US3192804A

US3192804A - Chain clamps

Info

Publication number: US3192804A
Application number: US225073A
Authority: US
Inventors: Petersen Christian; William L Becker; Emil A Allemeier
Original assignee: Petersen Manufacturing Co Inc
Current assignee: Petersen Manufacturing Co Inc
Priority date: 1962-09-20
Filing date: 1962-09-20
Publication date: 1965-07-06
Anticipated expiration: 1982-07-06
Also published as: GB990771A; DK107929C; DE1969093U; CH414495A

Description

July 6, 1965 Filed Sept. 20, 1

July 6, 1965 c. PETERSEN ETAL CHAIN CLAMPS 3 Sheets-Sheet 2 Filed Sept. 20, 1962 r cHR/s'T/A/v smess/v WILL/AM L. BECKER EM/L ,4. ALLEME/ER fld/ ATTORNEYS July 6, 1965 c. PETERSEN ETAL CHAIN CLAMPS 3 Sheets-Sheet 3 Filed Sept. 20, 1962 INVENTORS CHRIST/AN PETERSEN WILLIAM L. BECKER.

E'M/L A. ALLEME/E'R I MU ATTORNEYS United States Patent 3,132,894 CHAIN CLAMPS Christian Petersen, De Witt, Nehru, William L. Becker, Denver, Colo., and Emil A. Allemeier, Spencer-ville, Ohio, assignors to Petersen Mfg. Co., Inc., De Witt, Nehru, a corporation of Nebraska Filed Sept, 20, 1962, Ser. N 225373 4 Claims. (1. 81-66) This invention relates to clamping devices incorporating a length of chain as part of the clamping means thereof, and is particularly concerned with the provision of a wrench-type chain clamp adapted to be locked on a work piece and/or adapted to be used with a ratchetaction. Still further, the invention is concerned with improvements in clamping elements cooperating with a length of chain to provide for effective gripping of a work piece by the length of chain upon selected movement of the clamping elements.

Various types of clamping devices incorporating a length of chain as part of the clamping means thereof have previously been suggested. The most common and prob ably best known type of such devices are often referred to as chain pipe wrenches. In accordance with the prior suggestions in the field of chain pipe wrenches and the like, a pair of moveable members are normally incorporated and coupled together for selective adjustment, and a chain is secured to one member and engageable by the other for purposes of tightening the chain peripherally of a work piece. While tools constructed in accordance with such suggestions have proved satisfactory in some respects, they are generally subject to certain disadvantages, both from the standpoint of operating characteristics and from the standpoint of manufacturing costs. For example, with the prior constructions, it is necessary to provide a separate locking device, if any locking device is incorporated, to maintain the chain in desired engagement with the work piece. Moreover, Where there is an effective looping of the chain about the work piece in operation of tools constructed in accordance with prior suggestions, then either a separate jaw face must be used in the tool to cooperate engageably with the work piece, or the chain must be abruptly diverted laterally of the work piece at the point where the same is engaged by a clamping element cooperating therewith. In the former instance, manufacturing costs become substantial, and in the latter instance, if they chain is of sufficient length to accommodate work pieces which substantially vary in size, then there is always a length of free chain in the way of operating handles, or the like.

The foregoing discussion of prior suggestions relating to tools of the type with which the present invention is concerned presents only illustrative deficiencies, and it is to be understood that such discussion is not in any way intended to present all deficiencies, and is instead incorporated herein solely for the purpose of enabling a full comprehension of certain advantages of the construction provided hereby.

The present invention has as its primary object the provision of a chain-type clamping device which can be easily locked peripherally of, and on, a work piece, and/or which is adapted to be used with a ratchet-action, but which in addition provides for automatic locking and preferably release and permits the looping of the chain incorporated therein about the work piece for gripping thereof without requiring a separate jaw face or an abrupt lateral diversion of the unused portion of the chain.

Still further, it is an object of the present invention to provide a chain-type wrench having a pair of members movable toward one another to cause gripping of a work piece by a chain cooperating with the members and 3,192,894 Patented July 6, 1965 ice wherein one of the members has a claw portion releasably engageable with the chain and the other of the members has the chain attached thereto and is so constructed as to permit the chain to be passed thereby and maintained in a single plane without abrupt lateral diversion of the chain. Additionally, in this respect, it is an object of this invention to provide such a chain-type wrench wherein, if desired, the chain forming part thereof can be laterally abruptly diverted, if desired, to facilitate An even more specific yet important significant object.

hereof is to provide an arrangement of clamping elements and a length of chain cooperating therewith, which arrangement is readily adapted to replace the now conventional clamping jaws of a plier-type toggle wrench whereby the arrangement can be actuated by the toggle mechanism of such a wrench, and which arrangement, if desired, can also be utilized with other types of actuating mechanisms to increase the efi'iciency and convenience in operation thereof.

Still further, more detailed but significant objects hereof include: (a) the provision of a clamping arrangement and/ or a wrench construction conforming with the preceding objects and wherein an efiicient, inexpensive and easily operable release means is utilized to permit the rapid and trouble-free unlocking of the arrangement or wrench when it is desired to release the same from engagement with a work piece; (b) to provide such an arrangement or wrench construction wherein the chain forming part thereof can be either of the type having engagement pins or rollers between the links thereof or of the type engagement pins projecting laterally beyond the links thereof; (c) to provide such a wrench wherein a toggle actuating mechanism as disclosed in U.S. Patent No. 1,489,458 is utilized and the so-called fixed or stationary handle member thereof is formed as an integral chan-,

nelled piece having a forward claw portion releasably engageable with a chain provided on the wrench, while the so-called moveable handle thereof cooperates with a clamping element pivotally mounted with respect to the fixed handle, carrying the chain thereon, and having a recess therein through which the chain can pass when,

looped under the claw. portion of the fixed handle or handle member; (d) to provide such a wrench wherein the toggle actuating mechanism of the aforesaid U.S. Patent,

No. 1,489,458 is utilized, and the fixed handle carries the, chain at the forward end thereof and the movable handle cooperates with a clamping element pivotally mounted with respect to the fixed handle and having a claw portion thereon releasably engageable with the chain; and

(e) to provide such a wrench and/or clamping element;

conforming with all the preceding objects but which can be easily and comparatively inexpensively manufactured,

and which proves trouble-free in operation with continued use.

The invention lies in the combination, arrangement andv cooperation of elements and/ or parts provided hereby and incorporated in a clamping device constructed in accordance herewith. The invention will be better understood, and objects other than those set forth above will becomeapparent, when consideration is given to the following detailed description. Such description makes reference to the preferred and illustrative embodiments of the invention shown in the annexed drawings, wherein:

"FIGURE 1 is a side view, partially broken away and partially in section, of the wrench constructed in accordance wit-h the preferred embodiment hereof;

FIGURE 2 is a side view of the wrench shown in FIG- URE l with the components thereof in released position, as opposed to closed position;

FIGURE 3 is a side view, partially broken away and partially in section, of the wrench shown in FIGURE 1, but with the pair-ts thereof in partially released position, and with the chain thereof diverted laterally or doubled back;

FIGURE 4 is an end view of the wrench shown in FIG- URE 1, and shows the same with the parts thereof in clamping position and as viewed looking into the left of FIGURE 1;

' FIGURE 5 is a side view, partially broken away and partially in section, of a modified form of wrench constructed in accordance herewith, and presents the parts thereof in clamping position;

FIGURE 6 is a side view of the wrench shown in FIG- URE 5, but with the parts thereof in released position; and

FIGURE 7 is an end view bf the wrench shown in FIG- URE 5 as viewed looking into the left of FIGURE 5.

Referring now more specifically to the drawings, in the embodiment of FIGURES 1 through 4, hereinafter refrred to as the prefenred embodiment, the wrench shown therein is generally designated by the numeral 2. The wrench 2 includes a handle member 4 having a forward portion, generally designated by the numeral 6, and providing a stationary clamping element. A moveable clamping element 8 is mounted on the handle member 4, and a toggle mechanism comprising an elongated handle member 10 and a toggle link member 12 is incorporated. The

elongated handle member 10 is pivotally engaged at its a forward end lila to the moveable clamping element 3. The toggle link member 12 is pivotally engaged at its upper end 12a wit-h the elongated handle member 10 intermediate the ends thereof. The other end 125 of the toggle link member is engaged with the handle member 4, and particularly the abutment end 14a of the adjustment screw 14 which forms part of the handle member 4. Preferably the forward end 16a of the handle member 1% is bifurcated or forked at its forward or upper end 10a, and the moveable clamping element Shas a foot portion 3a disposed within the fork or between the bitfurcation arms. A pivot pin 15 having suitable enlarged heads at opposite ends thereof pivotally couples the haudle member 10 to the moveable clamping element 8. Similarly, the handle member 4 is preferably channelled shaped, as shown, and receives the projecting leg 81) of the moveable clamping element 3 within the channel thereof. Addition-ally, the moveable clamping element 8 is pivotally coupled with the handle member 4 by a pivot pin 18 having suitable enlarged heads at opposite ends thereof, which pivot pin passes through suitable apertures in the handle member 4 and projecting leg 8b.

The handle member l0, like the handle member 4, is preferably channelled and the upper end 12a of the toggle link member 12 is disposed in the channel of the handle member 10 and pivotally coupled with the handle member 16 by means of a pivot pin 20 which is similarto the

pivot pins

16 and 18 forming an additional but corresponding pivotal coupling. The end 12b of the toggle link member 12 has a foot 22 preferably secured thereto, and this foot, as noted above, engages the abutment end 14a of screw 14. The screw 14 cooperates with the threaded end portion 24 of handle member 4 whereby the length of the screw within the channel of the handle member 4 can be adjusted, and the position of the lower end of the toggle link member 12 can be selectively changed, as desired.

A spring means, preferably in the form of a coil spring, 26 is secured between the handle member 4 and the moverable clamping element 8, as shown, to urge the clamping element 8 away from the stationary clamping element provided at the forward portion 6 of the handle member 6.

In the preferred embodiment, a release lever 28 is incorporated. The release lever 28 is an elongated lever extending longitudinally and rearwardly in the space between the handle member if) and the toggle link member 12 in posit-ion to be engaged by a finger of a hand holding the wrench. The release lever 23 is pivotally coupled as by pivot pin 3t} within the handle member 10 and is provided with cam means in the form of a forwardly projecting tip 32 engageable with a projection 34 extending latertally of and in off-set relation to the body of toggle link member 12. With this construction, when the release lever 28 is rocked about its pivot, the handle members 4 and 19 are moved relatively away from one another.

' Exclusive of the particular form of the handle member 4, or at least the forward portion thereof, and exclusive of the form of the moveable clamping element 8, the wrench mechanism and toggle construction hereinabove described in detail conform substantially in all material respects with the construction described in United States Petersen Pa-tent No. 1,489,458, referred to above. Moreover, such construction, the operation thereof, and the specific operation of the release lever incorporated therein is well set forth in United States Patent No. 2,514,130 issued to Jones on July 4, 1950. As explained in both of such prior patents, closing of a wrench incorporating such a toggle mechanism is effected by moving the relatively moveable handle member it toward the relatively fixed handle member 4. This movement forces the upper end 12a of the toggle link member 12; to move inwardly toward the handle member 4. The pivot pin 20 also moves inwardly, and when such pivot pin has its central axis loved to the left of the axis A joining the center of pivot pin 16 and the pivot point of foot 22 on abutment end 14a of screw 14, the wrench is locked closed.

It will be appreciated that the specific operation of the wrench mechanism and toggle construction set forth in the aforesaid Unhed States patent concerns a tool having fixed and moveable jaw elements, whereas the present invention is concerned with a tool having a chain and fixed and movcable clamping elements cooperating with the chain whereby the chain provides the gripping portion of the arrangement. In fact, in its basic aspects, the provision of a chain-type clamping arrangement, as opposed to a jaw construction, per se, is a basic feature of the present invention. Still, for purposes of understanding in detail the operation of the toggle actuation preferably incorporated in'a tool construction in accordance herewith, the

aforesaid United States patents are adequate.

In the preferred embodiment of the instant invention, after the toggle mechanism has been closed and locked, easy and efiicient release or opening thereof can be achieved by moving the lower end of release lever 28 toward the base of the channel in handle member 1tli.e,, moving the release lever 28 to the position thereof shown in FIGURE 3. This movement causes the projecting tip 32 of the lever to engage the projection 34 on the toggle link member i2 and results in forcing the pivot pin 2% outwardly and to the right of the dead-center axis A. The aforesaid Jones patent discloses such an operation.

While the release lever 28 incorporated in the preferred embodiments hereof is pivoted on the handle member 10 and cams against the toggle link member 12 to cause release in the manner described above, it will be readily appreciated by those familiar with the toggle wrench art, that a similar release lever which functions in the same manner to produce the same result, can be mounted pivotally on the toggle link member to cam against the handle member 16, can be pivotally mounted on the handle member it to cam against the fixed handle 4, or in other suitable fashion whereby the same effects an easy release of the toggle mechanism from the locked position thereof.

Having now described at some length the preferred type of wrench construction and toggle actuating mechanism used therein in accordance with the invention, attention can be directed to the improved and novel clamping arrangement provided hereby.

In a generic sense, the invention is useable in any wrench having a pair of members moveable toward one another to effect gripping of a work piece. In the preferred embodiment, the members in this sense would be the forward portion of the handle member 4 and the moveable clamping element 8. One of these members, namely, the moveable clamping element 8 in the preferred embodiment has a forwardly extending arm portion generally designated by the numeral 40. A length of chain generally designated by the numeral 42 is attached to the arm portion 40 preferably at the forward end thereof. The chain 42 is adapted to be releasably peripherally engageable with a work piece such as that designated by the numeral 44. The other of the moveable members in this instance would be the forward portion 6, as noted above. By reference to FIGURE 1 and FIGURE 4, it will be noted that the portion 6 is bifurcated and includes a pair of arms or tines 6(a) and 6(b) forming a claw or claw portion preferably having a chain engaging recess. The recess, in detail, is formed by aligned substantially semi-circular grooves 46 in the respective arms 6(a) and 6(b).

The chain 42 utilized in the preferred embodiment includes a successive series of links 43 and 50 joined by pivot pins 52 which project laterally of opposite sides of the chain 42. Link chains of the type incorporating projecting pivot pins are well known, and accordingly further detailed discussion thereof appears unnecessary. It is significant to note, however, that the first pivot pin 52 (a) of the chain 42 is used in accordance herewith to pivotally connect the forward end 46(0) of the arm 40 with the chain, or conversely to pivotally connect the chain with such forward end. This construction feature is preferred, but of course, any pivot connection can replace pin 52(a), or a fixed connection can be used, although the same imposes certain limitations on operating characteristics.

In addition to having the chain 42 attached to the forward end theerof, the arm portion 49 of the moveable clamping element 8 has a longitudinally offset recess 6% formed therein intermediate the ends thereof and positioned to receive the chain 42 when the chain is looped under the claw portion formed at the forward end of the handle member 4. Accordingly, when the appropriate projecting pivot pin 52 is engaged within the recesses es of the respective arms 6(a) and 6(1)) of the claw portion, the unused length of the chain can be passed'in aligned relation to the gripping portion of the chain by and effectively through the arm portion 449. This operation may be described appropriately as permitting the chain to be maintained in a single plane, and without requiring any abrupt lateral diversion thereof. The advantage of having the chain pass by and free of the clamping arrangement and actuating mechanism therefor is obvious-the unused chain does not get in the way.

Notwithstanding the above, in certain instances, as where the tool is to be used in a minimum of space, it can be desirable to grip a work piece with the chain, but divert the unused portion thereof abruptly rearwardly substantially as shown in FIGURE 3. The construction of the present invention permits this alternative operation while also affording the above described advantageous operation of passing the chain by the clamping arrangement so that the same is completely free of the actuating or toggle mechanism and handles.

It will be appreciated that the above described tool is adapted to accommodate work pieces of varying size by mere adjustment of the length of the portion of the chain used for gripping purposes. Moreover, it should be apparent that where the tool is used with different Work pieces, there may be some necessity in adjusting the position of the rear or base end 12(1)) of the toggle link member 12 to permit proper locking of the toggle mechanism and the result proper gripping of the work piece by the used portion of the chain. The required adjustment in this regard can readily be obtained by movement of the screw 14, as will be noted by the alternate positions of the abutment end 14(a) thereof shown in FIGURE 3.

Here again, the manner in which the abutment screw 14 effects adjustment, or the manner in which a corresponding abutment mechanism can be operated is described in the aforesaid United States patents.

While the preferred embodiment has been discussed as the same would be used in tightly gripping a work cutter tool, and easy adjustment can be achieved for successive cuts, as desired.

The preferred embodiment possesses substantial advantage from the manufacturing standpoint in that the same incorporates a minimum number of components, and in that the relatively fixed handle member 4 thereof is formed as a single or one-piece body substantially entirely, or except for the adjustment screw 14 forming part thereof. Additionally, the moveable clamping element 8 can be easily formed as a single piece readily adapted for the described cooperation and disposition with other elements of the toggle mechanism which are already available.

Aside from the provision of a tool which embodies the preferred arrangement discussed, the invention also contemplates certain modifications including the modified construction shown in FIGURES 5 through 7 and hereinafter referred to as the modified embodiment. The

modified embodiment corresponds in most all respects to the preferred embodiment, and thus prime numerals have been used to designate component parts of the modified embodiment which are the same as components of the.

preferred embodiment unless otherwise noted below.

In the modified embodiment, the moveable clamping element is generally designated by the number 70, and

is shown as replacing the moveable clamping element 8 1 The moveable clamping of the preferred embodiment. element 79 is the clamping element having a claw portion 76(a) releasably engageable with the chain which is here designated by the numeral 72. The chain 72, in this instance, is a roller-type link chain preferably and includes a successive series of cooperating

links

74 and 76 which are joined together by pivot pins 78. The rollers 89, as well known, are rotatable on the pivot pins 78 between the opposed inner faces of the links 76. The claw portion 70(a) of the moveable clamping element 70 includes an arcuate recess 82 dimensioned to engage any roller to thereby releasably grip the chain 72 and tighten the same, in operation of the wrench, peripherally of a work piece.

Just as the moveable clamping element 70 has the claw portion 70(a) thereof and replaces the moveable clamping element 8 of the preferred embodiment, the handle member 4' of the modified embodiment has a forward portion 84 forming a forwardly extending arm or arm portion. The forward portion 84 is preferably a separate piece integrally attached to the main body of the handle member 4' as by yielding, and the handle member 4' is channelled to receive the base end 86(1)) of such In this inpiece, which is designated by the numeral 86. The piece 86 forming the forward portion or arm portion as described above, has the longitudinally offset recess 9% therein, and this recess corresponds to the recess 60 incorporated in the preferred embodiment construction. In essence, the attachment of the chain '72 to one of the clamping elements of the modified embodiment is the same as the attachment of the chain to one of such ele ments in the preferred embodiment. Specifically, the first pivot pin 78 is passed through a suitable aperture in the forward end 86(a) of the piece 86, and also through corresponding apertures in the first link 76. Naturally, the pivot pins 78 have enlarged heads to maintain the cooperative engagement of the chain with the piece 36 and the cooperative engagement between the chain links.

.The operation of the modified embodiment is essentially the same as the operation of the preferred embodiment. With the modified. embodiment, as the relatively moveable handle member 19' is moved inwardly toward the relatively fixed handle member 4', the recess 82 of the claw portion (70a) releasably engages a roller of the chain 72 thereby drawing the chain tight about a work piece between the attachment of the chain with the forward portion of the handle member 4jand the claw portion itself. In the preferred embodiment, the operation, during closing of the tool, is such that the forward portion 6 of the relatively fixed handle member 4 is effectively moved inwardly by virtue of the arm portioin 40 moving toward the same with forces transmitted to the moveable clamping element 8 by the toggle actuating mechanism. In a basic sense, the arrangement of parts andoperation of the modified embodiment is the reverse of the arrangement of the clamping parts and operation of the preferred embodiment.

. As should be apparent, the moveable clamping element 70 of the modified embodiment is dimensioned to be received in the channel of the handle member 4, as well as in the bifurcated forward end portion 19(a) of the handle member 10'. Additionally, it should be apparent, that while the first pivot pin '78 of the chain 72 has been described as corresponding to the other pivot pins of the chain 72, the first pivot pin can be a pivot shaft having bores extending transversely therethrough at opposite ends thereof and adapted to receive cotter pins to maintain the end or first links 76 pivotally coupled with the forwardly extending arm portion formed by piece 86.

Just as FIGURES 1 through 3 show the parts of a tool constructed in accordance herewith in closed, open and intermediate positions, respectively, FIGURES 5 and 6 show a tool constructed in accordance with the modified embodiment hereof and 'withthe parts thereof in closed and open positions, respectively.

Having now described in detail illustrative and preferred embodiments of the present invention, it will be apparent that various modifications, other than those specifically suggested herein, may be made within the scope and spirit thereof. At the same time, it will be apparent that the objects set forth at the outset of the instant specification have been successfully achieved. Accordingly, what is claimed is: a

1. In a wrench having a pair of relatively movable hand gripping members, the improvement which comprises one of said members having a forward end extending beyond the forward end of the other-of said members, said one member forward end forming a claw portion, a movable clamping element interconnecting said members, said movable clamping element including a leg pivotally connected at one end to the forward end of said other member and at its other end to said one member beneath said claw portion; said element including an integral armprojecting from said leg, a length of chain pivotally connected to the end of said arm, said chain being adapted to be wrapped peripherally of a work piece and to then extend past said arm, said arm having a portion thereof'oif-set from the plane of the remainder of said arm, said offset portion having a base portion out of alignment with said claw portion, said base portion and the remainder of said arm defining between them an opening in alignment with said claw portion whereby said chain is disposed within said opening when extending past said arm, said claw portion being engagcable with said chain upon manual operation of said members whereby said chain grips tightly against a major portion of the periphery of said work piece.

2. The improvement defined in claim 1, wherein said claw portion comprises a fork having recesses in the arms thereof, and wherein said chain is'a link chain having pivot pins therein projecting from opposite sides thereof and engageable by said recesses.

3. In a wrench having a pair of relatively movable hand gripping members, the improvement which comprises one of said members having a forward portion extending beyond the forward end of the other of said members, a movable clamping element interconnecting said members, said movable clamping element including a leg pivotally connected at one end to the forward end of said other member and at its other end to said one member beneath said forward portion, said element including an integral arm projecting from said leg, said arm terminating in a claw portion, a length of chain pivotally connected to the forward portion of said one arm, said chain being adapted to be wrapped peripherally of a work piece and to then extend past said forward portion, said forward portion having a section thereof offset from the plane of the remainder of said portion, said offset section having a base portion out of alignment with said forward portion, said base portion and the remainder of said forward portion defining etween them an opening in alignment with said claw portion whereby said chain is disposed within said opening when extending past said forward portion, said claw portion being engageable with said chain upon manual operation of said members whereby said chain grips tightly against a major portion of the periphery of said work piece.

4. The improvement defined in claim 3 wherein said chain is a link chain and wherein said claw portion comprises a hook adapted to fit within a recess formed by aligned side links of said chain.

References Cited by the Examiner UNITED STATES PATENTS 694,084 12/99 Bohner 81-67 1,174,764 3/16 Riesenberg til-68 1,209,049 12/16 Sheets 8168 1,670,583 5/28 Lawrence 81-64 X 2,514,130 7/50 Jones 81380 X 2,664,774 1/54 Harvie 3l380 X 2,793,433 5/57 Wheeler 30-100 X 2,932,226 4/60 Seppola 81-67 X WILLIAM FELDMAN, Primary Examiner.

Claims

1. IN A WRENCH HAVING A PAIR OF RELATIVELY MOVABLE HAND GRIPPING MEMBERS, THE IMPROVEMENTS WHICH COMPRISES ONE OF SAID MEMBERS HAVING A FORWARD END EXTENDING BEYOND THE FORWARD END OF THE OTHER OF SAID MEMBERS, SAID ONE MEMBER FORWARD END FORMING A CLAW PORTION, A MOVABLE CLAMPING ELEMENT INTERCONNECTING SAID MEMBERS, SAID MOVABLE CLAMPING ELEMENT INCLUDING A LEG PIVOTALLY CONNECTED AT ONE END TO THE FORWARD END OF SAID OTHER MEMBER AND AT ITS OTHER END TO SAID ONE MEMBER BENEATH SAID CLAW PORTION; SAID ELEMENT INCLUDING AN INTEGRAL ARM PROJECTING FROM SAID LEG, A LENGTH OF CHAIN PIVOTALLY CONNECTED TO THE END OF SAID ARM, SAID CHAIN BEING ADAPTED TO BE WRAPPED PERIPHERALLY OF A WORK PIECE AND TO THEN EXTEND PAST SAID ARM, ARM HAVING A PORTION THEREOF OFF-SET FROM THE PLANE OF THE REMAINDER OF SAID ARM, SAID OFFSET PORTION HAVING A BASE PORTION OUT OF ALIGNMENT WITH SAID CLAW PORTION, SAID BASE PORTION AND THE REMAINDER OF SAID ARM DEFINING BETWEEN THEM AN OPENING IN ALIGNMENT WITH SAID CLAW PORTION WHEREBY SAID CHAIN IS DISPOSED WITHIN SAID OPENING WHEN EXTENDING PAST SAID ARM, SAID CLAW PORTION BEING ENGAGEABLE WITH SAID CHAIN UPON MANUAL OPERATION OF SAID MEMBERS WHEREBY SAID CHAIN GRIPS TIGHTLY AGAINST A MOJOR PORTION OF THE PERIPHERY OF SAID WORK PIECE.