US3140623A

US3140623A - Predetermined torque release wrench

Info

Publication number: US3140623A
Application number: US134772A
Authority: US
Inventors: William E Van Hoose
Original assignee: PENDLETON TOOL IND Inc
Current assignee: PENDLETON TOOL IND Inc
Priority date: 1961-08-29
Filing date: 1961-08-29
Publication date: 1964-07-14
Anticipated expiration: 1981-07-14
Also published as: DE1503011A1

Description

July 14, 1964 w. E. VAN HoosE PREDETEEMINED ToEQuE RELEASE WRENCH yFiled. Aug. 29, 1961 United States Patent() 3,140,623 PREDETERMINED TORQUE RELEASE WRENCH William E. Van Hoose, Bell, Calif., assignor, by mesne assignments, to Pendleton Tool Industries, Inc., Los Angeles, Calif., a corporation of Delaware Filed Aug. 29, A1961, Ser. No. 134,772 Claims. (Cl. 81-52.4)

This invention relates generally to torque-applying tools and, particularly, to an improved predetermined torque release wrench.

One of the major difficulties in the design and manufacture of a predetermined torque release wrench is attaining accuracy and precision in the release of the wrench under torque load while retaining simplicity and economy of manufacture and assembly. VIn other words, the three basic requirements of a torque wrench are (l) accuracy, meaning that the wrench must release exactly at a specified applied torque load or exactly at each of the several applied torque loads for which the wrench may be preset to release, (2) precision, meaning that the applied torque load at which the wrench releases at any given torque release setting must repeat, i.e., remain constant during repeated release of the wrench at the given setting, and (3) simplicity and economy of manufacture, meaning that the wrench must be capable of being sold at a reasonable cost.

A general object of this invention is to provide a predetermined torque release wrench which possesses both accuracy and precision of operation and yet is relatively simple in construction and economical to manufacture.

Other objects, advantages,.and features of the invention will become evident as the description proceeds.

A presently preferred illustrative embodiment of the invention will now be described Vby reference to the attached drawing, wherein:

FIG. 1 is a longitudinal section through a predetermined torque release wrench embodying Vthe improvements of this invention, showing the wrench parts in their normal positions;

FIG. 2 is a view of the forward end of the wrench in FIG. l showing the wrench parts in the positions they occupy after release of the wrench;

FIG. 3 is a section taken along line 3--3 in FIG. 1; and

FIG. 4 is a section taken along line 4-4 in FIG. 1.

The predetermined torque release wrench illustrated in this drawing is equipped with a tubular handle 12. Handle 12 is flattened at its forward end portion 12a in the usual way. Pivotally mounted on the forward end of the handle, for turning on a pivot axis 14 transverse to the longitudinal axis 16 of the handle, is a torque transmission member 18 through which a torque load is transmitted from the handle 12 to a workpiece (not shown).

Torque transmission member 18 is journaled in aligned bearing holes in the forward, ilat walls 20 of the handle and includes a square stud 22 located exteriorly of the handle. This stud is shaped to receive various wrench sockets or yother work-,engaging elements (not shown) in the well-known way. Y

Extending longitudinally through the forward part of the handle 12 is a tang or arm 24. Tang 24 has a square hole 26 into which the square body of the torque transmission member 18 is vpress fitted. Arm 24 is, therefore, rigid on the member 18 and'pivots with the latter. During the application of a torque Sload to a workpiece, the handle 12 is rotated in aclockwise direction on the axis 14, as the wrench is viewed in the drawing. The handle 12 and member 18 tend to rotate with respect to one another on the axis `14 as the torque load is applied, member 18 and arm 24 tending *to rotate in the counterclockwise direction in the handle.

y 3,140,623 Patented July 14, 1964 ICC At the rear of arm 24 is a plunger 28 with which this invention primarily is concerned. Plunger 28 is preferably in the form of a sleeve 30 for convenience of manufacture. Behind the plunger is a spring 32 which seats at its forward end against the rear end of the plunger sleeve 30. The rear end of spring 32 seats against the forward end of a cylindrical part 34 which is slidable in the wrench handle 12.but is keyed against rotation in the handle by means of aradial pin 36 in the part engaging ing in a longitudinal slot 38 Vin the handle.

Threaded on the outside of the handle 12, at its rear end, is a sleeve 40. A threaded insert 42 is fixed in the rear end of this sleeve. Insert 42 has a central bore 44 through which extends a lock screw 46. Lock screw 46 is threaded in the rear end of part 34 and is formed with a rear enlarged head 48. Insert Ibore 44 is counterbored at its rear end, as shown, to receive the lock screw head. The lock screw is turnable by lgrasping a rib 50 thereon.

It is evident that when lock screw 46 is tightened, cylindrical part 34 and insert 42 are clamped tightly together and sleeve 40 is thereby locked against rotation. When lock screw 46 is loosened, sleeve 40 may be rotated with respect to the part 34 and on the handle 12. Rotation of sleeve 40 in one direction advances the part 34 against the spring 32 to increase the spring pressure on the plunger 28. Rotation of the sleeve in the opposite direction retracts the part 34 rearwardly in the handle to relieve the spring pressure on the 4plunger 28.,

The forward end of the central opening-52'through the plunger 28 forms a recess in which is positioned a casehardened cam roller 54. Roller 54 is arranged with its central axis approximately normal to the plunger axis and approximately parallel to the pivot axis 14. Extending axially through the camv roller 54 is an axle pin 56 on which the roller is rotatable. The ends of pin 56 are supported in the plunger 28. Roller 54 projects slightly-beyond the forward end of the plunger, as shown. The forward end of the plunger is beveled slightly at 58 to clear arm 24 as the latter swings in the handle.

Fixed in the rear end of the rarm 24, as by being press fitted in a cutaway bore 60 extending through the arm parallel to the pivot axis 14, is a casehardened pin 62. Pin 62 provides a cam element engageable with thecam roller 54. Threaded in the rear end of the arm 24, and extending about normal to the pivot axis 13, is a calibration screw 64. Calibration screw 64 is .accessible through a hole 66 in the handle 12, which hole may be closed by a screw 68.

In the normal position of the -wrench parts illustrated in FIG. 1, cam roller 54 is disposed in the path along which the rear end of arm 24 moves during relative counterclockwise (as the wrench is viewed in the drawing) rotation of the arm in the handle. When a torque load is first applied to a workpiece, by clockwise rotation of handle 12, cam pin 62 on the arm 24 engages the 'cam roller and the latter blocks relative rotation of the handle 12 and torque transmission member 18 on the pivot axis 14. Member 18 is, therefore, forced to rotate in the clockwise direction with the handle so that the torque which is applied to the wrench handle is `transmitted through the member 18 to the workpiece.

As the torque load is applied, cam pin` 62 presses againstthe curved surface of the cam roller 54. A caniming action is thereby created which produces a rearward force component on plunger 28 tending to move the latter rearwardly in the handle 12 against the action of the spring 32. As the torque load increases, the rearward camming force on the plunger increases. Eventually the latter force overcomes the spring pressure on the plunger, whereupon the latter is suddenly forced rearwardly and the arm 24 is released to swing in the counterclockwise direction in the handle. In other words,

the wrench releases What actually happens when the wrench releases, of course, is that the arm 24 and torque transmission member 18 remain stationary while the handle 12 rotates slightly in the clockwise direction.

This sudden release of the wrench handle affords a rst indication that the predetermined torque load has been reached. A second indication that the predetermined torque load has been reached is afforded by the click which occurs when, after release of the handle, the latter rotates into impact with the rear end of the arm 24 (FIG. 2).

In the released position of the wrench parts, shown in FIG. 2, the cam pin 62 has not quite reached a deadcenter position on the cam roller 54. As a result, when the applied torque is removed from the wrench handle, a reverse camming action is developed on the pin 62, by virtue of the spring pressure of the cam roller 54 thereagainst, which returns the wrench parts to their normal position of FIG. 1.

Proceeding now to the improvement features of the present invention, it will be observed that the camming action which occurs between the cam roller 54 and carn pin 62 during the application of a torque load to a workpiece creates on the plunger 28 not only the rearward camming force discussed above but also a lateral camming force, or, more strictly speaking, a lateral force component. This lateral force component forces the plunger upwardly and toward the upper inner surface of the wrench handle 12, as the wrench is viewed in the drawing. If the plunger were forced directly against the inner surface of the handle, the resulting friction between the wrench handle and the plunger, which would vary with the applied torque as well as with other factors, would introduce error into the wrench operation and cause a loss of both accuracy and precision.

The present invention proposes to reduce to a minimum the frictional forces acting on the plunger 28, and thereby maximize both the accuracy and precision of the wrench, as follows: Formed in the upper side of the plunger sleeve 30, adjacent the forward end of the sleeve, are two circumferentially spaced bores or holes 70. These holes open into the central opening or recess 52 in the plunger opposite the cam roller 54. Bores 70 are proportioned to rotatably receive bearing balls 72 of such a diameter that the balls will seat against the surface of the cam roller and against the inner surface of the wrench handle 12. Balls 72 thus project slightly beyond the outer surface of the plunger 28 and provide a low friction rolling contact between the plunger and wrench handle.

The present ball bearing arrangement in which bearing balls 72 seat directly against the cam roller 54 has several advantages. In the first place, balls of greater diameter may be used than if the balls were simply seated in depressions in the outer surface of the plunger, for example. Bearing balls of greater diameter are desirable since they are less prone to crushing or other deformation under the loads imposed on the balls in operation of the wrench. As a result, greater torque loads may be applied with the present wrench.

Another advantage of the present bearing ball and cam roller arrangement is that maximum rolling contact between the plunger 28 and wrench handle 12 is achieved. Thus, the bearing balls 72 not only have rolling contact with the wrench handle 12, but also with the cam roller 54. It will be observed that since movement of cam pin 62 past cam roller 54 during release of the wrench tends to turn the roller in the clockwise direction in FIGS. 1 and 2 and the friction between the handle and bearing balls 72 tends to rotate the balls in the counterclockwise direction during rearward movement of the plunger 2S in the handle, the bearing balls and cam roller move in the same direction at their points of contact. There is, therefore, primarily rolling contact between the cam pin 62 and cam roller 54, between the cam roller and bearing balls 72 and between the bearing balls and the inner surface of the handle. Moreover, it will be observed that during the application of a torque load, the lateral thrust on the plunger is transmitted from the cam pin 62 to the cam roller 54, from the cam roller to the bearing balls 72, and from the bearing balls to the wrench handle 12. Thus, there is little, if any, lateral load transmitted through the plunger sleeve 30 so that no part of the sleeve is urged with any great force against the inner surface of the wrench handle. As a result, frictional resistance between the plunger 28 and wrench handle is appreciably minimized, whereby the accuracy and precision of the wrench are maximized.

The present wrench construction is obviously relatively simple and economical to manufacture and assemble.

The torque release value of the wrench is adjusted in the usual way by rotating the sleeve 40 to vary the pressure of the spring 32 against the plunger 28. Suitable indicia (not shown) are provided on the wrench handle 12 and sleeve 40 to indicate various predetermined settings of the wrench. Screw 64 is used to calibrate the wrench. Thus, adjustment of the calibration screw 64 shifts the point of contact of the cam pin 62 with the cam roller 54 around the axis of the roller. This has the effect of changing the rearward force component on the plunger 28 for any given pressure of the cam pin 62 against the roller surface and, therefore, the torque release value of the Wrench.

While the illustrated Wrench utilizes ball bearings between the cam roller and wrench handle, a. needle bearing might be used by making the inner surface of the handle engaged by the bearing flat rather than cylindrical and providing the plunger with an opposing at rather than cylindrically curved surface. In this case, of course, the plunger would be provided with a transverse slot to receive the needle bearing rather than circumferentially spaced holes as in the illustrated wrench.

Clearly, then, the invention is capable of attaining the objects and advantages preliminarily set forth.

What is claimed is:

l. A predetermined torque release wrench, comprising:

a tubular handle,

a Work-engaging member rotatably mounted on said handle for turning on a transverse axis of the handle,

an arm rigidly secured at one end to said member and extending longitudinally through said handle,

a plunger longitudinally movable in said handle opposite the other end of said arm,

a rst roller on the end of said plunger adjacent said other end of said arm,

a spring acting between said handle and plunger for urging the latter toward said arm to a position wherein the curved surface of said roller engages said other end of said arm to releasably restrain the latter and said member against turning in one direction with respect to said handle, whereby an applied torque which tends to turn said arm and member in said one direction relative to said handle creates a longitudinal camming force on said plunger tending to retract the latter against the action of said spring and thereby release said arm and member for rotation in said one direction relative to said handle, and a lateral thrust on said roller directed toward one side of said handle,

said plunger including a longitudinally extending wall between said roller and said one side of said handle, and said wall having an opening opposite said roller, and

a second roller in said opening seating against said rst roller and the inner surface of said handle, whereby the lateral thrust of said arm against said irst roller is transmitted directly through said rollers to said handle and said rollers cooperate to support said plunger for free longitudinal movement in said handle.

2. A predetermined torque release wrench, comprising:

a tubular handle,

a rst roller on the end of said plunger adjacent said other end of said arm,

said plunger including a longitudinally extending wall between said roller and said one side of said handle, and said wall having a pair of openings spaced transversely of said plunger and located opposite said roller, and

second rollers in said openings, respectively, seating against said first roller and the inner surface of said handle, whereby the lateral thrust of said arm against said irst roller is transmitted directly through said rollers to said handle and said rollers cooperate to support said plunger for free longitudinal movement in said handle.

3. A predetermined torque release wrench, comprising:

a tubular handle,

a generally cylindrical roller mounted on the end of said plunger adjacent said other end of said arm with the axis of said roller extending approximately parallel to said turning axis of said Work-engaging member,

a spring acting between said handle and plunger for urging the latter toward said arm to a position wherein the curved surface of said roller engages the other end of said arm to releasably restrain the latter and said member against turning in one direction with respect to said handle, whereby an applied torque which tends to turn said arm and member in said one direction relative to said handle creates a longitudinal camming force on said plunger tending to retract the latter against the action of said spring and thereby release said arm and member for rotation in said one direction relative to said handle, and a lateral thrust on said roller directed toward one side of said handle,

said plunger including a longitudinally extending wall between said roller and said one side of said handle, said wall having a pair of openings spaced in the axial direction of and located opposite said roller, and

bearing balls in said openings, respectively, seating against said roller and the inner surface of said handle, whereby the lateral thrust of said arm against said roller is transmitted directly through said roller and bearing balls to said handle and said roller and balls cooperate to support said plunger for free longitudinal movement in said handle.

4. A predetermined torque release wrench, comprising:

a tubular handle,

a roller on the end of said plunger adjacent said other end of said arm,

a hardened pin carried on said other end of said arm and extending approximately parallel to said turning axis, and

a spring acting between said handle and plunger for urging the latter toward said arm to a position wherein said roller engages said pin to releasably restrain said arm and member against turning in one direction with respect to said handle, whereby an applied torque which tends to turn said arm and member in said one direction relative to said handle creates a longitudinal camming force on said plunger tending to retract the latter against the action of said spring and thereby release said arm and member for rotation in said one direction relative to said handle.

5. The subject matter of claim 4, wherein:

said pin is frictionally held in a generally semi-circular groove in said other end of said arm and protrudes through the open side of said groove into contact with said roller.

References Cited in the tile of this patent UNITED STATES PATENTS 2,704,472 Booth Mar. 22, 1955 2,887,921 Livermont May 26, 1959 2,918,834 Cranford Dec. 29, 1959 2.972,271 Gill Feb. 21, 1961

Claims

1. A PREDETERMINED TORQUE RELEASE WRENCH, COMPRISING: A TUBULAR HANDLE, A WORK-ENGAGING MEMBER ROTATABLY MOUNTED ON SAID HANDLE FOR TURNING ON A TRANSVERSE AXIS OF THE HANDLE, AN ARM RIGIDLY SECURED AT ONE END TO SAID MEMBER AND EXTENDING LONGITUDINALLY THROUGH SAID HANDLE, A PLUNGER LONGITUDINALLY MOVABLE IN SAID HANDLE OPPOSITE THE OTHER END OF SAID ARM, A FIRST ROLLER ON THE END OF SAID PLUNGER ADJACENT SAID OTHER END OF SAID ARM, A SPRING ACTING BETWEEN SAID HANDLE AND PLUNGER FOR URGING THE LATTER TOWARD SAID ARM TO A POSITION WHEREIN THE CURVED SURFACE OF SAID ROLLER ENGAGES SAID OTHER END OF SAID ARM TO RELEASABLY RESTRAIN THE LATTER AND SAID MEMBER AGAINST TURNING IN ONE DIRECTION WITH RESPECT TO SAID HANDLE, WHEREBY AN APPLIED TORQUE WHICH TENDS TO TURN SAID ARM AND MEMBER IN SAID ONE DIRECTION RELATIVE TO SAID HANDLE CREATES A LONGITUDINAL CAMMING FORCE ON SAID PLUNGER TENDING TO RETRACT THE LATTER AGAINST THE ACTION OF SAID SPRING AND THEREBY RELEASE SAID ARM AND MEMBER FOR ROTATION IN SAID ONE DIRECTION RELATIVE TO SAID HANDLE, AND A LATERAL THRUST ON SAID ROLLER DIRECTED TOWARD ONE SIDE OF SAID HANDLE, SAID PLUNGER INCLUDING A LONGITUDINALLY EXTENDING WALL BETWEEN SAID ROLLER AND SAID ONE SIDE OF SAID HANDLE, AND SAID WALL HAVING AN OPENING OPPOSITE SAID ROLLER, AND A SECOND ROLLER IN SAID OPENING SEATING AGAINST SAID FIRST ROLLER AND THE INNER SURFACE OF SAID HANDLE, WHEREBY THE LATERAL THRUST OF SAID ARM AGAINST SAID FIRST ROLLER IS TRANSMITTED DIRECTLY THROUGH SAID ROLLERS TO SAID HANDLE AND SAID ROLLERS COOPERATE TO SUPPORT SAID PLUNGER FOR FREE LONGITUDINAL MOVEMENT IN SAID HANDLE.