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Publication numberUS3890859 A
Publication typeGrant
Publication date24 Jun 1975
Filing date9 Aug 1974
Priority date9 Aug 1974
Publication numberUS 3890859 A, US 3890859A, US-A-3890859, US3890859 A, US3890859A
InventorsGrabovac Bosko, Vuceta Ivan N
Original AssigneeCons Devices
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Torque driver tool
US 3890859 A
Abstract
A torque driver tool comprising an elongate tubular body with front and rear ends, a block in the front end of the body, an elongate drive shaft rotatably engaged in the block and having a work-engaging head forward of the block and a rear end in the body, a thrust between the shaft and block and novel clutch means comprising a driven plate with a rear surface having radially extending channels arranged rearward of the block, a thrust bearing between the block and drive plate, means coupling the shaft and drive plate, radially extending cam parts in said channels with convex portions projecting rearwardly from said surface, an axially shiftable drive plate with a front surface having a radially extending channel and spaced from the driven plate, a radially extending drive bar fixed in the body and having a portion engaged in the channel in the drive plate, spaced ball bearings between the front and rear surfaces and engaged with and between the bar and convex portions of the cam parts and spring means normally yieldingly urging the drive plate toward the driven plate under predetermined pressure.
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Description  (OCR text may contain errors)

United States Patent Grabovac et al.

[451 June 24, 1975 1 1 TORQUE DRIVER TOOL [75] Inventors: Bosko Grabovac, Mission Viejo;

Ivan N. Vuceta, San Gabriel, both of Calif.

[73] Assignee: Consolidated Devices, Inc., El

Monte. Calif.

[22] Filed: Aug. 9, 1974 [21] Appl. No.: 496,099

[52] US. Cl 81/52.4 R [51] Int. Cl. B25b [58] Field of Search 81/524 R, 52.5; 64/29 [56] References Cited UNITED STATES PATENTS 2,968,979 l/l96l Aijala 81/525 X 3,119,247 l/1964 Grabovac... 64/29 3,695,059 10/1972 Laubach 64/29 3,772,942 11/1973 Grabovac 81/525 Primary E.raminer.lames L. Jones, Jr. Attorney, Agent, or Firm-Georges A. Maxwell [57] ABSTRACT A torque driver tool comprising an elongate tubular body with front and rear ends, a block in the front end of the body, an elongate drive shaft rotatably engaged in the block and having a work-engaging head forward of the block and a rear end in the body, a thrust between the shaft and block and novel clutch means comprising a driven plate with a rear surface having radially extending channels arranged rearward of the block, a thrust bearing between the block and drive plate, means coupling the shaft and drive plate, radially extending cam parts in said channels with convex portions projecting rearwardly from said surface, an axially shiftable drive plate with a front surface having a radially extending channel and spaced from the driven plate, a radially extending drive bar fixed in the body and having a portion engaged in the channel in the drive plate, spaced ball bearings between the front and rear surfaces and engaged with and between the bar and convex portions of the cam parts and spring means normally yieldingly urging the drive plate toward the driven plate under predetermined pressure.

12 Claims, 11 Drawing Figures B A 10 Ja -1'1 a4 afi 4 4; 1 m w e ,4 //V//////// \R\\\ 12 3 5/ H] w l lii I M J 1; 1 425 /////f i l E 8 4(9 /0 ,i I, L49 6 TORQUE DRIVER TOOL In the art of hand tools, there exists a special class of tools adapted to direct torsional forces onto related work and which are provided with means to control or indicate the magnitude of force applied thereby to the related work. Such tools are generally referred to as torque tools." Basically, such tools fall into two basic types, the first being characterized by a manually engageable pivotal lever arm extending radially from the axis of the work and commonly referred to as torque wrenches" and the other being characterized by manually engageable, rotatable parts, adapted to be arranged concentric with the work and commonly referred to as torque drivers."

The instant invention is particularly concerned with the second noted type of torque tool, that is, a torque driver.

In both of the above noted classes of torque tools, there has developed three basic sub-types of tools, the first being torque release, or torque limiting" type tools which are such that when predetermined or set forces are applied by the tools to related work, drive means within the tools release; the second being clicktype tools" and such that when predetermined or set forces are applied by the tools, driving mechanisms within them operate to transmit an audible signal and the third being dial-type tools, wherein the forces exerted thereby onto related work are indicated on visually readable dial faces and the like.

The instant invention is concerned with the first above noted sub-class of torque driver, that is, a torque release type of tool with drive means adapted to release when a set or predetermined torque is directed thereby, onto a related piece of work.

Torque release and click-type tools of the type referred to are divided into preset type tools wherein the drive means thereof operate to release or transmit the signal when one predetermined force is reached between the tools and the work and adjustable type tools wherein the force at which the drive means thereof operate can be adjusted and set as desired or as circumstances require.

The instant invention is primarily concerned with an adjustable type of torque release driver, but is such that it can be advantageously embodied in preset type, releasable torque drivers.

In accordance with the foregoing, the instant invention has to do with an adjustable, torque releasing type torque driver and is more particularly concerned with an improved drive means for that special type of hand tool.

In torque drivers of the general class and type here concerned with, the prior art has provided many different forms of drive means intended to release when subjected to predetermined or set torsional forces. The most common form or type of releasable drive means provided by the prior art has involved a form of jaw clutch such as the common spiral-jaw clutch. wherein opposing drive and driven disc-shaped plates or members are arranged in a manually engageable, handle like body, the driven member being axially shiftable and fixed against rotation in the body and the other drive member having a shaft with a work-engaging head thereon projecting axially from the body and being rotatably carried by the body and held against axial movement therein. The driven member is spring loaded and urged into engagement with the drive member with a desired, set or predetermined force.

With the above basic drive means. it will be apparent that when the tool is used, the clutch will release and driving engagement thereof will be broken when the torsional forces tending to cause the teeth or jaws of the members to ride and shift relative to each other, exceeds the force of the spring which tends to hold the jaws or teeth relatively immovable and engaged.

While the above, basic type and form of drive means would appear effective and practical in principle, such means have proven to be wanting in several basic respects. First, due to the substantial opposing surface areas in such clutches, excessive friction is generated thereby, which friction is variable and uncontrollable to such an extent that the accuracy and dependability of the resulting tools is for outside the minimum accuracy requirements and standard which have been set for such tools. Second, rapid and excessive wear of the opposing surfaces of such clutches results in further inaccuracies and instabilities. Third, the establishing and maintaining of tolerances and those quality controls necessary to establish clutch members of the character referred to which would or might prove to be capable of establishing a satisfactory and sufficiently accurate drive means for a torque driver are unattainable from the standpoint of present day economical and practical commercial production procedures and practices.

Other clutch means that have been used in torque drivers of the general character referred to have, for the most part, involved modifications of the above noted basic jaw clutch and have consisted of the provision of hardened rollers arranged between the opposing clutch plates to reduce the friction and wear otherwise encountered and/or have involved the provision of circumferentially spaced opposing sockets in the clutch plates and ball bearings normally engaged and seated in the opposing pairs of sockets and adapted to ride out of the sockets and roll between the plates when the torsional forces are sufficient to urge the driven plate axially against the resistance of the related spring means.

The latter noted modified pressure plate and ball type clutch has proven to be reasonably satisfactory, but has not proven to be sufficiently accurate and dependable to meet the ever changing and more demanding requirements of accuracy and dependability for torque drivers. This is due to the fact that the balls rapidly tend to deform and displace the metal stock of the plates about the upper edges or rims of the sockets as they roll into and out of engagement therewith, as the clutch means are operated, thereby destroying the accuracy and dependability of the tools. This is due to the fact that the edges or rims of the sockets are weak and relatively unstable, sharp, corners defined by the converging surfaces of the sockets and faces of the plates. Further, the establishment of the plates in such circumstances with the tolerances and quality controls that are demanded is not practical and feasible with present day commercial manufacturing practices and in light of economic considerations.

It is an object and feature of our invention to provide a torque driver of the character referred to above having an improved pressure plate and ball-type releasable drive clutch means having convex jaws or lobes relative to and over which the balls of the clutch means are caused to move, whereby no weak deformable corners and/or edges are presented and against which the balls must engage and work.

It is another object of our invention to provide a structure of the character referred to wherein the convex jaws or lobes of the clutch means are established and defined by side portions of lengths of ccnterless ground, hardened, cylindrical drill steel carried by a plate part whereby the tolerances and quality control of the relative working surfaces of the clutch means can be easily, effectively and economically established and controlled.

In those torque drivers of the general character referred to above, provided by the prior art, the force transmitting shafts with the work engaging heads and which are rotatably carried by the manually engageable bodies are commonly fixed directly to the clutch plate related thereto to establish driving engagement therewith and such that any axial and/or radial play and movement of the shafts relative to the bodies result in axial displacement and/or misalignment of the plates carried thereby. Such displacement and/or misalignment of the noted plates necessarily results in adversely affecting the accuracy of the clutch means and the accuracy and dependability of the tools as a whole.

An object and feature of our invention is to provide a structure of the general character referred to wherein the clutch plate related to the drive shaft of the tool is bearing supported in accurate alignment with its related parts of the clutch means, independent of the shaft and a structure including semi-universal axially shiftable coupling means between the shaft and its related clutch plate whereby the clutch means is unaffected by axial shifting and misalignment of the shaft resulting from normal and required working tolerances within the construction.

In tools of the character here concerned with, which have been provided by the prior art, the clutch means have pressure plates engaged by springs which serve to urge the pressure plates axially toward the plates on the shafts. The pressure plates are engaged in the tool bodies for axial shifting and are held against rotation therein and relative to their related opposing plates. It has been common practice to make the pressure plates long and in the nature of plungers, slidably engaged in the bodies and to key them against rotation by means of spline-type means, comprising longitudinal keys and keyways in and between the said plates and bodies. Such means have been found to be wanting in that the spring means tends to urge the plates out of alignment in the body and to thereby cause the plates to bind and generate frictional drag in and with the bodies. This results in notable adverse effects. In efforts to overcome the above noted binding effects, the prior art has resorted to increasing the longitudinal extent of the pressure plates so that they are substantially selfaligning in the bodies. While such lengthening of the plates prevents misalignment and binding, it extends the overall length of the tools, increases the weight and expense thereof and materially increases the frictional drag encountered.

An object and feature of our invention is to provide novel means to hold, retain and maintain the pressure plate within the body for free axial shifting therein and for self-alignment with its other related opposing plate.

It is an object and feature of our invention to provide a tool of the general character referred to, wherein the drive shaft and clutch means is axially compact and short whereby the effects of radial deflection or axial misalignment of the parts thereof is maintained at a minimum and whereby the necessary overall longitudinal extent of the tool is maintained at a minimum.

Yet another object and feature of our invention is to provide a tool of the general character referred to having means for adjusting the force of the spring acting upon the clutch means to vary and adjust the force at which the clutch means releases, which means has parts telescopically related with the body of the tool and with each other whereby the longitudinal extent of the tool need not be excessively extended to accommodate the adjusting means and a short, neat and compact tool is provided.

The foregoing and other objects and features of our invention will be apparent and fully understood from the following detailed description of typical preferred forms and applications of our invention, throughout which description reference is made to the accom panying drawings, in which:

FIG. I is a side elevational view of a tool embodying the present invention;

FIG. 2 is a detailed sectional view taken as indicated by line 2-2 on FIG. 1;

FIG. 3 is an enlarged sectional view taken as indicated by line 33 on FIG. 2;

FIG. 4 is an enlarged sectional view taken as indicated by line 44 on FIG. 2;

FIG. 5 is an enlarged sectional view taken as indicated by line 5-5 on FIG. 2;

FIG. 6 is an enlarged sectional view taken as indicated by line 66 on FIG. 2;

FIG. 7 is an enlarged sectional view taken as indicated by line 7--7 on FIG. 2;

FIG. 8 is an exploded isometric view of the clutch means that we provide;

FIG. 9 is a sectional view taken as indicated by line 99 on FIG. 2;

FIG. 10 is a sectional view taken as indicated by line l0l0 on FIG. 2; and

FIG. 11 is a side elevational view of another form of the invention, with portions broken away and shown in sections to illustrate details of the construction.

Referring to the drawings, the tool that we provide includes generally, an elongate tubular body B with a central bore 10 and open front and rear ends 11 and 12, an elongate cylindrical journal block J releasably fixed in the front end of the bore 10 of the body and having a central longitudinal bearing opening 14, an elongate cylindrical drive shaft D rotatably engaged in the opening 14 in the block J and having a front end projecting from the block and formed with a work engaging head H and a rear end portion projecting rearwardly from the block and into the body. The tool next includes bearing means M between the block J and shaftD, clutch means C within the body B rearward of the block J and shaft D, bearing means N between the block J and the means C, coupling means E between the shaft D and clutch means, spring means S in the body rearward of the clutch means C to engage the clutch means and adjusting means A in and/or about the rear portion of the body and acting upon the spring means to vary the force exerted thereby onto and through the clutch means C.

The body is a simple tubular metal part. The forward portion of the bore 10 thereof is suitably threaded.

The journal block is an elongate machined metal part and has a rear threaded portion engaged in the threaded front portion of the bore I0 of the body B and has a formed, forwardly tapered front portion projecting from the body, clearly shown in the drawings. The block J is preferably locked in the body by a suitable set screw 15. The rear end of the block defines a flat, radially extending axially rearwardly disposed seating face.

The drive shaft D is a rather short elongate cylindrical member extending through the opening 14 of the block J with running clearance. The work engaging head H at the front end of the forward portion of the shaft, projecting forward from the block can vary widely in form and in the case illustrated is a squared portion of the shaft adapted to engage in the drive openings in wrench sockets and the like.

The rear portion of the shaft D projects freely into the body B from the rear seat surface of the block.

The bearing means M between the shaft D and block B comprises a radially outwardly opening annular race in the central portion of the shaft D, a pair of radial ports 21 in the block, rearward of the front end of the body B and a pair of radilly aligned ball bearings 22 arranged in each part, with the radial inward portion of the radially innermost of the balls engaged in the race 20. The balls are retained in position by the body and serve to support the shaft for free rotation and against axial shifting in and relative to the block (See FIGS. 2 and 3 of the drawings).

The clutch means C includes an elongate, cylindrical, front, driven plate 24 with a flat front face 25 spaced from and opposing the rear seat face of block J, a flat, radially extending, rearwardly disposed rear surface 26, a central forwardly opening socket opening 27 into which the rear portion of the drive shaft D freely projects and a pair of diametrically aligned radially and forwardly opening elongate slots 28 communicating with the socket opening. The plate 24 is arranged in the body B with free running clearnace with the bore 10.

The coupling means serves to couple the front drive plate 24 and rear end of the shaft D for rotary drive therebetween and for free relative axial shifting therebetween and includes a transversely extending drive pin 29 engaged through the rear portion of the shaft occurring within the socket 27 and having opposite end portions projecting from the shaft and into engagement in the slots 28, as clearly illustrated in FIGS. 2 and 5 of the drawings.

The bearing means N between the means C and the block J comprises an annular, anti-friction, ball-type thrust bearing assembly or unit engaged freely about the shaft D, within the body B and in pressure bearing engagement with and between the front seat face 25 of the driven plate 24 of the means C and the rear seat surface of the block J.

In addition to the foregoing, the driven plate is characterized by a pair of straight right angularly related, intersecting, radially and rearwardly opening channels 30 in its rear surface 26 and, in the preferred carrying out of the invention, a central, rearwardly projecting, rearwardly convergent ball orienting cone 31, which cone is intersected by said channels 30. The channels 30 are shown rectangular in cross-section and as having flat bottoms and flat parallel sides at right angle to said bottoms (as clearly shown in FIG. 8 of the drawings).

The means C next includes cam parts 32, which parts are directly related to the driven plate 24 and can be considered as parts of the driven plate assembly. The cam parts 32 comprise a pair of right angularly related lengths of cylindrical tool steel rod substantially equal in longitudinal extent with the diametric extent of the driven plate and notched intermediate their ends and arranged with said notches engaged so that the central axes of the two rods occur on a common radial plane and intersect one another, as clearly shown in FIGS. 6 and 8 of the drawings.

The rods are greater in diametric extent and less in radial extent than the depth of the channels 30 in the plate 24, are substantially equal or less in radial extent that the lateral extent of said channels and are arranged and seated in said channels so that the rearmost portions of the rods project axially rearwardly from the rear surface 26 of the plate 24 and define what constitute four (4) right angularly related, circumferentially spaced, radially projecting convex cam lobes at the rear surface 26 of the plate 24.

The clutch means C next includes an elongate, cylindrical, rear drive plate 34 arranged concentrically in the body for free axial movement therein, rearward of the plate 24. The drive plate has a flat forwardly disposed front surface 35 in spaced opposing relationship from the rear surface 26 of the plate 24, a flat rearwardly disposed rear seat face 36 and a straight, transversely extending, axially forwardly and radially outwardly opening rectangular channel 37 entering said front surface thereof and having a flat forwardly disposed bottom and flat, parallel sides at right angle to said bottomv The means C next includes an elongate transversely extending, rectangular in cross-section. drive bar 38 arranged in the body B forward of the drive plate 34 and having a central longitudinal axle shaft 39 with opposite ends projecting from the ends of the shaft and rotatably engaged in diametrically opposite axle bearing openings 40 in the body B. The rearmost portion of the drive bar 38 is slidably engaged in the forward portion of the channel 37 of the drive plate 34 whereby the plate is held against rotation and is free to shift axially relative to the drive bar and within the body to the extent required for operation of the construction.

Finally, the means C includes a pair of ball bearings 41 arranged in bearing engagement with and between the rear and front surfaces 26 and 35 of the plates 24 and 34, to occur at and engage opposite sides of the drive bar 38 and to occur between, opposite, adjacent pairs of the cam lobes 32 of the driven plate assembly.

The balls 41 are greater in diametric extent than the combined distance the bar 38 projects forward from the surface 37 of the plate 34 and the distance the cam lobes project rearwardly from the surface 26 of the plate 24 and so that the lobes and bar are maintained in axial spaced relationship one from the other by the balls at all times.

The spring means S comprises an elongate helical compression spring with front and rear ends arranged freely within the body rearward of the rear drive plate 34 with its front end seated on the rear seat face 36 of the plate 34, a plate-like spring follower 40 is arranged in the body in seated engagement with the rear end of the spring, a plug 41 is fixed in the body rearward of the follower and has a central threaded opening. An elongate adjusting screw 42 is threadedly engaged in and through the plug and has a forward end engaging the follower and has a rear end accessible at or from the open rear end of the body.

The plug 41 is a cylindrical spool-like member slidably engaged in and with the bore of the body B and is fixed in the body by suitably stacking or roll forming the body into tight intimate engagement therewith, as clearly illustrated in the drawings.

In operation, the force of the spring acting upon and through the clutch means C is varied, adjusted and set by advancing the screw 42 axially forwardly or rear wardly to effect axial compression or expansion of the spring, as desired and as circumstances require.

In the preferred carrying out of the invention, the follower has a rearwardly projecting, central bearing teat formed thereon, which teat engages and seats in a detent in the front end of the screw 42. The teat and detent serves as a needle bearing support and serve to maintain the screw and follower aligned.

With the construction set forth above and without the aforementioned adjusting means A, a complete and operable basic tool is provided. In FIG. 11 of the drawings, the basic tool thus far described is illustrated as an alternative or modified form of the invention. In FIG. 11 the elements and parts of the construction which are the same as and/or correspond to like parts and portions of the first form of the invention shown in FIGS. 1 and 2 of the invention are identified by similar reference characters. The second form of the invention shown in FIG. II of the drawings is referred to as a preset tool, and is that form of tool which is established to operate at or under one predetermined set operating force. Such tools are generally less costly than adjustable tools, are not subject to being inadvertently maladjusted, and are widely used in production line procedures where a multiplicity of like screw fasteners are to be regularly advanced to predetermine set torque.

Referring once again to the first, preferred form of the invention shown in FIGS. 1 through of the drawings, the tool includes manually operable adjusting means A to selectively advance the screw 42 axially forwardly and rearwardly in the body B to vary the axial pressure normally exerted by the spring means S on and through the clutch means C and to thereby adjust and set the operating force of the tool.

The means A illustrated in FIGS. 1, 2, 9 and 10 of the drawings includes the afore-described plug 41, screw 42 and follower 40; and, further, includes an elongate polygonal drive sleeve or nut 45 threadedly engaged on and projecting from the rear end portion of the screw. The nut is locked in fixed, longitudinal adjusted relationship with the screw by a lock screw 46 engaged in the rear portion of the nut and engaging the rear end of the screw therein. The means A next includes an elongate manually engageable drive sleeve 47 having a forward portion axially and rotatably, slidably engaged about the exterior of the body B and an inner rear portion axially slidably engaging the unit 45, in rotary driving engagement therewith and which is shiftable forwardly into and rearwardly out of rotary lock engagement in and with the rear portion of the body.

The driver sleeve 47 is preferably a unitary cast or molded plastic part characterized by a manually engageable outer sleeve portion engaged about the exterior of the body and normally overlying approximately the rear three quarters of said body in bearing support therewith and a central core portion projecting forwardly into the sleeve portion from the rear end thereof and into the rear portion of the body A. The rear end of the driver, where the outer sleeve portion and inner core portions join, normally projects a short distance from the rear end of the body B. The rear portion of the core portion is splined as at 48 and the rear portion of the bar 10 of the body B is splined at 49 to normally cooperatively engage the splines 48 of the core and establish positive rotary driving engagement between the drive sleeve and body, as shown in the drawings.

When the drive sleeve 47 is moved rearwardly relative to the body B to its rear or actuated position the splines 48 and 49 disengage and the driver sleeve is free to be manually rotated relative to the body and to thereby rotate the nut 45 and screw 42 to adjust the pressure of the spring S.

The central core portion of the drive sleeve 47 has an elongate central opening with a polygonal front portion which slidably receives and establishes driving engagement with the forward portion of the nut 45 and an enlarged rear portion which freely accommodates the rear portion of the nut. The rear portion of the nut carries a stop ring 50 which serves to engage and stop on the forward bottom end of the enlarged rear portion of the opening in the nut and to thereby limit rearward shifting of the driver sleeve in its displacement from engagement with its related parts of the construction.

The rear end of the central opening in the driver sleeve is normally closed by a plug 51 and the rear end of the sleeve is finished by suitable decorative cap 52.

The forward end portion of the sleeve portion of drive sleeve is forwardly and inwardly tapered as at and is provided with suitable calibrating marks or line 61. The forward portion of the body A which is normally covered by the forward portion of the said sleeve portion and which is or can be exposed and/or uncovered when the driver sleeve is moved rearwardly relative to the body to its rear actuated position is provided with and carries longitudinally spaced calibrating marks or lines with appropriate symbols (not shown) and with which the marks or lines 61 on the sleeve are adapted to be related.

In practice, the calibrations on the body are established on a band 62 arranged and fixed in an annular recess established in the exterior of the body.

The longitudinally spaced calibrations on the body and the circumferential calibrations on the sleeve serve to indicate the reltive longitudinal location of the sleeve relative to the body (when the sleeve is in its actuated position) and thereby indicate the extent of axial compression of the spring S, which determines the force exerted thereby and the operating force of the tool. Accordingly, it will be apparent that by suitably calibrating the body and the sleeve, the sleeve can be rotated and advanced axially of the body to a position where the tool is set to operate at a predetermined force, within its range of operation forces.

In addition to the above noted normal adjustment of the tool, a more finite preliminary setting and adjustment of the spring is effected by releasing the set screw 46 in the nut 45 and advancing the nut 45 axially of the screw, as desired and as circumstances require.

The adjusting means A that we provide and which is disclosed in the drawings and briefly described in the foregoing is illustrated and described in greater detail in US. Pat. No. 3,772,942, entitled Adjustable Torque Wrench, issued to the instant co-inventor,

Bosko Grabovac, Nov. 20, 1-973. Reference is therefore made to the above identified patent for a more detailed consideration of said adjusting means.

In operation, when the adjusting means has been operated to bias the spring S to a predetermined extent and the manually engageable driven sleeve or handle 47 has been urged forwardly into its normal locked position with the body B and when the work engaging head H is mechanically drivingly coupled with a screw fastener or the like (not shown). in axial alignment therewith as by means of a drive socket or the like (not shown), the handle or sleeve 47 is manually engaged and the tool is rotated clockwise or counter-clockwise about its central axis to advance the related fastener in the desired direction. As the tool, sleeve and body are rotated, the vertical sides of the drive bar 38 engage the spherical balls 41 and urges them into driving engagement with the convex, lobe-like portions of the cam parts 32 projecting rearwardly from the rear surface 26 of the plate 24 whereby the plate 26, shaft D and the related fasteners are rotated with the sleeve and body. When the fastener tightens and is seated or otherwise resists rotation, continued turning of the sleeve, body and of the drive bar 38 drives the balls 41 onto the cam parts 32 with increasing force and until the opposing, engaged, convex surfaces of the balls and cam parts coact to urge the drive plate 34 rearwardly against the resistance of the spring and the balls ride and move circumferentially over the cam parts. When sufficient force is exerted to cause the balls to move and ride over the cam parts in the above noted manner, driving engagement between the body B and shaft D is broken and the predetermined, set and limited torsional force has been transmitted by the tool onto the fastener or work.

It is to be particularly noted that the balls 41, being spherical, and the ball engaging portions of the cam parts being convex, the angle of engagement between the balls and cam parts is acute as the balls are urged circumferentially toward the cam parts and at no time is a sharp, fragile and/or weak corner or edge structure subjected to the operating forces exerted into and through the tool.

It is to be further noted that the working or inclined plane angle between the balls 41 and cam parts 32 is greatest when the balls are initially brought into engagement with the cam parts and become less or more acute as the balls advance over the cam parts. As a result of the above relationship of parts, the balls do not tend to ride over the cam parts until the set or established operating torsional force is exerted between the balls and cam parts and that once the balls commence to ride over said cam parts, the working angle therebetween commences and continues to reduce progressively, whereby less force is required to effect related movement between the balls and cam parts. As a result of the above, the instant structure is such that the clutch means immovably maintains driving engagement until the operating force is reached whereupon it rapidly and substantially instantaneously releases (so long as application of the required operating force is sustained).

As a result of the above, there is no tendency for the relative working parts of the instant tool to slowly slide and/or creep relative to each other as the desired operating force is reached, as is the case in the great majority of torque tools of the general class here referred to, provided by the prior art.

Having described two typical preferred forms and embodiments of our invention, we do not wish to be limited to the specific details hereinabove set forth, but wish to reserve to ourselves any modifications and/or variations which appear to those skilled in the art and which fall within the scope of the following claims:

Having described our invention, we claim:

1. A torque driver tool comprising an elongate tubular body with front and rear ends, a block in the front end of the body and having a central, axially extending opening, an elongate drive shaft rotatably engaged in said opening and having a work engaging front end projecting from the block and body and a rear end projecting into the body, thrust bearing means between the shaft and block, a driven plate with a rear surface and radially extending and rearwardly opening channels rotatably positioned in the body rearward of the block, a thrust bearing between the block and drive plate, coupling means coupling the rear end of the shaft and drive plate in rotary driving engagement, radially extending cam parts engaged in the channels in the drive plate in rotary driving engagement therewith and having convex portions projecting rearwardly from the rear surface, an axially shiftable drive plate with a front surface in the body in rearward spaced relationship with the driven plate and having a radially extending forwardly opening channel, an elongate radially extending ball engaging drive bar fixed in the body between the plates and having a rear portion slidably engaged in the forward portion of the channel in the drive plate, circumferentially spaced balls positioned between and normally engaging the front and rear surfaces and engageable with the drive bar and the convex portions of the cam parts and spring means in the body rearward of the drive plate and normally yieldingly urging the drive plate forwardly in the body toward the driven plate with the balls in bearing engagement therebetween.

2. A structure as set forth in claim 1 wherein said block has a flat axially disposed rear surface, the driven block has a flat axially disposed front surface and wherein said thrust bearing comprises an annular antifriction bearing assembly between the rear and front surfaces of the block and driven plate.

3. A structure as set forth in claim 1 wherein said coupling means comprises a central opening entering the front end of the driven plate and freely receiving the rear end of the shaft, radially and axially extending slots in the driven plate communicating with the opening therein and a radially extending drive pin carried by the rear end of the shaft and engaged in the slots.

4. A structure as set forth in claim 3 wherein said block has a flat axially disposed rear surface, the driven block has a flat axially disposed front surface and wherein said thrust bearing comprises an annular antifriction bearing assembly between the rear and front surfaces of the block and drive plate.

5. A structure as set forth in claim 1 wherein said thrust bearing means between the block and shaft comprises and annular radially outwardly opening ball race in the shaft, a radial opening in the block communicating with the race, a ball bearing engaged in and between the radial opening and the race and means in said opening retaining the ball.

6. A structure as set forth in claim 5 wherein said block has a flat axially disposed rear surface, the driven 1 1 block has a flat axially disposed front surface and wherein said thrust bearing comprises an annular antifriction bearing assembly between the rear and front surfaces of the block and driven plate.

7. A structure as set forth in claim 6 wherein said coupling means comprises a central opening entering the front end of the driven plate and freely receiving the rear end of the shaft, radially and axially extending slots in the driven plate communicating with the opening therein and a radially extending drive pin carried by the rear end of the shaft and engaged in the slots.

8. A structure as set forth in claim 1 wherein the spring means includes an elongate helical compression spring in the body rearward of and engaging the drive plate, a plug in the body rearward of the spring, a spring follower between the spring and the plug and an elongate screw threading engaged through the plug to engage the follower and accessible at the rear end of the body.

9. A structure as set forth in claim 8 which further includes an elongate manually engageable sleeve with front and rear ends telescopically engaged about the body and axially shiftable relative to the body from a normal forward position to an actuated rear position, a central core in the sleeve projecting forwardly from the rear end thereof into the body and having a central polygonal opening, and elongate axially shiftable nut fixed on the rear end of the screw and slidably engaged in the polygonal opening, releasable spline means on and between the rear portion of the body and the sleeve establishing rotary driving engagement therebetween, when the sleeve is in its normal position, circumferentially spaced calibrations on the front end of the sleeve and axially spaced calibrations on the body cooperatively related to the calibrations on the sleeve when said sleeve is in its actuated position.

10. A structure as set forth in claim 9 wherein said block has a flat axially disposed rear surface, the driven block having a flat axially disposed front surface and wherein said thrust bearing comprises an annular antifriction bearing assembly between the rear and front surfaces of the block and driven plate 11. A structure as set forth in claim 10 wherein said coupling means comprises a central opening entering the front end of the driven plate and freely receiving the rear end of the shaft, radially and axially extending slots in the driven plate communicating with the opening therein and a radially extending drive pin carried by the rear end of the shaft and engaged in the slots.

12. A structure as set forth in claim 9 wherein said thrust bearing means between the block and shaft comprises an annular radially outwardly opening ball race in the shaft, a radial opening in the block communicating with the race, a ball bearing engaged in and between the radial opening and the race and means in said opening retaining the ball.

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Classifications
U.S. Classification81/474
International ClassificationB25B23/142, B25B23/14
Cooperative ClassificationB25B23/1427
European ClassificationB25B23/142B2