US2298788A - Head sheave block for clamshell bucket or the like - Google Patents

Description

Oct. 13,1942. v 1 E. 1.. HARRINGTON ,298 8 HEAD S HEAVE BLOCK FOR CLAMSHELL BUCKET 0R TEE LIKE Filed Sept. 10, 1941 3 Sheets-Sheet 1 Q INVENTOR l 0ct. 13, 1 942. HARRlNGTdN 2,298,788

HEAD "SHEAVE BLOCK FOR CLAMSHELL BUCKET OR THE LIKE Filed Sept. 10, 1941 3 Sheets-:Shet 2 INVENTOR Oct. 13, 1942. E L HARkm i'oN 2,293,738

' HEAD 'SHIAVE BLOCK FOR CLAMSHELL BUCKETiOR THE LIKE Filgd Sefit. 10, 1941 3 Sheets-Sheet 3 MQM Patented Oct. 13,1942;

nun SHEAVE aLocx FOR ommsnnu nncim'roa 'rna LIKE Edward L. Harrington, Pittsburgh, Pa, assignmto Blaw-Knox Company, Pittsburgh, Pa... a corporation of New Jersey Application September 10, 1941. Serial No. 410,291 7 .4 Claims. (or 37-183) This invention relates to a sheave block and, in

particular, to 'a sheave block particularly suited for use as the head or upper block of a clamshell bucket or the like, although it is also useiul in other applications. I V

In clamshell buckets which are operated "in the bighto! the line"-that is to, say, buckets operated by two lines, 'one termed a closing line and one termed a holding line,- both of the lines being reeved entirely through the bucket and' their ends carried to an overhead supporting structure through which the hoist power is apporting a sheave pin or axle. I mount the central or holding sheave fixedly on the pin and journal the outer or closing sheaves on the pin applied to the central or holding sheave without.

plied, it is usual in certain types of buckets to have a single sheave for the hold'line mounted between twoor more sheaves which are used to draw the bucket head towardsthe closing block which is mounted in some articulated portion of the bucket below. Where this is the case; the

' leads of the ropes into the bucket must be such as to co-operate with the sheaves in the hoist-ing 'mechanism from which the bucket is suspended.

Clamshell buckets are frequently operated from I a trolley of a traveling bridge crane, and in such installations it is important that the cable leads from the bucket run vertically, or substantially so, to the hoisting mechanism. It frequently happens that the spacing between the cabl leads at the trolley is relatively close. This has led to attempts to improve the construction of sheave blocks in order to obtain corresponding close spacing of the cable leads at the bucket. Venable Patent No. 1,880,608 shows one form of block which has 'been satisfactorily employed bothas an upper block and as a lower block. I In the case of the buckets of the larger capacities, furthermore, another problem i encountered, viz., the limited bearing area of the sheaves on the usual sheave pin or axle which results from the aforementioned eiforts to keep the. cable runs close together by making the sheaves of the minimum thickness axially. In

order to solve this difli'culty, several expedients. have been proposed, such asjmounting thecentral or holding sheavecf the head block on a level above that of the outer or closing sheaves,'

but this is very objectionable as it makes the bucket height greater and thus sacrifices headroom available beneath an overhead crane.

I have invented a novel form of sheave block particularly suited for use as a head block in'.

clamshell buckets, which overcomes the difiiculties outlined above in a simpl and highly effective manner. In a preferred embodiment of the invention, I provide a sheave block composed of spaced hanger brackets having bearings for supthereto.

for rotation relative thereto. I thus provide ample bearing area on the pin to sustain the load reducing the area. available for sustaining the loads appliedto the pin through the closing sheaves.

According to a further feature of the invention, my block is mounted as a unit in tlie head frame of a bucket or the like and is secured therein by removable means whereby it may be easily installed or removed. Inaddition, the sheaves are disposed in planes making an angle less than with the axes on which th bucket arms are pivoted. This further assists in bringing the cable.

leads from the bucket close together so they may extend vertically to the hoisting mechanism on the trolley.

The invention may b more fully understood from the following detailed description and explanation referring to the accompanying drawings illustrating th preferred embodiment. In the drawings,

Fig. 1 is a view partly in plan and partly in horizontal section through the frame of a ,clamshell bucket having the sheave block of my invention mounted therein with parts broken away;

Fig. 2 is a side elevation with the bucket arms and other parts omitted; line I--I of Fig. 2 illus-, trates th plane of the section shown in Fig. 1;

Fig. 3 is a partial transverse section taken along the plane of line III-III 0! Fig. 1; and

Figs. 4 and bare partial sections taken along the planes of lines IV-IV and V--V of Fig. 3.

Referring now in detail to the drawings, a head frame I0 for a clamshell bucket is composed of side channel II and cross channels I! welded The webs of the channels II are extended adjacent the ends thereof to receive bearing sleeves I3 welded thereto. Cross shafts M are journaled in bearing bushings l5 seated in the sleeves l3 and bucket arms l6 are pivoted on the projecting ends of the shafts H. The present invention is not concerned with the particular style of the bucket arms nor their mounting on the head frame. It so happens, however, that in the illustrated embodiment the bucket arms l6 have inwardly projecting portions I! with meshing toothed segments l8 thereon to maintain the proper alignment of the head block and the lower block. The outwardly and downwardly projectofi'in Fig. 1.

The head frame I6 includes also a deck plate l9 welded to the webs of the channels II and I2, and having suitable openings therethroughfor the passage of cables arranged in a manner to be described later. Plates 26, 2| and 2| extend across the deck plate I9 and are provided with bearing sleeves 22 in which are journaled longitudinal guide rollers 23 and transverse guide rollers 24.

Hangers 25 are disposed near the sides of the head frame I6, each hanger including a generally .longitudinal plate 26 and generally transverse plates 21 and 28 welded to each other and to the channels H and I2. The plates 21 and 28 have portions or lugs depending below the bottom flanges of the channels Ill and i2, with aligned holestherethrough for a purpose which will .appear shortly. The plate 26 are not perpendicular to the channels l2 but make an angle of more than 45 therewith, and the plates 21 and'28 are similarly disposed relative to the channels H.

Referring now more particularly to Figs. 3 through 5, a sheave block indicated generally at 39 comprises a pair of spaced plates or hearing brackets 3| and 32 secured in parallel relation by 4 bolts 33 having spacer sleeves 34 thereon between the plates. Bearing sleeves 35 are suitably secured in aligned openings inthe plates 3| and 32 and are provided with anti-friction bearings 36. A sheave pin or axle 31 is journaled in the bearings 36.

The pin 31 has a substantially central enlargement or shoulder 38. A central sheave 39 comprises a hub 40 secured to the shoulder 38 as by welding, and a rim or peripheral portion 4| detachably secured to a flange on the hub by bolts 42. The sheave 39 is rotatable with the pin 31 and the latter turns in its bearings 36 on rotation of the sheave. As illustrated, the hub 46 has a relatively small axial thickness. This is permissible since the sheave .39 does not turn on the pin 31 and there is no need for an extended bearing area.-

Outer sheaves 43 and 44 are journaled onthe pin 31 between the sheave 39 and the bearings 36. The sheaves 43 and 44 turn on the pin 31 by virtue of anti-friction bearings 45. These bearings extend partly within the planes of the lateral arially than the hub 40. A guard plate 46 secured to the lower pair of bolts 33 extends'around the lower half of the periphery of the sheave 39 and prevents a cable trained" around the sheave from leaving the score thereof. A. guard plate 41 similarly extends around the upper halves of the sheaves 39, 43 and 44 to prevent cables trained around the sheaves 43 and 44 from leaving the score thereof. The guard plate 41 is cut out as at 48 to clear upwardly extending runs of a cable trained around the central sheave.

The brackets 3| and 32 have ears 49 extending laterally therefrom having aligned holes therethrough. The sheave block may be inserted as a unit in the frame I6 and supported therein by pins 56 passing through the holes in the ears 49 and the holes in the depending portions of the hanger plates 21 and 28, with which they are in alignment. Both the earsand the hanger plates have bearing sleeves 5| welded in suitable holes therein to provide increased bearing area for the pins 56:

Having described a preferred embodiment, the operation thereof in connection with one form of clamshell bucket will be explained. In addition to the head frame In and the sheave block 36 mounted therein, the usual clamshell bucket application requires the use of a lower block, for example, that shown in Venable Patent No.

1,880,608, secured to an articulated joint connecting the bucket halves. A holding line 52 is trained around the central sheave 39 of the upper block from a hoisting drum, for example, to a fixed anchorage on the crane trolley. The closing line 53 extends downwardly from a hoisting drum or the like between pairs of adjacent guide rolls 23 and 24 and through a guide 541: secured to the bracket 3| directly around one of the outer sheaves of the lower block, thence around outer headblock sheave 43, the central sheave of the lower block, headblock sheave 44, the other outer sheave on the lower block, and thence upwardly through guide 54b and the guide rollers to the trolley. The bucket is operated in the usual manner, i. e., it is closed by taking in the closing line, after which the bucket may be hoisted by taking in both the holding and closing lines, and is dumped by paying out the closing -tion and explanation that the invention is charllne while securing the holding line.

It will be apparent from the foregoing descripacterized by important advantages over conventional sheave blocks for use in clamshell buckets or the like. The center sheave of the block does not turn on the sheave pin so that it requires no extended bearing area thereon. Its hub, therefore, may have an axial thickness much less than that of the outer sheaves. Ample bearing area for supporting the pin is provided by the bearing sleeves carried in the brackets 3| and 32. This leaves ample bearing area for the outer sheaves between the center sheave and the pin bearings while maintaining a close spacing of the outer sheaves relative to the center sheave. As clearly shown in Figure 5, the bearings 45 for the outer sheaves 43 and 44 extend partly within the 7 planes defined by the lateral faces of the periph- ,ery of the-center sheave39. This in turn permits the sheavesof the lower block to be positioned close together whereby the cable leads therefrom which extend directly to the hoisting mechanism are closely spaced. The close spacing of the sheaves permits a shorter and smaller axle or sheave pin to be used than would otherwisebe required, and this reduces the size and cost of the bearings therefor.

The invention thus provides a. compact block construction which is particularly advantageous for use with crane trolleys in which the incoming cable leads are close together. By virtue of the novel construction described, the cable leads between the block and hoist mechanism are substantially vertical so there is little or no tendency for the bucket to twist about its vertical axis when the load is transferred from the closing cable to the holding cable, or vice versa.

A further advantage of the invention is the possibility of removing the block as a unit from the head frame of the bucket. It is not necessary,

furthermore, to disturb the guide rollers when

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