frequency of the system including the mass represented by said plank frame and the components carried thereby, and a spring component acting between said compactor bar and the support absorbing the reaction forces.
15. Apparatus according to one of claims 1, 2 or 3, characterized in that the pulsating force frequency is equal to or higher than the natural frequency of the system including the mass represented by said plank frame and the components carried thereby, and a spring component acting between said compactor bar and the support absorbing the reaction forces, wherein, in diagrammatic representation, the pulsating force pulses from half-wave shaped curves being of a narrower and more pointed shape as compared to a sinus wave configuration.
16. Apparatus according to one of claims 1, 2 or 3, characterized in that the pulsating force frequency is equal to or higher than the natural frequency of the system including the mass represented by said plank frame and the components carried thereby, and a spring component acting between said compactor bar and the support absorbing the reaction forces, wherein, in diagrammatical represent-ation, there is a time interval between each two pulsating force pulses, the length of said interval being greater, particularly several times greater than the half wave length of a force pulse.
17. Apparatus according to one of claims 1, 2 or 3, characterized in that the magnitude of the time interval between each two pulsating force pulses is adjusted to the travelling speed of the finisher apparatus in such a manner that the longitudinal section of the surface layer compacted by said compactor bar at a single force pulse is shorter than the width of the lower surface of said compactor bar in the direction of travel.
18. Apparatus according to one of claims 1 or 2, characterized in that said spring component is provided by the hydraulic fluid column acting in said system for actuating said compactor bar.
19. Apparatus according to one of claims 1 or 2, characterized in that the connection between said hydraulic cylinder and said plank frame or levelling plank, respectively, is resilient so as to provide said spring component.
20. Apparatus according to one of claims 1 or 2, characterized in that the connection between said hydraulic cylinder and said plank frame or levelling plan, respectively, is resilient so as to provide said spring component, said connection being formed by a resiliently bendable beam cantilevered in a direction vertical to said linear pulsating forces.
21. Apparatus according to one of claims 1, 2 or 3, characterized in that along its working width extending transversely of the travelling direction said compactor bar is divided into at least two sections interconnected by a hinged joint in such a manner that the lower surfaces of said sections contacting the surface of said road surface layer are adapted to be angularly adjusted relative to one another without being adjustable to staggered levels relative to one another.
22. Apparatus according to claim 1, characterized in that along its working width extending transversely of the travelling direction, said second levelling plank is divided into at least two sections interconnected by a hinged joint in such a manner that the lower surfaces of said sections contacting the surface of said road surface layer are adapted to be angularly adjusted relative to one another in accordance with the road pro-file without being adjustable to staggered levels relat-ive to one another, the separation line between said sections being rectilinear and extending obliquely to the travelling direction.
23. Apparatus according to one of claims 1, 2 or 3, characterized in that along its working width extending transversely of the travelling direction said compactor bar is divided into at least two sections interconnected by a hinged joint in such a manner that the lower surfaces of said sections contacting the surface of said road surface layer are adapted to be angularly adjusted relative to one another without being adjustable to staggered levels relative to one another, the trailing end of the separation gap of said compactor bar being laterally offset by a small amount relative to the leading end of the separation gap of said second levelling plank.
24. Apparatus according to one of claims 1, 2 or 3, characterized in that along its working width extending transversely of the travelling direction said compactor bar is divided into at least two sections interconnected by a hinged joint in such a manner that the lower surfaces of said sections contacting the surface of said road surface layer are adapted to be angularly adjusted relative to one another without being adjustable to staggered levels relative to one another, the trailing end of the compactor bar separation gap being laterally offset relative to the leading end of the levelling plank separation gap by an amount corresponding at least to the width of the separation gap.
25. Apparatus according to claim 1 or claim 2, characterized in that said compactor bar is connected by at least one resilient element to a pressure beam itself guided for linear upward and downward movement and coupled to a crank or cam drive means mounted in said plank frame, a plurality of pre-stressed compression springs being located between said pressure beam and said compactor bar.
26. Apparatus according to claim 1 or claim 2, characterized in that said compactor bar is connected by at least one resilient element to a pressure beam itself guided for linear upward and downward movement and coupled to a crank or cam drive means mounted in said plank frame, a plurality of pre-stressed compression springs being located between said pressure beam and said compactor bar, said compression springs being helical compression springs mounted on guide rods of said compactor bar, said guide rods extending through said pressure beam into engagement with vertical guides located on said levelling plank, or planks, respectively.
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19813114049 DE3114049C3 (en) | 1981-04-07 | 1981-04-07 | CEILER |
| DEP3114049.1 | 1981-04-07 | ||
| DEP3209988.5 | 1982-03-18 | ||
| DEP3209989.4 | 1982-03-18 | ||
| DE19823209989 DE3209989A1 (en) | 1981-04-07 | 1982-03-18 | Road-surface finisher |
| DE19823209988 DE3209988A1 (en) | 1981-04-07 | 1982-03-18 | Road-surface finisher |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1189373A true CA1189373A (en) | 1985-06-25 |
Family
ID=27189253
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000399809A Expired CA1189373A (en) | 1981-04-07 | 1982-03-30 | Bituminous finisher |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US4493585A (en) |
| CA (1) | CA1189373A (en) |
| CH (1) | CH655966A5 (en) |
| DD (1) | DD202324A5 (en) |
| DK (1) | DK150906C (en) |
| GB (1) | GB2100324B (en) |
| IT (1) | IT1190763B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110857546A (en) * | 2018-08-22 | 2020-03-03 | 卡特彼勒路面机械公司 | Oscillating assembly for a road paver |
Families Citing this family (50)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3300092A1 (en) * | 1983-01-04 | 1984-07-12 | Abg-Werke Gmbh, 3250 Hameln | SCREED FOR A PAVER |
| FR2570723B2 (en) * | 1983-11-17 | 1986-12-12 | Gtm Ets Sa | SLIDING FORMWORK MACHINE WITH TWO EXTRUSION PLATES FOR THE PREPARATION OF CONCRETE PAVEMENTS |
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| US8371770B1 (en) * | 2012-04-09 | 2013-02-12 | Caterpillar Inc. | Apparatus for tamping paving material |
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| DE102013007061B4 (en) * | 2013-01-28 | 2021-09-02 | Bomag Gmbh | Height adjustment device for an extendable screed of a road paver and road paver with such a height adjustment device |
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| US1840970A (en) * | 1929-11-27 | 1932-01-12 | Roads Construction Company Ltd | Road paving machine |
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| US3816014A (en) * | 1972-02-14 | 1974-06-11 | Dow Chemical Co | Screeding apparatus |
-
1982
- 1982-03-26 CH CH1890/82A patent/CH655966A5/en not_active IP Right Cessation
- 1982-03-30 CA CA000399809A patent/CA1189373A/en not_active Expired
- 1982-03-30 GB GB8209357A patent/GB2100324B/en not_active Expired
- 1982-04-01 DK DK148582A patent/DK150906C/en not_active IP Right Cessation
- 1982-04-05 DD DD82238761A patent/DD202324A5/en unknown
- 1982-04-06 US US06/366,004 patent/US4493585A/en not_active Expired - Lifetime
- 1982-04-07 IT IT20630/82A patent/IT1190763B/en active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110857546A (en) * | 2018-08-22 | 2020-03-03 | 卡特彼勒路面机械公司 | Oscillating assembly for a road paver |
| CN110857546B (en) * | 2018-08-22 | 2022-03-29 | 卡特彼勒路面机械公司 | Oscillating assembly for a road paver |
Also Published As
| Publication number | Publication date |
|---|---|
| IT1190763B (en) | 1988-02-24 |
| US4493585A (en) | 1985-01-15 |
| DK148582A (en) | 1982-10-08 |
| GB2100324B (en) | 1985-04-03 |
| DK150906B (en) | 1987-07-13 |
| DK150906C (en) | 1987-12-28 |
| CH655966A5 (en) | 1986-05-30 |
| IT8220630A0 (en) | 1982-04-07 |
| DD202324A5 (en) | 1983-09-07 |
| GB2100324A (en) | 1982-12-22 |
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