US3922935A

US3922935A - Automatic torquing tool

Info

Publication number: US3922935A
Application number: US545491*A
Authority: US
Inventors: Walter E Dahlem
Original assignee: Individual
Current assignee: Individual
Priority date: 1975-01-30
Filing date: 1975-01-30
Publication date: 1975-12-02
Anticipated expiration: 1992-12-02

Abstract

A thrust and/or twist torque wrench is provided in the form of the combination, with modifications, of a reciprocal motion automatic screwdriver and an angular motion torque-limiting wrench. The modifications include use of the body of an automatic screwdriver as the barrel or drive member of the torque-limiting wrench, and by alteration of the reciprocal shaft of an automatic screwdriver to have a spline therealong in place of a right-hand helical groove. The front end of the reciprocal shaft is adapted to receive a wrench socket or the like. The wrench is operable to turn a threaded fastener or the like to a condition of initial snugness by reciprocal motion of the handle of the wrench, following which angular motion applied to the handle applies torque to the fastener up to a predetermined torque limit defined by the wrench. The reciprocal shaft of the tool may be locked relative to the body and handle assembly for driving a threaded fastener in a reverse direction if desired.

Description

United States Patent l l n11 3,922,935

Dahlem 1 Dec. 2, 1975 l54l AUTOMATIC TORQUING TOOL [57] ABSTRACT [76] Inventor'- Walter P 700 Oceum seal A thrust and/or twist torque wrench is provided in the Beach Cahf' 90740 form of the combination, with modifications. of a re- [22] Filed: Jan. 30, 1 ciprocal motion automatic screwdriver and an angular motion torque-limiting wrench. The modifications inlzl] Appl' 5453491 clude use of the body of an automatic screwdriver as the barrel or drive member of the torque-limiting 2 s Cl 81/524 74/57; 145/53 wrench, and by alteration of the reciprocal shaft of an 51 im. cl. B25B 17/00 automatic Screwdriver to have 11 Spline therefllong in [58] Field of Search 81 /52.4 R, 57.39; 145/53, Place Of 11 right-hand helical groove The fwm end of 145/54; 173/163; 74/57; 144/32 the reciprocal shaft is adapted to receive a wrench socket or the like. The wrench is operable to turn a [56] References Cited threaded fastener or the like to a condition of initial UNITED STATES PATENTS snugness by reciprocal motion of the handle of the wrench, following which angular motion applied to the g f r' g 23; handle applies torque to the fastener up to a predeter 32789896 2/1972 cl ok eviiiiiigi'lj 11. 145/54 mined torque limit defined by the wrench" T recip' 3.8021517 4/1974 CoOke Yarb0mugh u 173N613 rocal shaft of the tool may be locked relative to the body and handle assembly for driving a threaded fastener in a reverse direction if desired.

10 Claims, 8 Drawing Figures US. Patent Dec. 2, 1975 v MI H- HW ii H AUTOMATIC TORQUING TOOL BACKGROUND OF THE INVENTION 1. Field of the Invention This invention pertains to hand tools for applying a selected maximum amount of torque to screws, nuts, bolts and the like. More particularly, it pertains to such tools in which one or more strokes of linear pushing motion of the handle produces rotation of the screw, e.g., for initial setting or drawing up of the same, and in which either rotary or linear motion of the handle produces the desired torque to the selected limit, after which further rotary or linear motion of the handle is ineffective to apply additional torque.

2. Review of the Prior Art While the present tool has utility in many areas of in dustry in connection with various types of threaded fasteners, the tool was developed initially to overcome problems and to produce economies in the plumbing industry. The utility of the tool is described with reference to the plumbing industry, and its advances and advantages over the prior art are set forth herein principally in this context, but only for the purposes of example rather than limitation.

In the past few years, significant advances have been made in the interconnection of sanitary plumbing pipes as used in virtually all types of structures. Formerly, sanitary pipes, then and now made of cast iron, were made with a bell-like hub at one end and with a plain end at the other. The plain and hub ends of adjacent pipes were mated, the joint packed with oakum or the like around the plain end within the hub, and the joint then filled with molten lead which solidified to form the finished joint. Now, sanitary pipes are hubless in that they have plain tublar configurations at the opposite end.

Hubless sanitary pipes are interconnected by various types of hubless connections, notable among which are the so-called stainless steel and iron connections. These connections use resilient elements in the nature of gaskets and threaded fasteners which must be tightened to specified torque levels in order that the assembled connection may pass, or be assured to pass, applicable inspections.

A stainless steel hubless sanitary line connection is comprised of a molded neoprene sleeve, a surrounding strip of pleated (accordian folded) stainless steel sheet, and two or more stainless steel hose clamps; see for example, U.S. Pat. No. 3,233,922. The adjacent ends of two hubless sanitary pipes are inserted into the opposite ends of the neoprene sleeve to abut an inwardly extending annular rib integral with the sleeve. The hose clamps, each of which includes a bolt-headed rotary worm, are then tightened securely by application of a selected amount of torque to the worms thereof. Sixty inch-pounds of torque is a typical torque level in the industry for a 2 inch connection to be assured of passing an inspection. In some communities, a building inspector will waive the static pressure test if he is assured that the fasteners of the connections are tightenedto established torque levels.

T-shaped ratcheting torque-limiting hand wrenches are commonly used by plumbers installing hubless sanitary lines; an example of such a wrench is shown in U.S. Pat. No. 2,826,107. Existing torque-limiting wrenches of this type, incorporating a hex socket or their driving stems for cooperation with the hex-headed worms or bolts of stainless steel or iron hubless connections, are not easily rotated through an arc of or more as required where the worm or bolt is being initially drawn snug prior to application of the desired level of torque. When the threaded fastener (in this context the worm of a stainless steel hubless connection is a threaded fastener akin to a bolt) is not snug, the ratcheting structure of these wrenches is not effective. Thus, existing T-shaped torque-limiting hand wrenches are very time consuming to use for the purposes of snugging or initially drawing up a threaded fastener. The ratcheting feature of these wrenches is very useful in tightening the fastener to the desired torque level after the fastener has been snugged down enough to enable the ratcheting assembly to function during reverse rotation of the wrench handle.

In limited circumstances, electric or pneumatic powered torque-limiting tools can be used to advantage. Such tools are expensive and substantially larger and heavier than the T-shaped hand wrenches, which have the advantage of being small so as to be carried in a belt tool holder or the like. In many, if not most plumbing situations in new construction, sanitary plumbing is installed before electric or pneumatic power is made available for later stages of construction.

It is thus seen that a need exists for a compact, inexpensive, manual, torque-limiting wrench which can be used easily and expeditiously to turn a threaded fastener to an initial state of snugness and, thereafter, to apply a selected amount of torque to the fastener.

The prior art considered in the preparation of this patent application includes U.S. Pat. Nos. 2,732,746, 2,826,107, 2,895,359, 2,979,089, 3,001,430, 3,208,316, 3,292,678, 3,535,958 and 3,789,896.

SUMMARY OF THE INVENTION This invention provides a compact, inexpensive, effective and reliable manually operable torque-limiting wrench for initially setting or snugging threaded fasteners and for applying a predetermined amount of torque to the fastener. The present wrench retains the advantages and desirable features of prior manual torquelimiting wrenches without their disadvantages. Thus, the present wrench preferably has an easily held T- shaped handle and a ratcheting feature which is useful in applying the desired limited amount of torque to a snugged or drawn up threaded fastener. The wrench relies upon linear rather than angular motion of the handle to initially drive the fastener to a snugged or drawn up state, thereby avoiding the disadvantage of ratcheting features of prior wrenches. The wrench does not require that a fastener initially be drawn up to any requisite state of snugness in order to assure that the correct amount of torque is applied to the fastener. The torque-limiting mechanism is associated with angular motion rather than linear motion and thus is not dependent on linear stroke of the handle or the extent of such stroke.

A preferred form of the present wrench uses principles and components which have proved, in the context of other tools, to be effective, reliable and economical.

Generally speaking, this invention provides a thrusttype torque wrench which includes an axially hollow body. A shaft is disposed in the body for rotation therein about the axis of the shaft and for axial movement relatively into and out of one end of the body.

One end of the shaft extends from the one end of the body and defines means adapting the shaft for torquetransmitting engagement with the head of a threaded fastener and the like. Means are provided, cooperating between the body and the shaft, for converting axial motion of the body along the shaft toward the one end of the shaft into angular motion of the shaft in one direction about its axis; these means also prevent angular motion of the body relative to the shaft in the same direction essentially irrespective of the axial position of the shaft in the body. There are means associated with the body which are operable essentially irrespective of the axial position of the shaft in the body for preventing effective application to the shaft of torque in excess of a selected torque value; preferably these means include a handle rotatably mounted to the body and torque limiting clutch means coupled between the handle and the body to fix the handle angularly on the body when torque applied to the handle is less than the selected torque value.

DESCRIPTION OF THE DRAWINGS The above-mentioned and other features of this invention are more fully set forth in the following detailed description of a presently preferred embodiment of this invention. which description is presented with reference to the accompanying drawings, wherein:

FIG. 1 is a cross-sectional elevation view of the wrench;

FIG. 2 is a cross-sectional elevation view of the spline bushing of the tool;

FIG. 3 is an end view of the bushing shown in FIG. 2;

FIG. 4 is a cross-sectional elevation view of the helix bushing of the tool;

FIG. 5 is a fragmentary plan view of a portion of the tool shown in FIG. 1;

FIG. 6 is a view taken along line 66 of FIG. 1;

FIG. 7 is a section view taken along line 77 of FIG. 1; and

FIG. 8 is a view taken along line 88 of FIG. 1.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT An automatic torquing tool 10 is shown in crosssection in FIG. 1. The tool is provided as a generally T- shaped torque-limiting wrench for use with threaded fasteners and the like. The term automatic is used with reference to tool 10 in the same context as the term is used with reference to push and/or twist type screwdrivers such as are manufactured and sold by The Stanley Works under the trademark Yankee" and also by others. A prototype of tool 10 was made using a ma jority of the components from a Stanley Works automatic screwdriver.

Tool 10 is composed principally of an elongate body 11 having an axial passageway 12 therein extending between and opening to front and rear ends 13 and 14 of the body, respectively. The body also includes a handle 15 which rotatably journals the exterior of the rear portion of body 11. The handle preferably is T-shaped as shown in FIG. 1, but it is within the scope of this invention that handle 15 can have any configuration desired so long as it is capable of accommodating within it a torque-limiting clutch assembly which cooperates with body 11 in the manner hereafter described.

An elongate solid shaft 17 is disposed within body bore 12 for both rotary motion about and reciprocal motion along its axis relative to body 11. A retainer ring 18 is carried by the shaft adjacent its rear end for sliding cooperation with a rear portion 19 of bore 12. The body defines an inner annular shoulder 20 at about the mid-length of bore 12, which shoulder separates bore rear portion 19 from an enlarged diameter forward portion 21. The forward end of bore portion 21 is closed by a nose cap 22 which journals shaft 17 and which is threaded into the extreme forward end 13 of the body. A key or set screw 23 cooperates between the body and nose cap 22 for preventing the nose cap from unscrewing itself out of the body during use of tool 10 as described below.

The rear end of bore 12 is closed by a disc-like plug 24 which is disposed in the rear end of a cylindrical passage 25 through the handle. Plug 24 is held in place between a shoulder defined by the handle and by retainer ring in a conventional manner as shown in FIG. 1. A helical compression spring 16 is disposed within body bore 12 between end plug 24 and the extreme rear end of shaft 17 for normally biasing the shaft out of the for ward end of the body. The forward limit of travel of the shaft relative to the body is defined by interference between shaft retainer ring 18 and the rear face of shoulder 20. In a presently preferred form of tool 10, a 3- inch linear stroke of shaft 17 within the tool is afforded. For the purposes of compactness of tool 10, the stroke of the shaft of tool 10 is somewhat less than the stroke normally afforded to the shaft of a comparably sized automatic screwdriver. It will be understood, however, that the amount of stroke afforded to shaft 17 relative to body 11 can be defined at any value desired.

A circumferential semi-circularly profiled groove 26 is formed in shaft 12 adjacent its forward end 27. A pair of locking balls 28 are loosely received in a pair of radial holes 29 formed in nose cap 22. The balls are maintained in holes 29 by a locking ring 30 which is rotatably engaged about the exterior of the nose cap, but ring 30 is prevented from movement axially of the nose cap by containment between the flanged front end of the cap and the extreme front end of the body. The inner surfaces of the locking ring define a pair of cam ming surfaces 31. The locking ring has two limits of angular position about the nose cap. In one position, lock ing balls 28 are permitted to move radially away from the axis of shaft 17 sufficiently to be clear of shaft groove 26, thereby enabling reciprocal movement of the shaft in the body. In the other limiting position of the locking ring angularly of the nose cap, cam surfaces 31 engage the balls and force the balls into registry with groove 26, thereby locking the shaft in its retracted position within the body as shown in FIG. 1. When locking balls 29 are not urged into registry with the bottom of groove 26, spring 16 is effective to bias the shaft to its fully extended position forwardly out of body 11, as described above.

As shown clearly in FIG. 1, a pair of helical grooves 33 are formed in the exterior of shaft 17 and extend from. the rear end of the shaft to proximate the front end of the shaft. These helical grooves are disposed in a left-hand or counterclockwise manner proceeding from the back toward the front of the shaft. Grooves 33 constitute components in tool 10 of a mechanism for converting linear motion of body 11 forwardly along the shaft into clockwise or right-hand rotation of shaft 17. The shaft also'defines along its extent a pair of straight spline grooves 34 which extend from the rear end of the shaft to proximate the front end of the shaft, i.e., to groove 26. Grooves 34 are disposed parallel to the axis of the shaft and are located at diametrically opposed locations on'the shaft; only one of grooves 34 is illustrated in the accompanying drawings. Grooves 34 constitute components in tool of a mechanism for preventing angular motion of the body clockwise relative to the shaft.

Grooves

33 and 34 cooperate with bushings 35 and 36, respectively, which are located circumferentially of the shaft within bore portion 21; see FIG. 1. Bushings 35 and 36 are illustrated in cross-sectional elevation in FIGS. 4 and 2 respectively. The interior of bushing 35 defines a pair of inwardly extending, helically configured ribs 37, the helix angle and depth of the ribs corresponding to helix angle and depth of shaft grooves 33. The exterior of bushing 35 has a larger diameter at one end 38 than at the other; in this portion of its length, the bushing defines a plurality of ratchet grooves 39 at regularly spaced locations about its circumference. Grooves 39 are aligned parallel with the length of the bushing.

Bushing 36 is similar to bushing 35 except that it defines a pair of straight inwardly projecting ribs 40 at diametrically opposed locations on its inner diameter and has an overall length less than that of bushing 35. Ribs 40 cooperate with shaft spline grooves 34. Bushing 36 has a greater outer diameter at one end 41 thereof than the other, and a plurality of ratchet grooves 42 (identical to ratchet grooves 39 in bushing 35) are provided in this portion of bushing 36. Bushings 35 and 36 are made of different length to assure that they are correctly positioned within body bore portion 21 during assembly of tool 10.

As disposed in bore portion 21 circumferentially of shaft 17, bushings 35 and 36 are maintained in position axially of the body by a key 43 received in body 11 so as to project partially into bore portion 21, but not so far as to interfere with rotation of shaft 17; see FIG. 1. For ease of description hereinafter, bushings 35 and 36 are sometimes referred to as helix and spline bushings, respectively, since they cooperate with the helical and

spline grooves

33 and 34 formed in shaft 17.

Body 11 is prevented from rotating in a clockwise direction relative to shaft 17 by a pair of

identical keeper elements

44 and 45 which cooperate between the body and bushings 35 and 36. The keepers allow ratcheting rotation of the bushings clockwise with shaft 17 relative to body 11, but prevent the bushings from moving counterclockwise relative to the body.

Keepers

44 and 45 preferably are stamped from sheet metal and are disposed at opposite ends of an elongate opening 46 formed through body 11 from bore portion 21 adjacent to the position of bushings 35 and 36 within tool 10. As shown in FIG. 5, which is a top plan view of tool 10 with sleeve 51 removed, opening 46 is in the configuration of an elongate rectangle aligned with the length of the body. A laterally extending recess 47 is defined in the body to open to opening 46 at each corner thereof.

Keepers

44 and 45 have a width defined to mate snugly within the width of opening 46, and each has an ear 48 at opposite corners of one end thereof for cooperating within recesses 47 to maintain the keepers in position axially within opening 46. Each keeper has an elongate slender finger 49 projecting from the end of the keeper opposite from ears 48. As shown in FIG. 5,

keepers

44 and 45 are disposed in opening 46 so that their fingers 49 are aligned with each other, as opposed to being disposed adjacent opposite sides of opening 46. The edges of fingers 49 are abuttable against the side surfaces of the ribs formed between

adjacent ratchet grooves

39 and 42 of bushings 35 and 36, respectively, to prevent the bushings from rotating in a counterclockwise direction relative to body 11. The location of fingers 49 to the side of the maximum projection of bushings 35 and 36 into opening 46, however, enables the bushings to rotate in a clockwise direction about their axes relative to body 1 l.

Keepers

44 and 45 are biased into ratcheting engagement with bushings 35 and 36 by a leaf spring 50; see FIG. 1, which is compressed between

keepers

44 and 45 and the inner diameter of a closure sleeve 51 which is disposed about the exterior of body 11 so as to extend from adjacent locking ring 30 to about the position of shoulder 20 within bore 12. Spring 50 is maintained in its proper position with opening 46 by cooperation of a button 52 or the like, carried by a spring, within a correspondingly configured aperture 52 in the sleeve. Sleeve 51 is held in position on the exterior of body 11 by a screw 54 as shown in FIG. 1.

As shown in FIGS. 1 and 6, shaft 17 adjacent its front end 27 carries at least one, and preferably a pair, of radially extending lugs 55 which cooperate within correspondingly configured recesses 57 formed in the front end face of nose cap 22. When the shaft is in its fully retracted position within body 11, lugs 55 and recesses 57 cooperate to prevent any rotation of the body relative to the shaft, particuarly counterclockwise rotation of the body relative to the shaft. It will be noted that nose cap 22 is precluded from rotating relative to body 1 1, particularly in an unthreading manner, by the cooperation of key 23 between the nose cap and the body. It will also be recalled the rotation of the body in a counterclockwise direction relative to the shaft is the nature of rotation of the body normally afforded or permitted by bushings 35 and 36 and

keepers

44 and 45. Thus, the cooperation of lugs 55 and recesses 57, when shaft 17 is fully retracted in the body and held there by cooperation of locking balls 28 in shaft groove 26, enables tool 10 to be used to unscrew a threaded fastener. The lack of this feature in tool 10 would permit body 11 to rotate counterclockwise relative to the shaft, thereby making it impossible to apply any effective counterclockwise torque to a threaded fastener for the purposes of unscrewing the same with the tool.

The extreme forward end of shaft 17 defines a shank 58 of square cross-section (see FIG. 6) which carries a spring-loaded detent ball 59 along one side thereof. Shank 58 thereby adapts tool 10 to receive and retain a conventional wrench socket 60 in a conventional manner. Preferably shank 58 is A inch square to cooperate with wrench sockets designed for use with a A inch screwdriver. It is thus apparent that tool 10 is usable with substantially any size nut or bolt when a correspondingly sized wrench socket is engaged with shank 58. It is also apparent that tool 10 may be used to drive screws and the like by engaging on shank 58 a suitable adapter which is in turn arranged to receive any suitable type and size of screwdriver bit.

It was noted above that handle 15 is rotatably mounted on the rear end of body 11. The outer rear end of body 11 has a hexagonal configuration as shown best in FIG. 7 so as to define hex flats 62 which are components of a torque-limiting clutch assembly 63 incorporated within handle 15. As shown in FIG. 1, handle 15 preferably is of a T-shaped configuration. the arms 64 of which define co-axially aligned bores 65 which are internally threaded adjacent their outer ends. The hexagonally configured rear end portion of body 11 is centered on the axis of bores 65. A fiat-bottomed spring follower 66 is disposed in each bore 65 for cooperation with the hex flats 62 on the rear end of the tool body. Each spring follower is forcefully urged into engagement with a flat surface 62 by a strong compression spring 67 located in a corresponding bore 65 between the spring follower and the spacer disc 68 inter posed between the outer end of the spring and a threaded plug 69 screwed into the outer end of each bore 65. The position of each plug 69 in its bore determines the force with which the corresponding spring follower 66 is biased into contact with the hexagonal configuration defined at the rear end of body 11.

Plugs 69 provide means for adjusting the limit of torque which tool is to apply to a threaded fastener in use. That is, when the reaction torque applied to shaft 17 by a fastener being driven by the tool is less than the torque limit set by adjustment of plugs 69, spring followers 66 cooperate with flats 62 to prevent rotation of handle 15 relative to body 11. Under these circumstances, either clockwise angular motion of the handle and the body therewith, or axial motion of the handle and body forwardly along shaft 17, is effective to cause shaft 17 to rotate in a clockwise direction. In the other hand, when the fastener reaction torque on shaft 17 equals or exceeds a predetermined value set by the bias of springs 67, the cooperation between spring follower 66 and flat surfaces 62 is no longer effective to prevent rotation of the body within handle 15. Under these circumstances, continued clockwise rotation of the handle, or the application of force on the handle in a forward direction along the length of the tool, is ineffective to cause any further clockwise rotation of the shaft and of the threaded fastener engaged by the tool. From the foregoing description it will be apparent that tool 10 may be used effectively and efficiently to initially turn down to an initial state of snugness any threaded fastener capable of being effectively engaged by a wrench socket or other driving implement coupled to the tool via shank 58. Initial driving of a threaded fastener can be accomplished by rotating the tool about its axis, but is more conveniently accomplished by unlocking shaft 17 axially of the tool via locking ring 30, and by reciprocating handle 15 and body 11 back and forth along the shaft. Forward motion of the body along the shaft produces the desired clockwise rotation of the fastener. At some point. forward thrust on handle 16 will be inconvenient to accomplish further tightening of the fastener. At this point, the user of the tool need only rotate the handle through an arc of 90 to 180 in a cyclic manner, taking advantage of the fact that body 11 will ratchet in a counterclockwise manner relative to shaft 17, so that further driving torque is applied to the tool only during clockwise turning of handle 15. It will be seen, therefore, that tool 10 can be used very effectively and efficiently to rapidly draw down and thereafter apply desired levels of torque to the threaded fasteners encountered in stainless steel or iron hubless sanitary connections as presently used exten sively in the plumbing industry. It is equally apparent that tool 10 can be used with the same degree of efficiency and dispatch to set or initially snug down and thereafter apply a predetermined amount of torque to substantially any threaded fastener.

Tool 10, as illustrated in the accompanying drawings, is arranged for driving and torquing right-hand threaded fasteners to a predetermined level. A tool according to this invention may be used to accomplish these same objectives with left-hand threaded fasteners. in which case the only modification required of the previously described structure is to provide a righthand helix in place of left-hand helix 33, to define helix bushing 35 so as to have oppositely handed helical ribs 37 therein, and to turn

keeper elements

44 and 45 over in opening 46 so that fingers 49 thereof lie along the top of the opening rather than the bottom of the recess as viewed in FIG. 5.

It was stated above that a prototype of tool 10 has been constructed using components of two commercially available products. Accordingly, handle 15 and the elements found within bores 65 thereof. as well as the rear end configuration of body 11, find substantially exact correspondence in a No. 902 RIDGID torque-limiting wrench as manufactured and sold by Ridge Tool Company, Elyria. Ohio. Similarly, the remaining structural features of tool 10 find counterparts in a No. A Yankee automatic screwdriver as manufactured by The Stanley Works, New Britain, Conn., but with the following material differences:

1. In tool 10, spline grooves 34 are provided in place of two right-hand helical grooves having the same pitch as left-hand helical grooves 33;

2. Spline ribs 40 are provided in bushing 36 in place of helically configured ribs for cooperating with the two right-hand helical grooves in the shaft of a conventional automatic screwdriver;

3. Key 23 of tool 10 is not found in a conventional automatic screwdriver;

4. Leaf spring 50 has only one operative position axially of tool 10, whereas in a conventional automatic screwdriver this spring has three different operative positions axially of the tool;

5. In a conventional automatic screwdriver, fingers 49 of

keepers

44 and 45 are aligned along opposite sides of opening 46 rather than co-axially aligned as shown in FIG. 5;

6. Lugs 55 and recesses 57 find no counterpart in a conventional automatic screwdriver; and

7. So far as known, an automatic screwdriver has not heretofore been provided with a ball detented shank 58 so as to adapt the tool for use with any one of a set of wrench sockets of corresponding size.

In view of the preceding description, it will be apparent that these modifications in the structure of a conventional automatic screwdriver, and the combination thereof with certain aspects of a commercially available torque-limiting wrench. provides a unique, compact and efficient tool which has enhanced utility in the industry for which it was originally conceived, as well as myriad other applications.

Workers skilled in the act to which this invention pertains will readily appreciate that variations and modifications in the previously described structures may be made without departing from the scope of this invention. Thus, it will be appreciated that torque-limiting clutch assemblies having configurations and features different from assembly 63 may be provided as desired, and that other mechanisms may be used for converting axial motion of the tool body along shaft 17 into angular motion of the shaft. The preceding description has been presented in furtherance of an explanation of the structural features and organization of a presently preferred embodiment of this invention, rather than as an exhaustive catalogue of all forms which this invention may take. Accordingly, the foregoing description should not be considered as limiting the scope of this invention.

What is claimed is:

l. A thrust-type torque wrench comprising an axially hollow body, a shaft disposed in the body for rotation therein about an axis of the shaft and for axial movement relatively into and out of one end of the body, one end of the shaft extending from the one end of the body and defining means adapting the shaft for torque transmitting engagement with the head of a threaded fastener and the like, means cooperating between the body and the shaft for converting axial motion of the body along the shaft toward the one end of the shaft into angular motion of the shaft in one direction about its axis and for preventing angular motion of the body relative to the shaft in the same direction essentially irrespective of the axial position of the shaft in the body, and means associated with the body operable essentially irrespective of the axial position of the shaft in the body for preventing effective application to the shaft of torque in excess of a selected torque value.

2. A tool according to claim 1 wherein the means associated with the body includes a handle coupled to the body and said means is operable for preventing effective application to the body of torque in excess of the selected torque value.

3. A tool according to claim 2 wherein the handle is coupled to the body for transmission to the body of thrust applied to the handle.

4. A tool according to claim 2 including means for adjusting the selected torque value.

5. A tool according to claim 2 wherein the means cooperating between the body and the shaft includes means for accommodating angular movement of the body about the shaft in the opposite direction.

6. A tool according to claim 5 wherein the means cooperating between the shaft and the body includes a helical groove in the shaft and an axial groove in the shaft.

7. A tool according to claim 6 wherein the helix of the helical groove is a left-hand helix, and including means engageable in the helical groove and cooperating with the body for converting axial motion of the body toward the one end of the shaft into clockwise rotation of the shaft about its axis.

8. A tool according to claim 5 including means for locking the shaft in an axially retracted position in the body, and means cooperating between the body and the shaft in said retracted position of the shaft for preventing angular motion of the body about the shaft in the opposite direction.

9. A tool according to claim 1 wherein the means defined at the one end of the shaft adapts the shaft for receipt and retention of a wrench socket and the like.

10. A tool according to claim 1 wherein the means associated with the body includes a handle coupled to the body for transmission to the body of thrust applied to the handle, and means cooperating between the handle and the body for fixing the handle angularly relative to the body when torque between the handle and the body is less than the selected torque value and for enabling angular motion between the handle and the body when torque therebetween equals or exceeds the selected torque value.

Claims

1. A thrust-type torque wrench comprising an axially hollow body, a shaft disposed in the body for rotation therein about an axis of the shaft and for axial movement relatively into and out of one end of the body, one end of the shaft extending from the one end of the body and defining means adapting the shaft for torque transmitting engagement with the head of a threaded fastener and the like, means cooperating between the body and the shaft for converting axial motion of the body along the shaft toward the one end of the shaft into angular motion of the shaft in one direction about its axis and for preventing angular motion of the body relative to the shaft in the same direction essentially irrespective of the axial position of the shaft in the body, and means associated with the body operable essentially irrespective of the axial position of the shaft in the body for preventing effective application to the shaft of torque in excess of a selected torque value.