US3062384A - Boom and jib assembly - Google Patents

Description

Nov. 6, 1962 s. POLLACK 3,06

BOOM AND JIB ASSEMBLY Filed May 11, 1962 2 Sheets-Sheet 1 lNVENTOR s'liy PoZZac/n ATTORNEY Nov. 6, 1962 s. POLLACK 3,062,384

BOOM AND JIB ASSEMBLY Filed May 11, 1962 2 Sheets-Sheet 2 INVENTOR M Emu/4W ATTORNEY United States Patent 6 3,062,384 BOOM AND JIB ASSEMBLY Selig Pollack, Bronx, N.Y., assignor to Seljo Development Crp., Bronx, N.Y., a corporation of New York Filed May 11, 1962, Ser. No. 194,140 6 Claims. (Cl. 212144) This invention relates to a jib construction for booms, derricks, cranes or like manipulating devices. More particularly, this invention relates to an improved boom device of the general type shOWn in United States Patent No. 3,034,661 of May 15, 1962, which patent is based on application Serial No. 58,668, filed September 27, 1960, by Joseph Pollack and myself. This application is a continuation-in-part of the aforesaid joint application.

The aforesaid application is directed to a device having a main, vertically pivotal boom, and a vertically pivotal jib carried adjacent a terminal end of the boom. The angular orientation of the jib with respect to the horizontal in the aforesaid device is maintained automatically constant throughout all adjusted positions of the boom, such automatic orientation of the jib being effected by guying means which articulate the jib with respect to the boom when the latter is articulated with respect to a base, chassis or other boom support.

The present invention accordingly relates to novel means which when used, particularly in conjunction with a jib device in accordance with the above noted patent, enhance the desirable features of such device.

Still more particularly, this invention relates to an improved boom device having an adjustable jib characterized by the inclusion of a prestressing apparatus which renders the device safer, more accurate in operation and easier to use.

Accordingly, it is an object of the invention to provide in combination with a boom having an adjustable jib, a prestressing device which urges the free or terminal end of the jib downwardly to prevent possible damage due to shock loading, reduced deflection of the outer end of the jib upon loading, and prevents the possibility of reverse or counter-rotative movement of the jib with respect to the boom.

A further object of the invention is to provide automatic prestressing apparatus for use with an automatically adjusted jib, such as is illustrated and described in the aforesaid patent, wherein the jib will be prestressed to a selected level throughout all adjusted positions of the boom and jib.

A further object of the invention is to provide a novel boom and jib assembly which includes jib prestressing means which are operative for the purposes aforesaid and yet do not reduce or detract from the load carrying capacity of the jib.

To attain these objects and such further objects as may appear herein or be hereinafter pointed out, reference is made to the accompanying drawings, forming a part hereof, in which FIGURE 1 is a side elevational view schematically illustrating a device in accordance with the invention in several positions thereof;

FIGURE 2 is a magnified rear elevation taken in the direction of the arrows 2-2 of FIGURE 1.

Making reference to the drawings, indicates a Caterpiller tractor tread assembly, to which assembly a cab chassis or base assembly 11 has been mounted for relative movement in a horizontal plane. A main boom 12, having at the lower end thereof a horizontally disposed massive trunnion 13 is pivotally mounted to chassis 11 by means of spaced bearing members 14 (one being shown) which are fixed to the chassis. The boom 12 adjacent its upper terminal end 15 pivotally carries jib member 16 which is supported on horizontally disposed trunnion assembly 17 made fast to the upper end of the boom. The boom is thus pivotal in a vertical plane about a first horizontal axis provided by trunnion 13, and the jib is in turn pivotal vertically with respect to the boom about a second horizontal axis provided by trunnion 17.

In Patent 3,034,661 there is illustrated and described a novel guying arrangement for maintaining the jib 16 automatically in a fixed angular relation with respect to the horizontal, notwithstanding angular articulation of the boom 12 about the first axis. Such guying arrangement will be herein described only to the extent necessary for an understanding of the illustrated embodiment of the invention.

A first massive quadrant 20 is fixed to the chassis 111, with the generally circular peripheral portion 21 thereof concentrically disposed with respect to the axis of trunnion 13. A second massive quadrant 22 congruent with quadrant 20 is formed on the end 23 of jib 16 and the circular peripheral portion 25 thereof being concentricmly disposed with respect to the axis of trunnion assembly 17.

As best seen in FIGURE 2, the quadrants 20, 22 are provided with spaced track or guide portions 26, 28, respectively, for receipt of the flexible guy members which control the jib 16. Optionally but preferably, a first pair 30, 31) of equal lengthened flexible guys, formed of heavy cable, chain or the like, are secured at their upper ends 32, 32 to opposed ends 33, 34 of a cross beam 35. The lower ends 39a of the guy members are fixed at the lowermost portion of quadrant 20. A pair of spaced sheaves 36, 37 are fixed to the upper face of beam 35. An upper guy member 40 of similar nature to guy members 30, 30 is reaved through the sheaves, the upper ends 40a, 46a of said guy member being fixed to the uppermost portion of the upper quadrant 22. A turnbuckle 41 is optionally but preferably interposed in guy 40 to permit variation of the tension in such guy.

The net result of such guying arrangement, as fully set forth in the aforesaid patent, is to cause the jib 16 to articulate about trunnion 17 as the boom 12 is articulated about trunnion 13 by reason of the winding and unwinding of guys 30 and 40 about quadrants 22 and Zil, respectively. The Winding and unwinding action aforesaid causes the jib to be maintained in fixed angular relation to the horizontal throughout all reach and retractive movements of boom 12. The incorporation in the construction aforesaid of the beam 35 is particularly advantageous in that it permits the use of quadrants which are of different widths, i.e. the lower quadrant 26 may be of a greater lateral dimension than the upper quadrant 22, in conformity with the relatively narrow jib width. Similarly, the provision of a unitary upper guy which passes under sheaves 36, 37 assures that the two segments of the guy 40 will be of equal length at all times. The turnbuckle 41 permits length adjustment of guy member 41 for accurate angular orientation of the jib.

The prestressing of the jib is effected by a quadrant assembly similar to the jib control assembly above described. The prestressing assembly includes a lower quadrant mounted on chassis plate 14 and having a generally circular peripheral surface which is concentrically disposed with respect to and positioned beneath lower trunnion 13. An upper quadrant is fixed to jib 16 beneath trunnion 17, said upper quadrant being congruent with respect to the quadrant 56 and including a circular peripheral portion 56 which is concentrically disposed with respect to the upper trunnion assembly 17. The surfaces 51 and 56 of quadrants 5t 55 are spaced from trunnions 13 and 17, respectively, in a manner to "3 dispose the axes of said trunnions at the radii of the respective arcuate surfaces 51 and 56.

The quadrants 5t} and are guyed to each other by a heavy flexible guy assembly 69. While the assembly may comprise a single guy wrapped over guadrants 50 and 55, tangentially to engage surfaces 51 and 56 thereof in all articulated positions of the boom, the assembly 651 is preferably formed of upper and lower paired guy segments separated by a beam, as employed for the main quadrants 2t) and 22. In such preferred guying assembly, only the right hand side of which may be seen in FIG- URE 1, a pair of lower guy members 61 are fixed at their lower ends 62 beneath the arcuate section 51 of said lower quadrant. The upper ends 63 of said guy members are fixed to beam 65 in laterally spaced-apart relation. A pair of sheaves 66 are fixed in laterally spaced relation to the upper surface of beam 65, a single strand 67 of heavy flexible guying being passed beneath both the sheaves 66. The uppermost ends 68 of the strand 67 are fixed at the uppermost edges of the peripheral surface 56 of quadrant 55. A turnbuckle 69 is interposed in the strand and by the adjustment of such turnbuckle, the tension in the entire prestressing guy assembly 60 may be varied.

It will be seen from the above described guying assembly that as boom 12 is articulated, the jib 16 is likewise articulated and the guy 60 will be wrapped on one of the quadrants at the same rate as the same is unwrapped from the other quadrant and, thus, the distance or length of guy 60 disposed between the points of tangential engagement of the guy and the quadrants 50, 55 will remain substantially the same throughout all movements of the boom.

In FIGURE 1, lift hooks 70 and 71 represent load carrying elements reaved through support elements (not i shown) made fast to the jib 16.

When a load is applied to jib 16, for instance by application of the load to hooks 70 or 71, the applied force tends to rotate the jib clockwise, as shown in dot and dash lines, FIGURE 1, about trunnion 17. In the absence of a prestressing force, the unloaded jib will, as exaggeratedly shown in dot and dash lines, FIGURE 1 (intermediate position), occupy a position in which the jib is counterclockwisely rotated about trunnion 17 as compared to the position such jib will occupy when loaded. The counterclockwise rotation is due in part to the force generated by the weight of the jib control guy assembly. Such counter-rotative force becomes increasingly great as the boom is lowered, i.e. as the jib control guy approaches a theoretical catenary position as shown in the lowermost dot and dash view of FIGURE 1.

Where, as in the device of Patent No. 3,034,661, there is a dendency to counter-rotative movement of the jib, the application of a load to such jib will cause an immediate and considerable clockwise rotation of the jib, which rotation will be abruptly arrested as the jib control guys are fully extended. The shock of such abruptly arrested forces, repetitively encountered, will result in an undue amount of wear, and also possible fracture of certain of the force absorbing elements of the device, rendering frequent repairs probable and leaving a possibility of disastrous consequences.

A further undesirable effect encountered in the use of an un-prestressed jib is that the relatively large jib encounters deflection when such a jib is first loaded, rendering uncertain the ultimate, loaded angle which will be assumed by the jib. To be able accurately to determine the ultimate angle which will be assumed by the jib is of particular importance where a continued horizontal disposition of the jib is sought, as where the jib is provided with tracks and with a longitudinally shiftable trolley which may be shifted along such tracks. Such an arrangement is illustrated in the above noted patent.

The prestressing quadrant and guying assembly above described eliminates all the above noted disadvantages by stressing the jib substantially to the position it will ultimately occupy when loaded. Thus, the angle which the jib will ultimately occupy will be nearly exactly ascertained and the addition of the load will not vary the same. Also, since there is no movement of any substantial magnitude, the addition of a load to the jib will not induce any sudden shock to the device, thus eliminating the disadvantages previously noted as existing in un-prestressed jibs. Also, the prestressing device will prevent the jib from falling backward, an action which may occur in unloaded and un-prestressed jibs, particularly where the boom is raised and abruptly stopped.

It is of particular importance to note that the prestressing device herein disclosed does not detract from the load carrying capacity of the jib. This important feature is due to the fact that the slight additional deflection induced in the jib by the addition of a load relaxes the pressure exerted by the guying system of the prestressing assembly, and thus the prestressing forces are effective only when they are required, i.e. when the jib is unloaded. This should be compared to prestressing through the use, for instance, of a weight. If a counterweight were employed for the purpose of prestressing the jib, this weight would also exert a deflecting force on the jib and boom when a load was supported on the jib, thereby detracting from the effective load carrying capacity of the device.

A further desirable feature of the prestressing device lies in the fact that the prestressing force exerted is automatically varied in accordance with the position of the boom. As pointed out above, the upsetting force exerted by the jib control guy assembly 40 increases progressively as the boom is lowered, i.e. as the guy assembly approaches a horizontal or catenary conformation. It will be readily recognized that the prestressing guy assembly similarly exerts a greater force as the boom is progressively lowered and as it approaches the catenary, thus offsetting the increasing upsetting effects of the control guy assembly. Preferably, the two guy assemblies are disposed in parallelism.

From the above it will be seen that there is provided a novel crane assembly having means for applying a prestressing force to the jib, which force will be applied automatically in all adjusted positions of the jib and which force will be relieved when a pay load is placed on the jib.

The prestressing feature is particularly useful when employed in conjunction with a self-leveling (or self-adjusting, if horizontal disposition is not required) jib assembly as shown in Patent No. 3,034,661.

By the use of the turnbuckles in the prestressing guy or tie assembly, shock loading resulting from counterdeflection of the jib and/or slackness in the jib control guy assembly may be eliminated, or at least greatly reduced. Similarly, the jib may be angularly oriented to a desired position with the knowledge that the addition of a load to the jib will not materially vary the position of the jib.

While the invention is described as utilized in conjunction with a caterpillar tractor base, it will be readily recognized that the same will be applicable in a wide variety of applications and, hence, the invention should be broadly interpreted within the scope of the appended claims.

Having thus described the invention and illustrated its use, what is claimed as new and is desired to be secured by Letters Patent is:

1. A crane rigging device comprising a supporting base chassis, a main boom pivotally supported on said chassis on a first horizontal axis, to be pivotable in a vertical plane, a beam jib having a free end and an inner end pivotally mounted about a second horizontal axis on bearing means disposed adjacent the upper terminal end of said boom, a first pair of congruent quadrant means fixed, respectively, to said chassis and said jib, first flexible guy means engaging said first pair of quadrant means tangentially in all vertically pivoted positions of said boom with respect to said chassis, a second pair of congruent quadrant means, one of said second pair being fixed with respect to said chassis and the other of said pair being fixed with respect to said jib, the peripheries of the quadrants of said second pair being downwardly directed and concentrically disposed with respect to said first and second horizontal axes, respectively, and disposed in opposition to the peripheries of said first pair, second flexible guy means tangentially contacting the peripheries of said second pair of quadrants and means for stressing said second guy means.

2. A crane rigging device comprising a supporting base chassis, a main boom pivotally supported on said chassis on a first horizontal axis, to be pivotable in a vertical plane, a beam jib having a free end and an inner end mounted pivotally about a second horizontal axis on hearing means disposed adjacent the upper terminal end of said boom, load support means operatively connecting said jib and said chassis for maintaining a fixed angular relationship between said jib and the horizontal throughout all vertically pivoted positions of said boom with respect to said chassis and means applying a downward stress to said free end of said jib in the unloaded condition of said jib throughout all vertically pivoted positions of said boom with respect to said chassis comprising first and second members including quadrant portions having congruent peripheries, said members being mounted, respectively, on said chassis and said jib, with said peripheral portions concentrically located with respect to said first and second axes, respectively, and flexible guy means tangentially engaging said peripheries throughout all vertically pivoted positions of said boom with respect to said chassis.

3. In a crane rigging device having a main boom and a supporting base chassis upon which said boom is pivoted for retraction and reach, a beam jib pivoted at one end on a horizontal axis adjacent the upper terminal end of said boom and having a free end spaced from said boom and jib support and control means including guying means for articulating said jib to maintain the jib automatically in fixed angular relation to the horizontal in all angular relations of the boom and chassis, the combination of prestressing means for said jib comprising first and second congruent quadrant members mounted, respectively, on said jib and said chassis, a flexible guy member tangentially engaging the peripheries of said first and second quadrant members and having its upper and lower end portions operably connected, respectively, with said jib and chassis, said guy member being tensioned to urge said free end of said jib downwardly.

4. A crane device comprising a base chassis, a main boom mounted on said chassis for pivotal movement about a first horizontal axis, a beam jib having a free end and an end mounted adjacent the upper terminal end of said boom for pivotal movement about a second horizontal axis, jib support and control means for articulating said jib about said second axis responsive to vertical pivotal movement of said main boom with respect to said chassis to maintain said jib automatically in fixed angular relation to the horizontal, and means stressing said free end of said jib downwardly comprising first and second congruent quadrant members mounted, respectively, on said jib and chassis, said quadrant members being disposed concentrically with respect to said first and second horizontal axes, respectively, and flexible guy means under tension and having its opposite ends operably connected to said jib and chassis and tangentially engaging an undersurface of both said quadrants in all adjusted positions of said boom about said first axis.

5. A crane device comprising a main boom mounted on a support to be pivotal about a first horizontal axis, a jib having a free end and an end mounted to said main boom to be pivotal about a second horizontal axis, means for automatically articulating said jib with respect to said boom as said boom pivots about said first axis to maintain said jib at a fixed angle with respect to the horizontal, and means for prestressing said free end of said jib downwardly in all articulated positions of said jib with respect to said boom, comprising first and second take-up means having downwardly directed, generally circular portions operably connected, respectively, to said support and said jib, flexible guy means connected between said take-up means and tangentially engaging said circular portions, the distance between the points of said guy means engaged with said circular portions being substantially constant in all positions of said jib and boom.

6. A device in accordance with claim 5 and including means for varying the tension in said guy.

No references cited,

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