US 3792555 A
A five section telescopic crane boom is extended and retracted by a pair of three section hydraulic rams which are fully enclosed by the boom and independently suspended therein. The suspension means for the rams compensates for cocking and bending of the boom sections when the latter are extended under load and relieves the rams of bending stresses and allows them to remain substantially straight, thus preventing leakage of the ram operating fluid.
Description (OCR text may contain errors)
United States Patent 1191 Sung 1 1 Feb. 19, 1974 1 FIVE SECTION FULL POWERED 3,353,686 11/1967 Cowan 212 55 O IC CRANE O 3,398,492 8/1968 Nansel 52/115 3,212,604 10/1965 Garnett 212/55 lnvemori Fu-Tlen g, waynesboro, 3,398,645 8/1968 Nansel 52 115  Assignee: Kidde Walter & Company, Inc.,
Clifton, NJ. Primary Examiner-Henry C. Sutherland Assistant Examiner-Les1ie K. Braun  1971 Attorney, Agent, or Firm--Brady, OBoyle & Gates  Appl. No.: 132,407
.  ABSTRACT 2% 8 52/115 52/ 53 A five section telescopic crane boom is extended and d retracted by a pair of three section hydraulic rams 1 o earc which are fully enclosed by the boom and independently suspended therein. The suspension means for the rams compensates for cocking and bending of the  ,References Clted boom sections when the latter are extended under UNITED STATES PATENTS load and relieves the rams of bending stresses and al- 3,722,154 3/1973 Sakamoto et a1. 52/121 lows them to remain substantially straight, thus pre- 3,624,979 12/ 1971 Przybylski 52/115 venting leakage of the ram operating fluid. 3,445,004 I 5/1969 Grider et a1. 212/55 1 3,243,052 3/1966 Grove 212/55 16 Claims, 16 Drawing Figures PATENTEDFEBI 9mm" SHEET 1 [If 4 FIG. l5
INVE NTOR FU-TIEN SUNG ATTORNEYS PATENTEU FEB 1 9 I974 SHEET 2 0F 4 SHEET 3 OF 4 PATENIE FEB 1 9 I874 FIVE SECTION FULL POWERED TELESCOPIC CRANE BOOM BACKGROUND OF THE INVENTION are now quitecommon but generally speaking booms of greater length having more than four sections have not been practical to construct for a number of reasons. Among these reasons is the inability to mount the required number of operating rams inside of the hollow telescopic boom without increasing the cross sectional size of the boom beyond reasonable limits. Additionally, where attempts have been made to employ a smaller number of rams containing more than the customary two sections, a serious leakage problem is encountered when the boom is extended. A significant degree of cocking necessarily occurs between the extended boom sections plus some bending of these sections under loading. This cocking and bending is transmitted to the plural section rams when they are rigidly connected with the boom sections, causing them to flex or bend, giving rise to the serious leakage of fluid. At least one prior art effort has been made to provide a five section telescopic boom in which the internal hydraulically operated rams are interconnected so as to be mutually self-supporting, as in US. Pat. No. 3,21 2,604 to Garnett. However, in this prior art structure, when the boom is extended andthe rams are under heavy loading, they are subjected to very severe bending stresses and the above leakage problem is necessarily present. v
Theobjective of the present invention is, therefore, to provide an entirely practical and economically feasible five section telescopic crane boom in which the operating rains for the boom are fully enclosed and independently supported in sucha manner that the inherent cocking and flexure of the extended boom is nottransmitted to 'the'rams as a severe bending stress, and consequently the rams are able to remain substantially straight atall times and the problem of severe leakage is largely avoided. In the invention, it has been found feasible to employ a single pair of double telescoping rams, each ram having three sections, and the rams being fully enclosed within the five section boom. All sections of the telescopic boom are fully powered by having each extensible section of each ram connected with one extensible boom section. The suspension or mounting means for the rams is such that a certain degree of relative lateral movement between the boom sections and rams may occur to relieve the rams of bending stresses during the inevitable cocking and bending of the bo'om'sections when the boom is extendedfThe inventionpossesses other unique features and advantages which appear during the course of the following description.
BRIEF DESCRIPTION OF DRAWING FIGURES ,embodying the subject matter of the invention.
FIG. 2 is a diagrammatic side elevation of the boom and its operating rams fully extended.
FIG. 3A is a fragmentary longitudinal vertical section on an enlarged scale showing that portion of the boom designated FIG. 3A in FIG. 2.
FIG. 3B is a similar view showing that portion of the boom designated FIG. 3B in FIG. 2. 7
FIG. 4 is a longitudinal vertical section through the boom when the-same is fully retracted.
FIG. 5 is an enlarged fragmentary end elevation, partly in section, taken .on line 5-5 of FIG. 3B.
FIG. 6 is an enlarged transverse vertical section taken on line 6-6 of FIG. 3B.
FIG. 7 is a fragmentary horizontal section taken on line 77 of FIG. 6. 1
FIG. 8 is a similar view taken on line 8-8 of FIG. 6
FIG. 9 is an enlarged transverse vertical section taken on line 9-9 of FIG. 3B.
FIG. 10 is a similar view taken on line 10-10 of FIG. 3B. 1
FIG. 1 l is a similar view taken on line 1 1-1 1 of FIG. 3A.
FIG. 12 is a fragmentary horizontal section taken'on line 12-12 of FIG. 11. I
FIG. 13 is an enlarged transverse vertical section taken on line 13-13 of FIG. 3A.
FIG. 14 is a diagrammatic side elevational view of the extended boom showing on an exaggerated scale the cocking and bending of the boom sections and also-illustrating the relative straightness of the extended rams.
FIG. 15 is a fragmentary perspective view of a modified mounting means for a ram.
DETAILED DESCRIPTION Referring to the drawings in detail wherein like numerals designate like parts throughout the same, a crane boom shown in its entirety at 20 comprises a base section 21, first, second and third mid-sections 22, 23 and 24 and a fly section 25, all telescopically interfitting. As shown in FIG. 6, each boom section is rectangular in cross section and fabricated from welded plate stock as disclosed in prior copending application Ser. No. 200,352, now-Pat. No. 3,690,742, issued Sept. 12, 1972, a continuation of Ser. No. 90,373, filed Nov; 17, 1970, for CRANE BOOM now abandoned. This fabricated construction allows the placementof wear pads 26 or similar bearing means substantially in direct alignment with the vertical walls of the box-like boom sections, thus greatly reducing transverse flexure of the bottom walls ofthe several sections and permitting the use of thinner material for these walls. Equivalent upper bearing means 27in the form of rollers or wear pads is also provided between-the adjacent telescoping boom sections.
The means to extend and retract the telescopic boom consisting of the five boom sections comprises a pair of double-acting, double-telescoping, three section bydraulic rams 28 and 29 arranged totally inside of the hollow boom and each independently-supported therein in a manner to be fully described. The mounting or suspension means for the rams 28 and 29 forms a very important part of the invention. The inner or rearward ram 28 includes a cylinder section 30, ram mid-section 31 and a rodsection 32. The cylinder section 30 is pivotally secured at its rear end to the base section 21 of the boom by a suitable fixed pivot element 33. The cylinder section 30 extends forwardly into the first mid-section 22 even when the crane boom is fully extended, FIG. 3A, and its forward end portion is supported by a wiper ring 34 whose upper end carries an upstanding pin 35 rigid therewith, having a head 36 on its upper end resting on the top of a compression spring 37. The bottom of this spring is seated on the bottom wall of a suspension bracket 38, dependingly rigidly secured to the top wall of the first mid-section 22 of the telescopic boom. Therefore, the forward end portion of the cylinder30 of ram 28 is resiliently suspended for limited vertical movement through the wiper ring 34 and the associated spring suspension means from the rear end portion of the first mid-section 22. It will be understood that the wiper ring 34 and associated parts move with the first mid-section 22 as the boom is extended or retracted and therefore the wiper ring moves outwardly and inwardly over the cylinder 30 between the positions shown in FIGS. 3A
and 4 where the boom is fully extended and fully retracted, respectively.
Adjacent the cylinder 30 and mid-section 31 of inner ram 28 is a fabricated housing 39 made from welded rod stock so that the housing is similar in construction to a certain type of truss formed of welded rod stock. The housing is channel-like and U-shaped in cross section and has its top open. It includes corner longitudinal rods 42, whose rear ends are rigidly secured to a rear end plate 43 on the first mid-section 22 of the boom. The forward ends of the rods 42 are similarly anchored to a head plate 44 on the forward end of ram mid-section 31. Consequently, when the inner ram 28 is extended and its mid-section 31 moves forwardly, the first mid-section 22 of the..boom will be pulled forwardly by the housing 39 due to the connection of the rear end of the housing with the plate 43.
In turn, the forward end of the housing 39 is additionally supported by a wiper bearing or suspension element 45 which is rectangular in cross section, FIG. 11, and slidably contacts the corner rods 42 of the housing 39, as shown. The wiper bearing 45 at its top carries an upstanding pin 46 having a rigid head 47 bearing downwardly on a compression spring 48, seated on a suspension bracket 49, dependingly rigidly secured to the top wall of the second boom mid-section 23. Thus, the housing 39 and ram 28 are additionally resiliently supported for limited vertical movement within the boom through the elements 45 through 49, described immediately above. When the boom is extended or retracted, the wiper bearing 45 will slide over the truss-like housing 39 either forwardly or rearwardly between the extreme positions depicted in FIGS. 3A and 4. In FIG. 1 1, the boom is extended and the wiper bearing 45 is near the outer end of housing 39. Due to the cantilevered attachment of the housing 39 to boom mid-section 22, its outer end is free to move vertically and the force of spring 48 is sufficient to elevate the forward end of the housing 39 as depicted in FIG. 11. When the boom is fully retracted and the wiper bearing 45 is close to the rear end of the housing 39 where this housing is rigid with boom mid-section 22 and cannot yield, the spring 48 will be compressed and there will be a substantial gap between the elements 45 and 49. When the boom is extended, the wiper bearing 45 may contact the bracket 49 or move very close thereto, FIG. 11, and in like manner the head 47 may substantially contact the top wall of boom mid-section 23.
Another housing 50 also constructed from rod stock and being channel-like or U-shaped in cross section, FIG. 10, is adapted to telescope over the housing 39. Both of these truss-like housings lend rigidity in two directions because of their deep channel configurations. The corner rods 51 of the housing 50 are anchored at their rear ends to a plate 52 at the rear end of the second mid-section 23. The forward end of the housing 50 is rigidly secured to a head plate 53 on the rod section 32 of ram 28. Thus, when ram 28 is extended and the rod section 32 moves forwardly, the housing 50 at its rear end pulls the second mid-section 23 of the boom forwardly.
The leading end of rod section 32 carries a cross pin 54 rigid therewith having a lost motion connection with a pair of upstanding support plates 55 through vertical slots 56 formed in the latter. The plates 55 have their lower ends rigidly anchored to the base or cylinder section 57 of the second three section ram 29. Both of the rams 28 and 29 are preferably constructed in the manner disclosed in prior copending application Ser. No. 76,373, filed Sept. 28, 1970, for MULTl-SECTION HYDRAULIC RAM, now Pat. No. 3,696,712, issued Oct. 10, 1972. The support plates 55 form a rest for the forward extremity of the rod section 32 on the cylinder section 57 but limited vertical movement between the elements 32 and 57 is allowed due to the slots 56. The plates 55 form the only direct connection between the two hydraulic rams 28 and 29 which are otherwise independently suspended or supported within the telescopic boom.
The ram 29 is disposed beneath the ram 28 with the cylinder section 57 directly below the rod section 32, FIG. 2, when the boom is fully extended. The rear end of cylinder section 57 is pivotally secured at 58 to the inner end of the second mid-section 23 of the boom. As shown in FIG. 11, this pivotal connection comprises trunnions on the cylinder section 57 pivotally supported within bearings 59, rigidly secured to the vertical side walls of the second mid-section 23.
Referring to FIGS. 3B and 9, the cylinder section 57 is further supported by a wiper bearing 60 which engages slidably over the cylinder section 57 and has its base 61 fixedly secured to the bottom wall of the third mid-section 24. Another housing 62 formed of rod stock and including only two truss-like side webs 62, FIG. 9, is disposed below the housing 50 and has its rear end rigidly secured to a vertical plate 64 spanning the rear end of third mid-section 24 and rigid therewith. This plate 64 has an opening receiving the cylinder section 57, FIG. 10. The top and bottom sides of the housing 62 are left open as shown in FIG. 9 and this allows the truss-like housing to clear the plates 55 which are fixed to the top of cylinder section 57 during retraction of the boom, FIG. 4.
The mid-section 65 of ram 29 has its leading end secured rigidly to a block 66 and the forward end of housing 62 is also rigidly secured to this block through the corner rods 67 of the two housing sides. Referring to FIGS. 6, 7 and 8, the block 66 is supported floatingly in a pair of opposing vertical guide channels 68 by the action of a compressible spring 69 upon which the block 66 is seated. The spring, in turn, rests upon a fixed plate 70 or bracket secured to a skid base 71 integral with the two guide channels 68. The skid base 71 slides on the botton wall of the extensible and retractable boom fly section 25. A pin extension 72 dependingly rigidly secured to the block 66. projects through the bore of spring 69 and carries a head 73 below the fixed plate 70 to limit upward displacement of the block. The plate or bracket 70 also has a transverse elongated slot 74 therein, FIG. 8, to allow some lateral displacement of the block and the mid-section 65 of the ram 29 to which it is attached. Therefore, the leading end of the ram mid-section 65 is floatingly supported resiliently in the vertical direction by the spring and guide means and can have limited lateral movement. Extension of the ram mid-section 65 will pull the boom mid-section 24 forwardly becausethe housing 62 has its rear end connected with the plate 64 on the midsection 24.
In some cases, the wiper bearing 60, FIG. 9, may be spring-mounted like the block 66. In such cases, guide channels, like the channels 68, will be fixed to boom mid-section 24 near its rear end. With proper clearances, however, the mounting shown in FIG. 9 is sufficlent.
The ram 29 has a leading rod section 75 extending to substantially the forward end of fly section 25 and car-' rying a cross pin 76 similarto the pin 54 of rod section 32. The pin 76 engages slidably within vertical slots 77 of upstanding anchoring plates 78 having their lower ends fixedly secured to the bottom wall of the boom fly section. This arrangement allows the forward end of rod section 75 to have limited vertical movement relative to the fly section 25, and as evidenced by the lengths of the slots 77, the extent of this movement is I greater than the possible movement of the rod section 32 allowed by the shorter slots 56. The plates 78 stabilize the rod sections 75 against lateral movement in the same manner that the plates 55 act on the rod section 32 of the ram 28. i 1
'Referring to diagrammatic FIG. 14, there is illustrated with considerable exaggeration how the mounting of the two three-section rams 28 and 29 within the telescopic boom in the described manner allows these rams to remain substantially straight and thus free of leakage despite the inherent cocking and some bending of the several boom sections, particularly when the boom is fully extended. Even though this cocking and bending is considerable in practice as emphasized by the diagram, the two hydraulic rams are allowed to remain relatively free of bending stress normal to their axes because of their independent mountings and their resilient and lost motion supporting points, abovedescribed.
In the operation of the five section boom, the rams 28 and 29 should normally be operated in sequence. That is to say, if only a limited boom length is required, the ram 28 is actuated so that the boom sections 24 and 25 will remain fully retracted. This results in a much stronger boom than would be the case were the ram 29 extended first.
In FIG. 15, there is shown a modified form of wiper bearing having a limited universal adjustment or movement, and in some cases this structure may be employed in lieu' of the spring-suspended wiper ring 34in FIG. 13 and the similar suspension means for the housing 39 shown in FIG. 11. In FIG. 15, the wiper bearing element which would receive the ram base section is indicated by the numeral 79, and this element is spherically formed externally for universal swiveled movement within a carrier block 80 having a spherically curved recess 81. The block 80 is spring-mounted above and below by suitable springs 82 and 83 seated within recesses 84 of a cage 85 attached fixedly to the first mid-section 22 of the boom in lieu of the bracket 38. In terms of this modification, the mounting for the particular ram provides for limited movement within the boom in all directions or universally, in addition to resilient support primarily in a vertical direction This structure is also adaptable for use in lieu of floating block 66, FIG. 6, or wiper bearing 60, FIG. 9. In the use of this modification for floating block 66, rods 67 and ram mid-section 65 are connected to spherical element 79.
It may now be seen that the invention solves successfully the principal problems which have retarded the manufacturing and using of a five section hydraulically operated telescopic crane boom. By means of the invention, the two three-section hydraulic rams and their 'required housings which connect them back to the rear ends of certain boom sections have all been successfully mounted within the interior of the boom. Each extensible section of each ram is positively connected with one of the four extensible boom sections so that the boom is fully powered. Additionally two rams are separately mounted so that any stresses developed by the extension of one will not be transmitted to the other. Each ram is resiliently supported at critical points or is supported through lost motion connections with the adjacent boom sections so that the inevitable cocking and bending of the boom will not be reflected by bending and misalignment of the rams. Serious leakage of the rams is-thus avoided.
The terms and expressions which have been employed herein are used as terms of description and not of limitations, and there is in intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof but it is recognized that various modifications are possible within the scope of the invention claimed.
1. A fluid pressure actuated extensible boom comprising plural telescopically interfitting extensible and retractable boom sections including a base section, a mid-section, and at least one further section, fluid pressure operated telescoping ram means extending longitudinally within said boom sections and operable to extend and retract such sections, said ram means com prising at least a three-section double telescoping ram having a base section, a mid-section and a rod section of successively decreasing diameters, the base section of the ram connected to the base section of the boom, a housing on the mid-section of the ram secured to the leading end of the ram mid-section and having its rear end secured to the rear of said boom mid-section said further section adapted to telescope over said housing, the rod section of said ram connected to said further section of the boom, and resiliently yielding intermediate suspension means for the ram within the boom sections comprising a first resiliently yielding suspension unit connected adjacent the rear end of said boom midsection and being slidably engaged on the outside surface of the ram base section and a second resiliently yielding suspension unit connected adjacent the rear of said further boom and being in slidable supporting engagement with the outside of said housing.
2. In a crane boom, plural telescopically interfitting extensible and retractable boom sections including a base section, first, second and third mid-sections and a fly section, first and second three section double telescoping rams within the boom sections operable to extend and retract such sections, each of said rams having a base section, a mid-section and a rod section, the base section of the first ram secured to the boom base section and the base section of the second ram secured to the second mid-section of the boom, first and second housings on the mid-section and rod section of the first ram having their rear ends secured respectively to the first and second boom mid-sections, the second housing adapted to telescope over the first housing, a third housing on the mid-section of the second ram having its rear end connected to the rear end of the third midsection of the boom, said first, second and third housings formed of rods in the form of a lattice structure, the rod section of the second ram having a connection with the fly section of the boom, and yielding suspension means for the rams within the boom sections comprising plural suspension units for the first and second rams having connections with plural sections of the boom, whereby the rams are relieved of stresses caused by cocking and bending of the boom sections.
3. The structure of claim 2, and at least the first and second housings being of box-like formation in cross section.
4. The structure of claim 2, and said rams in all operating positions arranged at least partly in side-by-side overlapping relationship, and a lateral member on one ram having a lost motion connection with a section of the other ram.
5. The structure of claim-2, wherein one of said suspension units comprises a resilient support on the midsection of one of said rams including a shoe element having sliding engagement with the fly section of the boom.
6. In a crane boom, plural telescopically interfitting extensible and retractable boom sections including a base section, first and second mid-sections, and at least one further section, fluid pressure operated telescoping ram means within the boom sections operable to extend and retract such sections, said ram means comprising a three-section double telescoping ram having a base section, a mid-section and a rod section, first and second housings on the mid-section and rod section of said ram having their rear ends secured respectively to the inner ends of said first and second boom midsections, the second housing adapted to telescope over said first housing, said further section adapted to telescope over said first and second housings, and yielding suspension means for the ram means within the boom sections, whereby the ram means are relieved of stresses caused by cocking and bending of the boom sections.
7. The structure of claim 6, and said yielding suspen sion means including plural suspension units for the ram means at spaced points along the length of and intermediate the ends of the ram means, and means in said plural suspension units rendering said units resiliently yielding.
8. The structure of claim 7, and said units serving to supportingly interconnect individual telescoping sections of the ram means with a corresponding number of boom sections.
9. The structure of claim 8, and wherein at least one of said suspension units includes a suspension bearing having sliding supporting engagement with a section of the ram means.
10. The structure of claim 9, and wherein said suspension unit further comprises a spring suspension means for said bearing having a connection with an adjacent section of said boom.
11. A crane boom as set forth in claim 6 in which said yielding suspension means for the ram means includes plural suspension units for the three section ram including a first unit on the first mid-section of the boom having sliding supportive engagement with the base section of the three section ram, and a second unit on the second mid-section of the boom having sliding supportive engagement with said first housing.
12. A crane boom as set forth in claim 6 in which said yielding suspension means includes plural mounting units which interconnect sections of the ram means with adjacent sections of the boom.
13. The structure of claim 12, and at least one of said mounting units for said ram including a bearing member supporting a section of the ram and a spring support for the bearing member having a connection with an adjacent section of the boom.
14. The structure of claim 12, and wherein at least one of said suspension units includes a bearing having sliding supporting engagement with a section of the ram means, and a carrier for said bearing allowing the bearing to swivel universally.
15. The structure of claim 14, and a spring mounting for said carrier.
16. The structure of claim 6, wherein said yielding suspension means comprises plural suspension units for said ram having connections with plural sections of the boom.