US2924484A

US2924484A - Drum grabs

Info

Publication number: US2924484A
Application number: US498887A
Authority: US
Inventors: William A Tolsma
Original assignee: Individual
Current assignee: Individual
Priority date: 1955-04-04
Filing date: 1955-04-04
Publication date: 1960-02-09
Anticipated expiration: 1977-02-09

Description

W. A. TOLSMA Feb. 9, 1960 DRUM GRABS 4 Sheets-Sheet 1 Filed April 4, 1955 INVENTOR. WILL/AM TOLS'MA AffOE/VE V5 W. A. TOLSMA DRUM GRABS Feb. 9, 1960 4 Sheets-Sheet 2 Filed April 4, 1955 Feb. 9, 1960 w, o s 2,924,484

DRUM GRABS Filed April 4, 1955 j 4 Sheets-Sheet s V EN TOR.

70L SMA ur a Feb. 9, 1960 w. A. TOLSMA I DRUM GRABS 4 Sheets-Sheet 4 Filed April 4, 1955 INVENTOR. W/LL/AM A. TOL5'MA United States Patent DRUM GRABS William A. Tolsma, Seattle, Wash.

Application April 4, 1955, Serial No. 498,887

4 Claims. (Cl. 294-87) The grab of the present invention is particularly adapted for gripping a plurality of drums of the type used for the shipment of oil, whether they are full or empty, in order that they may be hoisted.

A principal object of the invention is to provide such a drum grab which can be designed to grip simultaneously several drums to be hoisted, and which will hold such drums securely while suspended from a hoist. The grab may be applied quickly and easily to such drums in their normal storage disposition, namely in rows standing on end. To place the drums for engagement by the grab, therefore, minimum shifting of the drums will be required, such shifting being only that necessary to locate the drums in approximately the proper spaced relationship.

Another object is to provide such a drum grab in which while of rugged construction so that it will withstand rough usage, its parts and their arrangement are of relatively simple construction.

It is particularly an object to provide a grab which can be applied to grip several drums quickly and released from them just as quickly so as to expedite the handling of the drums as much as possible. In accomplishing this object the gripping operation is effected by operation of the hoist and the drums may be released automatically by the hoist operation as well.

Another object is to provide a drum grab which while designed to hoist a maximum number of drums simultaneously can be used equally well to hoist a fewer number of drums without requiring any special adjustment and without any risk of injuring or dropping such a partial load of drums.

Drum grab mechanism capable of accomplishing these objects may include a horizontal frame which may rest upon the upper ends of drums to be hoisted, which are arranged in a group. Preferably such drums are disposed in rows and the frame carries journals such as two shafts arranged in spaced, parallel relationship along opposite sides of the frame and drum group. These shafts constitute journals for upright rocker arms pivoted generally centrally between their ends and carrying drum engaging shoes on their lower ends. Above the frame is a hoisting beam which may be moved vertically relative to the frame to actuate toggle joint mechanism for swinging the rocker arms between drum clamping and drum released positions. If the drums to be hoisted are arranged in more than one row between the rocker arms, central gripping means also are provided which include one or more clusters of wedge-spread shoe carrying arms also actuated by movement of the hoisting beam relative to the frame. Fixed posts may also be interposed between the drum rows, depending from the frame to cooperate with the drum gripping rocker arms.

As an upward force is exerted on the hoisting beam, therefore, it will move the rocker arm shoes inward and the wedge-spread shoes outward to grip the drums of the group for hoisting the drums. Conversely, when the upward force is removed, the weight of the hoisting beam will cause it to move downward onto the frame supported by the drums, and such movement will efiect drum releasing swinging of the rocker arms and drum releasing contraction of the wedge-spread shoes, so that the drums will be released. The hoisting beam may be latched in its lowered position to hold the grab in drum-released condition so that it may be lifted off the drum group by again applying an upward force on the grab hoisting beam. When the grab has been lowered onto another group of drums, the latch may be released voluntarily to enable the drums of such group to be clamped and lifted by elevation of the grab.

Figure 1 is a top perspective view of the grab with the parts in drum clamping position, but with the drums shown in phantom.

Figure 2 is a similar view of the grab but showing the parts in drum-released position and portions of the grab being broken away.

Figure 3 is an enlarged, fragmentary top perspective view of an end portion of the grab.

Figure 4 is a fragmentary end elevation view of a portion of the grab on an enlarged scale with portions broken away.

Figure 5 is a horizontal sectional view through a portion of the grab, taken on line 5-5 of Figure 7 and showing drums in phantom.

Figure 6 is a vertical, longitudinal sectional view through one end portion of the grab with portions broken away and showing the parts in drum released position.

Figure 7 is a similar view with the parts in drum clamping position.

The various components of the grab are supported from a frame preferably of box girder construction. The length and breadth of this frame extend horizontally coextensive with the group of drums to be engaged by the grab. The particular form of grab illustrated in the drawings is designed to hoist six drums arranged into two side-by-side rows each including three drums. This grab could, however, hoist any fewer number of drums, and the same principles as utilized in the present grab can be applied to a grab designed to hoist a greater or smaller maximum number of drums. It will be understood, therefore, that the particular grab shown in the drawings and described in detail hereafter is merely exemplary.

The frame of the grab shown in the drawings includes a backbone girder 1 of nominal I-beam section, having a lower flange increased effectively in width by the addition of the plate 10. This plate may be integrated with fabricated wings 11 of short, cantilever box girder construction extending horizontally oppositely from the opposite sides of the backbone 1. The upper and lower plates of these box girders may have lightening holes 12 in them to reduce their weight. These wings project from the backbone 1 at locations respectively corresponding to the locations of the several drums of the group of maximum size to' be hoisted by the grab.

On the opposite sides of the frame defined by the aligned tips of the wings 11 are mounted parallel shafts 13 which are suitably secured to the tips of the wings 11. Such shafts may, for example, be received in sleeves 14 welded to the edges of the upper and lower webs of the box girder wings 11. Such sleeves will be of a length equal to the width of the wings 11 respectively and the ends of adjacent sleeves and the adjacent sides of adjacent wings 11 will be spaced apart far enough to receive between them rocker arms 2. Approximately midway between their' ends these rocker arms carry sleeves 15 preferably of the same size as the sleeves 14 and having a close bearing fit on the shafts 13.

As far as functioning of the grab is concerned, it is immaterial whether the sleeves 15 move relative to the shaft 13 extending through them or the shaft 13 moves within the fixed sleeves 14. Whichever construction is used, arms 2 can rock about the axis of their shaft 13. The lower ends of these rocker arms carry shoes 20 spaced below the pivotaxisabout which the arms rock'sufiicientlyfarso that the Sl'lOBSg-Wlll engage thedrums at. about midwaybetween their. upper and lower ends. Preferably these shoes are concave to a degree approximating, the curvature .of a drum, and such concave surface may befacedwith friction material. Also the shoes preferably are mounted pivotally onT the arms for slight angular. adjustmentso as. to engagethe sides of the drums contiguously.

In orderto grip the group of drums ,allthe arr ns 2 should berocked simultaneously. To-move. toward each other the sets. of shoes; carried by the arms. swingable;

about the axes of the opposite shafts-,1 3 -,it;is necessary to swing: aw y m a hot r: heupp r adss he etsfof. oc ms. u h vv g n au: a-,-ct c cos viently by toggle joint mechanism interppsed etween; the

ends of, the arms of. the; twosets, Mprepverlsuch arm mov m nt a e t d.ta1 matica r y. ni ati n the hoisting operation when mechanism: o f-;the-.type shown in the drawings is employed, Swinging of the drum clamping arms 2 is. eifecteiby-inovement upward; away from the grab frame fahQiSting-beam 21. extending parallel to the shafts;13 -and,disposed,substantially midway between them.

Thehoisting beam 21; is guided forqvertical movement relative to the backbone beaml by. guide rods-.22 spaced lengthwise of the backbone andhoishbeams. Downward movement of the hoisting beamjwilhof course-,be limited automatically byengagement, with: the backboneof the frame. Upward movement of thehoist. beam is. limited by nuts 23 on the upper ends of. rods 22, and these nuts 'may be adjusted to establish the desired range of moven ment of thehoist beam relative to the frame- The hoist beam 21 itself may be lifted relative to the frame by a hoisting cablebride 24.=secured to.locations on the hoist beam spaced lengthwise-of. it and at locations arranged symmetrically about its center. Alternatively such hoist beam could be lifted by the fork of a fork lift truck or in any other suitable way. Such. upwardforce on the hoist beam will be transmitted through therods 22 and nuts 23 to hoist the grab frame.

Upward movement of the hoist beam.21 relative-to the grab frame 1, 11 .prior to engagement of the hoist beam with the nuts 23 effectsv straightening movement of the toggle joint mechanism composed of links 25 each having one endpivoted to the hoist beam 21 and its other end pivoted: either directly to a rocker arm 2'or, as preferred, to a yoke bar 26: interconnectingadjacent rocker arms. The ends. of the links25; pivoted totherocker arms or to the, yokes 26 interconnecting them cannot be raised appreciably relative to the frame 1, 11, but raising of the ends of such links relative tothe frame 1, 11 which are pivoted to, the hoisting beam 21 will, move the opposite. links 25 toward alignment and consequently will force the upper ends of the levers 2 in the opposite sets away from eachzother, which will effect movement of the lower ends of the armsinthe twosets and their shoes 20 toward each other intov drumgripping positions.

If theframe 1, 11 were of a width only corresponding to the diameter ofa drum to be hoisted, movement of thetwo sets of shoes 20 toward each other would effect gripping of a single row of drumsQwhich could beof any reasonable length, dependingupon-the length of the frame and of the hoisting beam. Itis preferred, however, that the grab straddle two rows of drums, and consequently it is preferred that drum engaging shoes be provided at the center=vertical plane of the-grab-between the two shafts 1-3. While such additional shoes orother drum engaging members couldbe stationary, it is preferred that they be movable between drumgripping and drum released-positrons.

The central drum engaging members-conveniently can be supported in position depending from the wide'flange- '4 plate applied to the lower surface of the backbone beam 1. A plate wider than the flanges of the beam 1 affords a better support for drum engaging elements depending from it. Such elements may include the two posts 3 depending from the opposite ends of the plate 10 be neath the backbone beam. These posts are of semicylindrical cross section for the most part, but, as shown best in Figures 6 and 7, each includesone-half of a frustoconical surface at its 1ower. endwhich, upon engagement with the upper endofa drum, will guide lateralshifting of the grab during its lowering movement so that the frame 1, 11 Will descend into-properposition for. therocker arms to straddle the group of drums.

Between the end-posts 3-depending-from the backbone are intermediate posts 31 having their axes spaced lengthwise of the backbone distances generally corresponding to the spacing between the axes of the drums in a row, but staggered relative to the locations of, th e,drum axes. These posts have frustoc on'ical lower ends .3. ,,.wh ich cooperate t h .w iaa ur es. Btbqf he ne ts; 1 locate h grab frame relative ,to the group of drums as the frame is lowered onto such; group. Whileihe ,sizeof theposts 3 and 31 could beselected so that thedrum peripheries would .engag e.them directly as the lowerends of the rocker arms 2,are swung toward' each other at oppositesidesof the framel, 11, itis preferred that at least the posts other than the end posts be equipped with movable drum engagingshoes so as to enhance the grip on the drumswithout requiring that the drums inthe group 'beshifted appreciably relative to eachother duringzengagement of the grab with them.

While the rocker arms 2 at the ends of the frame 1, 11 carry only a single drum engaging shoe, theintermediate rocker arms are loeated in positions registering generally with the spaces, between-adjacent. drums. Consequently, each of the intermediate armscarriestwodrum engaging shoes disposed angularly relative to each.other, as shown best in Figure 2. Similarly,; the. posts 31 carry shoes 33 arranged. to engagethesides of more than one drum, the axis of each post 31 being, in a plane perpendicular to the backbonebeam 1 which includestwo opposite-rocker arms 2. Becausethese posts are located between the rows of drums, each intermidiate-p.ost.has,four. shoes. 33 engageab le respectively with four drumsarranged around the post.

To avoid. slidingthe postsorshoes downward, in con tact with four, drums, while-Vat, the. same tirneavoiding the necessity ofshiftingjhe. drumstpwardsuch posts during the drum engaging actuation of the grab, four-movable shoes 33; areuutilizeda in. conjunction with chanism to effect. simultaneous.spreading. moyen ent of. ,alhfour shoes. To. avoid the possibility. ofdtrnagingdhe shoes associated with the posts. $1,.ttzhilethegrabds beinglowered onto a groupof drums, i t -is d esirablethatsuch shoesberetractable inwardly ofthe. surfaee oftheinPQSts so that the. shoes will not constitute. projections from the posts while the, isbeing lowered into; place.

Preferably. the shoes 33, as s hg wn best, in Figures 6 and: 7, are supported on arms ,.'.a 4 respectively, the upper ends of. which are pivotally supportedfor swinging of their lower ends in radial planes of the cylindrical; posts 31. Suchswinging of armsfid may, be utilized-"to, elfect retraction. of the shoes 35 within the hollow posts, asshown in Figure 6, while the grab is being lowered, :onto a group; of drums,

When the, grab has been lowered into aposition such that the. frame 1, 11 rests on theuppcr ends of the drums, the arms, S tmay. be swung. to project the concave. shoes 35 through-windows 35in the sides of thehollow posts 31 and into engagement withthe respective walls of the-drums arranged around; each post. Becausethe: drums will be located quite-close together; if. not: actually in engagement, and the posts 31 will be selected: so as to be ,of a sizeto fit closely betweenthe drums, the shoes 33. can be engaged with the drum wallsby small. radial movement such-as 5 from the positions shown in Figure 6 to those shown in Figure 7.

As has been discussed previously, the arms 2 are rocked into drum gripping engagement by upward movement of the hoist beam 21 relative to the frame 1, 11 during initiation of a hoisting operation. The shoes 33 should be moved outward from their posts 31 at the same time, and consequently it is desirable for such movement of shoes 33 also to be effected by raising of the hoist beam 21 relative to the frame. The mechanism shown in Figures 5, 6 and 7 is capable of accomplishing such movement of the shoes.

The actuating mechanism for spreading the shoes 33 is of the wedging type and includes the plunger rod 36 extending axially through the post 31 and adjustably secured to the hoist beam 21 by a long thread and lock nuts engageable with the upper and lower flanges of the beam, as shown in Figure 6 and Figure 7. The lower end of this plunger rod carries the wedging head 37 having a frusto-conical wedging portion engageable with inclined cam' surfaces 38 on the adjacent edges of the shoe carrying arms 34.

As the wedging plunger is raised, therefore, by upward movement of the hoist beam 21, engagement of the frusto-conical surface 37 with the inclined wedging surfaces 38 of the arms 34 will swing the shoe carrying ends of such arms outward about the arm supporting pivots 39 to project the shoes through their respective windows 35. Engagement of the wedging surfaces 38 of the arms with the conical wedging plunger surface 37 will be maintained by springs 4 encircling guide rods 4% which are reciprocable through the backbone beam 1 in paths parallel to the path of movement of the wedging plunger 36 relative to the beam 1. Downward movement of rods 40 by the force ofsprings 4 will be limited by engagement of a nut 41 on each of the rods with a flange of the backbone beam 1. The lower end of each rod 40 engages a toe 34' on the upper end of the arm 34 disposed eccentricallyof the pivot 39.

The pressure exerted by the rod 40 produced by the spring 4 on the toe 34 of each arm 34 will swing such arm in a direction to press the wedging surface 38 or shoe 33 toward the wedging plunger 36. The degree of spread ing action of the shoes 33 effected will depend upon the amount of separation of the wedging surfaces 38 of the arms 34. The degree of such separation, in turn, will be governed by the diameter of the portion of the wedging plunger engaged with a particular location on each arm wedging surface 38 at any selected time. For a given disposition of the arm support and contour of an arm, therefore, the amount which it is swung will depend upon the size and position of the wedging plungers conical portion 37. Consequently the degree of swing of arms 34 outward and consequently the projection of shoes 33 can be governed by the stroke of the wedging plunger. Such stroke may be adjusted by shifting the supported end of the plunger 36 relative to the hoist beam 21, or by altering the position of lock nuts 33 on guide rods 22 to vary the amount of vertical movement of the hoist beam relative to the frame backbone beam 1, or by altering both adjustments. Consequently, by proper relative adjustment of these two adjustable elements, the timing and degree of spreading movement of the shoes 33 can be coordinated accurately with the inward swinging of the shoes 20 carried by rocker arms 2. g

It will be evident that by utilization of the mechanism described upward movement of the hoist beam 21 relative to the backbone beam 1 by exerting an upward force on the bridle 24 will simultaneously effect projection of shoes 33 from posts 31 and inward swinging of shoes 20 effected by rocking of arms 2. By the time the hoist beam is engaged with the nuts 23, therefore, as shown in Figures 1 and 7, all the drums in the group, whether one or more, will be gripped securely by the shoes 29 and 33 and by the posts 3 to be lifted as a unit. More over, when the drums and grab are lowered and the upward force on the bridle 24 relieved, the hoist beam 21 because of its weight will move downward toward backbone beam 1 automatically to effect swinging of arms 2 for moving shoes 20 outward. Simultaneously the wedging surface 37 of each wedging plunger 36 will be lowered from engagement with the arm wedging surfaces 38 so that the springs 4 by movement of the rods 40 will swing the arms 34 to retract the shoes 33.

If a hoisting force should be applied again to the hoisting bridle 24, the grab again will grip the drums of the group, as described above, so that the grab could not be lifted free of such drums for application to drums of another group. To enable the grab to be raised from a group of drums without gripping them, latching mechanism is provided to restrain lifting of hoist beam 21 relative to the frame when an upward force is exerted upon such hoist beam. Such latching mechanism as shown in Figures 1, 2 and 3 includes a latch bar 5 extending upward from a pivot 50 mounting such latch bar on the frame, such as on one of the wing beams 11. This bar passes through apertures 51 and 52 in the lower and upper flanges, respectively, of the hoist beam 21.

One edge of the bar 5 has a latching book 53 formed in it, which is engageable with the upper side of the hoist beam 21. When the hook is thus engaged, as shown in Figures 2 and 3, the latch bar acts as a tie member preventing upward movement of the hoist beam relative to the frame 1, 11. The latch bar 5 will normally be held resiliently in this latched position by a spring cartridge 54 anchored to the frame and urging arm 55' carried by shaft 56 in a clockwise direction as shown in Figure 3. The torque thus exerted on such shaft tends to swing arm 57, which is also fixed on such shaft in a clockwise direction. The force is transmitted through links 58 interconnecting arm 57 and latch bar 5 so as to urge the latch bar itself to swing clockwise for maintaining its hook 53 in engagement with the surface of hoist bar 21 at the margin of slot 52.

As long as the latch bar 5 is thus engaged with the hoist beam 21, such hoist beam can move only a small amount relative to the frame 1, 11, which is insuflicient to actuate the toggle joint links 25 enough to swing the arms 2 into drum clamping position. When it is desired to pick up a group of drums with the grab, therefore, it is necessary to release the latch mechanism by withdrawing the latch bar hook 53 from engagement with the margin of slot 52, so that such slot will pass over the hook as the hoist beam 21 is raised relative to the frame 1, 11. The hook may be withdrawn from its latched position by swinging latch bar 5 in the counterclockwise direction, as seen in Figure 3, and such movement may be effected by rotation of shaft 56 to swing arm 57 in a counterclockwise direction, which will cause links 58 to pull the latch bar 5 to the left as it appears in Figure 3.

Shafts 56 may be rotated in a counterclockwise direction for the purpose of releasing the latch by exerting a pull to the left on the upper end of arm 55 which is attached to such shaft. This pull opposing the force of compression spring cartridge 54 may be effected by the latch releasing bar 6 pivoted to the upper end of arm 55 and connected by pivot 60 to the latch releasing lever 61 which is mounted by pivot 62 on the frame, such as on a wing beam 11 at one end of the frame. The swinging end of this lever constitutes a handle 63 which may be grasped by the hand and pulled in the direction indicated by the arrow in Figure 3 to swing lever 61, arm 55, arm 57 and latch bar 5 all in the counterclockwise, latch-releasing direction.

When the latch mechanism has been released and the hoisting beam 21 has been lifted relative to the frame to move the

shoes

20 and 33 into drum clamping position, upward movement of the hoist beam relative to the frame 1, 11 will be limited by engagement of its upper side with nuts 23 on guide rods 22, as shown in Figures l and 7' and explained-previously. Latch bar, is of, a

length suchthat-its upper'end portion projects-upwardly.

above. notch 53 farcnough so that the. slot,52 .isneyer lifted beyond theuppenendmfthis latch bar. Figurel showsthat even With the .hoistgbeamin its limiting upper position, the upper endiof the,latch bar projects. asubstantial distance. above the hoist beam. It is therefore impossible forthe latch bartomoveout of. registry with slot 52, as long as the componentslof the. grab ,are m lifted relative .to theframel, U to a; Position such that its uppersideis abovethe latch barhook 53, the latch cannot bereengaged, The.side, .5 9 of thelatch barwill, however, be,held;against:thecorrespondingfend of slot 52 y the 9 ce fspr s. o hat eni lqade rab has been lowered and the lifting force. isfurther reduced to allow hoist,beam 2 1 tohe moved downward by gravity, if unrestrained, for opening the drum. engaging shoes, such hoist beam will be lowered. to a position. such that its upper surface descends below hook 53,0 f the latch a reuponl p n 54 wi ve .thrpu h rm 55 and 57, to swing thelatch bar into latching ;pos ition again. Thelatch bar will then remainin such latched condition untilthe latchisrcleased by pulling thelatchreleasing lever handle 63 as describedabove.

It may be preferable for a load ofdrums; not to be releasedfrom the grab automatically by free downward movement of the hoist beam 21 when the loaded grab is dropped. Friction holding or Snubbingmechanism may beprovided to restrain appreciable descent of the hoist beamrelative to the grab frame 1,11 until such mechanism is. released voluntarily. Such holding or snubbing mechanisnrrnay be a brake which reacts between elements carried respectively by the hoist beam and the frame.

Such a brake, shown best in Figures I, 2: and 4, may be releasedat will be a handle 7 which is secured to an oscillatable shaft 70 journaled in the wing beams- 11 at one side of the backbone beam 1 and extending substantiallythe fulllength of the. frame parallel to such backbone beam. The handle 7 has. abrake, actuating arm 71 projecting laterally from it toward the backbone beam 1, which. arm has in it a slot 72 extending radially of shaft 70 andreceiving in it a pin 73. This pin is secured in a brake shoe 74, which is disposed for frictional engagement with a. brake bar 75 secured to the hoist beam 2 1 by thepivot 76. This brake bar. passes downward through apertures in the upper and lower flanges of the backbone beam 1, into the hollow post 3, at one end of the frame.

Parallel links 77 disposed close together and swingable in a vertical plane are anchored to the frame atone end by supporting pivots 78. The opposite ends of these links are connectedby pivots 79 to the brake shoe 74 so as to maintain the right edge of the brake shoe as seen in Figure 4 always vertical, and consequentlypan allel to the adjacent surface of the brake bar75. As the brake, shoe is moved downward, the parallel links 77 will guide the brake. shoe for movement toward the brake bar 75, and, conversely, as the brake shoe is raised the links 77 will guide it for movement away from the brake bar.

As the hoist-beam21 is raised, drawing brake bar 75 upward, any contact between such brake bar and the brake shoe 74 will tend-to move such brake shoe upward so that the links 77 shiftthe brakeishoe away from brake bar 75- to. maintain the brake released automatically. As the. hoist beam 21 de cend ow r p hing, brakebar 75 downward, frictional engagement between such-brake bar and the.shoe -74 willtend-tomove such shoe downward, in which case parallel links 77 will tend o raw he rake. shoettowa drake. b 75 Q ncrea ing he fr ional si tancetasdcwn ard mo emen o ch.. a e. ar, and... h hoist beam which arri t- Ordinarily; the frictional; engagement exerted by brake barf75;,on the,, brake shoe 74 will not bev suflicient to prevent involuntary movement of the hoist beam downward to release-the grab. Consequently, it is preferredthat a continual; force pressing the brake shoe against the brake bar be provided.

As has been mentioned, the brake actuating arm 71 and the brake shoe 74 are interconnected by the slot 72 and pin 73. If the arm 71 isurged downward, as seen in Figurfislband 4, by the tendency of rod 70 to be rotated in a clockwise direction as seen in. these figures, the links 77 would press the brake shoe continually against thebrake bar 75. Rod 70 may be urged continuously inaclockwise direction; by the force of spring. cartridge 8, shown in EigureZ, interconnecting an arm on rod 70 and the frame. The torque thus sustained on the rod by tending to depress the brake shoe 74 will cause it by such pressure to increase the holding effect of the brake, andof even greater importance, will produce friction betwen the brake shoe and the brake bar, which will greatly increase the tendency of the brake bar to move the brake shoe down with it as a downward load is exerted on the brake bar by the hoist beam 21.

Because of the continued pressure of the br ake shoe againstthe brake bar, the tendency of suchbrake bar. to move downward will-produce an immediate snubbing action of the brake shoe on the brake bar, which will arrest downward movement of the hoist beam 21 after a very slight travel. Irrespective of the severity of the jolt on the hoist beam 21 which may be produced by the suddenness with which a load contacts the ground therefore, this brake snubbing mechanism will prevent; the grab from being released inadvertently from the load. By swinging the handle 7 to the left, as seen, in Figures 2 and 4, however, the force of spring cartridge 8 may readily be overcome, and the brake shoe 74 raised to release it from the brake bar 75. Thehoistbeam 21 will then slide down guide rods 22 toward the frame to swing arms 2 and move plungers 36 downward to release the drum load.

In order to afford a balanced snubbing. effect of the brake mechanism on the hoist beam, it is preferred that duplicate brakes be provided at opposite ends of such beam. While only a single brake release handle 7 need be provided, theshaft 70 which extends substantially the.

fulllength ofthe frame 1, 11 may carry arms 71- at its opposite ends. In addition, the brake bar 75, brake shoe 74, pin 73 and brake shoe guide linkage 77 will be duplicated at opposite ends of the hoist beam so that, by turning shaft 70, the arms 71 and brake shoes 74 at opposite ends of the hoist beam will be moved in synchronism either to exert a snubbing action on the brake bars 75 or to relieve the braking effect. For convenience, a brake release handle 7 may beprovided at each end of the shaft 70 if desired. A

I claim as my invention:

1. Drum-hoisting mechanism comprising, a horizontal frame, a first upright post depending from the central portion of-said frame, two parallel axle means carried by said frame at. opposite sides of said first post, respectively, a first pair of upright armsthe arms of;which pair are located, respectively, on oppositesides of and spaced equally from said firstpost and mounted on said axle means, respectively, for pivotal movementin a firstvertical plane generally normal to said parallel axle means and passing through said firstpost, two drum-engaging members carried by each of the arms of -said-first pair of upright arms below said axlemeans, a second pair of upright arms the arms of which pair are mounted on said axle means, respectively, for pivotal movement in a second vertical plane parallel to and at one side of said first vertical plane and spaced therefrom a distance approximately equal to the spacing of each of the arms of said first pair of upright arms from said first post, at least one drub-engaging member carried by each of the arms of said second pair of upright arms below said axle means, a second upright post depending from said frame substantially in said second vertical plane and substantially midway between the arms of said second pair of upright arms, a third pair of upright arms the arms of which pair are mounted on said axle means, respectively, for pivotal movement in a third vertical plane parallel to and at the side of said first vertical plane opposite said second vertical plane and spaced from said first vertical plane a distance approximately equal to the spacing of each of the arms of said first pair of upright arms from said first post, at least one drum-engaging member carried by each of the arms of said third pair of upright arms below said axle means, a third upright post depending from said frame substantially in said third vertical plane and substantially midway between the arms of said third pair of upright arms, and means interconnecting all of said arms for swinging all of said arms simultaneously about the axes of said axle means by which they are pivotally mounted for gripping drums between said posts and said drum-engaging members carried by said arms.

2. The drum-hoisting mechanism defined in claim 1, in which the horizontal frame includes a horizontal backbone beam and a plurality of cantilever horizontal wing beams projecting in coplanar relationship oppositely from opposite sides of said backbone beam, said wing beams carrying the two parallel axle means.

3. The drum-hoisting mechanism defined in claim 1, including a hoist beam disposed above the frame parallel to and midway between the two axle means, a plurality of arms pivotally mounted in the first post, a drumengaging shoe carried by the lower portion of each of said arms in the first post, means operatively interconnecting all of said arms in the first post and said hoist beam for moving all of said arms in the first post simultaneously into positions projecting the drum-engaging shoes from the first post into drum-engaging positions in response to movement of said hoist beam upwardly from the frame, the means interconnecting the arms of the three pairs of upright arms for swinging simultaneously including toggle means connected to said hoist beam for 10 arm-moving actuation by movement of said hoist beam upward from the frame.

4. Drum-hoisting mechanism comprising a horizontal frame, a first upright post depending from the central portion of said frame, a first pair of upright arms the arms of which pair are located, respectively, on opposite sides of and spaced equally from said first post and depending from said frame in a first vertical plane passing through said first post, a second pair of upright arms depending from said frame in a second vertical plane parallel to and at one side of said first vertical plane and spaced therefrom a distance approximately equal to the spacing of each of the arms of said first pair of upright arms from said first post, a second upright post depending from said frame substantially in said second vertical plane and substantially midway between the arms of said second pair of upright arms, drum-engaging shoes, shoesupporting means supporting said shoes from said first post for movement relative thereto into engagement with drums between said posts and said arms, and hoisting means operatively connected to said shoes for projecting said shoes away from said first post by a lifting force exerted by said hoisting means to grip drums between said drum-engaging shoes, the arms of said pairs of arms and said second post.

References Cited in the fileof this patent UNITED STATES PATENTS 762,759 Reuter June 14, 1904 791,944 Pugh June 6, 1905 910,062 Holmberg Jan. 19, 1909 1,594,844 McArthur Aug. 3, 1926 1,683,463 Healy Sept. 4, 1928 1,794,306 Liberge Feb. 24, 1931 2,138,498 McMillan Nov. 29, 1938 2,548,064 Reinhart Apr. 10, 1951 2,572,499 Light Oct. 23, 1951 2,576,193 Reynolds Nov. 27, 1951 2,597,760 Strahm May 20, 1952 2,614,711 Houser Oct. 21, 1952 2,634,156 Crimmel Apr. 7, 1953 2,656,212 Eckstein Oct. 20, 1953 2,732,247 Violette Ian. 24, 1956 2,768,019 Brooks Oct. 23, 1956' FOREIGN PATENTS 739,719 Great Britain Nov. 2, 1955