US2588276A

US2588276A - Block lifter

Info

Publication number: US2588276A
Application number: US789014A
Authority: US
Inventors: Jacob D Naillon
Original assignee: Individual
Current assignee: Individual
Priority date: 1947-12-01
Filing date: 1947-12-01
Publication date: 1952-03-04
Anticipated expiration: 1969-03-04

Description

J. D. NAILLON 2,588,276

BLOCK LIFTER March 4, 1952 Filed Dec. 1, 1947 3 Sheets-Sheet l N G; R

N n A INVENTOR.

XMJ 27 March 4, 1952 Lo 2,588,276

BLOCK LIFTER Filed Dec. 1, 1947 3 Sheets-Sheet 2 4 6O 7 i 32 32 46 2% 25 53 49 am al g 45 34 IN V EN TOR.

March 1952 J. D. NAILLON 2,588,276

BLOCK LIFTER Filed Dec. 1, 1947 5 Sheets-Sheet 5 IN V EN TOR.

, vertical.

Patented Mar. 4, 1952 UNITED STATES PATENT OFFICE BLOCK LIFTER J acobD. Nai llon, Oakland, Calif.

ApplicationDecember 1, 1947', Serial No; 789,014 i,

18 Claims.

This invention relates to the art of handling materials, and, more particularly, to a lifter or loader for picking up and changing the spacing of blocks, such as bricks, boxes and the like. The invention finds especial application in the handling of objects which are manufactured in standardized or uniform sizes and arestacked in regular patterns, such as concrete masonry, but

is not limited thereto, being useful also for handling any objects which can be clamped.

The invention is, more particularly, concerned with an improved clamping device for clamping a blockor a row of blocks betweengrippingjaws;

and with a lifting device wherein a series of clamping frames provided with such gripping jaws are mounted for longitudinal motion, \Vhfilby each of such frames may be clamped to one or more blocks and the interval between such blocks may be altered by moving the loaded frames on the supporting'structure.

The embodiment of the invention described in this specification is designed particularly for handling concrete masonry bricks which have been stacked in a storage yard by the telescoping carrier described in my copending application Ser. No. 772,772, filed September 8, 1947. carrier disclosed in said application deposits-concrete masonry bricks in the storage yard in eighteen vertical tiers of bricks, each tier containing a plurality of bricks, e. g., six to twelve, depending upon the sizes of the bricks. The tiers of bricks are arranged on the ground in parallel ,rows or ranks containing six tiers of bricks, the

tiers in each row being without horizontalintervals, or substantially without such intervals. The

rows, however, are spaced onefrom the other so that a small longitudinal interval, usually about two inches, is provided between the bricks.

, In the aforesaid application the individual bricks are arranged with their longest dimensions disposed parallel to the length of the composite stack, i. e., perpendicular to the transverse rows;

when half size bricks are handled, e. g., con- The crete masonry bricks having dimensions of l 4 in. x 8in. x 16 in., the smallest dimensions'are However, the instant invention is not limited to any specific orientation of the bricks.

It is an object of this invention to provide -a lifting blocks, such as concrete masonry bricks,

which have been'stackecl in the manner described in the foregoing paragraph, and which can ,decrease the longitudinal interval between the blocks. More particularly, it is anobject to provide a block loader for picking up a numberiof bricks from a stack of the type described and loading them on atruck, pallet, or other vehicle Without horizontal intervals between bricks.

Another general objectof this: invention is to provide a block lifting device for clamping and lifting a plurality of blocks which have. been stacked in a regular pattern, viz., a rectilinea pattern.

Still another object is to provide a blockllifter which is adapted to clamp a plurality of? bricks or a plurality of rows of bricks or a plurality of tiers of bricks or'a plurality of rows of. tiers of bricks which are initially'spacedwith longitudinal spaces between bricks, and which lifter is'adapted to reduce or eliminate said spaces, whereby the bricks can be deposited in the same or in another locationin a more compact stack Still another object is to provide a clamping mechanism for a block lifter provided with gripping jaws wherein the gripping jaws-are selfclamping or self-locking, and wherein the clamp actuating mechanism is of: simple construction.

Afurther object is to provide a block-clamping device wherein gripping jaws for clamping one or more blocks are supported from a frame by supports urging the jaws closertogether as the jaws are moved relatively to the frame, by the load, and the jaws are urged apart by said support when the jaws are movedrelatively to the frame in the opposite direction, whereby the weight or drag on the block tends to clamp the jaws together and a simple shifting of the jaws releases the block.

Still a further objectis to provide an improved and simplified clamp-actuating mechanism provided with an operating member so arrangedthat the clamping jaws may be moved into clamping position inpart by inertia imparted to the operating memben-e; g., by meansof an operatingcable. The operatingmember may, for example, be a pivoted operating lever connected to an operating cable passing through a cable guide or ring located intermediate :the extreme :positions ofthe lever.

stilla further object is to provide at blockclamping frame provided with cooperating grippingjaws which is readily adjustable to .accommo'd'ate blo ksof diiferent" sizes, or rows of blocks of variable numbers of blocks; and to provide a frame of the type described wherein the effectiveness of the clamping action does not depend upon the accuracy of the adjustment whereby the interval between the gripping jaws is controlled.

Another object is to provide a block lifter of the type described having a plurality of gripping jaws for clamping blocks arranged in a common frame, for eifecting dependable clamping action despite irregularities in the blocks and/or the failure of some of the gripping jaws to function.

Still another object is to provide a block lifter of the type described having a plurality of gripping jaws, arranged on the same or on a plurality of block-clamping frames, having a simple mechanism for actuating all clamping jaws simultaneously.

Still further objects are to provide an improved block lifting and loading device which is adapted to be supported from an overhead monorail, bridge crane, wheeled vehicle or industrial type crane or similar device for lifting any desired number of blocks from a stack to another desired location, or to the same or another location .with a different spacing between the blocks; to provide a device wherein the power required for clamping the jaws to the blocks and for unclamping .the blocks is easily applied manually, and wherein the spacing between the blocks can be .varied by the simple operation of rocking an operating lever; and to provide a loader which is dependable, simple to operate by comparatively unskilled personnnel, and is of simple construction.

With these and other objects in view, which will become obvious in part and be pointed out in part in the course of the following description .of the elements and applications of principles constituting the invention, reference is made to the accompanying drawings forming a part of the to Fig. 3, portions being shown in section;

, Fig. is an enlarged sectional view of one side of the block-clamping frame, taken on line 5-5 of Fig. 2;

Fig. 6 is an enlarged sectional view taken on line 6-6 of Fig. 3;

Fig. 7 is an elevation view showing portions of the clamp-actuating mechanism in clamping position and, in dotted lines, in unclamping position;

Fig. 8 is a fragmentary sectional view taken on line 88 of Fig. 1, showing the spacing mechasm. The block lifting device according to this invention comprises, briefly, a supporting structure 3 adapted to be suspended and having a pair of longitudinal beams extending to both ends of the structure. A plurality of'block-clamping frames are slidably suspended from these beams on each end of the center of the supporting structure. To vary the longitudinal spacing of these frames a space-regulating bar is provided for each end a of the device, the two bars being connected by linkage at the center of the supporting structure so that they may be moved simultaneously to-, ward the ends or simultaneously toward each vergent downwardly.

other. The space-regulating bars are fixed to the outermost block-clamping frames and connected to the other frames by lost motion arrangements permitting progressively increasing relative movement between the bar and the frames from the outermost frames toward the center, whereby movement of the bar causes a maximum movement in the outermost frames and progressively smaller movements in successive frames.

The block-clamping frames have depending legs which are laterally adjustable, whereby the transverse, horizontal interval between the legs can be adjusted. The legs carry movable gripping jaws having vertical engaging surfaces. The jaws are mounted on the legs by supports which constrain the jaws to approach each other upon a movement of the jaws downwardly. Such support may be of any type, e. g., a parallelogram linkage or a simple sliding engagement with depending legs, which may, for this purpose, be con- In the preferred embodiment, described in detail herein, the supports are in the form of cam pins extending through inclined cam slots in guides or flanges on the gripping jaws. Such jaws are brought into clamping position by their own weight, and, when the frame is lifted, the added weight of the blocks clamped between the jaws tends to force the jaws still further together. The jaws may be released by lifting them relatively to the frame.

The clamp-mechanism comprises a longitudinal clamp-actuating bar on each side of the device traversing all frames and suspended by links from actuating levers. The several gripping jaws are suspended from the clamp-actuating bar, whereby an upward movement of the bar releases all gripping jaws, and a downward movement of the bar permits all jaws to drop to clamping positions. For operating the actuating levers I may use any operating arrangement; in the embodiment shown there are two operating levers rigidly connected to the actuating levers and extending from their pivot points toward the center of the device. They are arranged to have raised clamped positions and lowered unclamped positions. A cable guide, in the form of a ring, is fixed on the supporting structure between the ends of the operating levers a short distance above their unclamped positions; a connecting cable connects the ends of the operating levers, above the cable guide; and an operating cable extends through the cable guide, being connected to the middle of the connecting cable. With the levers in their raised positions and the connecting cable almost taught, a powerful pull on the connecting cable can be effected by a relatively light pull on the operating cable to initiate the unclamping operation; continued tension moves the levers to their lower positions, the last portion of their travel being by inertia, after passing the level of the cable guide. When in their lower, unclamping positions, the connecting cable is looped up through the cable guide and extends downwardly to the ends of the operating levers; a sharp tug of the cable lifts these levers, and

. inertia, together with the weight of the clampactuating bars and the suspended gripping jaws, causes the levers to continue their motion to their upper positions.

The invention will be better understood by reference to the drawings. Referring particularly to Figs. 1-3, reference number 20 represents the main, longitudinal supporting member, formed of an I-beam and connected to eyes 2| and Zla by which the entire lifting device may and 22a.

be suspended from a hoist, crane, or the like. Transverse I-

beams

22 and 22a are bolted to the ends of the supporting member 2i] and are rigidly connected by main, longitudinal,

tubular beams

24 and 24a, which extend throughout the length of the device and are welded to the I-beams 22 The block-clamping frames are suspended slidably from the beams 24 and? 4a. The parts described above form the supporting structure.

Six block-clamping frames are provided in the specific embodiment shown in the drawings, disposed in a longitudinal column, three in each end of the supporting structure. Each frame comprises two transverse inverted U-frames spaced apart longitudinally. One of the inverted U- frames is shown-in part in Fig. 4, and the composite block-clamping frame is shown in Figs. 3, 5 and 6. Each inverted U-frame comprises: an intermediate, horizontal supporting section 25; side sections 25 and 26a forming vertical legs and having short horizontal arms; and a pair of

horizontal tubes

21 and 21a. The intermediate section and the side sections are of cellular construction and the

horizontal tubes

21 and 21a are mounted within these sections, being fixed to the intermediate section by means of bushings 28 welded thereto. Bushings 29, welded to the side sections, are slidable on the

tubes

21 and 21a, whereby the side sections may be moved laterally to vary the horizontal interval between the legs.

Sleeves

30 and 3% are fixed to the top of the section 25 and have sliding fits with the

beams

24 and 24a, respectively.

The-two inverted U-frames forming one blockclamping frame are joined by connectors 3| and 3la, each connector consisting of a pair of bars welded at their ends to the respective side sections and, at their intermediate portions, to

internally threaded blocks 32. A tie rod 33 is in threaded engagement with the blocks 32 and has square ends. Thev threads at one end are right-handed and at the other end are lefthanded, whereby the spacing between the side sections can be varied by turning the tie rod 33. A stop 34, fixed to the intermediate sections 25 by connecting bars 311), prevents axial movement of the tie rod and thereby prevents the side sections from swaying laterally with respect to the intermediate sections. The side sections of the two inverted U-frames are, further, connected by angles 35 and 35a. Each of these angles supports two parallel sleeves 36 by means of horizontal supports 3] formed of bar metal welded to the sleeves and to the angles 35 or 35a. These sleeves are axially aligned with holes 38 in the vertical legs (see Fig. 4). Cam pins 39 extend through these holes and sleeves. Eight rollers 49 are rotatably mounted on each cam pin, there being one roller on each side of each sleeve 38 and one on each side of each leg. The six rollers between the frame legs are retained in position by three spacer bushings 4| those on the outside of the legs are retained by washers 42, secured in turn, by cotter pins.

Four gripping jaws 43 are slidably mounted on each side of the frame. Each jaw is provided with a vertical engaging surface carrying a coating of resiient or yieldable material 44, such as neoprene or other rubber-like material having,

a good wearing quality and a high coeflicient of friction. The sides of the jaws are bent back away from the engaging surfaces and perpendicular thereto, forming guides or flanges 43a;

port them. Theguides are reinforced-by having their thickness doubled at levels opposite the cam pins 39. The two outer gripping jaws on each side ofthe frame are mounted with the inner 5 faces of the guides 43a in sliding engagement with opposite sides of the frame legs; the two intermediate jaws have the inner faces of their guides in engagement with the ends of thesleeves 36. Inclined cam slots 431) are cut through the reinforced portions of the guides and have the widths necessary to accommodate the rollers 40. The cam slots are inclined to slope upwardly and outwardly (i. e., away from the engaging surface). They are inclined to the vertical at an angle smaller than the angle whose tangent equals the coefficient, of friction of the block being lifted against the coating. 44 or, in the case in which several blocks in a row are to be clamped together, the coeflicient of friction of the blocks to each other, which ever coefficient is smaller.

For example, in the embodiment illustrated, designed for handling concrete masonry blocks, the slope is four on one (approximately 14 to the vertical, corresponding to a tanget of 0.25). As

a consequence of the upwardly and outwardly inclined cam slots the jaws on opposite sides of the frame move apart when they are raised and move toward each other when they are lowered.

The gripping jaws are held in their raised positions by a clamping mechanism,fto be described. When thus raised, the frame is lowcred over a block or a stack. of blocks and the jaws are lowered. In the specific embodiment described herein, the jaws move downwardly by gravity upon being released by the clamping mechanism. They move downwardly until their engaging surfaces come into contact with a block.

An initial clamping action takes place as the jaw is wedged between the block and the cam pin, the coating 44 being thereby compressed. It is, however, also within the purview of the invention to supplement the action of gravity by providing a spring or other means for urging the jaws downwardly and increasing the initial 5 clamping action. When the frame is then raised the weight of the block or blocks tends to carry the gripping jaws still farther down and urges the jaws still closer together, thereby effectively clamping the block or blocks.

t For best operation it is desirable to provide rollers 46 having a minimum of' friction, although in certain instances, as when the materials handled have high coefiicients of friction, such anti-friction rollers may be omitted. By providing a plurality of independently mounted gripping jaws on each side of the frame a good contact with the block is assured, despite irregularities in the shapes of the blocks. Moreover, it should be noted that it is desirable to maintain the engaging surfaces of the jaws on opposite sides of the frames parallel; in the embodiment described they are maintained vertical, and this is preferred, although not in every case essential. Maintenance of the parallel relationship during movement of the jaws is particularly desirable when vertical tiers of blocks, e; g., several superposed layers of bricks, are to be clamped. To achieve this the jaws are made to move together or apart in essentially translatory motion by providing a plurality of cams at different levels. It is, of course, not essential that the cam slots 43b be straight, as illustrated, since curved cam slots may be used; however, all cam slots'should have essentially the same theseguides stiffen the gripping jaws and supshapes and. slopes, so that the jaws will. move loaded;

without deviating from their vertical positions. Moreover, it is desirable to locate the holes 38 and sleeves 36 to make provision for deflection or deformation of the frame when placed under a load. Thus, when blocks are clamped the lower ends of the legs will be urged apart to an extent depending upon the horizontal thrust and the size of the frame. The extent of this deformation can be readily calculated by methods Well known in the art, and the holes 38 and sleeves 38 are preferably located so that they are not in a truly vertical row when the frame is uninstead, they are located farther inwardly progressively towards the bottom, so as to assume a vertical relationship when the frame is loaded. This slight departure from the vertical when the frame is unloaded is too small to be shown on the drawings. The correction for load deflection can, of course, be provided in other ways, e. g., by thickening the coating A l toward the bottom, or by locating the cam slots 432) at varying distances from the engaging surfaces, or by modifying the shapes of the cam slots slightly. All of these are too small to be illustrated in the drawings. In many cases, however, it is not necessary to take such a precaution in design, particularly when the weight of the blocks is small in relation to the strength of the frame.

While I have shown the cam slots in the grip' ping jaws and the cam pins on the frame, it is evident that these may be interchanged by a simple mechanical modification.

The clamping mechanism comprises: A pin 5 fitted in holes in the upper portions of the guides of each gripping jaw and extending through a link 46'; clamp actuating bars 4? and 47a; and levers for raising and lowering the bars. One bar is provided on each side of the device and extends through all of the links 46 on its respec- ,5

tive side, whereby each clamp actuating bar supports twenty-four links.

Transverse rods

48 and 48a are journalled in sleeves 49 bolted to the bottoms of the I-

beams

22 and 22a, respectively. Actuating levers B are fixed to the rods 48 above each bar 4'! and 47a and are pivotally connected by rigid, curved suspension links 5! to eyes in bands on the bars 6! and Ma. Each bar is, therefore, suspended at two, longitudinally spaced points. In the position shown in Figs. 2 and 6 the

rods

48 and 48a, levers 50, links 5! and actuating bar 47 are in their raised positions. When the rod 48 is rotated counterclockwise and the rod 48a is rotated clockwise, the bar M is first raised slightly as the ends of the levers 50 pass through top dead center; thereafter they are lowered, permitting the links 45, pins t5 and gripping jaws 43 to descend by gravity.

Each of the rods 48 and 38a carries an operating

lever

52 or 52a, fixed so as to extend toward each other and to be slightly downwardly inclined when in their unclamping position shown in Fig. 2 and in dotted lines in Fig. 7. The actuating lever 50 and operating lever form a bell crank. A connecting cable 53 connects the ends of the operating levers and has a length equal to the distance between the levers when in their raised, clamping positions, shown in solid lines in Fig, '7. A cable guide, in the form of a ring 54, is fixed to one of the block-clamping frames near the center of the device and is located between the ends of the operating levers within the sectors defined by their clamping and unclamping posi tions, but nearer to their unclamping positions. An operating cable 55 extends through the cable tion connection to the necting cable 53.

When the gripping jaws are in their downward positions and loaded with blocks, the frame is lowered to support the blocks externally, e. g., on a truck platform or on other blocks, before unclamping them. With the blocks thus supported, and the operating levers in their clampin positions, the mechanism is operated by pulling on the operating cable 55. A relatively light pull on the cable will result in a considerably greater tension on the connecting cable, thereby rotating the operating levers toward each other. This large initial force is necessary because the gripping jaws are clamped to the blocks and must be lifted against the frictional resistance of the blocks to disengage them. Once the blocks have been disengaged the resistance to the motion of the operating levers is decreased, being opposed only by friction and weight of the parts, and the levers continue their motion, coming to rest in the positions shown in Fig. 2 (and in dotted lines in Fig. 7). It should be noted that the connecting cable is drawn partly through the cable guide during this action. It is, however, not pulled so far as to stop the operating levers when they come opposite to the cable guide, slack being .left to continue to permit movement to their lowest positions shown.

When the parts are in the unclamping position they remain in that position because the actuating levers 5t have been rotated beyond top dead center, i. e., beyond the point at which the gripping jaws have been raised to their highest positions. To return the parts to the clamping positions the operating cable 55 is given a sharp tug .or pull downward. This lifts the ends of the operating levers to the level of the cable guide. The levers then continue to move past the cable guide by momentum and by the weight of the gripping jaws and clamp-actuating bars, the actuating levers 56 havin by this time moved beyond top dead center.

For moving the block-clamping frames longitudinally along the

beams

24 and 24a I provide a pair of space-regulating bars 56 and 56a, one for each end of the device and traversing the three frames in the respective ends. Each space-regulating bar is fixed to the outermost frame by nuts 51 and has a lost-mointermediate frames. The lost mot-ion connections on each bar comprise

sleeves

58 and 59 fixed to the respective bar and engageable with corresponding lugs 60 and (ii, respectively, carried by the connectors 3th on the block-clamping frames. The

lugs

66 and 6| have engaging flanges for alternate engagement with the ends of the

sleeves

58 and 59. T .e play between sleeves 59 and lugs 6! on the innermost frames is greater than the play between sleeves 58 and the lugs 88 on the intermediate frames. For example, if the device is to be used to clamp six rows of blocks which have 2 inches of free space between the rows, each bar 56 or 56a will have a longitudinal travel of five inches, this being also the travel of the outermost frames; the intermediate frames will have a travel of three inches, and the innermost frames a travel of one inch; hence the play at the lugs 69 should be two inches, and at the lugs 6| it should be four inches. When the device is loaded with blocks which are fully spaced longitudinally and the bars 56 and 56a are moved inwardly, the outmost frames are pulled inwardly with them; when the sleeves 58 and lugs 60 come are moved inwardly during the lastinch of travel.

When the reverse action takes. place, the bars. aremoved outwardly and, initially, only the outermost, frames. move; then the sleeves 58 and, lugs 60, are, engaged and the rtermediate frames begintheir outward movement; firally, the sleeves 5.9 and lugs iii are, engaged. and all, frames move during the last part of the, movement.

The space-regulating barsare actuated by

links

62 and 63 pivotally connected to the bars, 56 and 5612 through eyes in flanges fixed to the sleeves 59, and to the ends of a double lever comprising parallel bars. 64 and 64a, mounted. on a. transverse shaft 85. This shaft is journalled in the main supporting structure by sleeves 66. carried by a T-beam l0 welded to the

beams

24 and 24a. The end of the shaft 65 carries an operating lever 61 having cables 68-and6 9. By pulling on these cables the shaft 65'and, the lever 64 may be rotated to move thebars 56- and. 56a. inwardly or outwardlyto vary the longitudinal. spacing of the frames.

I claim as my invention:

1. A devicefor lifting blockscornprising aframe providing a plurality of pairs of, gripping. jaws spaced apart horizontally and having parallel, vertical engaging surfaces, the jaws on at least one side of the frame being movable vertically with, respect to said frame, each said, movable jaw having a. guide extending away from .the engaging surface thereof and slidingly guided by said frame, and a. plurality of vertically. spaced cam means supporting said movable jaws on the frame, each cam means having an-upwardly and. outwardly inclined cam slot. and a, cooperating camv pin, one on theframe and the other. on said guide, for moving said movable jaws. in. translatory motion toward the other jaws of the respective pairs when said, movable jaws move downwardly with respect to said frame.

2.. A device for clamping lookscomprising a frame adaptedto be moved inadirection of thrust for moving blocksinsaid direction, a pair of legs at opposite. sidesof said frame and, extending generally in a directionparallel to said direction, said legs being rigidlyconnected and adjustable to permitthe interval between. said legs to be varied, a gripping jaw slidably mounted on each leg, said jaws having parallelengaging surfaces substantially parallel. to said direction, and cam means between. each ofjsaid, legs and the corresponding jaw. arranged. to. move each jaw toward the other jaw in. essentially; translatory motion upon a movement. of thejaws .withrespect to the legs in a directionopposite to said direction of thrust;

3. A. device for clamping blocks comprising a frame, having a pair of substantially vertical legs, slide means at the upper ends of said legs arranged. to maintain said legs rigidly at any selected horizontal interval, positioning means for adjusting the horizontal interval between said a gripping jaw oneach of said legs, said jaws having parallel engaging surfaces substantially :a a el, at leastone of said jaws being movable cally withrespect toitsrespectiveleg, said movable jaw being guidingly. supported on its respective leg for mnvement. toward; the other,

jaw upon a, downward movement thereof while,

maintainingthe parallel relationship between the.

engaging surfaces, and actuating means for raising said, movable jaw with respect to the frame.

4. A device for lifting blocks comprising a frame having an intermediate supporting section and apair of depending legs at the sides thereof, at least one of said. legs, being laterally movable to permit the horizontal interval between said legs to be varied, means for securing the legs at any desired interval comprising a tie rod connecting said legs and adjustably attached, thereto, a gripping. jaw movably mounted on each leg,,said jaws having. parallel, vertical engaging surfaces, and supporting means between each of said. legs and the, corresponding jaw arranged to move each jaw toward theother jaw while maintaining the parallel relationshipv between the engaging surfaces. upon. a. downward movement of the jaws with. respect, to said. legs.

5.. A devicefor lifting blocks comprisingaframe providing, a pair of depending legs on each side thereof, a movable gripping jaw for each of said. less, said jaws providing parallel engagingsurfaces, each jaw having a guide, extending, away from the. engaging surface thereofand slidingly guided by the respective. leg, a. plurality of. vertically spaced. camslots in. eachof said guides extending upwardly and outwardly, and cam pins. on said legs extending through saidcam slots for supporting said jaws.

6. A device for. lifting, blocks comprising aframe. providing a.pair of] depending, legs on each side. thereof, there being, an interval between. legson the same. side of the frame, a movable, gripping jaw on each of said legs, said'jaws. providing,

parallel engaging surfaces, each. jaw: having a plurality of vertical. guides. extending away from theengaging surfacethereof and slidingly guided by the. respective leg, intermediate movable engaging jaws with, parallel engaging surfaces betweenthe gripping jaws on the legs on-thesame side ofthe frame, aplurality of. vertical guideson said intermediate,jawsextending away from the engaging surfacesthereof, a .plurality of vertically spaced, upwardly and outwardly inclined cam slots in each of saidguides on the intermediate jaws, and cam pinsconnecting the legs on the same side of the frame. extending through. the cam slots of. the guides on the several jawson the same side of the-framefor supporting saidjaws.

l. A block lifter, comprising, a. supporting. structure, a plurality of: block-clamping frames. dis.- posed longitudinally along. said structure, each frames providing a. pair ofcooperating gripping jaws: spaced. apart horizontally, atleast one of said, jaws oneach framebeing movable verticallyv with respect. tosaid. frame, a. support for each" movable jaw arranged to. :move. said movablejawtoward theother jaw'in'the same frame when said movable: j aw moves downwardly with respect to said frame and away from said other jaw when said'jaw moves upwardly" with respect tosaid frame, and actuating means common to several longitudinally spaced frames having'a clamping position and an unclamping positionforraising the movable jaws on the several frames when moved to its unclampingposition and for-releasing said jaws for individual downward movement when moved to its clamping positionsaid last-named means comprising a longitudinal clamp actuating bar on the supporting structure, suspension means connecting saidmov able jawstothe clamp actuatingybar, and means 11 i for raising and lowering the clamp actuating bar.

8. A block lifter comprising a supporting structure, a plurality of transverse block-clamping frames disposed longitudinally along said structure, each of said frames providing a pair of cooperating gripping jaws with vertical, parallel engaging surfaces movably mounted in said frames, a plurality of vertically spaced cam means for each gripping jaw supporting the respective jaw on the respective frame, said cam means having an upwardly and outwardly inclined cam member and a cooperating cam pin, one on the jaw and the other on the frame, for moving said jaws in essential translatory motion toward each other when said jaws move downwardly with respect to their respective frames and away from each other when said jaws move upwardly with respect to their respective frames,

and actuating means on said supporting structure common to several longitudinally spaced frames having a clamping position and an unclamping position for raising the jaws on the several frames simultaneously when moved to its unclamping position and for permitting individual downward movement of the jaws on the several frames when moved to its clamping position.

9. The block lifter according to claim 11 wherein the means for raising the jaws comprises a plurality of transverse shafts on the supporting structure, a longitudinal clamp actuating bar on each side of said structure connected by linkage to said shafts for simultaneous upward or downward movement of said bars, and suspension means connecting the gripping jaws to said clamp actuating bars.

10. A block lifter comprising a block-clamping frame having gripping jaws mounted for relative motion, and means for actuating said jaws comprising a movable operating member operatively connected to said jaws to decrease the interval between the jaws when the operating member is in its clamping position and to increase said interval when the operating member is in its unclamping position, a cable guide fixed intermediate to the clamping and unclamping positions of said operating member, and a cable extending through said cable guide and connected to said operating member.

11. A block lifter comprising a block-clamping frame having cooperating gripping jaws, at least one jaw being movably mounted on said frame, a support for said movable jaw arranged to restrain said movable jaw to approach the other jaw upon a downward movement of said movable jaw and to move away from said other jaw upon an upward movement of said movable jaw, and means for actuating said movable jaw comprising a pivoted actuating lever, linkage connecting said lever to said movable jaw for lifting said jaw, said lever having a clamping position in which the movable jaw is in its lowered po ition and unclamping position in which the movable jaw is in a rai ed position, the actuating lever being arranged to move beyond the position at which .the movable jaw is lifted to its highest position when said actuating lever is moved pivotally to its unclamping position, whereby the weight of the movable jaw tends to hold the lever in its unclamping position.

12. In combination with the block lifter according to claim 14, an operating lever associated with said actuating lever and movable therewith to a clamping position and to an unclamping position, a cable guide fixed intermediate the clamp 12 ing and unclamping positions of said operating lever, and a cable extending through said cable guide and connected to said operating lever.

13. A clamp-actuating mechanism for a block lifter having movable gripping jaws arranged to be unclamped when raised and clamped when lowered, comprising a pair of operating levers pivotally mounted on the block lifter and connected to said gripping jaws for lifting said jaws, said levers extending toward each other from their pivots and having raised clamping positions in which the gripping jaws are lowered and lowered unclamping positions in which the gripping jaws are raised, a cable guide fixed to the block lifter within the sectors defined by the clamping and unclamping positions of the said levers and near to the unclamping positions thereof, a connecting cable joining the free ends of the operating levers and having a length substantially equal to the distance between said free ends when said levers are in their clamping positions, and an operating cable extending through said cable guide and connected to an intermediate point on said connecting cable.

14. A block lifter comprising a supporting structure, a plurality of transverse block-clamping frames disposed in a longitudinal row and movable longitudinally on said structure, each frame providing a pair of cooperating gripping jaws at opposite sides of said structure and having vertical, parallel engaging surfaces, at least one of said jaws in each frame being movable to decrease or augment the interval between the jaws of the same frame, means for actuating said 'movable jaws on the several frames simultaneously, and means for varying the longitudinal spacing between said frames along said supportin structure.

15. The block lifter according to claim 14, wherein the means for varying the longitudinal spacing comprises a longitudinal space-regulating bar secured to one of said transverse frames and having a lost-motion connection to another of said frames.

16. A block lifter comprising a supporting structure, a plurality of transverse block-clamping frames disposed in a longitudinal row and movable longitudinally on said structure, each frame providing a pair of cooperating gripping jaws on opposite sides of said structure, said jaws having vertical, parallel engaging surfaces and being movably mounted on said frames for upwardly divergent and downwardly convergent movement, a longitudinal clamp actuating bar connected to said gripping jaws for lifting the jaws, and a longitudinal space-regulating bar for varying the longitudinal spacing between the frames on said supporting structure.

4 1?. A block lifter comprising a supporting structure extending from a longitudinally intermediate point thereon to form two ends, a plurality of transverse block-clamping frames dispo ed in a longitudinal row and movable longitudinally on said structure, each frame providing movable gripping jaws for clamping blocks, means for actuating said jaws, a longitudinally movable space-regulating bar for each end or the supporting structure, each of said bars being connected to the several block-clamping frames on the same side of said intermediate point through a lost motion arrangement for moving successively more. outlying frames progressively greater longitudinal distances as said bar is moved longitudinally, and means for moving said bars simultaneously outwardly or simultaneously inwardly for increasing or decreasing, respectively, the longitudinal spacing between said block-clamping frames.

18. A block lifter comprising a supporting structure, means for suspending said structure from the center thereof, said structure having a plurality of supporting beams extending longitudinally from said center to form two ends of the structure, a plurality of transverse blockclamping frames longitudinally slidable on said beams on each of said ends, each frame providing movable gripping jaws for clamping blocks, means for simultaneously actuating the gripping jaws on a plurality of said frames, a longitudinally movable space-regulating bar for each of said ends of the supporting structure, each of said bars being fixed to the outermost block-clamping frame and traversing the other frames, engaging means on said bar for said other frames and cooperating stops on said other frames, said engaging means and stops being positioned to provide progressively more lost motion between said engaging means and the stops on successive frames toward said center, a lever pivotally mounted near the center of the supporting structure rotatable about a transverse axis at a point intermediate to the ends of the lever, and links connecting each end of the lever to a difierent one of said space-regulating bars.

JACOB D. NAILLON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS