US2205325A - Clamshell bucket - Google Patents

Description

June 18, 1940- w. M. VENABLE 2,205,325

cLAusHELL BUCKET Filed Aug. 1s. 1'939 s sheets-sheet 1 fig. 1

INVENTOR June 33,1940- w. M. VENABLE CLAMSHELL BUCKET I5 Sheets-Sheet 2 Filed Aug.' 18, 1959 MIM June 1a 1940. w.-M. VENABLE 2205,325

cLAlsnELL BUCKETl EiledAug. 1s, 1939 s sheets-sheet s INVENTOR Patented June 18, 1940 A UNITED STATES PATENT OFFECE` GLAMSHELL BUCKET Application August 18,

3 Claims.

This invention relates to clamshell hoisting buckets and, particularly, to buckets of large capacity, i. e., several tons.

Various types of clamshell buckets have been known heretofore, among them a bucket of such construction that the cooperating scoops thereof are actuated in such manner that their initial closing movement causes tilting of the scoops so that on further closing, the scoops execute a shoveling action as contrasted to the scraping action effected by scoops of the construction usually employed in buckets of small capacity. Brown Patent 802,133 discloses one form of bucket so constructed that its scoops perform a digging rather than a scraping movement. The construction disclosed in this patent, however, in common with all other buckets of similar construction with which I am familiar, has a serious disadvantage in that the guide mechanism employed to center the scoop hinges extends below the lower extremity of the movement of such hinges and is thereby subjected to impact as the bucket is dropped on a pile of material to be hoisted. yThis condition vhas been the source of 25 much trouble and expense in the maintenance of large capacity buckets.

I have invented a novel construction of clamshell bucket wliich overcomes the aforementioned objection to bucket constructions previously known and provides a structure which is much simpler and less expensive than those employed heretofore. In the preferred embodiment of the invention, I provide a supporting frame or shroud to which a pair of cooperating scoops are pivotally connected by links. The scoops have arms or hinge plates pivoted to a closing sheave block. Inside the shroud are centering guides for the closing sheave block. The guides terminate short of the lowermost position of the block and are thus protected from contact with the material being handled at all times.

The pivotal axes of the scoops and their sup-- porting links are so disposed that on the 'initial closing movement, the scoops move rapidly from a substantially vertical position to a position inl 1939, Serial N0. 290,807

(Cl. 37-188) I the scoops in approximately central position,v although permitting departures therefrom in either direction to a limited extent.

Further details of the construction and the advantages thereof will become apparent during the 5 course of the following description which refers to the accompanying drawings illustrating a Apresent preferred embodiment. In the drawings,

Fig. 1 is a side elevation, partly broken away and partly in section;

Fig.- 2 is a side elevation showing successive positions of the scoops and related parts during the closing operation; and

Fig. 3 is an end elevation, partly broken away and partly in section. 1

Referring now in detail to the drawings, the bucket of my invention comprises generally a supporting superstructure in the form of `a shroud or fram-e I and cooperating scoops II and I2 secured thereto by links I3 and I4. The frame -20 or shroud I0 is preferably a fabricated plate structure including side plates I5 and end plates I6 riveted or otherwise suitably secured together. Stiiening' channels II extend along the lower edges of the side plates I5 and cross braces I8 25 are secured to the inner surfaces of the end walls I6 to give the shroud rigidity transversely.

A head casting I9 is mounted on top of the shroud and is provided with anchorages for holding lines 2| and rollers 22 forguiding the 30 ends of closing lines 23 which are taken into eect a closing operation of the bucket. The other ends of the closing lines indicated at `23a are secured to dead ends on the crane by which the bucket is lifted. 35

A head block 24 is secured in the upper portion of the frame I0 and is provided with sheaves 25.' The structure of the head block is not illustrated in great detail since the present invention does not concern it particularly and various de- 40 signs of head blocks are already known. y

The closing lines 23 are effecting to raise o lower a closing sheave block 26 in which sheaves 2l are journaled. The reeving of the closing cables may be traced by starting at the ends 23. Commencing at the head casting I9, the lines 23 extend downwardly around one of the two middle sheaves 21, thence upwardly around one ofthe two middle sheaves 25, which are disposed at an angle so as to guide the cable downwardly in alin-ement with the second sheave from the outside of the lower block. After passing around this sheave, the cable then passes around the outside sheave 25 and thence'around the outside sheave 55 21, and thence, as the xed closing line 23a, to a dead end on the crane.

The scoops I I and I2 have arms or hinge plates 28 extending inwardly and upwardly from each side thereof. Castings 29 secured to the plates -28 provide trunnions cooperating with hinge with stops 33 on the sheave block 1% to limitA angular movement of the scoops. The extreme widespread position of the scoops is shown in Fig. 2 in chain lines.

Guide rollers 34 are journaled on shafts 35 projecting from opposite ends of the sheave block 26. Centering guides 36 extend downwardly inside the frame or shroud I6 along op posite side plates. These guides are in the form of channels with their lower ends flaring downwardly as at 31. They are formed by plates SEB welded edgewise in spaced relation to the side plates I5. It `will be noted that these plates terminate at the lower flange of the channels Il. The centering guides 36 cooperate with the rollers 34 to centralize the sheave block 26 relative to the frame I6 as it is drawn upwardly scoops.

therein to effect a closing `operation of the Bent bars 39 are welded to the sheave block 26 in overhanging relation to the rollers 34 to act as a guardy for the latter to preserve them from shock or impact when the bucket is opened.

The links vI3 and I4 may be castings but inthe l 46 embodiment shown are fabricated from pieces of plate, one link being pivoted to each corner of the shroud or frame as at 46 and to one of the rear upper corners of the adjacent scoop as at 4I.` The links pivoted to each scoop are connected by angle bars 42 and a web plate 43. This framework connecting the links pivoted to the same scoop givesy the whole structure great stiffness laterally.

The links I3 and I4 have portions 44 extending inwardly and upwardly relative to the shroud. Cross channels 45 extend between the stii'ening channels I1. Stop plates 4S are Welded between the channels 45 and Il in the `path of the ends of the portions 44 so.as to limit angular movement of the links i3 and I4. Thefcooperation between the upper projections on the links and the stop plates 46 `is clearly shown in Fig. 2.

The operation of the bucket of my invention will now be explained with. particular reference to Fig. 2. It will be assumed in the rst place that the parts occupy the positions shown in chain lines, the scoops being at their extreme outspread position and the sheave block 26 being at thelower extremity of its path, the bucket being suspended on the holding lines 2l and the closinglines 23 being slack. Under these conditions, the ends of the projections 44 are spaced slightly from the stop plates 46 and the rollers 34 are clear of the guides 36 so that the scoops and the sheave' block may move laterally to a limited extent relative to the shroud I0 when the bucket is set down and the holding lines slackened so that the weight is all supported on the lips of the scoops. The extent of this lateral movement, of course, is limited by the engagement of the ends of the projections 44 with the material.

plates 46 on either side. If the lips are set down on a level surface the direction of this lateral movement is a matter of chance, but if set down on a slope the head will move toward the lower bucket lip, until engagement of stops 44 and 46 on the opposite side prevents further movement.

Assuming that the bucket has been deposited with its scoops widespread, upon a pile of material, the closing linesl 23 are taken in when it is desired to close the bucket to lift a load of the No matter to which side the head structure has moved until restrained by the stops 45, the bringing of the lower block and the upper block closer together will bring the lower block guide sheave 34 and the guide 36 into better alignment, until the alignment is practically perfect when centers of pins 4I and 36 are all in the same plane and the pins 4l at their maximum distance apart. In this position, the stops 44 and 46 almost engage on both sides of the bucket, only sufficient clearance being allowed to prevent binding.' The full lines in Fig. 2 show the parts in the position occupied when the pins 36 are a little above the plane dened by pins 4I. There is then a slightly greater clearance between the stops on one side or the other. v

In the fully open position indicated for the scoops by broken lines in Fig. 2, the axis of the pins 36 is below the axis of the pins 4I. As the block is raised, the pins 4I first spread, until they reach their maximum spread, and thereafter come closer together, the iinal position as shown ,A in Fig. 1 being considerably closer than in the stride the roller 34 when the stops 44 on both sides are nearly in alignment. This, however, would necessitate lengthening the guide, and bringing its bottom nearer to the material to be handled, and for that reason the guide is preferably flared, instead of lengthened.

It will be apparent that the structure of .my invention provides centering guides for the closing block which ,are effective during the upper portion of the path traversed by the block, to-

gether with means (the projections 44 and stop i plates 46) for maintaining the block approximately centered relative to the frame lll after the moving block has passed beyond the lower ends of the centering guides. When the scoops are in their extreme widespread position, furthermore, they are free to move oli center to a limited extent. Such movement is not great enough to be any serious detriment to the operation ofthe bucket.

pile of material or has been swung from one side to the other as is necessary when unloading material from the hatches of a ship.

The principal advantage of the structure oi jiny invention is the simplicity of the construc- In fact, under some circunistances, it is a positive advantage. for example, lwhen the bucket has been lowered onto a sloping closing characteristics common to buckets havf ing link connections instead of corner bars pivoted to one another, without the disadvantages of other guide mechanisms hitherto used. My guide mechanism imposes no unfavorable restrictions upon the layout I may make the length of the links 13, and their inclination in the closed position shown in Fig. l, upon which the final closing power in part depends, Whatever is found desirable without introducing undesirable features in the guide mechanism. The scoops thus act eiectively in picking up material. There is no depending central portion, furthermore, as in the structures previously known which has to penetrate the material. Instead of keeping the closing block accurately fixed on the centerline throughout its movement, as in the buckets known previously, I simplify the structure by terminating the center guides above the lowermost position of the blocks and provide an additional means to maintain the block approximately in central position.

Although I have illustrated and described a preferred embodiment of the invention, it will be recognized that changes in the construction and arrangement disclosed may be made without departing from the spirit of the invention or the scope of the appended claims.

I claim:

l. In a clamshell bucket, a frame, links pivoted on opposite sides of said frame near the bottom thereof, a pair of scoops, said links being pivoted to said scoops, respectively, a closing block adapted to be raised from below said frame to within said frame, said scoops having arms pivoted to said block, a guide member on said block, guide means Within said frame for guiding said block guide member as -the block is raised within the frame, and cooperating stop means on said frame and links eiective to bring said block guide member into alignment with the frame guide when the pivots connecting the scoops to the links are spread as far as the scoop arms will permit.

2. In a clamshell bucket, a frame, links pivoted to opposite sides of said frame near the bottom thereof, a pair of scoops, each link being pivoted to one of said scoops, a closing block, arms eX- tending from each scoop separately pivoted to said closing block, means for co-ordinating the rotation of said scoops about the blockA pivots, means for raising said block from positions entirely below said frame to positions within said frame thereby closing said scoop, a guide .member on said block, straight guide means within said frame, for keeping said block in alignment after entry, said straight guide means terminating above the lowest position of said block, and flaring guide means below said straight guide means for facilitating initial alignment.

3. In a clamshell bucket, a frame, links pivoted lto opposite sides of said frame near the bottom thereof, each link being pivoted to one of a pair of scoops, a closing .block to which each scoopv vis separately pivoted, means for co-ordinating vthe rotation of said scoops about said block motion of said links with respect to said frame when said block is below the lower limit of said guide means.

WILLIAM MAYO VENABLE.

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