US 3818618 A
An elevator located at the open end of a scraper bowl is rotatable upon a pair of links connecting the upper end of the elevator sidewalls to the bowl sidewalls. A pair of cams resiliently mounted on the bowl sidewalls to extend forwardly and upwardly support one end of a pair of extensible hydraulic cylinders pivotally connected to the bowl sidewalls. The cylinders include rollers as cam followers linked to the extensible end of the cylinders and rotatable upon the supportive cam surfaces. A pair of bowl hoist hydraulic cylinders pivotally connect a draft frame to the bowl near the lower open end of the bowl where a transverse scraper blade is secured. In operation, the bowl hoist cylinders are hydraulically positioned by hydraulic control means to set the position of the blade. The extensible cylinders are hydraulically controlled to position the rollers upon the cam surfaces, thus moving the lower end of the elevator in a predetermined path relative to the blade, i.e., sloping generally upwardly and forwardly.
Claims available in
Description (OCR text may contain errors)
[111 3,818,618 [451 June 25, 1974 LINKAGE FOR GROUND POSITIONING OF AN EARTH SCRAPER ELEVATOR John H. Hyler, Peoria, ll].
 Assignee: Westinghouse Air Brake Company,
 Filed: Sept. 19, -1972 211 App]. No.: 290,422
 US. Cl. 37/8, 37/124  Int. Cl 860p l/36  Field of Search 37/4, 8, 124; 214/8326; 198/117, 122
 References Cited UNITED STATES PATENTS 3,210,868 10/1965 Ltess 37/8 3,292,278 12/1966 Johnson 37/8 3,427,641 2/1969 Duke 37/8 3.431.660 3/1969 Keith et a]. 37/8 3,466,764 9/1969 Smith 37/8 3,483,640 12/1969 Anderson et a1. 37/8 3,564,737 2/1971 Simmons et a1. 37/8 3,7(1(l;383 10/1972 Boersma 37/8 Primary Examiner-J. Reed Fisher Assistant Examiner-Eugene H. Eickholt Attorney, Agent, or FirmFrank Wattles [5 7] ABSTRACT An elevator located at the open end of a scraper bowl is rotatable upon a pair of links connecting the upper end of the elevator sidewalls to the bowl sidewalls. A
' pair of cams resiliently mounted on the bowl sidewalls to extend forwardly and upwardly support one end of a pair of extensible hydraulic cylinders pivotally connected to the bowl sidewalls. The cylinders include rollers as cam followers linked to the extensible end of r the cylinders and rotatable upon the supportive cam surfaces. A pair of bowl hoist hydraulic cylinders pivotally connect a draft frame to the bowl near the lower open end of the bowl where a transverse scraper blade is secured. In operation, the bowl hoist cylinders are hydraulically positioned by hydraulic control means to set the position of the blade. The extensible cylinders are hydraulically controlled to position the rollers upon the cam surfaces, thus moving the lower end of the elevator in a predetermined path relative to the blade, i.e., sloping generally upwardly and forwardly.
12 Claims, 9 Drawing Figures LINKAGE FOR GROUND POSITIONING OF AN EARTH SCRAPER ELEVATOR BACKGROUND OF THE INVENTION 1. Field of the Invention This invention generally relates to an earth-working scraper having an endless conveyor or elevator for moving material into the scraper bowl, and specifically to such a scraper having means for positioning the lower end of the elevator along a predetermined path relative to the ground and the scraper blade.
2. Description of the Prior Art In the conventional earth scraper which includes an endless conveyor or elevator for assisting in the loading of the scraper bowl, the elevator is typically pivot mounted or link mounted at its upper end onto the bowl structure and separately pivot mounted at its lower end onto the bowl structure. Additionally, the lower end rests upon resilient stops on the bowl. The elevator inclines upwardly and rearwardly from its lower end and is permitted to be raised and lowered by movement upon the pivots or links upon encountering various quantities of materials and sizes of objects which may enter the scraper bowl during the digging operation.
The rate at which material may be loaded into the bowl is affected by the depth of cut. The lower end of the elevator must be located at a suitable distance above the ground and in position to have its flights sweep the disturbed earth into the bowl. Conventionally, the relative position of the lower end of the elevator with respect to the cutting blade is set by limiting stops. The elevator is supported upon the bowl structure and its weight forces it against a lower stop located on the bowl. To adjust the blade-elevator relative position, the stop maybe manually repositioned, as for example by placing shims under the stop to elevate it or other means for elevating the stop. To increase the space between the elevator and cutting blade, the lowest point of the elevator must shift upward or upward and rearwardwith reference to the cutting blade.
To permit relatively large objects, e.g., boulders, to enter into the bowl, the elevator must be raised or permitted to rise vertically. Conventionally, to permit the elevator to be raised and lowered to provide large blade-elevator separation and entry of large objects, the elevator is hinged at its upper connections to the bowl. The elevator moves upon a link with two pivots so that it can be forced vertically upward. Thus, the lower end of the elevator may be forced upward by'the material or objects or powered upon a crane linkage.
One disadvantage of conventional devices is that they have at most only one proper setting for digging a selected soil. Advance of a cutting blade at a certain depth will produce a shear plane dividing disturbed soil from undisturbed soil. The angle of shear plane depends upon the soil conditions. The elevator should be positioned so that the tips of its flights will pass tangentially to the ground surface at a point slightly forward of the intersection of the shear plane with the ground surface. In this position the flights will not strike undisturbed soil which can produce shock to the elevator with accelerated wear and breakage. Furthermore, unnecessary power is used in having the powered flights encounter undisturbed soil. In a proper placement,'the
quires the elevator be moved vertically and horizontally forward. A change in soil conditions may require a similar adjustment. Conventional devices can only reposition the lower end of the elevator vertically or vertically and horizontally rearward along the longitudinal axis of the inclined elevator. Thus, a proper adjustment cannot be made and compromises in operation become necessary. The flights may be caused to strike undisturbed soil producing loss of power and increased wear, tear and breakage. On the other hand the flights may be positioned too far above the ground so that disturbed soil is not swept-into the bowl and maintained there. Furthermore, any adjustments must be made manually by repositioning the limiting stops.
The following patents are representative of conventional devices:
US. Pat. No. 3,270,443 Earth Scraper with Self- Loading Endless Conveyor US. Pat. No. 3,191,322 Earth Scraper with Pivoted Conveyor US. Pat. No. 3,048,934 Conveyor Mounting for Elevating Scraper The present invention avoids the shortcomings of the conventional art. The elevator is supported upon a pair of laterally spaced cams mounted on the bowl sidewalls. The cam surfaces are inclined upwardly and forwardly from the bowl sidewalls. The lower link between the bowl and elevator may be a pair of pivoted hydraulic cylinders above the cam surfaces. Rollers or the like formed at the ends of the cylinders about the elevator lower link pivots provide cam followers and elevator supports upon the upper cam surfaces. Control means are operatively connected to the hydraulic cylinders.
The position of the elevator and its lower end relative to the blade can be adjusted by hydraulically, or other control means, extending or retracting the length of the lower link and moving the cam follower roller along the cam surface to a new position. The positioning and/or shape of the cam will determine the path of adjustment and can be designed to accommodate proper positioning of the elevator for a relatively wide range of soil conditions and digging depths.
A further advantage of the present invention is the shock cushion provided-by resilient mounting of the cams.
A still further-advantage of the present invention is the repositioning of the cams by shim inserts disposed under the cams.
These and other advantages will become apparent upon a reading of the detailed description of the inventron.
SUMMARY OF THE INVENTION Briefly, the invention provides a self-loading earth scraper with an elevator positionable with respect to ground and blade. The earth scraper comprises conventionalground wheels and an open end bowl supto the bowl. The draft members are supported at one end onto the draft frame and at the other end are pivotally connected to the bowl. Means are provided for raising and lowering the scraper blade by rotating the bowl upon the wheels. An inclined endless conveyor is positioned at the open end of the bowl with transversely spaced sides and a lower end in proximity to the scraper blade for conveying material into the bowl. The conveyor includes laterally spaced sidewalls and a lower end in proximity to the scraper blade. A laterally spaced pair of upper conveyor links at one end is pivotally mounted on the sidewalls of the bowl and at the other end is pivotally mounted on the sidewalls of the conveyor at the upper end for pivotal movement about a first transverse axis. Cams means at one end is mounted on the sidewalls of the bowl extending forwardly and upwardly. Means are provided for supporting the lower end of the conveyor on the cam means. Another means is for moving the lower end of the conveyor forwardly and upwardly on the cam means.
BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:
FIG. 1 is a graphic representation of the scraper blade in relative position to the elevator for selected depths of soil cut and selected soil conditions;
FIG. 2 is an elevation view of a scraper including the elevator in a travel position supported upon a cam support;
FIG. 3 is a plan view of the scraper of FIG. 2;
FIG. 4 is an elevation view of one embodiment of the upper linkage and lower linkage and cam support and illustrating in outline various positions of the elevator lower end relative to the scraper blade;
FIG. 5 is an elevation view of another embodiment of the upper linkage and lower linkage and cam support and illustrating in outline various positions of the elevator lower end relative to the scraper blade;
FIG. 6 is a schematic view of a manual control means for controlling the extensible cylinder;
FIG. 7 is a schematic view of an automatic control means for controlling the extensible cylinder;
FIG. 8 is a schematic view of an automatic control means with manual override means for controlling the extensible cylinder; and
FIG. 9 is an elevation view of the bowl hoist cylinder with automatic switch and means for activating the switch.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now particularly to FIG. 1, the optimum operating conditions areillustrated for a scraper blade and elevator at selected dig depths and for selected soil conditions. A scraper blade m is illustrated at selected dig depths a, b, c for soil conditions having shear planes of 45, 30, 25 from horizontal. An elevator has a longitudinal axis or centerline d with the axis of rotation of a lower idler at e. Flights n, n, n" are illustrated with their tips tangential to their respective ground surfaces b, a, c with the paths of the tips traced respectively at b, a, 0'.
At an average depth b the flight n tangentially approaches surface b between the 45 shear plane and 30 shear plane. This lowest point of flight path is slightly forward of the intersection of the 45 shear plane with surface b. Optimum conditions exist for soil conditions producing a shear plane of 45 for a digging depth and vertical separation of blade m and flight n represented by b. Flight path b passes above ground intersection of the 30 shear plane. The flight n is unable to sweep all the disturbed ground and is inefficent. Furthermore, flight n is in a downward movement as it approaches the 30 intersection and can encounter a roll m of disturbed or slightly disturbed soil forward of the 30 intersection. The downward force of flight n will compress the roll m against supporting nondisturbed soil in the shaded region forward of the 30 shear plane and produce a shock or drag on flight n. For a 25 shear plane, flight n misses'a substantial amount of disturbed soil.
At shallower depth a the idler and flight n must be vertically adjusted to the position of flight n to have the flight tangentially approach the ground surface. After the vertical adjustment the optimum operation condition is not present for any of the soil conditions. The tangential point appears too far forward of the 45 intersection and is slightly rearward of the 30 intersection; however, both of these soil conditions may be suitably compromised. Nevertheless, the adjustment for flight n is improper for a 25 shear plane and a forward horizontal adjustment would be necessary to suitably compromise for digging its soil.
For a dig depth b and a setting of the flight at n, the elevator may be damaged. The shaded areas forward of the 45 plane represent undisturbed soil struck by flight n. Similarly, undisturbed soil is struck forward of the 30 shear plane. The shock to the elevator causes by striking the undisturbed soil can cause expensive damage and should be avoided. An overcorrection to avoid damage can be represented by setting the flight at n" or n. Neither flight paths b or 0' would produce adequate sweep of the disturbed soil.
For a depth 0 and a flight setting at n, some horizontal adjustment towards the 45 intersection can be effected as compared with a setting at n or n, but it becomes readily apparent that only by actually adjusting the lower idler and flight in a horizontal direction in addition to a vertical direction can an adequate selection of settings be made suitable to various dig depths and soil conditions. The desired vertical-horizontal adjustment of the elevator can be accomplished by moving the idler about a remote pivot near the upper end of the elevator (now shown in FIG. 1). The desired adjustment is done in the scraper hereinafter described.
FIGS. 2 and 3 illustrate a self-loading scraper generally designated by the refer'ence character 10. The scraper 10 comprises a bowl 12 having bowl sides 13 and an open front designated at 14. The scraper bowl 12 at its open front 14 has connected thereto a transversely extending scraperblade 15 suitably secured to a bowl bottom 16. The rear end of the how] 12 includes a movable ejector gate 17 suitably supported and guided by a structurally extending member 18. A rearwardly extending pusher structure is designated at 19 and includes-a pusher block 20 conventional in the art. A fluid ram 21 is suitably connected to the ejector gate 17 for moving the same forwardly to dump material from the bowl and to retract the same to its original position. A rear axle structure is designated at 23 and is suitably supported on ground wheels 24 which are journalled on axles 25 supported on the members 18.
A draft structure generally designated at 26 includes a gooseneck structure 27 which has its forward end suitably connected to a conventional two-wheel tractor and its rearward end is secured to a transversely extending torsion tube 28 having opposite ends connected to rearwardly extending side draft members 29 which, as indicated at 30, are pivotally connected to the bowl 12. A pair of hydraulic rams 31 are pivotally connected as indicated at 32 to the torsion tube 28, the rams 31 including extendable rods 33 pivotally connected as indicated at 34 to the bowl 12 of the scraper 10.
The scraper described is a conventional scraper with which the invention to be described fonns a part. The description herein of the scraper and elements thereof is not intended to limit the scraper upon which the invention may be used. For example, the scraper blade 15 may be secured to a movable bottom 16 which may be separate from and supported by the bowl and allows variable positioning of blade 15 relative to the bowl 12. Additionally, ejector gate 17 may be omitted together with its ancillary elements member 18, pusher l9, block 20, and ram 21, or other conventional means for evacuating the loaded material may be substituted. Also apparent is that any elevated supporting structure may be substituted for the draft frame 26 and gooseneck 27, and that the tractor need not be two-wheeled. The rams 31 and rods 33 are illustrative of more generally described means for raising and lowering the scraper, blade.
The scraper I0 includes an endless conveyor or elevator, generally designated by the reference character at 35. The elevator 35 comprises a frame 36 including a pair of horizontally-spaced sidewalls 37 supporting at their upper ends a shaft 38 and at their lower ends a pair of stub shafts 39. The shaft 38 supports a pair of sprockets 40 and the shafts 39 support a pair of wheels 41. Endless chains 42 are trained about the sprockets 38 and wheels 41, the chains being connected to conventional conveyor flights 43. A pair of arms 44 are disposed on opposite sides of the elevator 35, the arms 44 being pivotally mounted upon sidewalls 37 as indicated at 46 and upon sidewalls 13 of the bowl 12 as indicated at 47 so that the elevator with the arms 44 may be rotated upon pivots 46, 47 as a unit, thus enabling a combination of vertical and horizontal movement of idler wheels 41. The pair of pivots 46 have an axis 48 which is transverse to elevator sidewalls 37. Alternately, adding torsion stifi'eners such as resistance springs or increased friction contacts to either or both pairs of pivots 46, 47, provides a means for stabilizing the upper links 44 and the elevator 35 by resisting vibrating movement.
In the embodiment illustrated in FIG. 4, lower links of elevator 35 include a pair of extensible cylinders generally designated by the reference character at 52. Cylinders 52 are hydraulic-type cylinders comprising a base cylinder 53 and reciprocable member 54. Cylinders 52 are disposed on opposite sides of the elevator 35, the base cylinders 53 being pivotally mounted upon bowl sidewalls 13 as indicated at 55 and the reciprocable members 54 being pivotally mounted upon elevator sidewalls 37 as indicated at 56. A rearward section of each reciprocable member 54 is nested within one base cylinder 53 as illustrated in two positions. The dotted outline of extensible cylinders 52 shows the retracted position with the rearward section of members 54 completely nested within base cylinders 53. The solid outline of cylinders 52 shows-the extended position with the rearward section of members 54 telescoped forward so only a small part of the rearward section is nested within base cylinders 53. The pair of pivots 56 have an axis 57 which is transverse to elevator sidewalls 37. A pair of cams 60 are disposed on opposite sides of the elevator 35, one end of each cam being securely mounted on the sidewalls 13 of the bowl 12 as indicated at 61. The mounting of the cams 60 upon sidewalls 13 may be by any rigid fastening means such as welding, bolting, or integrally forming the cam 60 and sidewalls 13. The forwardly inclined cam 60 will deflect slightly downward near its forward end in response to large forces such as bouncing of the elevator 35 supported thereon. Such deflection of cam 60 is progressively reduced at points closer to mount 61. Although the forward end of each cam 60 is resilient about mount 61, additional resilient means 63 may support the cams 60 upon extensions 64 of bowl sidewalls 13 to provide the desired rates of deflection at various points on the upper cam surface. Extension 64 extends sidewalls 13 under the forward end of cams 60. Resilient means 63 such as heavy duty springs are sandwiched between extensions 64 and cams 60. Shims 66 or other spacing means may be placed between each resilient means 63 and extension 64 to adjust the normal location of the cam surface and thereby to adjust the height at which elevator 35 is supported. A roller-type cam follower 70 is mounted at each pivot connection 56 to rotate upon the pivot 56 about transverse axis 57. Cam followers other than rollers can be used at pivot 56; however, the low friction roller is preferred because it requires less energy to reposition upon the upper cam surface. Although the cam surface is illustrated as a flat inclined surface, other shapes of cam surfaces may be substituted depending upon the path of elevator movement desired.
The embodiment of the invention illustrated in FIG. 5 is identical to the embodiment of FIG. 4 except for the reciprocable members 54 of extensible cylinders 52. In FIG. 5, each reciprocable member generally designated by the reference character at 75 comprises a rearward section member 76 which nests within the base cylinder 53. Each member 75 further comprises a first lower link 77 and a second lower link 78 which are integrally joined and pivotally secured to sidewall 13 as indicated at 79 and a third lower link 80 pivotally mounted about transverse axis 57 at pivot 56. The links 78, 80 are pivotally connected as indicated at 81 and member 76 and link 77 are pivotally connected as indicated at 82. The extreme forward position of rollers and elevator 35 is illustrated in solid line representation of the reciprocable members 75. Each member 76 is completely nested within base cylinder 53 and the links 77, 78 disposed upon pivot 79 so pivot 81 and link 80 are in an extreme forward position. The dotted outline of member shows rollers 70 and elevator 35 in an extreme rearward position. Each member 76 is telescoped forward with only a small part thereof nested with base cylinder 53. The links 77, 78 are rotated together about pivot 79 to place pivot 81 and link in an extreme rearward position.
The embodiments of FIGS. 4, 5 include means for reciprocating the reciprocable members 54, 75 respectively. A hydraulic circuit for controlling a hydraulic cylinder provides the reciprocating means and three embodiments are illustrated in FIGS. 6, 7, 8. Additionally, the embodiments of FIGS. 4, 5 include means for 7 operating the bowl hoist cylinders 31. The extensible cylinders and the bowl hoist cylinders of the embodiments of FIGS. 4, are preferably hydraulic cylinders and, thus, the means of their control, i.e. reciprocation or operation, is the same for each of the cylinders. The descriptions that follow shall be applied to a hydraulic cylinder understanding that the descriptions are equally applicable to any one of the hydraulic cylinders of this invention.
In FIG. 6, the hydraulic cylinder 90 comprises a base cylinder 91 and a reciprocable member 92. Hydraulic pressure means are provided by a hydraulic circuit generally designated by the reference character 93. Circuit 93 comprises a relief tank 94 hydraulically supplied through line 95 from pump 96. A check valve 97 in line 95 between tank 94 and pump 96 provides a means for regulating the supply of fluid to the tank. Line 95 also connects one end of the base cylinder 91 with the input to the tank 94 and the check valve 97. Line 98 connects the output of the tank 94 with another end of base cylinder 91. A switch generally designated by the reference character 100 is operatively connected into line 95, 98 and by positioning at 101, 102 or 103 the reciprocable member is extended, maintained in hold (not moved), or retracted, respectively. A manual control 104 is operatively connected to the switch positions I01, 102, 103. In the extend mode 101, a pressure drop is produced in the direction of the member 92 extension. The hold mode 102 blocks fluid pressure and, thus, equalizes the pressure across cylinder 91. The retract mode 103 reverses the lines 95, 98 to produce a pressure drop in an opposite direction to the extension mode 101. I
A two-position automatic switch is illustrated in FIGS. 7, 9. The hydraulic cylinder 90 and hydraulic circuit 108 are identical to the embodiment of FIG. 6 with a two-position switch 109 substituted for the threeposition switch 100 and manual control 104. The switch 109 provides an extend position 110 and retract position 111 and it provides pressure drop to correspondingly extend or retract member 92. Switch 109 has a cam follower 112 protruding therefrom to contact cam surface 113 of support extension 64 as. illustrated in FIG. 9. Switch 109 is biased hydraulically or by springs or the like to obtain one position 110 or 111 when the hoist cylinder 31 is in a fully retracted position and the frame 11 is elevated into a travel position as illustrated. As the hoist cylinder 31 is extended to lower the frame 11 and blade 15, the cam 113 is lowered and encounters cam follower 112 progressively forcing the switch 109 into the other position. Where switch 109 is a valve means or the like, the hydraulic pressure can be continuously varied between the extremes of the two positions 110, 111 and the designed shape of cam 113 willdetermine the hydraulic pressure supplied atthe hydraulic cylinder 90 for any position of hoist cylinder 31. ltis apparent that other move-, ments of the earth scraper and its component parts similarly can control the reciprocation of the hydraulic cylinders.
FIG. 8 illustrates an automatic two-position switch with a manual three-position override switch. The hydraulic cylinder 90 and hydraulic circuit 115 are identical to this embodiment of FIG. 6 with the two-position switch 109 and cam follower 112 inserted into lines 95, 98 between switch 100 and base cylinder 91. Positioning switch 100 in mode 101 will have no effect upon the hydraulic pressure at cylinder 91 produced by switch 109. Mode 102 position will block pressure change and the hydraulic pressure at cylinder 91 will remain unchanged. Mode 103 position will reverse the pressure effect produced by switch 109 at cylinder 91 so that member 92 will retract instead of extend or vice versa.
In operation, FIG. 2 shows the scraper 10 in a travel attitude. Elevator 35 rests upon the load of earth in bowl 12 and is prevented from moving downward along the path established by its mounting linkage by the support from the load of earth, by support of the cam follower on the cam, or a combination of these supports. To commence digging scraper blade 15 is lowered by extending bowl hoist cylinders 31 and rotating bowl 12 with blade 15 about axles 25 of the rear wheels 24. Elevator 35, upper links 44, lower links, and cams 60 rotate with the blade 15 until the hoist cylinder 31 stops extending and the blade 15 is set at a digging depth. The elevator 35 is normally carried in a retracted position with the cam followers toward the rear of the cam surfaces. As the blade is lowered to a desired digging depth or independently of the lowering of the blade, the lower end of the elevator may be raised and extended forward relative to blade 15 to a desired position for loading as is illustrated by the outline of lower idler 41. In the embodiment illustrated in FIG. 4, the elevator 35 is raised and moved forward by extending hydraulic cylinder 52 to position rollers further forward upon cams 60. The upper links 44 are rotated to the position illustrated in dotted lines. The lower idler wheels 41 are outlined in dashed lines for the elevated position of the elevator 35. The outline 121 for idler-wheels 41 is to represent the elevated position of the elevator 35 with the conventional stops. The outline 120 is slightly higher and substantially forward of the outline 121. For varied soil conditons or dig depths,
the cylinders 52 can be repositioned to properly position the elevator 35 within the range of cylinders 52 and cams 60. In the embodiment illustrated in FIG. 5, the blade 15 is positioned in the same manner described for the embodiment of FIG. 4 and the elevator is raised and moved forward by extending members 75 from base cylinders 53 to reposition rollers 70 upon earns 60. Upper links 44 are rotated to the position represented in dotted lines and the reciprocable members are rotated upon pivots 79, 81, 82 to the new position represented by dotted lines. The idler wheels 41 are illustrated in dashed lines 125 for the position of the elevator in the fully elevated position with rollers 70 positioned forwardly on cams 60. Comparatively, the position of the lower idler wheels 41 (and elevator 35) with conventional stops is illustrated by dashed outline 126. Again, the new position 125 is slightly higher and substantially forward of the outline 121. For any varied soil conditions or'dig depths, the cylinders 52 can be repositioned to properly position the elevator 35 within the range of reciprocable members 75 and cams 60.
Animproved means for ground related positioning of an elevator on an earth scraper has been described. Modifications of this invention described are made apparent by this disclosure. Those modifications also are within the scope of this invention and as set forth in the claims.
1. 'An earthscraper comprising:
an open end bowl supported on the wheels, said bowl comprising a floor section extending between spaced sidewalls;
a scraper blade supported by the bowl adjacent its open end;
a draft frame;
a laterally spaced pair of draft members at one end supported on the draft frame and at the other end pivotally connected to the bowl;
means connected intermediate the bowl and the draft frame for raising and lowering the scraper blade by rotating the bowl upon the wheels;
an inclined endless conveyor positioned at the open end of the bowl and including laterally spaced sidewalls and a lower end in proximity to the scraper blade for conveying material into the bowl;
a laterally spaced pair of upper conveyor links at one end pivotally mounted on the sidewalls of the bowl and at the other end pivotally mounted on the sidewalls of the conveyor at the upper end for pivotal movement about a first transverse axis;
a laterally spaced pair of cams each including an upper cam surface with one end mounted on the sidewall of the bowl and extending forwardly and upwardly;
a means for supporting the lower end of the conveyor on the upper cam surfaces comprises a laterally spaced pair of extensible cylinders each comprismg:
a. a base cylinder at one end pivotally mounted on the sidewall of the bowl behind and above the cams; and
b. a reciprocable member including a rearward section nestable within the base cylinder and adapted to telescope forwardly, the forward end of said reciprocable member pivotally mounted on the sidewalls of the conveyor for pivotal movement about a second transverse axis and adapted to reciprocate upon one cam upper surface; and
means operatively connected between the conveyor and reciprocable members for reciprocating the reciprocable members to move the conveyor lower end.
2. An earth scraper as recited in claim 1 wherein the means for raising and lowering the scraper blade comprises: I
a laterally spaced pair of bowl hoist cylinders connected to the bowl and draft frame; and
means for operating the bowl hoist cylinders.
3. An earth scraper as recited in claim 2 wherein: the draft frame comprises a rearward end with a transverse extending tube formed thereon; and each one end of the draft members are supported on opposite end of the transverse tube.
4. An earth scraper as recited in claim 3 wherein each reciprocable member of the extensible cylinders comprises:
a rearward section member nestable within the base cylinder with a forward end extending outside the base cylinder;
10 a first lower link and a second lower link pivotally secured to one sidewall of the bowl at a common connection having a transverse axis and adapted to pivot together about said transverse axis of said common connection, the unsecured end of said first lower link pivotally connected to the forward end'of the rearward section member; and
a third lower link pivotally connected to the second lower link and the pivotal mount about the second transverse axis.
'5. An earth scraper as recited in claim 3 wherein the bowl hoist cylinders and extensible cylinders are hydraulic cylinders and wherein the reciprocating means and the operating means include hydraulic pressure means.
6. An earth scraper as recited in claim 5 wherein the section of the forward end of each reciprocable member adapted to reciprocate upon one upper cam surface defines a roller rotatably mounted at said forward end for rotating contact upon said cam surface.
7. Anearth scraper as recited in claim 6 and further comprising a resilient support means mounted on the bowl sidewalls for resiliently supporting the cams and conveyor.
8. An earth scraper as recited in claim 7 and further comprising means for stabilizing the pair of upper conveyor links and maintaining alignment of the conveyor with the bowl sidewalls by torsionally stiffening the movement of said links upon its pivotal mounts.
9. An earth scraper as recited in claim 7 and further comprising spacing means disposed under the cams for adjusting the position of the cams and conveyor supported thereon.
10. An earth scraper as recited in claim 7 wherein each reciprocable member of the extensible cylinders comprises:
a rearward section member nestable within the base cylinder with a forward end extending outside the base cylinder;
at first lower link and a second lower link pivotally secured to one sidewall of the bowl at a common connection having a transverse axis and adapted to pivot independently about said transverse axis of said common connection, the unsecured end of said first lower link pivotally connected to the forward end of the rearward section member; and
a third lower link pivotally connected to the second lower link and the pivotal mount about the second transverse axis.
l 1. An earth scraper as recited in claim 7 wherein the reciprocating means further comprises means responsive to change of position of a component of the earth scraper for automatically switching-the hydraulic pressure means to a retract or extend mode.
12. An earth scraper as recited in claim 11 wherein the reciprocating means further comprises manual control means for manually overriding the automatic switch means to change the hydraulic pressure means to a retract, extend or hold mode.