US2615747A - Grab - Google Patents

Description

W. J. OLSON Oct. 28, 1952 GRAB 4 Sheets-Sheet 1 Filed Jan. 26, 1949 INVENTOR. WALTER J. OLSON ATTORNEYS Oct. 28, 1952 w. OLSON GRAB 4 Sheets-Sheet 2 Filed Jan. 26, 1949 ATTORNEYS W. J. OLSON Oct. 28, 1952 GRAB 4 Sheets-Sheet I5 Eiled Jan. 26, 1949 FIG.3

W E W EEMEE,

INVENTOR. WALTER J. OLSON Wwwuww ATTORNEYS 4 Sheets-Sheet 4 IN VEN TOR.

ATTORNEYS w. J. OLSON GRAB Oct. 28, 1952 Filed Jan. 26, 1949 WALTER J. OLSON BY WW ,J CW

Patented Oct. 28, 1952 GRAB; M J Walter JnOlson, .Clifton, N.J.,' asagmmmagican Brake Shoe Company New "Kerk, .Y.-,- a Y I corporation of .'Delaware;

Application January 26, 1949, s rm se}. 72.815

' UNITED: STATES This invention relates to grabs and more particularly to grabs .of the type especially well adapted to be used with power hoists "in factories, foundries, and similar places 'for picking up and transporting heavy articles such as molds, flasks; heavy stacks of sheet metal, and the like. Grabs and grapples of the general nature to whichv thisinvention relates have, long been employed in lifting and transporting heavy articles such as molds, flasks, stacks of material such as sheet metal, and the like. grapplesareemployed for such purposes, they are .commonly used in conjunction with power hoists, gantrys, trolleys, or other "power lifting machines, the grabs or grapples being used to grip the workto be lifted 'andtransported, and

the .power lifting machinery being connected to the graband being effective to raise and transport the grab and the work engaged thereby.

Variousv types of. grabs have beenhere-tofore known and usedin the art.i' However, such grabs have .had'severalinherent, disadvantages such as, for. example,,being,costly and difficult .to manufacture; being vdiilicult to operate, and the like. .25,

A .primary object of my invention. is toiovercomethese disadvantages and to afford a-novel grab. which may be economicallymanufactured andis efficient in operation.

One of the primary disadvantagesgof grabs heretofore known in the art has been that the ,various par-tghaire been so constitutedxandarranged that excessive binding of .various movable parts thereof occurred during operation of the grabs,. and.especiallywhen the grab was beingoperated under load.

One of the principal objects of my invention is toafiord a,novel;.gr abi wherein thevarious partsthereof. are constituted and arranged-in a noveland expeditious manner whereby the various parts thereof operate efficiently and freely when the grab is being operated either with or without a load.

Anobject ancillary. .to the foregoing is to afford ;.a .grab having ,grapplingfarmstforengaging the. work-load, wherein the grappling arms are supportedon rollers in a novel and expeditiousmanner whereby the arms maybe relatively easily moved, into andout .of workengagingposition.

Another, object .of my invention is. to afford a grab of the aforementioned type wherein the grappling arms are guided and supported .by rollers in both ah'orizontal and vertical direc- 7 tion, and in a .novel andexpeditious manner.

A further object is to enable, a grab of the fore- I 5 Claims; (01.294461);

mentioned type to be constructed in za, mannter When grabs and wherebythegrappling arms giare suDDQIted by the carriages, .and ithesloadtis ,supportedby e grappling arms,..in anovel' manner; whereby the rams exerted ornthe. l-grappling-anmsain supporting the loadareisubstantially vertical;

Other and furthernobiects of the present in,- vention. will be :apparent from the .fo11owing.. description and/claims aandare illustrated. inthe accompanying drawings which, by w-ay of illustration show .2.. preferred embodiment and. the

principles thereof and :what I new considergato bethe best mode inwhichI have contemplated applying those principles.

'vention and. the purview of. the appendedclaims.

In the drawings: Fig. 1 is a perspective view of argrab illust ating a 'preferred embodiment. of-:my invention;

Figp 2 is a topplan view of 'the-grabishownin Fig.1;

Fig. 3 is-a sectional view .jtaken-substantially along the line 3-3 in'Fig. 2;

Fig. 4 -is' asectiohal view taken substantially along the line l--liniFig' Z Fig.=5 is a. sectional view taken along the line 5-5 inFig. .4;

Fig. 6 is azdetailsectional view takenrsuhetantially along-the line 66 in Fig. 3;

Fig. 7 is a-detail sectional. viewtakenstlbStantially along the .li'nex1-'1 in Fig. 3;

Fig. 8 is a detail sectional viewtakensubstansub an ially many along the line sea in Fig; '1;

Fig. 9 is a 'detailsectional viewqtaken, substantially along the line 9+9 in-Fig. 2; and

Fig. 10 is a detailsectional viewtakenxsubstantially along theline- I 0-.-.-l 0 in Fig. 9.,

The-grab 20*shownin Figs. 1 to. 10.. inclusive,

to illustrate a preferred embodiment :of my ,invention, comprises, in general. a frame ;;on which-are movably mounted two grappling . arms 24 and 25; the grappling arms 24 :and .25.?bein adapted to be moved on the frametoward and away from-each other as will be discussed-fi greater detail presently.

The'frame 22 comprises two elongated boxes or guide-housings 21 and 28 whichare :disposed 'in parallel spaced relation to each. other and a'reconnected at their ends by two side, bars,

, The box 21, Fig. 1, comprises a top-wall 32,

Other'embodlments ofithe-invention embodying the same or; equi;va-'

the walls being formed of any suitable material such as sheet metal and being connected together by suitable means such as welding 39. The bottom wall 31 has a slot M and 42, Figs. 1 and 2, formed in the opposite end portions thereof. End guards 44 and 45 are mounted on opposite end portions of the top wall 32 and extend down over the upper end portion of the ends of the box 21 for a purpose which will be discussed in greater detail presently.

The guide-housing 28 is substantially the same as the guide-housing 21, having a top wall 52, side walls 54 and 55 and a'bottom wall 51, connected together by suitable means such as welding, and having slots BI and 82 formed in the bottom wall 51. Two guards 64 and 85 are mounted on the opposite end portions of the guide-housing 28 in a manner similar to that in which the guards 44 and 45 are mounted on the housing 21. I

Two lugs 61 and 68 extend upwardly from the top walls 32 and 52, respectively, of the guidehousings 21 and 28, and are adapted to be engaged by the usual hook, not shown, on a hoist or crane, whereby the grab may be lifted and transported by the hoist or crane.

Four carriages 18, 1|, 12 and 13, Fig. 2, are mounted in the housings 21 and 28, with two carriages 18 and II disposed in the housing 21, and two carriages 12 and 13 disposed in the housing 28. Each of the carriages 18, 1|, 12, and 13 comprises an elongated body member 15 comprising a central member 11 having two cars 19 and 88 mounted on opposite faces of one end thereof in spaced relation to each other and attached thereto by any suitable means such as welding. Two pairs of rollers 82 and 83 are rotatably mounted on shafts 85 and 85 extending through the lower portion of the body member 15, each of the rollers 82 and 83 in each of the pairs being disposed on the side of the body member 15 opposite to that on which the other roller in the same pair is dis-' posed, and each of the rollers 82 and 83 projecting downwardly below the lower edge of the body member 15 to thereby afford a peripheral edge portion which may reston the bottom wall of the guide-housing within which the carriage is disthe bottom wall of the housing.

In addition to the vertically disposed rollers 82, 83, 88, and 88, a roller 94 is horizontally disposed in a slot 86 formed in the body member 15 of each of the carriages 18, H, 12, and 13 and is rotatably mounted on a pin 98 extending in a vertical direction through the slot 96, each roller 94 projecting horizontally outwardly from the sides of the body member 15 past the rollers 82, 83, 88, and 88, and being adapted to engage both side walls of the housing within which it is disposed to thereby afford guide means for guiding the carriage on which the roller is mounted between the side walls of the housing during movement of the carriage longitudinally of the housing.

Hence, it will be seen that the carriages 1813 are well supported and guided for relatively fric- 4 tionless movement longitudinally of the housings 21 and 28, the rollers 82, 83, 88, 89, and 94 affording rolling contacts between the carriages and the walls of the housings.

The grappling arm 24 comprises a horizontally disposed jaw member IM to which are connected two drop legs I83 and I84. The jaw member I8I comprises an elongated bar I86 formed of suitable material such as an angle iron and to which a plurality of spacers I81 are connected by any suitable means such as welding. Gusset plates I89 and I I8 are welded to the lower end portions of the drop legs I83 and I84, respectively, and the drop legs I83 and I84 are connected to the jaw member IN by bolts H2 and nuts II3, the bolts I I2 extending through the plates I89 and I I8.

The grappling arm 25 is similar to the grappling arm 24, including a jaw member I I5 having a bar II1 to which are connected a plurality of spacers II8. Two drop legs H9 and I28, having gusset plates I22 and I23 attached to the lower end portions thereof, respectively, are connected to the bar I I5 by bolts I25 which extend through the plates I22 and I23.

The spacers I81 and H8 are preferabl dis.- posed on the respective grappling arms 24 and 25 in such a manner that each spacer I81 is disposed in position opposite to the corresponding one of the spacers H8, Fig. 2. As will be appreciated by those skilled in the art, Work to be picked up by the grab 28 may be supported on top of the spacers I81 and I I8, or may be gripped between the spacers I81 and H8 or the bars I86 and H1, depending on the size and contour of the work to be engaged.

The drop legs I83 and I 84 on the grappling arm 24 extend upwardly through the slots M and 6| in the bottom walls of the guide-housings 21 and 28, respectively, and the upper end portions of the drop legs I83 and I84 are disposed between the ears 19 and 88 on the body members 15 of the carriages 18 and 12, respectively, and are connected thereto by any suitable means such as welding. As is best seen in Figs. 1 and 2, the shafts and SI, which extend through the ears 19 and 88 of the carriages I8 and 12, respectively, also extend through the drop legs I83 and I84 so that the drop legs I83 and I84 are supported substantially vertically below the pair of rollers 82, and the jaw I8I is so disposed on the drop legs I83 and I84 that it is suspended in substantially vertical alignment with the central portions of the body members 15 of the carriages 18 and 12 between the two pairs of rollers 82 and 88, and 83 and 89, mounted on the opposite end portions, respectively, of the body members 15.

The grappling arm 25 is similarly connected to the carriages H and 13, the drop legs I I9 and I28 of this latter grappling arm extending upwardly between the ears 19 and 88 on the carriages H and 13 and being connected thereto by any suitable means such as welding. 7

Hence, it will be seen that the grappling arms 24 and 25 are mounted on and suspended from the pairs of carriages18 and 12, and H and 13, respectively, and are movable therewith longitudinally of the housings 21 and 28 between the outer positions wherein the carriages 18 -13 engage the guards 44,45, 64, and 65, respectively, and the inner positions wherein the drop legs I83, II9, I84, and I28 engage the inner ends of the slots M, 42, 8 I ,and 62, respectively.

Also, it willbe seen that, in my novel grab the grappling arms24 and 25 and the carriages 18, TI, 12, and 13 are so constituted and arranged that'the'jaws Nil and H5, by which'the work' to be lifted by the grab is engaged, aref-in all positions of adjustment, disposed in substantially vertical alignment with the central portion of the body member 15' from which they are suspended so that the load carried by each carriage is substantially equally distributedbetween the rollers 82 and 83 mounted on'opposite end por tions of'the carriage, and comprises a substantially vertically applied'loa'd thereon. I

To afford means for moving the grappling arms24and 25' toward and away fromeach other I provide two endless chains I26 and I29,'Figs. .1, 3 and'4, which are trained over two pairs of sprocket wheels I3I and I32, and I34 andl35, respectively. The sprocket wheels I32 and-I34 are mounted 'on,'and rotatable with,"the opposite end'portions of a shaftl31, which extends substantially the length of the "frame 22 and is rotatably mounted in brackets I40 and MI mounted on the outer faces of the side walls35 and 55 of .the housings 21 and 28, respectively The sprocket wheelsISI and I35 are mounted *on, and rotatable with stub shafts I43 and I44,which are journaled in brackets I46 and I41 mounted on the side walls 35 and 55, respectively.

To'afiord means for adjusting the tension on the'chain I28, the bracketI-I'G, 3,comprises "a block I49 welded to the outer face of the side Wal135 of the housing 21, and a plate II which is adjustably' mounted on the block I49 by a bolt I53 extending through an elongated -'-'slot I54 formed in the plate I5I, and overhanging lip I56 on the block I49 engaging the upper edge of the plate" I5I and preventing the latter from turning on the bolt I53. Similarly, to afiord meansfor adjusting the tension onthe chain I29, the bracket I41 comprises a block I59 welded to the sidewall 550i the box 28, and a plate-I6I which is mounted on the block I59 by a bolt I63 extending through an elongated" slot I64 in the plate I6 I-,

an overhanging lip I66 on the block I59 preventing the plate IEI from turning on the bolt I63. Thus it will be seen that the positions of plates I51 "and I-6I may be adjusted on the blocks I49 and I59 to thereby properly tension the chains I28 and I29 on their respective pulleys;

As is best seen in Figs. 3 and 4, the chain I28 is disposed on the pulleys I3I and l32,'below the housing '21, in such a position that vertically spaced upper and lower runs or passes I68 and I69, "respectively, are afforded thereon; and the 'cliainfl29 is so disposed on the pulleys I34 and I35, below the housing 28, that vertically spaced upperand lower passes or runs HI and I12 are afforded; As will be described in greater detail presently, the chains I28 and I29 are connected to the legs I03, I04, H9, and I20 of the grappling arms 24 and 25 in such a manner that upon rotation of the chains I28 and I29 in one direction the grappling arms 24 and 25 are moved along the guide-housings 21 and 28 toward each other, e

and, when the chains are rotated in the other direction, the grappling arms 24 and 25 are moved along the housings 21 and 28 away from each other;

Interconnection of the drop legs I03, I04, H9, and I20 with the chains I28 and I29 is effected by elongated links or rods I15, I16, I11,and I18, respectively, Figs. 3 and 4, the rods I15, I16, I11

and I18 being connected at one end to the drop -legs I03, I04, H9 and I20 by suitable means'such aspins I80, and being connected at the other end tothe chains I28 and I29 by brackets I82 and I 83.

- Each'of the brackets-I82 is mounted on-the last' to the upper passof a respective one of the chains 1 I28 and I29 by a cross bar I81 extending through a linkof the chain, Figs. Sand 8. v

As is best seen in Figs. 3 and 4, the legs I03 and I04 of Lthe grab 20 shownv in the drawings are connected to the 'upperruns I68 and-I1I of the chains I29 and I29 by the rods. I15 and respectively, and the legs I I9 and I20 are connected to' the lower runs ;I69 and I12; by. the rods I11 and I18. Thus. it will be seenthatuponrotation of the chains I28 and I29 in a clockwise direction, as viewed in Fig. 3, the grappling arms 24 and 25 will be moved along the guide-housings '21 and 28 toward each other,,whereas, when the chains are'rotated in a counter-clockwise direction' the. grappling arms will be moved away from each other. i

/ To afford means for so rotating, oroscillating, the chains I28 and :I29, I. provide an air cylinder I having a piston I92 reciprocably. mountedin connected to'the guide-housing 21 by-two brackets I96 :andfl91, Figs. 2'and9,.which are welded to the outer. face of the sidev wall 34 of thehousing 21 -in such position'that the cylinder. I90 is suspended in position with the longitudinal axis of the housing I94 thereof disposed in substantially horizontally spaced parallel relation to the upper run-I68 of the chain I28, Fig. 9.

A plunger I99, Fig. 2, isconnected to the piston I92 and projects from one end of the housing I94 of the air cylinder I90 in axialalignment therewith. The free end portion of .theplunger I99 is slidably mounted in an opening 201 formed in a-supporting block 203, Figs. 2 and '7, connected to'the bottom wall 31 of the housing 21 by suitable means such as welding, and is mounted 'Jin'the bracket I83 connected to the rod I15, the latter bracket I83 being connected to the plunger I99 "'I3I and I32 andytherefore, through the interconnection of the chains I28 and I29 by the shaft -I31, is likewise effective to oscillate the chain I29 on the sprocket wheels -I 34 and I35. Such reciprocation ofthe plunger I99 and piston I92, as is 'wellknown to those skilled; in the art, may be effected b'yalternately feeding suitable working fluid such as, for example, compressed air, into one'end' and then the'other of the housing I94.

For this purpose, two feed pipes 2I5 and 2I6 are connected to the opposite end portions of the housing I94, Fig. 2, and are operableto alternately'serve as conduits for the feeding of compressed air into the housing I94 and for exhaustingair therefrom during a reciprocation of the piston I92.

To insure that the rods I15, -I16, In and 1n will'bereciprocated' by the chains-I28 and I29 insubstantially a straight line, I prefer to slidably mount the rods l1 5- -I 18 l in suitable .supporting-means "in a "manner similar tothat in which the plunger I99 of the air cylinder I90 is slidably mounted in the supporting block 203, as previously discussed. Thus it will be seen that I have provided supporting blocks 2I8, 2I9 and 220 in which are slidably mounted the rods I16, I11, and I18, respectively, the supporting blocks 2I8220 being welded to the lower end portion of the respective guide-housing beneath which the individual rod I16, I11 or I18 is mounted. As is best seen in Figs. 2, 3, 7 and 8, the rod I is slidably mounted in an opening 222 formed in the supporting block 203 within which the plunger I99 is mounted, as previously mentioned.

Operation In the operation of the device shown'in Figs. 1 to 10, inclusive, the grab 20 may be supported from a suitable hoist, trolley, or the like, by hooks, not shown, engaged in the openings in the lugs 51 and 68 mounted on the upper walls of the guide-housings 21 and 28.

In preparation for lowering the grab 29 over the article or articles to be lifted and transported thereby, the grappling arms 24 and 25 may be moved away from each other by feeding working fluid through the feed line 2I5 int the housing I94 and exhausting working fluid from the housing I94 through the feed line 2I6, thus causing the plunger I99 to be moved toward the left, as viewed in Fig. 3, to thereby cause counterclockwise rotation of the chains I28 and I29, as viewed in Fig. 3. The grab 20 may then 'be lowered over the article or articles to be lifted and transported thereby, and operation of the air cylinder I90 may be reversed, as will be readily understood by those skilled in the art, by feeding working fluid into the housing I94 through the feed line M6 and exhausting working fluid from the housing I94 through the feed line 2I5, thus causing the chains I28 and I29 to be rotated in a clockwise direction, as viewed in Fig. 3, to thereby move the grappling arms 24 and 25 toward each other into engagement with the work to be lifted by the grab,

Obviously the grab 20 may be maintained in either an open or closed position by maintaining a positive pressure in the housing I94 on the proper side of the piston I92 and maintaining a reduced pressure on the other side of the piston. Thus, for example, it will be seen that during a lifting and transporting operation of the grab 20 the grappling arms 24 and 25 may be positively held in engagement with the work to be so liftedand transported by maintaining a positive pressure on the left side of the piston I92, as viewed in Fig. 3, and maintaining a reduced pressure on the right side thereof.

As previously mentioned, the work to be lifted by the grab 20 may either be gripped between the grappling arms 24 and 25, or may be disposed on top of the spacers I91 and H8, the particular manner of supporting the work by the grab 20 being determined primarily by the size and contour of the work. However, it will be seen that whichever way the work is engaged by the grappling arms 24 and 25, the parts of my novel grab are so constituted and arranged that the forces applied to the carriages 10-13 are efficiently distributed, and the carriages are so mounted in the housings 21 and 28 that they may be moved relatively freely when desired and are operable to effectively support the grappling arms 21 and 28, and the load carried thereby, in a novel and expeditious manner. I

It will be understood that although I have shown an air cylinder as the power unit for effecting oscillation of the chains I28 and I29 in the preferred embodiment of my invention. shown in Figs. 1 to 10, this is by way of illustrating the preferred embodiment of my invention and not by way of limitation, and other means for moving the chains I28 and I29 may be used by those skilled in the art without departing from the purview of my invention.

From the foregoing it will be seen that I have afforded a novel and practical grab wherein the grappling arms of the grab are supported in a novel and expeditious manner whereby they may be moved relatively freely in either an unloaded or loaded condition during an operation of my device.

Furthermore, it will be seen that I have provided a novel grab wherein the parts thereof are constituted and arranged in a novel and expeditious manner to afford novel mechanism for the operation of the grab.

In addition, it will be seen that I have afforded a novel grab which is sturdy in construction, practical and efficient in operation, and which may be economically produced commercially.

Thus, while I have illustrated and described the preferred embodiment of my invention, it is to be understood that this is capable of variation and modification and I therefore do not wish to be limited to the precise details set forth, but desire to avail myself of such changes and alterations as fall within the purview of the following claims.

I claim:

1. In a grab, a frame including two elongated boxes each having walls and each having elongated slots formed in, and extending longitudinally of, one of the walls thereof, two pairs of carriages mounted in said boxes and movable longitudinally thereof, each of said carriages comprising a body member, and two pairs of rollers rotatably mounted on said body member with one of said pairs of rollers disposed outwardly of the other of said pairs of rollers longitudinally of one of said boxes, each of said carriages of each of said pairs being mounted in a respective one of said boxes with said rollers on said carriages in engagement with said box for supporting said body member therein, a pair of grappling members, each of said grappling members comprising a jaw member and two drop legs mounted thereon, each of said grappling members being supported by a corresponding one of said pairs of carriages with each of said legs extending vertically through a predetermined one of said slots and mounted on a respective one carriage of said corresponding one pair of carriages between said one pair of said rollers on said carriage, and means for moving said carriages longitudinally of said boxes to thereby move said grappling members toward and away from each other.

2. In a grab, a frame including two elongated boxes including bottom walls having elongated slots formed therein and extending longitudinally thereof, two pairs of carriages mounted in said boxes and movable longitudinally thereof, each of said carriages comprising an elongated body member disposed longitudinally in said box, and a plurality of rollers rotatably mounted on said body member with predetermined ones of said rollers disposed at one end portion of said body member and others of said rollers disposed at the other end portion of said body member, each of said carriages of each of said pairs being mounted in a respective one of said boxes with said rollers on said carriage in engagement with said box for supporting said body member therein, a pair of grappling members, each of said grappling members comprising a horizontally disposed bar and two drop legs mounted thereon and projecting upwardly therefrom, each of said grappling members being supported by a corresponding one of said pairs of carriages with each of said legs extending vertically through a predetermined one of said slots and mounted on a respective one carriage of said corresponding one pair of carriages in a manner such that said horizontal bar of said grappling member extends transversely below said pair of carriages in vertical alignment with the portion of said body members in said pair of carriages disposed between said rollers mounted on opposite end portions of said body members, and means for reciprocating said carriages and grappling members in said :boxes.

3. In a grab, a frame including two elongated guide-housings disposed in parallel relation to each other, carriages mounted in said housings for movement longitudinally thereof, two grappling members connected to said carriages for movement therewith, and means for reciprocating said carriages relative to each other in said housings to thereby move said grappling members toward and away from each other, said means comprising a pair of sprocket wheels roa link member connecting one of said runs to one of said grappling arms, a second link member connecting the other of said runs to the other of said grappling arms, an elongated member slidably mounted on said one housing in parallel jecting downwardly therefrom, said grappling members being connected to said carriages for movement with the latter, and means for reciprocating said carriages relative to each other in said housings to thereby move said grappling members toward and away from each other, said means comprising a pair of sprocket wheels rotatably mounted below one of said housings in spaced relation to each other, an endless chain trained over said sprocket wheels to afiord two spaced runs between said wheels, two elongated rods slidably mounted on said one housing in parallel relation thereto below said housing, one of said rods having one end connected to one of said runs and the other end connected to one of said grappling arms, the other of said rods having one end connected to the other of said runs and the other end connected to the 1o other of said grappling arms, and means con nected to said chain for oscillating the latter to thereby cause said rods to be reciprocated relative to said one housing and effect movement of tending slot formed in each end portion thereof, 1

two pairs of elongated carriages mounted in said guide-housings, said two pairs of carriages being disposed in opposite end portions of said guidehousings with each of said carriages of each of said pairs being disposed in a respective end of one of said housings, each of said carriages comprising an elongated body member disposed in longitudinal alignment with the guide-housing within which said carriage is disposed, a plurality of rollers rotatably mounted in pairs on said body member, predetermined pairs of said rollers being engaged with the bottom wall of the housing within which said carriage is disposed to mov ably support said body member of said carriage thereon, and other pairs of said rollers being engaged with the top wall of the housing within which said carriage is disposed to retain said predetermined pair of rollers in engagement with said bottom wall of said housing, and other rollers rotatably mounted on said body members and engageable with the side walls of said housing within which said carriage is disposed to guide said carriage therein, grappling arms supported by said carriages for movement toward and away from each other, each of said grappling members being supported by a corresponding pair of said carriages and comprising a jaw member and two drop legs mounted on said jaw member, each of said drop legs extending through a corresponding one of said slots in the bottom of one of said housings and being mounted on said body member of one of said carriages between the rollers in one of said predetermined pairs disposed on said body member, and means for moving said carriages back and forth in saidhousings to thereby move said grappling arms toward and away from each other.

WALTER J. OLSON.

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

UNITED STATES PATENTS Number I Name Date 1,235,453 Ferris July 31, 1917 1,615,115 Durhan Jan. 18, 1927 1,869,893 Haddlesay Aug. 2, 1932 1,876,904 Francis Sept. 13, 1932 2,276,905 Windsor Mar. 17, 1942 2,337,176 Breslav Dec. 21, 1943 2,462,691- Thompson Feb. 22, 1949

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