US2942269A - Bending tool - Google Patents

Description

June 28, 1960 Filed April 10. 1959 S. AUSTIN BENDING TOOL 2 Sheets-Sheet 1 INVENTOR Sa mueI Austin filmy/4 4 ATTORNEY June 28, 1960 s AUSTIN 2,942,269

BENDING TOOL Filed April 10, 1959 2 Sheets-Sheet 2 FIG. 20. 25 I9 34 @i 23 LQ L 40 .l I \\\I FIG. 5.

FIG. 4.

INVENTOR Samuel A usfin ATTORNEYS BENDING TOOL q Samuel Austin, 35 Colebrook St., Hartford 12, Conn.

Filed Apr. 10, 1959, Ser. No. 805,538

' Claims. 11. 1-422 The present invention relates to hand tools of the pliers type adapted to effect a bending operation; and is more particularly concerned with an improved tool for wrapping-a metal clip about a bundle of wires or the like simply, quickly and automatically.

In various assembly operations known at the present time, it is often desired to secure a bundle of wires or the like to one another, or to otherwise fasten two elements together. In wire bundling operations, e.g. the binding of a plurality of loose, insulated electric wires such as is commonly done in neon sign Wiring, electronics, telephone and similar applications, it has been the practice in the past to hand tape such a plurality of wires to one another. This procedure, which is tedious and often unsatisfactory from a structural point of view, has been supplanted in some instances by clipping-operations wherein a metal band is placed about the bundle of wires to produce a unitary multiconductor cable; but these clipping operations have ingeneral been characterized by the crimping of a metal band about such a bundle of wires, with the attendant possibility of rupturing the insulation of said wires; or in the alternative, have been characterized by the provision of a clip having a butt joint (such as will be described hereinafter) which has little mechanical strength. i

It has been recognized that the best form of; clip which can be employed for'bundling a group of conductors to one another takes the form ofa wrapped metal clip, i.e. one in which .the free ends of the clip overlap one another, in a manner analogous to the plural tape Wraps mentioned previously. Such wrapped clips, however, have not been widely employed heretofore inasmuch as the wrapping operation has necessarilyhad to be manual; and no tools have been available to expedite this manual clip wrapping technique. In particular, it will be appreciated that conventional pliers typetools are so constructed that the jaws thereof approach a center line together as the tool is actuated, whereby any attempt to use a conventional pliers in clip bending operations necessarily prevents a wrapped .clip from being formed since the proximity of the two jaws makes it impossible for one portion of a clip to be bent in overlyingrelation to another portion of that same clip;

The present invention, recognizing these deficiencies of conventional tools suggested heretofore as well as disadvantages of taping, crimping and clipping operations utilized in the past, is particularly concerned with a novel,

pliers type tool adapted to effect a true wrappingof a metal clip about a bundle of wires or the like. In this respect, therefore, the present invention is concerned with a pliers type tool having bending jaws and an associated mechanism so arranged that, upon actuation 'of the tool, one bending jaw is adapted to effect a bending operation and thereafter move out of the way to permit a subsequent bending operation by the other bending jaw of the tool. By using this tool, therefore, one seeking 'to produce a clipped bundle of wires can do so. by

a simple hand operation comprising a single squeezing 2 7 together of the tool handles; and this simple motion of the tool handles automatically produces a more complex motion of the tool bending jaws whereby said bending jaws operate in proper sequence to effect a clip bending and wrapping operation.

It is accordingly an object of the present invention to provide an improved bending tool of the pliers type.

Another object of the present invention resides in the provision of a hand tool adapted to produce a wrapped clip about a bundle of wires or the like.

Another object of the present invention resides in the provision of a pliers type tool so arranged that the jaws thereof approach a work location in sequence rather than simultaneously.

Still another object of the presentinvention resides in the provision of a pliers type tool having a pair of bending jaws so arranged and operated that one jaw is" adapted to effect a bending operationat a work location whereafter that one jaw is adapted to move away from the work location to permit a subsequent bending operation by the other jaw without interference from the first mentioned jaw.

Still another object of the present invention resides in the provision of a hand tool and associated linkage adapted to effect a reciprocating motion of at least one bending jaw on said tool, as said tool is actuated.

A further object of the present invention resides in the provision of a tool adapted to wrap a clip more quickly and efficiently than has been possible heretofore.

A still further object of the present invention resides in the provision of a hand tool designed to expedite the bundling ofwires and designed to permit the bundling pivot point, on one side of said pivot point," effects a similar motion of the operating portions of said handles dles of the pliers type tool are squeezed together,.the said.

located on the other side of said pivot point. Indeed; this forrn of mechanical motion is well known and ischar'acteristicof conventional pliers suggested heretofore; and it must therefore be understood that this form of structure and mechanical motion is contemplated in the subsequent description and appended claims when.- ever-the term pliers type tool is utilized.

a subsequent bending operation efi'ectedbythe other bending jaw. In providing for this operation, the toolof the present invention employs a movable bending jaw; on one of the operating handles mentioned previously,

associated with a linkage so arranged that as the hanmovable bending jaw is caused to quickly move to a work location at a time when the other bending jaw isl V relatively remote from said work location, whereafter said movable bending jaw moves away from that Work location as the .other bending jaw moves into the worklocation. The work location in particular can comprise a socket forming a unitary portion of the tool adapted. to receive a clip and bundle of wires, or .any other struc-' ture to be bent by the tool.

The foregoing objects, advantages, construction and operation of the present invention will become more readily apparent from the subsequent description and accompanying drawings, in which:

Figure 1A illustrates an unbent clip. of the type which may be employed in association with the tool of thepresent invention.

Figures 1B. and 1C illustrate clips which, may be formed from the structure of Figure 1A, with Figure 1B being particularly illustrative of an undesired form of bent clip, while Figure 1C is illustrative. of-the desired form of wrapped clip produced by the tool of the present invention.

Figures 2A through, 20 inclusive illustrate the im proved pliers type tool of the present invention in successive operation. V

Figure 3 is a 'view of the tool of the present invention taken on the side thereof reverse to the side shown in Figure 2A.

Figure 4 is a detail view of a portion of the tool taken on line 4-4 of Figure 3; and

Figure 5 is a further, detail view of a portion. of the tool taken on line 5-5 of Figure 3.

Referring now to the several figures, it will be. seen that, in order to produce a bundle of wires, a clip such as (Figure 1A) may be employed. This clip may, if desired, be of substantially U-shaped configuration initially, may comprise a relatively soft metal such as aluminum, and may have legs which are of the same or different lengths depending upon the degree of wrapping desired in the final clip. It should further be noted that the. metal clip shown in Figure 1A, and discussedhere. inafter, may have appropriate insulation thereon where an insulated clip is desired or required, or maybe fabricated of, suitable flexible materials including insulatingmaterials. The term clip used hereinafter, and in the appended claims, is therefore meant to include all of these various structures.

In a clipping operation, the bundle of; wires to-be secured to one another can be placed between the legsof the U-shaped clip 10, whereafter the free ends 10a and 10b of said clip can be bent toward one another to enclose the wires or the other structures to be secured. It will be appreciated that the bending operation described with regard'to free ends 1011 and 10b may be such as to produce a butt type joint (or indeed a crimped' joint); and such a butt type joint, which has been conventional heretofore, is in fact, illustrated in Figure 1B;

In, particular, it will be noted that the free ends 10a; andf10b of the clipshown in Figure 1B are disposed closely adjacent to one another along a'line 11 rather than being in overlapping 'relationto one another; and such :a butt type joint has been found in, practice to have little inherent strength whereby any stress placed'on the individual wires of a bundle retained by a clip such as that shown in Figure 1B causes a ready separation of the clip along the line 11, with the resultant considerable possibility that the wires will spread apart fromone another, and indeed disengage from the required or desired bundle.

It should be noted that whilethe'line 11 shown in. Figure 1B has been illustrated'as a substantially straight line, butt type joints of the, types intended to, be illustrated by Figure 13 can infact take other forms, whereby the two portions of the'clip interleave one, another along. a crenelated zigzag, or other irregular line; but, in all, such instances, the-characteristics of the butt type joint are nevertheless present, i.e. the facing portions of the clip. are merely juxtaposed to one another rather than overlapping one another.

The form of clip most desired. is that shown in Figure 1C; and this. particular clip may retaina bundle of wires 12 in a. cable. or assembled arrangement by a clip, having the free ends 10a and 10b physically. overlapping one another along a surface 13. It is. the, prime. purpose of the present invention to form a clip of the type shown in Figure 1C inasmuch as this sort of clip, which is effectively wrapped about the wires, exhibits the wrapped strength which has been associated heretofore with conventional taping operations wherein a length of tape is wrapped in successive layers about a bundle of wires. The present invention, however, and the tool to be described hereinafter, effects such a wrapped clip quickly and automatically by a. simple hand operation whereby the clip, of the type shown in Figure 1C, can be formed in a small fraction of the time normally required for hand taping.

It will be appreciated that a wrapped clip of the type shown in Figure 16 "cannot be formed by conventional pliers type tools. In particular, if a clip of the type shown in Figure 1A were to be placed between the jaws of a conventional pliers type tool and those jaws were then caused to move-toward one another, this movement is ordinarily such that the jaws approach one another at, the. same. time. The resulting clip must therefore, necessarily have either a crimpedconfiguration or a butt joint of the typev shown generally in Figure 1B. In order for a wrapped joint of the type shown in Figure 1C to be formed, however, the bending operation must be sequentialin nature whereby one free end of the clip, e.g. end10a, is first bent over the bundle of wires or the like, whereafter the second free end 10b of said clip is bent in overlying relation to the first bent end. Moreover, it willfbe appreciated that a simple sequential operation of the bending jaws is ordinarily not enough, since a jaw bending afree end such as 10a and thereafter remaining in place would tend to interfere with a later bending operation by another jaw seeking to bend free end 10b. Accordingly, a particular form of sequentialoperation is preferred, in that one bending jaw must bend a first portion of the clip and then moveout of the way to permit a subsequent bending operation of another portion, of the clip. These characteristic operations and motions are produced by'the tool of the present invention; and this structure and functioning of. said tool will become more readily apparent by reference to Figures 2 through 5' inclusive.

Referring now to the several Figures 2 through 5', it will be noted thatthe pliers type tool of, the present invention may comprise a pair of operating handles 15 and 16 cross-connected to one another at a pivot 17 located between the ends of'said. handles. The handle '16 extends beyond the pivot 17- as an elongated arm 18' having a unitarybending 'jaw 19 extending therefrom. The-jaw 19 is, as illustrated, of elongated configuration extendingtransverse, to the direction "of elongation of arm 18, wherefore the nose20 and underside 21 of'said' jaw :19 can bend one portion, of a clip, e.g. one of the legs ofthe" clip shown in Figure 1A.

The other handle 15. extends beyond pivot point 17 and takes the form of an enlarged block or head 22 havinga U-shaped depression 23' therein acting as a work locationor socket adapted to receive a clip such as 10 and'a bundle of wires such as 12 for the bending operations described previously. A portion of the head 22 may,.if desired, include an auxiliary member, as at 2311,,partially'sawed through and hardened, whereby one side of depression or socket 23 comprises a member. bent'slightly inward and acting as a fiat spring adapted to hold the clip 10 in socket 23 under light pressure. A spring 24 is disposed betweenv the armv 18 and head 22 to normally hold the, tool portions in the relative positions shown in Figure 2A; and it will be appreciated that operationof the tool, comprising a depression or squeezing. of handles 15 and 16 toward one another about pivot point, 17,. wil' cause a compression of spring, 24 whereby,,up,on release of the handles 15 and 16, the tool handles will spring-apart topermit another clipping operation,

fullyhereinafter. pp

.28, as illustrated.

The head 22 does not, per se, act as a bending jaw in the tool. Instead a bending jaw 25 bolted by bolts 26 toa channel shaped bracket 27 is provided; and said channel shaped bracket 27 extends alongboth sides of head 22 (see Figures 2A, 3 and 4) and is pivotally attached to said head 22 by a pivot 28. It will be noted therefore that upon pivoting of bracket 27 about pivot 28, the bending jaw 25 can be pivoted into and out of locations adjacent the uppermost portion of socket 23; and this mounting of bending jaw 25 therefore permits said bending jaw to describe a reciprocating motion with regard to socket 23, in the manner to' be discussed more Under normal conditions, the bracket 27 is maintained in such position that the bending jaw 25 is disposed to one side of the open end of socket 23 (see Figure 2A); and in particular, a spring 29 is disposed between bracket 27 and arm 22 to urge bending jaw 25 away from socket 23, with the rest position of jaw 25 being limited by a pin 30 extending outwardly from head 22 and engaging an outer fiat edge of bracket 27 at a position below pivot In order to provide a desired motion of bending jaw 25, upon simple movement or squeezing of handles 15 and 16 toward one another, the bracket 27 includes an operating arm 31 extending downwardly, as illustrated; and this operating arm may comprise an integral portion of bracket 27, or may in the alternative comprise an extending arm fastened thereto, whereby forces applied to the lower end of arm 31 tend to pivot bracket 27 about pivot 28 against the restraint of spring 29 thereby to move bending jaw 25 into a position over-. lying the top of socket 23.

This movement of bracket 27, through the agency of arm 31, about pivot point 28 is effected by a linkage 32. In particular, said linkage 32 comprises a substan-. tially L-shaped arm pivoted at a point 33 toarm 18, comprising the extension of. handle 16. Arm or linkage, 32 is normally urged'in-a clockwise direction about said pivot point 33 by a spring wire 34 fastened to the'upperrnost portion of arm 18 by means such as a nut and bolt 35, and engaging the L-shaped linkage 32 adjacent a lower portion thereof below pin 33, this arrangement being particularly shown; in Figures ZA-Cand; 5. The clockwise rotation'of linkage 32 is limited by a further. pin 36 extending outwardly from arm31 adjacent the lower portion thereof, and engaging a surface 37 formed asa, cut-out portion at the free end of linkage 32. The linkage 32 further includes a latching surface 38 extending upwardly from surface 37 adjacent said free'end and adapted to engage pin 36 in 'the mannerto be described; and the upper portion of linkage 32 describes a curved cam surface 39 adapted to cooperate with still a further pin 40, extending outwardlyfrom head 22 in. the manner to be described. e The actual operation of the tool shown in Figures 2 through 5' will become more readily apparent by a con sideration of Figures 2A, 2B and 2C in s'equence. Fig-, ure j2A illustrates the toolin a non-operating position, i.e. prior to a desiredclipping operation. Inthis position ofthe tool, the handles 15 and 16 are maintained in separated relation to one another by spring 24, and j the bending jaw 25 is held away fromsocket 23 by spring 299 The socket 23 istherefore open-and a clip such as; 10 containinga bundle of wires such as 12 may their be inserted into the socket 23 for a clipping operati011'.'.

. Inorder to produce'the clip shown;in Figure 1C, the

handles 15 and 16 are depressed in a continuous motion,

toward one another, i.e. in a conventional pliers type action. Figure 2B depicts the tool operation 'as the handles 15 and 16 are partially depressed toward one another. In particular, as the tool is manipulated from the condition shown inFigure 2A to that shown in Figure 2B, the arm 18 and head 22 are caused to approach one another. This'relative motion between arm 18 and head 22 causes the latching surface 38 of linkage 32 to engage pin 36 on arm 31, and to be held in engagement therewith due to spring wire 34, whereby, as the handles 15 and 16 are moved toward one another, surface 38 bearing upon pin 36 causes bracket 27 to pivot in a clockwise direction about pivot 28. As this operation proceeds, the arm 31 is of course moved away from stop pin 30 and the bending jaw 25 is rapidly moved into a position wherein it engages one side or leg of the clip 10 adjacent thereto and bends that side of clip 10 over the top of the bundle of wires 12, as shown in Figure 2B. It will be noted that during this bending operation by bending jaw 25, the other bending jaw 19 is still relatively remote from socket 23. I

In the initial portions of the operation depicted in Figure 2B, the pin 36 is located closely adjacent the junction of surfaces 37 and 38 on linkage 32. The upper cam surface 39 of said linkage 32 rides however upon pin 40 extending outward from head 22. Accordingly, as operating handles 15 and 16 are moved closer and closer to one another, the pin 40 forces linkage 32 downward about its pivot point 33 against the restraint of spring wire 34. As a result, latching surface 38 describes a downward sliding movement on pin 36 at the same time that it is engaging said pin to cause the pivotal motion of bracket 27 and bending arm 25, already described. At the time that bracket 27 is pivoted in'a clockwise direct-ion to the full extent desired, i.e. to the extent necessary to effect a bending operation of one side of the on the upper surface of linkage 32. Further depression,

of handles 15 and 16 toward one another will therefore have no elfect on the movement of bending jaw 25 since there is no driving engagement between linkage 32 and pin 36; andbending jaw 25 will be caused to remain at its quiescent position away from socket 23. As the handles 15 and 16 are fully depressed, bending jaw 19 slides across the upper portion of socket 23 to effect a second bending operation, i.e. the bending of the second portion or leg of the clip over the first portion already bent; and it will be noted that this second bending operation elfected by jaw 19 is done free of interference from bending jaw 25. Upon release of pressure on handles 15 and 16, spring 24 will cause those handles to move apart, whereafter spring wire 34 will lift linkage 32 back in the position shown in Figure 2A preparatory to a further clipping operation; and the bundle of wires having the wrapped clip thereabout can then be readily removed from the socket 23.

Summarizing the operation described, therefore, it will be noted that a wrapped clip is effected by a simple de-' pression or squeezing of the handles 15 and 16 toward one another. This simple motion causes one bending jaw to pivot into bending position adjacent a work location at a time when the other bending jaw is relatively remote from said work location; and as the handles of the pliers type tool are continuously moved toward one another, the first jaw snaps away'from the work location to permit a subsequent bending operation by the other jaw. In

actual practice, therefore, a wrapped clip may be formed by the simple expedient of squeezing the handles of a pliers type tool toward one another; and this simple permitsubsequent engagement of-the clip bythe other head.

It-will be appreciated that, during the clipping operation, the bundle of wires itself acts as a form about which the clip is wrapped and, in actual practice various numbers of wires may have to be bundled to one another. Itis particularly contemplated that anywhere from two to ten wires can be clipped together by the mechanism of the presentinvention. Adjustment means are provided in order to permit the operator of thetool to bundle any desired number of wires together. In particular, adaptor means are associated with socket 23, forming a movable floor for said socket whereby, as the number of wires to be clipped decreases, the floor of said socket may be moved upwardly to accommodate a'lesser number of wires,*with the resulting bundle of wires still'being arrangedso that the uppermost wires are adjacent the top of socket 23 to permit the'clip to be bent around thewires, over the top of that socket, and onto the top of the bundle of wires in the manner described. To this effect ('see Figures 3 and 4), the adaptor comprises an elongated bar 45 of L-shape, having a portion 45a extending into and across the bottom of socket 23. Adaptor bar 45includes an elongated slot 46 cooperating with a knurled set screw 47 extending through-said slot 46 into thread engagement with head 22. By simply loosening and thereafter tightening set screw 47, the adaptor 45 may be moved upwardly and downwardly, as illustrated by dotted lines 48 in Figure 3, to permit clips of various sizes and/or different numbers of wires to be *received by socket 23.

While I have thus described -a preferred embodiment of the present invention, it must be emphasized that the foregoing description :is meant to be illustrative only, and should not be considered limitative of my invention. Various modifications will be suggestedto those skilled in the art; and in particular, various alternative mechanical arrangements operating generally in accordance with the principles already described, can be effected. All such variations and modifications as are in accord with'the principles of the present invention are therefore'meant to fall within the scope'of theappended claims.

Having thus described my invention, I claim:

1. A pliers type tool adapted to wrap a clip about a bundle of wires, comprising a pair of operating handles pivoted to one another at a point between the ends thereof; a pair of bending jaws connected to corresponding firstends 'of'said pair of handles whereby manual movement of'theother endsof' said handles toward'and away from one another effects similar movement of said first ends relative to one another, at least one of said bending jaws being pivotally connected to one of said handles, and means responsive to movement of said handles toward one another for causing said one bending jaw to initially pivot on said one handle towardsaid other handle and thereafter away from said other handle as said handles are continuously moved toward one another.

2. The combination of claim 1 wherein said responsive means includes resilientmeans engaging said one bending jawfor normally urging said one jaw away from said other handle, linkage means extending between said one jaw and said other handle for moving said one jaw toward said other handle against the restraint of said resilient means, and means for rendering said'linkage means inoperative after said handles have moved toward one another beyond a predetermined point whereby said resilient means thereafter operates to move said one jaw away from said other handle.

3. The combination'of claim 1 including a projection on said one jaw, said responsive means. comprising linkage means extending from said other arm to removably engage. said projectionwhereby movement of said handles toward one another initially causes said linkagemeans to effect pivotal movemen-tof said one jaw, and, means. for disengaging said linkage means from said projection after said handles have passed a predetermined point in their movement toward one another.

4. The combination of claim 1 including a socket on said tool adapted to receive a clip to be bent, said socket beinglocated at a position between said bending jaws whereby said one jaw moves toward and thereafter away from said socket while the other jaw is relatively remote from said socket, whereafter said other bending jaw. moves to a position closely adjacent said socket upon continuous movement of said handles toward one another.

5'. The combination of claim 4 including resilient means on said tool adjacent said socket for resiliently retaining a clip Within'said socket.

6. A pliers type bending tool comprising a pair of arms pivotallyconnetced to one another at a position be tween the ends thereof, apair of bending jaws connected to corresponding ends of said arms, an openended socket on said tool adapted to receive a structure to be bent, and means responsive to continued movement of said arms toward one another about said pivotal connection for causing one of said jaws to move toward and thereafter away from the open end of said socket as the other of said jaws moves continuously toward said socket whereby said one jaw is'adapted to efiect an initial bending operation and'said other jaw is adapted to efiect a subsequent bending operation free of interference from said one jaw.

7. A readily portable manually operable bending tool comprising means defining a work location adapted to receive a device to be bent, a pair of bending jaws mounted on opposite sides of said work location, and hand operable operator means mechanically connected to both said jaws for simultaneously moving said jaws toward said work location, said operator means including means for causing one of said jaws to move toward said work location at a more rapid rate than the otherof said jaws whereby said one jaw is adapted to effect a bending operation at said work location in advance of a-subsequent bending operation efiected at'saidwork' 10- cationby the other of said jaws.

8.-A. bending tool comprising means defining a socket adapted to receive a device to be bent, a first bending jaw movably disposed adjacent one side of said socket, a second bending jaw movably disposed adjacent the other side of said socket, means for moving said second bending jaw toward said socket, linkage means extending from said second bending jaw to said first bending'jaw-and removably engaging said first jaw for moving said first bending jaw toward. said socket in response to movement of said second bending jaw toward said socket, said. linkage means moving said first jaw into a bending position at-sai'd socket whilesaid second jaw is remote from said socket, meansresponsive to movement of said second jaw toward said socket beyond a predetermined position for disengaging, said linkage means from said first jaw while. said second jaw is still remote from said socket, and spring means coupled to said first'jaw for moving said first jaw away from said socket upon disengagement of said linkage means therebyto permit sai'd'second jaw' to move'into a bending position at said socket.

9. The combination ofclaim -8 wherein said first jaw is pivotally mounted on said socket defining means, a first projection on said first jaw adapted to removably engage said linkage means, said linkage means including a cam surface, and a second projection extending from said socket defining means adjacent. said cam surface for movingsaid linkage means to a position of disengagement with said. first projection at said predetermined position of movement of said second jaw.

10. A, pliers type tool having a pair of handles adapted to be. manually pressed toward one another about a pivot connecting said handles, a block forming a unitary 375 portion of one of said handles on one side of said pivot,

said block including a recess adapted to receive work to be operated upon by said tool, a bracket pivot-ally attached to said block at one side of said recess, said bracket including a first jaw extending toward said recess and normally remote therefrom, a second jaw normally remote from said recess and extending from the other.

of said handles toward said recess at the other side of said recess, a linkage element movably attached to said other of said handles and extending into removable engagement with said bracket, whereby partial manual pressing of said handles toward one another causes said linkage element to pivot said bracket about its pivot point on said mlock thereby to move said first jaw to a position adjacent said recess while said second jaw is still remote from said recess, and means extending from said block and engaging said linkage element for moving said linkage element out of engagement with said bracket upon further manual pressing of said handles toward one another thereby to permit said second jaw to move to a position adjacent said recess unimpeded by said first jaw.

11. The combination of claim 10 wherein said bracket includes a pin extending therefrom, said linkage element including a latching portion engaging said pin.

12. The combination of claim 10 wherein said linkage element is pivotally attached to said other handle, and spring means extending between said linkage element and said other handle for normally urging said linkage element into engagement with said bracket.

13. The combination of claim 12 wherein said linkage element includes an elongated edge extending past said block, said means extending from said block and engaging said linkage element comprising a pin extending from said block and riding on said elongated edge during at least a portion of the movement of said linkage element relative to'said block.

14. The combination of claim 10 including adaptor means movably disposed in said recess for varying the effective size of said recess.

15. The combination of claim 10 including spring means attached to said bracket and normally urging said first jaw away from said recess whereby said spring means is operative, when said linkage element is moved out of engagement with said bracket, to move said first jaw away from said recess.

References Cited in the file of this patent UNITED STATES PATENTS 1,722,279 Davis July 30, 1929 2,097,955 Norton Nov. 2, 1937 2,391,891 Frankel Jan. 1, 1946 2,582,056 Mount Ian. 8, 1952

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