US2803979A

US2803979A - Predetermined torque release wrench

Info

Publication number: US2803979A
Application number: US460082A
Authority: US
Inventors: Alfred R Landis
Original assignee: James R Kearney Corp
Current assignee: James R Kearney Corp
Priority date: 1954-10-04
Filing date: 1954-10-04
Publication date: 1957-08-27
Anticipated expiration: 1974-08-27

Description

Aug. 27, 1957 A. R. ANDlS 2,803,979

' PREDETERMINED TORQUE REL EASE WRENCH Filed Oct. 4. 1954 2 Sheets-Sheet 1 INVENTOR.

g: ALFRED R. LANDIS 7/// /V Q Q s a fi TTOHNE Y Aug. 27, 1957 A. R. LANDIS v PREDETERMINED TORQUE RELEASE WRENCH 2 Sheets-Sheet 2 Filed Oct. 4, 1954 United e e t o 2,803,979 PREDETERMINED TORQUE RELEASE WRENCH Alfred R. Landis, St. -Johns Station, Mo., assignor to James R. Kearney Corporation, St. Louis, Mo., a corporation of Missouri Application October 4, 1954, Serial No. 460,082 19 Claims. (Cl. 81-525) This invention relates generally to torque wrenches, and more specifically to torque wrenches adapted for heavy duty use and so constructed and arranged that it gives off an audible signal when in the use thereof the maximum allowable torque is reached, the predominant object of the invention being to provide such a torque wrench which is of relatively simple construction and arrangement and is capable of performing itsintended function in a highly efficient manner.

Fig. 1 is a plan view of the improved torque wrench of this invention.

Fig. 2A is an enlarged, fragmentary section taken on line 2A-2A of Fig. l.

Fig. 2B is an enlarged, fragmentary section taken on line 213-213 of Fig. 1.

Fig. 3 is a fragmentary elevation of a portion of the improved torque wrench of this invention with the cover plate of said portion removed.

Fig. 4 is a fragmentary elevation similar to Fig. 3 of a portion of the improved torque wrench of this invention with the cover plate of said portion removed, parts located within said portion being in changed positions when compared with positions of said parts as shown in Fig. 3.

Fig. 5 is an enlarged cross-section taken on line 5-5 of Fig. 2B.

Fig. 6 is an enlarged cross-section taken on line 66 of Fig. 3.

Fig. 7 is a cross-section taken on line 7-7 of Fig. 2A.

Fig. 8 is a fragmentary cross-section taken on line '8--'8 of Fig. 2A. 7

In the drawings, wherein is shown for purposes of illustration, merely, one embodiment of the invention, A designates the improved torque wrench of this invention generally. The torque wrench A includes a hollow housing portion 1 having a fixed bottom wall 1*, opposite side walls 1*, and end walls 1 and 1 the end wall 1 being of curved formation. 7 The housing portion 1 also includes a removable top wall 1 which is secured in place by suitable fastening devices 2. The housing portion is widest approximately at its longitudinalcenter and from this point said housing portion tapers to narrower widths at its opposite ends, as is shown in Figs. 1, 3 and 4. Extended outwardly from the end wall 1 is an extension 3 which includes a stud 3' which is externally screwthreaded at its outer end, as shown at 4 in Fig, 2B, said extension having a shoulder which is located at the inner end of the stud 3'. screwthreadedly mounted on the stud 3 of the extension 3 is a slightly tapered, tubular member'6, there being a washer 7 interposed between the shoulder 5 and an end of said tubular member 6 (Fig. 2B), and a set screw 8 is provided for preventing unintended rotation of the tubular member with respect to the stud 3' of the extension 3.

A bore 9 is for-med through the extension 3 and the stud 3 thereof and this bore is provided with anend portion 9' which is of slightly greater diameter than the remainder of the bore, there being an annular inclined shoulder 10 at the point where the bore portions of diiferent diameters meet. Disposed within the bore 99 is a sleeve 11, said sleeve having a wall which is shaped in accordance with the shape of the bore 9-9; that is to say, the wall of said sleeve is provided with a relatively thick portion 11 which lies within the portion 9' of the bore, and the remainder thinner portion of the wall of said sleeve being disposed in the major portion of the bore 9.

Arranged within the opening through the sleeve 11 is a plunger 12 which normally extends slightly beyond an end of the sleeve as shown in Fig. 2B and at its oppo- 'site end has a portion 12 of reduced diameter which projects into the bore of a coil spring seat 13, said coil spring seat bearing against an annular shoulder 14 formed on the plunger 12. A coil spring 15, located within the tubular member 6, bears at one of its ends against a face of the coil spring seat 13 and at its opposite end against a face of a second coil spring seat 16, both of said coil spring seats being provided with extensions which project into the end portions of the coil spring and serve to center said coil spring relative to the coil spring seats.

The tubular member 6 adjacent to its outer end portion is internally screw-threaded as indicated by the reference character 17 and screwed into said internally screwthreaded portion of said tubular member is an externally screwthreaded tubular plug 18, the wall of said tubular plug being recessed as indicated at 19 in Fig. 2B, and this recess receives a disk 20 which is provided with a multiface-d opening 21. The coil spring seat 16 is provided with a correspondingly shaped opening 22 which is alined with the opening 21 of the disk 20, and disposed in said alined openings is a ball 23 which provides for free rotation of the screw-threaded, tubular plug 18. The tubular plug 18 is backed up by an externally screw-threaded ring 24 whose screwthreads engage the screwthreads 17 of the tubular member 6, said ring contacting with an end face of the tubular plug 18, as shown in Fig. 2B, and said ring 24 being secured in place by means of set screws 25 so as to prevent the plug 18 from being unscrewed from member 6 without first releasing ring 24. The outer end portion :of the tubular member 6 is provided with an annular raised portion 26 whose end portion is provided with an annular recess 27 in which a locking sleeve 28 is mounted, the outer end portion of the tubular member being tapered, as indicated by the reference character 6, in Fig. 2B.

The tool A of this invention includes a handle 18' which is an integral part of, but of lesser outside diameter than, the tubular, screwthreaded plug 18. The handle 18' is knurled adjacent to its outer end to facilitate rotation thereof by hand. Arranged in embracing relation with respect to the handle 18 is a tubular element 29, said tubular element being provided with a plurality of circumferentially spaced grooves 29 which extend rearwardly, from the forward edge thereof longitudinally of said tubular element for a portion of the length of said tubular element. Also, said tubular element at its opposite end is provided with a greater number of circumferentially spaced grooves 29 which extend longitudinally of said tubular element from the rear edge thereof, longitudinally of said tubular element for a portion of the length of said tubular element. The rear end portion of the tubular element 29 is externally screwthreaded between the grooves 29 and screwthreadedly mounted on said rear end portion of said tubular element is a locking sleeve 30 which is fixed to the handle 18 by means of a pin 30', and provided with a set screw the lower, tapered portion of which is extended into one of the grooves 29 for securing said locking sleeve against rotation relative to said tubular element 29.

Arranged within the housing 1 is a' pair of arms 31* and 31 said arm 31 being fixed to a shaft 32 which is supported for rotation by ball bearings 33 and 34, the ball bearing 33 being mounted in a cavity 35 formed in the bottom wall 1 of the housing 1, and the ball bearing 34 being fixedly mounted at the inner face of the removable top wall 1 of said housing 1 (see Fig. 2A). The arm 31 is bifurcated at its free end and a roller 36 is mounted for rotation on a pin 37 between a pair of spaced parts of the bifurcated end portion of said arm. The arm 31 is provided with a portion 38 having a screwthreaded opening formed therethrough, said opening receiving a screwthreaded pin 39 which is provided with a lock nut 40 for locking said pin in positions to which it has been screwthreadedly adjusted. The end of the pin 39 strikes the extension 41 formed on a side wall' 1 of the housing 1 to limit movement of the free end of the arm in one direction. The roller 36 contacts with a pawl 42 which is pivotally supported by a pin 43 between a pair of spaced portions 44, the upper portion of the pawl contacting with the end face of the plunger 12, and said pawl having a face which includes a curved upper portion 45 and an inwardly curved portion 45 which is adapted to receive a circumferential portion of the roller 36 in one position of the arm, as shown in Fig. 4. At the end of the arm 31* remote from the end thereof at which the roller 36 is mounted said armis provided with spur 46 which engages a spur 47' which is projected from an end of the arm 31 The arm 31 is provided at its end which is remote from the end thereof at which the spur 47 is located with a portion 48 that is located within the end portion of the housing 1, which is closed by the curved end wall 1. This portion 48 of the arm 31 is provided with a shaft 49 which is driven into an opening 49', Fig. 8, that is formed in said arm portion 48, the extreme upper portion 49 of said shaft being of slightly reduced diameter. Interposed between the portion 48 of the arm 31 and a portion of the housing 1, which is spaced from said portion 48, is a ball bearing structure 50, said ball bearing'structure comprising a pair of raceways 51 between which are interposed a plurality of balls 52. The outer raceway of the ball bearing structure 50 is frictionally in engagement with the wall 53 of an annular recess 54 and said outer raceway engages a shoulder 55, which forms a wall of said recess, and the inner raceway of said ball bearing structure is frictionally mounted on said portion 48. Likewise, the portion 49 of the shaft 49 has the inner raceway 56 of a ball bearing structure 56 frictionally mounted thereon, the outer raceway 56 of said ball bearing structure 56 being fixedly mounted on the inner face of an annular flange 57 which extends from a cover plate 58 which is secured in place with respect to the removable top wall of the housing by suitable fastening devices 58'. The portion 48 of the arm 31* has projected therefrom an extension 59 which projects through an opening 60 formed through the bottom wall of the housing 1, and this extension is provided with an opening in which is disposed a ball 61 that is urged toward the outer end of the opening by a coil spring 62, the wall of the opening being peened over, as indicated at 63 in Fig. 8 to prevent the ball from being forced by the coil spring entirely from the opening. The extension 59 is adapted to receive a suitable socket means and the spring-pressed ball secures the socket means to the extension.

At the end of the housing 1 at which the curved wall 1 is located, the tool A includes a yoke-shaped member 64, said yoke-shaped member being secured by bolt and nut assemblies 65 to the opposite side walls 1 of the housing 1, the shanks of the bolts of said bolt and nut assemblies passing through apertures formed through the spaced legs 64 of said yoke-shaped members and through said opposite side walls of said housing. The curved end wall 1 of the housing 1 is provided with a tapered recess 66 which receives the tapered end portion of a pin 67, said pin being mounted for movement in the boreof a sleeve 68 which is disposed in an opening 69 formed in the yoke-shaped member 64. The pin is provided with a head 67' which has a tapered portion, and a coil spring 70, which embraces the shank portion of the pin, is interposed between the head of the pin and an end of the sleeve 68. Screwthreadedly disposed in a screwthreaded opening 71 formed in the yoke-shaped member is a screw 72 having a knurled head 72', said screw having a tapered end portion 73 which contacts with the tapered portion 67' of the head of the pin 67. By rotating the screw 72 in the proper direction the pin 67 may be subjected to movement which will force the tapered end portion of said pin deep into the tapered recess 66 so as to rigidly connect the outer portion of said yoke-shaped member to the housing 1;, also, by loosening the screw 72 the coil spring will withdraw the tapered end portion of the pin 67 from the tapered recess 66. The yoke-shaped member includes a screwthreaded stud 74 on which is screwthreadedly mounted an elongated handle 75.

The screwthreaded, tubular plug 18 is screwed inwardly to increase the tension of the coil spring 15 and outwardly to reduce the tension of said coil spring, this being done by rotating the handle 18' in the appropriate direction. At this time the locking sleeve 28 is in the position in which it is shown in Fig. 5 where the depression 28 is in alinement with a ball 28 so that said ball may be elevated by surface portions of the tubular element located between the grooves 29*, into the depression 28 and thus permit rotation of the handle 18. Also, when the coil spring has been adjusted to the desired tension the locking ring 28 is rotated to move the depression 28 out of alinement with respect to the ball 28 whereupon the handle 18 will be fixedly locked in the position to which it has been adjusted.

As described above, rotation of the handle 18' with sleeve- 29 moves the plug 16 toward or away from plug 13 so as to further compress or relax spring 15, depending upon the direction in which the handle is turned. In so doing, the graduatitons on sleeve 29 are moved relative to the edge 6 of housing 6 so that the position of the edge 6' along the graduations on sleeve 29 indicates the torque value at which the wrench will trip. In order to calibrate the device, the invention provides two separate adjustments, neither of which may be altered without encountering more difiiculty than is involved in adjusting the trip value as just described, One such calibrating adjustment is provided by locking sleeve 30 which, when the set screw engaging groove 29 is released, permits the handle 18 to be rotated (and spring 15 either further compressed or relaxed) while sleeve 29 remains locked by ring 28 against rotation relative to body 6. The other'calibrating adjustment is accomplished by means of set screw 39 which controls the space between the end of lever 31 remote from its fulcrum 32 and surface 41 of side wall 1, and at the same time prcdetermines the radius at which roller 36 bears upon cam surface 45 ofpawl 42. The more set screw 39 is driven up to increase the space between surface 41 and the adjacent end of lever 31*, the more the radius of contact between roller 36 and cam surface 45 departs from alignment with the axes of

shafts

37 and 43 for the roller and pawl respectively, and the less the torque required to trip the device. Each of these calibrating adjustments may therefore be used in coordinating the scale on sleeve 29 with the particular spring 15 employed in the device. Such calibrating adjustments are not intended to be made by the workmen who use the wrench, and consequently, each of thesecalibrating adjustments requires the use of some tools in order to accomplish it, as distinguished from the variation in the tripping torque values which may be made without the use of tools by merely releasing locking ring 28 and then turning the handle 18' and sleeve 29 together.

In the use of the improved torque wrench of the present invention, when the torque being applied with the aid of the wrench exceeds the allowable torque for which the wrench is set, the arm 31 will swing from the position of said arm shown in Fig. 3 to the position in which said arm is shown in Fig. 4. Such movement of the arm 31 will swing the pawl 42 about its pivot 43 and the nose portion of said pawl which bears against the end of the plunger 12 will move said plunger so as to compress the coil spring 15. When the roller 36 moves forcibly into the position with respect to the pawl, as shown in Fig. 4, a clicking sound is produced and a slight jerking motion is applied to the wrench whereby the operator is notified that the limit of the allowable torque has been reached.

I claim:

1. A torque wrench comprising a housing portion, a pair of arms located within said housing portion and separately pivoted for swinging movement, a spur extended from an end of each of said arms and the spurs of said arms being in contact engagement with each other, one of said arms having an extended portion -adapted to engage a nutor bolt to beoperated on, the other of said arms having a roller at the end thereof opposite its said spur, a coil spring, a plunger arranged in engagement with said coil spring, a pivotally supported pawl arranged in engagement with an end of said plunger and with said roller, said pawl being provided with a face with which said roller contacts which includes portions describing reverse curves.

2. A torque wrench comprising a housing portion, arm means located within said housing portion, means disposed at an end of said arm means adapted for the reception of a nut or bolt socket, a coil spring, a plunger arranged in engagement with said coil spring, a pivotally supported pawl arranged in engagement with an end of said plunger, a rotatable element mounted at an end portion of said arm means and disposed in engagement with said pawl, and means for adjusting the tension of said coil spring, the last-mentioned means comprising an adjusting sleeve, a centering plug arranged at an end of said coil spring, and a ball bearing arranged between said plug and a part of said adjusting sleeve.

3. A torque wrench comprising a housing portion, arm means located within said housing portion, means disposed at an end of said arm means adapted for the reception of a nut or bolt socket, a coil spring, a plunger arranged in engagement with said coil spring, a pivotally supported pawl arranged in engagement with an end of said plunger, a rotatable element mounted at an end portion of said arm means and disposed in engagement with said pawl, and means for adjusting the tension of said coil spring, the last-mentioned means comprising an adjusting sleeve, a centering plug arranged at an end of said coil spring, a ball .bearing arranged between said plug and a part of said adjusting sleeve, anda locking ring for preventing unintended movement of said adjusting sleeve.

4. A torque wrench comprising a housing portion, arm means located within said housing portion, means disposed at an end of said arm means adapted for the reception of a nut or bolt socket, a coil spring, a plunger arranged in engagement with said coil spring, a pivotally supported pawl arranged in engagement with an end of said plunger, a rotatable element mounted at an end portion of said arm means and disposed in engagement with said pawl, and means for adjusting the tension of coil spring, the last-mentioned means comprising an adjusting sleeve, a centering plug arranged at an end of said coil spring, a ball bearing arranged between said-plug and a part of said adjusting sleeve, a locking ring for preventing unintended movement of said adjusting sleeve, and a bandle for rotating said adjusting sleeve.

5. A torque wrench comprising a housing portion, arm means located within said housing portion, meansdis. posed at an end of said arm means adapted for the reception of a nut or bolt socket, a coil spring, a plunger arranged in engagement with said coil spring, a pivotally 6 supported pawl arranged in engagement with an end of said plunger, a rotatable element mounted at an end portion of said arm means and disposed in engagement with said pawl, means for adjusting the tension of said coil spring, the last-mentioned means comprising an ad justing sleeve, a centering plug arranged at an end of said coil spring, a ball bearing arranged between said plug and a part of said adjusting sleeve, a locking ring for preventing unintended movement of said adjusting sleeve, and a handle for rotating said adjusting sleeve, and a tubular element embracing said handle and fixed thereto, said tubular element being provided with a plurality of grooves, and a ball which projects into any one of said grooves for locking said tubular element in different positions to which it has been adjusted.

6. A torque wrench comprising a housing portion, arm

, means located within said housing portion, means disposed at an end of said arm means adapted for the reception of a nut or bolt socket, a coil spring, a plunger ar ranged, in engagement with said coil spring, a pivotally supported pawl arranged in engagement with an end of said plunger, a rotatable element mounted at an end portion of said arm means and disposed in engagement with said pawl, means for adjusting the tension of said coil spring, the last-mentioned means comprising an adjusting sleeve, a centering plug arranged at an end of said coil spring, a ball bearing arranged between said plug and a part of said adjusting sleeve, a locking ring for preventing unintended movement of said adjusting sleeve, and a handle for rotating said adjusting sleeve, and a tubular element embracing said handle and fixed thereto, said tubular element being provided with a plurality of grooves, a ball which projects into any one of said grooves for locking said tubular element in different positions to which it has been adjusted, and a locking member for locking said ball in position where it projects into a groove of said tubular element.

7. A torque wrench comprising a housing portion, a pair of arms located Within said housing portion and supported individually for swinging movement, a spur extended from an end of each of said arms and the spurs of said arms being in contact engagement with each other, an extended portion related to one of said arms which is adapted to receive a nut or bolt manipulating socket, a coil spring, a plunger arranged in engagement with said coil spring, a pawl arranged in engagement with an end of said plunger, an element mounted at an end portion of one of said arms and disposed in engagement with said pawl, and a pair of handles extended outwardly from opposite ends of said housing portion.

8. A torque Wrench comprising a housing portion, a pair of arms located within said housing portion and supported individually for swinging movement, a spur extended from an end of each of said arms and the spurs of said arms being in contact engagement with each other, an extended portion related to one of said arms which is adapted to receive a nut or bolt manipulating socket, a coil spring, a plunger arranged in engagement with said coil spring, a pawl arranged in engagement with an end of said plunger, an element mounted at an end portion of one of said arms and disposed in engagement with said pawl and a pair of handles extended outwardly from opposite ends of said housing portion, and a yoke member to which one of said handles is fixed.

v 9. A torque wrench comprising a housing portion, a pair of arms located within said housing portion and supported individually for swinging movement, a spur extended from an end of each of said arms and the spurs of said arms being in contact engagement with each other, an extended portion related to one of said arms which is adapted to receive a nut or bolt manipulating socket, a coil spring, a plunger arranged in engagement with said coil spring, a pawl arranged in engagement with an end of said plunger, an element mounted at an end portion of one of said arms and disposed in engagement with said ber being pivoted to opposed side wallsof said housing portion.

10. A torque wrench comprising a housing portion, a pair of arms located within said housing portion and supported individually for swinging movement, a spur extended from an end of each of said arms and the spurs of said arms being in contact engagement with each other, an extended portion related to one of said arms which is adapted to receive a nut or bolt manipulating socket, a coil spring, a plunger arranged in engagement with said coil spring, a pawl arranged in engagement with an end of said plunger, an element mounted at an end portion of one of said arms and disposed in engagement with said pawl and a pair of handles extended outwardly from opposite ends ofsaid'housing portion, and a yoke member to which one of said'handles is fixed, said yoke member being pivoted to opposed side walls of said housing portion, and means for securing said pivoted yoke member against pivotal movement.

11. A torque wrench comprising a housing portion, a pair of arms located within said housing portion and supported individually for swinging movement, a spur extended from an end of each of said arms and the spurs of said arms being in contact engagement with each other, an extended portion related to one of said arms which is adapted to receive a nut or bolt manipulating socket, a coil spring, a plunger arranged in engagement with said coil spring, a pawl arranged in engagement with an end ofsaid plunger, an element mounted at an end portion of one of said arms and disposed in engagement with said pawl and a pair of handles extended outwardly from opposite ends of said housing portion, and a yoke member to which one of said handles is fixed, said yoke member being pivoted to opposed side walls of said housing portion, and means for securing said pivoted yoke member against pivotal movement, the last-mentioned means comprising a pin having a tapered end portion which extends into a tapered opening formed in a wall of said housing portion, and a screwthreaded member for moving and retaining said tapered end portion of said pin in said tapered opening.

12. In a torque wrench having an elongate body, work turning means mounted in said body for limited relative rotational movement coaxial with the work being turned, said work turning means having an arm extending lengthwise of said body for a distance substantially in excess of the transverse dimension of said. body, a lever fulcrumed in said body and engaging said arm, the point of engagement between said arm and said lever being remote from the axis of rotation of said work turning means but relatively close to the fulcrum of said lever, a spring for biasing said lever in the direction opposite that in which said arm urges said lever when said wrench is in use, and snap-action force transmitting means between said lever and said spring.

13. In a torque wrench having an elongate body, work turning means mounted in said body for limited relative rotational movement coaxial with the work being turned, said work turning means having an arm extending lengthwise of said body for a distance substantially in excess of the transverse dimension of said body, a lever fulcrumed in said. body and engaging said arm, the point of engagement between said arm and said lever being remote from the axis of rotation of said work turning means but relatively close to the fulcrum of said lever, and means acting upon said lever remote from its fulcrum to bias said lever in the direction opposite that in which said arm urges said lever when said wrench is in use, and means for adjusting the bias of said last mentioned means.

14. In a torque wrench having an elongate body, work turning. means mounted; in, said body for limited relative rotational movement coaxial with the work being turned, said work turning means having an arm extending lengthwise of said body for a distance substantially in excess of the transverse dimension of said body, a lever fulcrumed in said body and engaging said arm, the point of engagement between said arm and said lever being remote from the axis of rotation of said work turning means acting upon said lever remote from its fulcrum to bias said lever in the direction opposite that in which said arm urges said lever when said wrench is in use, and means for adjusting the bias of said last mentioned means, said snap-acting means including a pawl having a cam surface eccentric with its pivot engaging the end of said lever remote from its fulcrum.

15. The combination of claim 14 wherein said cam surface includes a convex surface engaging said lever in its normal position and a concave surface disposed to limit the movement of said lever in the direction in which it is urged by said arm when the wrench is in use.

16. The combination of claim 14 wherein said cam surface includes a convex surface engaging said lever in its normal position and a concave surface disposed to limit the movement of said lever in the direction in which it is urged by said arm when the wrench is in use, and in which the surface of said lever engaged by said cam is convex with its center of curvature substantially aligned with the pivot of the pawl and with the point of tangence with said concave surface when said lever is at the limit of its movement in the direction in which it is urged by said arm when the wrench is in use.

17. The combination of claim 14 wherein said cam surface includes a convex surface engaging said lever in its normal position and a concave surface disposed to limit the movement of said lever in the direction in which it is urged by said arm when the wrench is in use, and adjustable means for limiting the movement of said lever in the direction in which it is urged by said biasing means.

18. In a torque wrench having a release means controlled by a spring tensioned to predetermine the torque value at which the wrench is released by turning a handle part relative to a body part, and having indicia to indicate the torque values corresponding to different relative settings of said parts, the improvement comprising, said indicia being located on a member associated with the handle part, means for locking said member against movement relative to said handle part, said locking means being releasable to permit movement of the bandle part relative to said member and said body to vary the tension on said spring without changing the value indicated by said indicia, and said locking means being so constructed as to prevent release thereof by manual manipulation.

19. In a torque wrench having an elongate body, work turning means mounted in said body for limited relative rotational movement coaxial with the work to be turned, means for normally preventing said limited rotational movement, means responsive to a predetermined torque to release said preventing means, a member associated with said body and accessible on the exterior thereof for varying the torque value at which said restraining means is released and indicia associated with said member, the improvement comprising, means within said body for varying the extent of said limited rotational movement of said work-turning means, readily releasable means for locking said member at a given position relative to said indicia, and more difiicultly releasable exteriorly accessible means for adjusting the release torque value independently of said indicia whereby to calibrate said indicia with saiddifficulty releasable means.

(References on following page) a we References Cited in the file of this patent UNITED STATES PATENTS Cooney Nov. 3, 1942 Morris Dec. 19, 1944 Harmes Dec. 15, 1952 Garwood Feb. 2, 1954 Muth June 1, 1954 Poutot June 15, 1954