US3546933A

US3546933A - Force indicating device

Info

Publication number: US3546933A
Application number: US744007A
Authority: US
Inventors: Bosko Grabovac
Original assignee: Individual
Current assignee: Individual
Priority date: 1968-07-11
Filing date: 1968-07-11
Publication date: 1970-12-15
Anticipated expiration: 1987-12-15

Description

Dec. 15, 1970 B. GRABOVAC vFORCE INDICATING DEVICE ,2.Sheets-Sheet 1 Filed July 11,1968

Dec, 15, 1970 a. GRABOVAC 3,546,933

I FORCE INDIGATING DEVICE Filed July 11, 1968 2 Sheets-Sheet 2 Joye/42 01" ,Bo-S/PO @rabouac 3,546,933 FORCE INDICATING DEVICE Bosko Grabovac, P.O. Box 1685, Altadena, Calif. 91001 Filed July 11, 1968, Ser. No. 744,007 Int. Cl. G01l 5/24 U.S. Cl. 73-141 8 Claims ABSTRACT OF THE DISCLOSURE A device arranged between the lever arm or handle of a hand tool and the hand of an operator that will signal the operator when a predetermined force is exerted, by his hand, through the device and onto the tool handle. The device includes an elongate hand-engaging body, a tool handle engaging pad carried by the body between the ends thereof and an adjustable signalling means within and carried by the body.

Throughout industry, where screw type fastening means are employed, there is an ever-increasing requirement and/ or demand that the forces applied to such fasteners be a predetermined force, sufficient to establish the holding or fastening effect desired, but not so great as to cause distortion and/or to set up undesired and detrimental stress in the fastening means and in the work with which said means are related.

To satisfy the above requirement the prior art has provided torque wrenches, that is, hand tools which have means incorporated therein to limit the amount of torque or the forces that can be applied therethrough and onto a screw fastening means with which they are applied, or

having means incorporated therein which indicate the force applied through the tool onto the fastening means or which signal or in other suitable manners indicate when the desired predetermined force to be applied to the fastening means is reached.

Those torque wrenches or tools provided by the prior art vary considerably in details of construction and mode of operation, but are alike or similar to each other in the following respects. First, they are large, heavy and cumbersome. Secondly, they are designed and constructed for special situations and are such that their use is materially limited by the environment in which the fasteners upon which they are to be used are found. Third, there exists a limited number of such tools, suitable for use in a limited number of special situations, as compared with the infinite number of situations where screw type fastening means are employed, with the result that there is only a relatively small number of situations where proper torquing or tightening of such fastening means can be effected with the tools presently available. Fourth, such tools are extremely costly as compared with conventional tools, and, fifth, they are extremely delicate and are such that they must be handled and treated with extreme care.

While special adapters and attachments have been provided for the torque wrenches provided by the prior art, to extend their usefulness and adapt them for other and different application than for those special applications for which they were designed, such adapters and attachments have, for the most part, proven to be complicated, costly and troublesome means to employ. Further, they frequently create such undesirable drag and uneven distribution of forces applied therethrough that the accuracy and intended function of the torque wrenches is rendered undependable or useless.

In those situations where torque wrenches cannot be advantageously employed, tightening of screw-type fastening means is effected with conventional hand tools and the forces applied is left to the sense of touch and United States Patent 0 3,546,933 Patented Dec. 15, 1970 judgment of the operator in whose hands the tools rest.

An object of my invention is to provide a means or device by or with which an operator, when using conventional hand tools for tightening screw-type fasteners and the like, can accurately and dependably apply a predetermined force onto and through the fastening means and/or work.

Another object of this invention is to provide a means or device of the character referred to which is engageable between the hand of an operator and a hand tool and which is such that when a predetermined force is applied onto the hand tool by the operator, such fact or condition is effectively communicated to theloperator through his sense of touch, hearing and/or sight.

Yet another object of this invention is to provide a means or device of the general character referred to which is such that the forces applied by the operators hand through the subject means or device, is applied to a related hand tool at the predetermined location or point on the tool and so that the mechanical advantage afforded by the tool is predetermined and the force applied to the fastening means or the work by the hand tool, upon the application of force by the operator through the subject means or device and onto the tool, can be easily and conveniently determined and limited.

It is an object of this invention to provide a means or device of the character referred to which is small, light and compact and is such that it can be advantageously arranged and positioned between an operators hand and a hand tool in substantially all situations where sufficient spaces is afforded to permit engagement of the operators hand on the hand tool.

It is yet another object of my invention to provide a means or device of the character referred to including an elongate body section carrying a tool-engaging, forceapplying pad, an elongate, small, narrow hand-engaging section adapted to extend transverse and to be engaged by the palm and/ or fingers of an operators hand and movably or shiftably carried by the body section and adjustable or variable force indicating means in and between the sections to limit and/or indicate when a predetermined force is applied therebetween.

Still another object of the invention is to provide another form of device of the character referred to includ ing an elongate body adapted to extend transverse of and to be engaged by the palm and/or fingers of an operators hand, a force-applying pad to engage a hand tool and adjustable or variable force indicating means in the body and connected with the pad to signal or indicate when a predetermined force is applied through the body and pad onto the tool.

- Yet another object of the present invention is to provide a device of the character referred to which involves a small number of easy and economical to manufacture and assemble parts and a device which is rugged and durable and a device which is highly accurate, effective and dependable in operation.

The foregoing and other objects and features of my invention will be fully understood from the following detailed description of typical preferred forms and applica tions of my invention, throughout which description reference is made to the accompanying drawings, in which:

FIG. 1 is an isometric view of a force indicator device for hand tools;

FIG. 2 is a perspective view showing the device illustrated in FIG. 1 in use, between the handle of a tool and an operators hand;

FIG. 3 is an enlarged, longitudinal, sectional view of my new device showing it related to the handle of a tool;

FIG. 4 is a sectional view taken as indicated by line 44 on FIG. 3;

FIG. is a sectional view taken as indicated by line 55 on FIG. 3;

FIG. 6 is a sectional view taken as indicated by line 66 on FIG. 3;

FIG. 7 is a sectional view taken as indicated by line 77 on FIG. 3;

FIG. 8 is an enlarged detailed sectional view of a portion of the structure illustrated in FIG. 3 and showing parts in another or actuated position;

FIG. 9 is an elevational view of a second form of my invention;

FIG. 10 is a longitudinal sectional view of the structure shown in FIG. 9;

FIG. 11 is a sectional view taken substantially as indicated by line 11-11 on FIG. 10;

FIG. 12 is a longitudinal sectional view of a third form of my invention;

FIG. 13 is a sectional view taken as indicated by line 13-13 on FIG. 12; and,

FIG. 14 is a longitudinal sectional view of another and fourth form of the invention.

Referring to the drawings and to the preferred form of the invention, shown in FIGS. 1 through 7, the force indicating device A includes a body B, a tool engaging pad P carried by the body, a hand engaging bar H movably or pivotally carried by the body and pressure responsive signalling means S carried by the body and operatively related to the bar H.

In addition to the foregoing, the device A is provided with adjusting means C to vary and adjust the signalling means S.

The body B is an elongate tubular part and, referring to FIG. 3 of the drawings, is shown extending horizontally, as having opening front and rear ends 10 and 11 and longitudinally extending, laterally spaced inner and outer sides 12 and 13 (shown at the top and bottom sides of the body in FIG. 3 of the drawings).

The body is shown as being cylindrical in cross-section and as having a cylindrical bore 14. In practice, the body B can be of any other suitable cross-sectional configuration.

The tool engaging pad P is a saddle-like part fixed to the inner side 12 of the body at a point spaced between the front and rear ends thereof, to project laterally inwardly from the body. The pad P is provided with a central, longitudinally extending, laterally inwardly opening, substantially V-shaped channel 15 and/or a transversely extending, laterally inwardly opening substantially V-shaped channel 16, which channel or channels define laterally inwardly divergent tool engaging surfaces adapted to straddle a hand engaging part of a hand tool and to thereby centralize the body with the said hand engaging part of the hand tool and to prevent lateral shifting and displacement of the device from engagement with the hand tool.

In FIGS. 2, 3 and 5 of the drawings, the hand tool is shown as a socket wrench W having an elongate lever arm with an outer, cylindrical, knurled handle or hand engaging part 21. The body B is shown arranged in spaced parallel relationship to the tool handle 21 with said handle engaged and seated in the longitudinal channel 15 of the pad.

The channel 15 and/or the channel 16 in the pad P is, or are, of sufiicient longitudinal extent to provide a desired, limited amount of longitudinal stability between the device A and the tool handle 21 and yet sufiiciently short in longitudinal extent so that forces transmitted through the device A and onto the tool handle 21 are concentrated at a predetermined point longitudinally of the tool 21 (within allowable tolerances).

In practice and as will be explained in the following, the tool handle 21 can be suitably marked or scribed, as at 22, to establish and provide a suitable reference for the proper positioning of the device A, with the tool,

when the device A is employed in combination therewith.

It will be apparent that the device A can be arranged to extend transverse the tool handle 21 with said tool handle engaged in the channel 16 of the pad when desired or circumstances require.

It will be further apparent that when the tool handle 21 is engaged in one or the other of the

channels

15 or 16 the other of said channels provides a window-like relieved portion to facilitate viewing the mark 22 on the tool handle 21 and proper positioning of the device on said tool handle.

The hand engaging bar H that I provide is an elongate member, having front and

rear ends

25 and 26 and is arranged in spaced relationship with and along the outer side 13 of the body B.

The front end of the bar H is pivotally connected to the front end portion of the body B by pivot means M and carries a socket element of the signalling means S at its rear end.

In the case illustrated the bar H is an elongate, laterally inwardly opening, U-shaped or channel shaped part with a laterally outwardly disposed longitudinally extending base portion 27 which occurs along the outer side of the body and laterally inwardly projecting longitudinal side portions or walls 28 which occur at opposite sides of the body B.

The bar extends a limited predetermined distance longitudinally beyond the outer end 11 of the body B and is provided with an end wall 29 which overlies the end 11 and carries the socket element of the means S referred to above and which will hereinafter be described.

The pivot means M includes a pair of axially alligned screw fasteners 30 with suitable bearing shoulders rotatably engaged in aligned openings 31 in the front end portions of the side walls 28 of the bar H and engaged and fixed in the adjacent opposite sides of the body B, as clearly illustrated in FIG. 4 of the drawings.

The bar H is of limited longitudinal and cross-sectional extent and is such that it can be easily, conveniently and comfortably engaged across the palm and/ or fingers of an operator in the general manner show in FIG. 2 of the drawings.

In practice and as illustrated, the bar H is preferably normally arranged with its longitudinal axis longitudinally outwardly divergent relative to the axis of the body, as illustrated in FIG. 3.

The signalling means S that I provide includes a longitudinally shiftable plunger 40 in the rear end portion of the body B, a socket part or member 41 carried by the end wall 29 of the bar H, a sear block 42 between the plunger and socket part and a compression spring 43 in the body and normally yieldingly urging the plunger longitudinally outwardly towards the socket part and to maintain the block in predetermined pressure engagement therebetween.

The plunger 40 is a simple, elongate, cylindrical part slidably engaged in the rear end portion of the body B and is provided with a longitudinally rearwardly opening recess 45 with a flat, axially rearwardly disposed bottom 46 and rearwardly and longitudinally outwardly divergent sides 47.

In practice, the recess can be of any desired crosssectional configuration, but is preferably square, with two opposite sides thereof extending parallel and the other two sides extending normal to the plane in which the bar H swings,

In practice and if desired, suitable retaining means can be provided to maintain the plunger from being displaced from engagement in the body. In the case illustrated, retaining means comprising an annular, radially outwardly opening recess 48 about the plunger and a radially inwardly projecting annular snap ring 49, carried by the body and projecting into the recess 48, is provided.

The socket part 41 is a simple metal part or any suitable configuration and fixed to the longitudinally forwardly disposed side of the end wall of the bar H in any suitable manner and is provided with a longitudinally forwardly opening recess 50 with a fiat, axially forwardly disposed bottom 51 and forwardly and longitudinally outwardly divergent sides 52.

The recess 50 is normally in axial alignment and in longitudinally spaced opposing relationship to the recess 45 and is preferably the same in cross-sectional configuration and in the same axial rotative position as the recess '45.

The scar block 42 is an elongate, normally longitudinally extending block corresponding in cross-sectional configuration with the

bottoms

46 and 51 of the

sockets

45 and 50 and having flat, forward and rearends 55 and 56 normally establishing flat bearing engagement on the opposing

bottoms

46 and 51 of the

sockets

45 and 50, as clearly illustrated in FIG. 3 of the drawings.

The spring 43 is a simple, elongate, helical compression spring arranged in the body B to extend longitudinally therein and has an outer end bearing on the flat inner end of the plunger 40 and is stopped at its other or front end by suitable means, such as the adjusting means C and so that it exerts a predetermined force or pressure longitudinally rearwardly through the plunger, block and onto the socket part.

With the signalling means S set forth above, the plunger, block and socket part remain in that set, axial alignment shown in FIG. 3 of the drawings until a predetermined lateral inward force is exerted onto the bar H to the socket part 41 and sear block 42, which force exerts an inward turning force onto and through the block which is greater than the axial rearward force exerted onto the block by the plunger and the spring. The moment when the noted turning force exceeds the noted rearward force by a predetermined volume, the block tips and turns inwardly in the manner shown in FIG. 8 of the drawings, against the resistance of the spring.

The plunger 40 is free to move forwardly against the resistance of the spring 43 and so that the construction is not locked and can move in the manner set forth above.

When the means S shifts from its normal position as shown in FIG, 3 to its actuated position shown in FIG. 8, the movement is rapid and sharp and is such that a sharp clicking sound is heard and a shock can be felt when the construction bottoms out or stops in its actuated position and the movement of the bar H relative to the body B can be seen, with the result that the operator of the tool is signalled and made aware that that force necessary to actuate or trigger the means S has been applied onto and through the device.

It will be apparent that the force necessary to trigger the device is applied onto the bar H by the application of inward forces on the bar by the hand of the operator of the device.

The pivotal movement of the bar relative to the body and therefore the lateral inward movement of the socket part relative to the plunger, is limited so that the block is not pivoted a sufiicient extent to move it over-center and to such an extent that it will not be returned to its normal, unactuated position by the force of the spring, after the force which caused it to actuate is relieved. In the case illustrated, the rear end of the bar is stopped in the manner set forth above and for the reason or purpose stated by the body B, as illustrated in FIG. 8 of the drawings.

The adjusting means C is shown as including a discshaped spring stop 60 in the body B and at the forward end of the spring 43, a plug 61 fixed in the body as by means of the screw fasteners 30 of the means M an axially movable adjusting bolt 62 threadedly engaged through the plug 61 and having a rear end engaging the spring stop 60 and a front end portion, with a head 63 projecting forwardly from and accessible at the forward end of the body, a series of calibrations 64 about the front end portion of the body, an indicator sleeve 65 with a mark 66 thereon threaded on the forward portion of the bolt and having front and rear portions outward of and within the front portion of the body forward of the plug 61 therein and a set screw 68 releasably securing the sleeve 65 in fixed position on the bolt.

By advancing or withdrawing the bolt so as to vary the extent to which the spring is compressed, the device can be zeroed in or set to actuate upon the exertion of a predetermined base force.

When it is set to actuate at such a base force, the sleeve 65 is advanced fore or aft on the bolt until the mark 66 thereon is aligned with a desired calibration 64 on the body and is then locked in position on the shaft by the set screw 68.

With a means C such as set forth above, it will be apparent that the force or forces required -to actuate the device are predetermined and set and that adjustment of the forces required to actuate the device can be easily and conveniently varied as desired or as circumstances require.

In practice, for example, the device can be designed, adjusted and set so that there are ten numbered calibration lines on the body B, spaced circumferentially so that upon moving the mark 66 on the sleeve 65 fixed on the bolt 62 from one calibration to the other varies the force required to actuate the device ten pounds.

By adjusting and setting the bolt and sleeve so that when the mark is on the first calibration line a force of ten pounds is required to actuate the device, the operator can easily and conveniently increase the force progressively ten pounds at a time and to as much as pounds by simply manually turning the sleeve and registering the mark with appropriate calibration lines.

When the device is used as intended and in combination with a hand tool, the lever arm and mechanical advantage afforded by the hand tool is first determined. In this respect, consideration is first given to where the device A is most suitably and most likely to be engaged with or on the hand tool. When this is determined, it may be desirable and advantageous to provide the hand tool with a reference mark, such as the mark 22 on the handle 21 of the wrench W in FIGS. 2 and 3 of the drawings. Still further, it may be desirable and advantageous to mark and indicate the length of the moment arm of the tool, such as is illustrated at 22 on FIG. 3 of the drawings.

With the effective moment arm of the tool established and marked, it is easy to determine how many pounds of force must be exerted onto and through the tool to gain and apply a predetermined force onto the work.

In the case illustrated, if the moment arm of the wrench W, from the axis of the socket to the mark 22, is ten inches and it is desired to apply 200 pounds of torque onto the fastener with which the wrench is related, it is easy to determine that twenty pounds of force should be applied to the wrench at the mark 22. By setting the device A to actuate at twenty pounds, for example, by setting the mark 66 on calibration line number 2 and then turning the wrench W with and by means of the device A, the application of 200 pounds of force on the fastener can be accurately accomplished.

In FIGS. 9 through 11 of the drawings, I have shown another or second form of force indicating device A.

The device A distinguishes from the device A by eliminating the bar H and by combining the functions and certain of the structural features of the bar H, pad P and signalling means S of the first form of the invention in a novel pad P.

In this second form of the invention, a plunger 40 with a recess 46 similar to the plunger 40 in the first form of the invention is slidably engaged in a tubular body B. The plunger 40, like the plunger 40 is acted upon and urged longitudinally in the body B by a spring 43, under control of adjusting means S in a manner similar to the first form of the invention.

In advance of the plunger 40 and fixed within the body B is a stop plug or block 70 with an elongate trans- 7 versely extending semi-circular guide channel 71, which channel opposes the socket 45' in the plunger 40'.

The body B is provided with a lateral access opening 72 in axial alignment with the channel 71.

The pad P, like the pad P, is provided with laterally outwardly opening tool engaging channels and 16, but rather than being fixed to the body B as is the pad P in the first form of the invention, it is provided with a stem 72 which extends through the opening 72 in the body and is slidably engaged or seated in the channel 71 in the stop block 70.

The stem 72 is provided with an annular radially outwardly opening groove 73 with a straight cylindrical bottom 74 equal in axis extent with the lateral extent of the bottom 46 of the socket or recess 45 in the plunger and longitudinally and radially outwardly divergent ends 75.

A sear block 42', similar to the block 42 in the first form of the invention is arranged between the plunger 40 and the stem with one end seated on the bottom 46 of the recess in the plunger and its other end seated on the bottom 74 of the groove 73 in the stem 72 on the pad.

In the preferred carrying out of the invention the end of the sear block 42 engaging the groove in the stem is provided with a rounded channel 76 to cooperatively receive and seat about the bottom portion of the groove 73.

The device A is designed and constructed so that the pad P is arranged and positioned substantially centrally or between the ends of the body B and so that the forces exerted onto and through the device and a related tool can be most conveniently and effectively distributed and controlled.

In operation, the device A functions in a manner similar to the device A. When a predetermined force is applied onto and between the body B' and the pad P, the stem 72 is urged transverse the axis of the body turning and/ or tipping the sear block 42' against the resistance of the spring 43 and transmitting audible and sensory signals to the operator of the device.

In the drawings I have illustrated a different form of spring setting and adjusting means C. However, since the particular form and construction of the means C can vary widely without departing from the spirit of this invention, I have chosen not to show the means C in detail and will not burden this disclosure with a detailed description thereof. It will suffice to say that the means C' is such that it will perform similar functions and provide the same end results as the means C in the first form of the invention.

In FIGS. 12 and 13 of the drawings I have shown another or third form of the invention. In this third form of the invention the device A includes a body B bar H pad P signalling means S and spring setting and adjusting means C In this third form of the invention, the means S rather than involving a scar block as in the first form of the invention (and second), involves a cam-type of triggering means including a cam post 80 on the bar H remote from the pivot means M which connects the bar to the body B and which depends into the body. The post 80 is provided with an elongate, vertical, axially forwardly disposed cam surface 81 with a central lobe defining a forwardly and downwardly disposed concaved seat portion. Arranged within the forward portion of the body is a bell crank 82 with a forward vertical leg 83 and an upper leg 84 projecting rearwardly from the upper end of the forward leg. The lower end of the forward leg 83 is pivotally mounted in the body forward of the cam post. The upper leg extends rearwardly past the post and connects with the forward end of a tension spring 85, the rear end of which is connected with the means C The bell crank, at the junction of the

legs

83 and 84, rotatably carries a roller-type cam follower which follower normally engages and rests in the seat portion of 8 the cam surface 81. The spring normally yieldingly urges and maintains the cam follower in the above-noted unactuated position on the cam surface.

In the third form of the invention, actuation of the signalling means is effected by downward pressure applied on the bar H and cam post which is suflicient to urge the lobe of the cam surface downwardly past the spring loaded follower. Actuation of the means S like actuation of the means S, in the first form of the invention, is subject to delicate and accurate control by a thorough adjustment of the spring and the means C and is such that the moment the force necessary to elfect actuation is reached, operation of the device is rapid and sharp and provides those audible, sensory and/ or visual signals necessary to inform the operator of the fact that it has actuated.

The means C in this third form of the invention, like the means C in the first form of the invention, is such that it permits adjustment and setting of the spring 85, as desired and as necessary for carrying out the invention.

Since the means C can vary widely in form and construction without departing from the spirit of this invention and since the means C illustrated is only typical of the type of means that might be advantageously employed, I will not burden this disclosure with further detailed consideration thereof.

In FIG. 14 of the drawings I have shown a fourth form of my invention wherein the device A is similar in most respects to the first form of the invention, the principal distinction being that this last form employs a tension spring rather than a compression spring and those modifications of the basic structure employed in the first form of the invention which are necessary to make possible the use of a tension spring are included.

In this last form of the invention, the element 40 with the sear block socket or recess 45 therein is fixed in the body B and is provided with a central, axially extending opening 80. The scar block 42 is provided with an axially extending stem 81 which extends freely through the opening 80 and which is connected with its related end of the tension spring 43 The other end of the spring 43 is connected with the adjusting means C which means distinguishes from the means C in that it is designed in a manner suitable to vary and adjust the tension of the spring 43.

In this fourth form of the invention the end wall 29 of the bar H has a fiat portion on which the block 42 normally seats and is provided with a shoulder to engage and tip the block when the bar is urged toward the body. With this relationship of parts, the socket 41 provided in the first form of the invention is formed integrally with the bar.

When the structure shown in FIG. 4 is actuated by the application of force on the bar H and the force of the tension spring '43, which normally maintains the block 42 in its unactuated position, is overcome, the block tips and the bar H moves sharply and rapidly in the same manner that the block 42 and bar H in the first form of the invention tip and move.

Finally, in this fourth form of the invention, 1 have shown the centrally located pad P pivotally mounted on the body B on an axis extending transverse the axis of the body and for the purpose of showing and making it understood that the pad need not be movably fixed to the body as is shown in the first and third forms of the invention. Pivotally mounting the pad can be extremely advantageous and desirable for many circumstances since it permits full bearing support of the device on a tool handle and assures application of force on the handle at the proper location, even though the device, for any reason, is not in parallel alignment with the handle on a vertical plane.

It is to be understood that in the second form of the invention, the post on the pad P is free to rotate in the body and that the pad is, therefore, pivotally mounted and free to turn on a vertical axis. This function allows for extensive misalignment of the device on a horizontal plane without adverse elfect.

While I have not shown a pad pivotally mounted on both horizontal and vertical axes, for instance a structure combining the forms of pad mounting means in FIGS. and 13, with their attending functions, it will be apparent that such a structure could be provided without departing from the spirit of this invention.

Having described only typical preferred forms and applications of my invention, I do not wish to be limited or restricted to the specific details herein set forth, but wish to reserve to myself any modifications and/ or variations that may appear to those skilled in the art and which fall within the scope of the following claims.

Having described my invention, I claim:

1. A force indicating device adapted to be engaged in the hand of an operator and to engage a lever arm portion of a hand tool and to signal the operator when the the force applied by his hand through the device and onto the tool reaches a predetermined magnitude, said device including an elongate body having front and rear ends and inner and outer sides and engageable across the palm and/ or fingers of an operators hand, with its outer side disposed away from said operators hand, tool engaging means projecting laterally from the outer side of the body at a location substantially intermediate the ends thereof whereby the force exerted onto and through the body of the operators hand is resolved at said tool engaging means for transmission onto a related hand tool and signalling means carried by the body to generate and transmit a signal to the said operator when the force applied through the device and onto a tool reaches a predetermined magnitude, said signalling means including a spring loaded trigger mechanism between the body and a movable force-load carrying part.

2. A device as set forth in claim 1 wherein said movable force-load carrying part is an elongate bar positioned adjacent the inner side of the body to extend in substantially parallel spaced relationship therewith and to occur between the body and the operators hand, pivot means connecting one end portion of the bar to an adjacent end portion of the body and a part of said trigger mechanism carried by the bar at a point remote from the pivot means.

3. A device as set forth in claim 1 wherein said movable force-load carrying part is an elongate post intermediate the ends of the body and having an outer portion projecting outwardly from the outer side of the body and carrying the tool engaging pad and an inner portion within the body and carrying a part of said trigger mechanism.

4. A device as set forth in claim 1 wherein said movable force-load carrying part is an elongate bar positioned adjacent the inner side of the body to extend in substantially parallel spaced relationship therewith and to occur between the body and the operators hand, pivot means connecting one end portion of the bar to an adjacent end portion of the body and a part of said trigger mechanism carried by the bar at a point remote from the pivot means, said trigger mechanism including a plunger in the body with an axially opening recess with a flat bottom at one end, said part carried by the bar having a socket with a fiat bottom spaced from and opposing the recess and normally in axial alignment therewith, an elongate sear block with flat ends between said plun ger and part with its end opposing and normally in flat engagement on the flat bottoms and a compression spring in the body engaging the other end of the plunger to yieldingly urge the plunger toward the block and said part whereby said bearing engagement between the ends of the block and the flat, opposing bottoms is yieldingly maintained and pivoting of the bar relative to the body is thereby yieldingly prevented.

5. A device as set forth in claim 1 wherein said movable force-load carrying part is an elongate bar positioned adjacent the inner side of the body to extend in substantially parallel spaced relationship therewith and to occur between the body and the operators hand, pivot means connecting one end portion of the bar to an adjacent end portion of the body and a part of said trigger mechanism carried by the bar at a point remote from the pivot means, said part of the trigger mechanism carried by the bar including an elongate came extending transverse the axis of the body and having a lobe with a side disposed obliquely to the direction of pivotal movement of the bar, said trigger mechanism further including a cam follower shiftably carried by the body and normally engaging said side of the lobe and spring means normally yieldingly urging the follower into pressure engagement on the cam to yieldingly inhibit movement of the cam lobe relative to the follower and thereby yieldingly prevent pivotal movement of the bar relative to the body.

6. A device as set forth in claim 1 wherein said movable force-load carrying part is an elongate bar positioned adjacent the inner side of the body to extend in substantially parallel spaced relationship therewith and to occur between the body and the operators hand, pivot means connecting one end portion of the bar to an adjacent end portion of the body and a part of said trigger mechanism carried by the bar at a point remote from the pivot means, said part of the trigger mechanism carried by the bar including an elongate cam extending transverse the axis of the body and having a lobe with a side disposed obliquely to the direction of pivotal movement of the bar, said trigger mechanism further including a cam follower shiftably carried by the body and normally engaging said side of the lobe and spring means normally yieldingly urging the follower into pressure engagement on the cam to yieldingly inhibit movement of the cam lobe relative to the follower and thereby yieldingly prevent pivotal movement of the bar relative to the body, said cam follower being carried by a bell crank having one leg pivotally mounted in the body, said spring means including an elongate tension spring extending longitudinally in the body having one end fixed to the end of the other leg of the bell crank and its other end fixed to a longitudinally shiftable screw actuated adjusting means carried by the body.

7. A device as set forth in claim 1 wherein said movable force-load carrying part is an elongate post intermediate the ends of the body and having an outer portion projecting outwardly from the outer side of the body and carrying the tool engaging means and an inner portion within the body and carrying a part of said trigger mechanism, said part carried by the post extending transverse and intersecting the axis of the body and formed with an annular recess with a straight cylindrical bottom and inclined ends, said trigger mechanism further including an elongate plunger slidably engaged in the body with one end spaced from and opposing the part with the recess and having a socket with a flat bottom in said one end, an elongate sear block arranged centrally within the body in parallel relationship therewith and between said part and the plunger and having a fiat end normally establishing flat bearing engagement on the flat bottom and having a semi-circular channel in its other end normally establishing uniform seated engagement about the one-half of the straight cylindrical bottom opposing said plunger, and a compression spring in the body engaging the other end of the plunger and normally yieldingly holding the sear block in alignment and pressure seated engagement with and between the straight and fiat bottoms.

8. A device as set forth in claim 1 wherein said movable force-load carrying part is an elongate bar positioned adjacent the inner side of the body to extend in substantially parallel spaced relationship therewith and to occur between the body and the operators hand, pivot 11 means connecting one end portion of the bar to an adjacent end portion of the body and a part of said trigger mechanism carried by the bar at a point remote from the pivot means, said part of the triggering means carried by the bar having a fiat surface normal to and intersecting the central axis of the body and a shoulder projecting on the flat surface spaced from the axis of the body toward said bar, the trigger mechanism further including an elongate plug in the body with an end spaced from and opposing said fiat surface, a central axially opening conical recess in said one end of the plug and a central opening communicating between the bottom of the recess and the other end of the plug, an elongate cylindrical sear block with flat ends arranged in axial alignment with the body between the said flat surface and the plug and having one end normally establishing flat bearing engagement on said fiat surface and positioned adjacent said shoulder and its other end seated in said conical recess, an elongate stem on said other end projecting freely through the said opening and a tension spring in the body and connected with and normally yieldingly urging and holding the sear block seated in the recess in axial alignment with the body.

References Cited CHARLES A. RUEHL, Primary Examiner US. Cl. X.R. 73139