US3485117A - Torque wrench - Google Patents

Description

Dem 23, 1969 v. c. wares. :1- AL 3,485,117

TORQUE WRENCH Filed Feb. 26. 1968 FIG. I

27 i Z INVENTOR$ VINCENT C. TYRRELL 21 28 JAY R. BAILEY Q 29 I FIG. 7 %A0m ZM L /M ATTORNEYS.

United States Patent Olfice 3,485,117 Patented Dec. 23, 1969 3,485,117 TORQUE WRENCH Vincent C. Tyrrell, Torrance, and Jay R. Bailey, Woodland Hills, Calif., assignors to McCulloch Corporation, Los Angeles, Calif., a corporation of Wisconsin Filed Feb. 26, 1968, Ser. No. 708,388

Int. Cl. B25b 23/14 US. Cl. 8152.4 7 Claims ABSTRACT OF THE DISCLOSURE A torque wrench fabricated by bending a piece of resilient, metallic, rod stock to provide a straight shank, a partially helical, torque controlling loop, and a forceapplying handle extending tangentially of this loop portion.

BACKGROUND AND GENERAL OBJECTS OF INVENTION In the United States Bailey Patent 3,283,620, there is presented a significant advance in the torque wrench art. The torque wrench featured in this patent is fabricated from a single piece of rod stock and is automatically operable to indicate the application of a fixed amount of torque to a fastener.

The Bailey torque wrench includes a shank, a loop extending laterally of the shank, and a handle extending transversely of the loop. In this wrench, the two-dimensional character of the loop produces a loop location laterally of the handle. By applying rotary force to the handle, the loop is closed. The closing of the loop indicates to an operator that a fixed amount of torque has been applied to the shank.

The advantages of this structure notwithstanding, certain structural characteristics of the tool are susceptible to improvement.

In particular, it would be desirable to arrange the handle, in relation to the torque controlling loop, to ensure that force applied on the handle in a given direction would have substantially the same tendency to close the torque controlling loop. Since rotary force must be applied to the Bailey handle to elfect loop closing, i.e., a force directed circumferentially of the tool shank, it is possible that variations in the application of force to the handle may tend to alter the torque controlling properties of the loop. For example, force applied perpendicular to the handle, Where the handle itself extends perpendicular to a loop arm, may, to some extent, tend to bend the handle relative to the loop, as well as tend to close the loop.

It would also be desirable to provide means for improving the stability of the Bailey shank when it is subjected to applied torque.

It will be apparent that with the Bailey handle extending transversely of the loop arms, torque applied to the shank will be determined by bending force transmitted through two bends, i.e., the loop bend and the bend between the handle and one of the loop arms. By simplifying this force transmitting path, the possibility of operatorinduced error will be reduced.

The advance in the art afiorded by Bailey torque wrench could also be enhanced by providing indications of multiple torque levels and by providing structure to prevent loop deformations when a fastener was being unscrewed.

In order to avoid the possibility of the loop overclosing, i.e., the loop arm connected with the handle of the Bailey wrench moving over the top of the shank and the other arm of the Bailey tool, it would be desirable to position the loop arm connected to the handle of this tool So as to ensure its engagement with the shank portion of the tool when the loop is closed.

It would be equally desirable to minimize the bulk of the Bailey tool by reducing the number of bends. For example, it would be especially desirable to maintain the shank and one arm of the loop in one plane and the other arm of the loop and the handle in another plane so that the Width of the tool does not exceed the width of the loop itself.

Bearing these desirable improvements in mind, it is a prime object of the invention to provide an improved torque wrench incorporating the most desirable aspects of the Bailey wrench in combination with each of the desirable modifications above described.

It is likewise an object of the invention to provide such an improved torque wrench which simplifies the overall manufacture of the tool Without sacrificing functional or structural reliability.

It is an additional object of the invention to provide such an improved torque wrench which enables an operator to visually detect a series of torque levels instead of a single torque level indication as provided by the closing of the loop of the Bailey tool.

It is also an object of the invention to provide an improved torque wrench of the type featured in the Bailey patent which is not vulnerable to deformation when the tool is used to unscrew fasteners.

SUMMARY OF OVERALL INVENTION A torque wrench of this invention comprises a fastener engaging portion and a straight shank portion extending from the fastener engaging portion. A curved junction extends tangentially from the straight shank portion. A first arm portion extends tangentially of this curved junction and generally laterally of the shank portion. A helical loop portion extends tangentially of the first arm portion and is spaced laterally outwardly of the shank portion. A second arm portion extends tangentially from the helical loop portion generally toward the shank portion. This second arm portion is axially straight and exceeds the length of the first arm portion so as to cross and extend beyond the shank portion and be laterally spaced from this shank portion. A handle extends coaxially with the second arm portion, with the handle and helical loop portion being disposed on opposite sides of the shank portion. The second arm portion is displaced from the first arm portion and curved junction along the axis of the shank portion. The second arm portion is engageable with the shank portion, in response to a force exerted on the handle perpendicular to a plane coextensive with the shank portion and first arm portion and concurrently perpendicular to the handle.

Other individually significant facets of the invention reside in abutment means carried by a toque indicating device and operable to prevent undue separation of the first and second arm portions extending from the helical loop portion.

Of additional independent significance is a torque indicating structure slidably mounted on the coaxially aligned second arm portion and handle and having a series of axially displaced shank engaging abutments spaced at progressively varying distance, outwarrly of the common axis of the second arm portion and handle.

DRAWINGS In describing the invention reference will be made to a preferred embodiment illustrated in the appended drawings.

In the drawings:

FIGURE 1 is a side elevational view of a torque wrench fabricated in accordance with the present invention;

FIGURE 2 provides a top plan view of the FIGURE 1 torque wrench;

FIGURE 3 illustrates a torque indication mechanism mounted on the FIGURES 1 and 2 torque Wrench, operable to prevent undue separation of the torque controlling loop of this wrench, and additionally operable to indicate a variety of applied torque levels;

FIGURE 4 provides a transverse sectional view of the FIGURE 3 torque indicator as viewed along the section line 4-4;

FIGURE 5 provides a modified form of the FIGURE 3 torque indicator illustrating a stepped abutment slidably mounted on the torque wrench, with each abutment being egnageable with the torque wrench shank and operable in response to such engagement to reflect a different level of torque applied to the tool shank;

FIGURE 6 illustrates a modified form of the FIGURE 5 torque indicator with the t rque indicating abutments being reversed in axial sequence along the axis of one arm portion of the loop;

FIGURE 7 schematically illustrates a clip arrangement for slidably mounting the FIGURE 6 torque indicator, as viewed along the section line 77 of FIGURE 6; and

FIGURE 8 illustrates a m dified form of the FIGURE 1 torque wrench showing a transverse handle extension similar to the type employed in conjunction with a conventional brace and bit.

STRUCTURE OF WRENCH The wrench structure 1 shown in FIGURE 1 is fabricated from a piece of hexagonally cross sectional, resilient steel, rod stock.

Wrench 1 includes a fastener engaging portion 2. operable to engage a conventional, hexagonally configured, fastener head recess. A straight shank 3 extends axially from the fastener engaging portion 2. An arcuate junction 4 extends tangentially from the straight shank portion 3 at zone 5. A first straight arm portion 6 extends tangentially of the curved juncti n at zone 7. Arm portion 6 is inclined downwardly generally toward a plane intersection the fastenenengaging portion 2 and extending perpendicular of the axis of the shank 3. A helical loop portion 8 extends tangentially of the first arm portion 6 at zone 9. Helical loop portion 8 is spaced laterally outwardly of the shank portion 3 in the direction A, as shown in FIGURE 2.

A second straight arm portion 10 extends tangentially from the helical loop portion 8. As shown in FIGURE 1, straight arm portion 10 extends tangentially from junction 11 and is aligned with a plane extending perpendicular to the axis of the shank 3.

Wrench 1 includes element 10 which may be considered as comprising a second arm portion, or an arm or handle portion.

Arm portion 10 extends to rod stock zone or hand e junction 12 and substantially exceeds the length of the first arm portion 6. Thus, the arm portion 10, of the wrench loop zone, crosses and extends beyond the shank portion 3 and is spaced laterally from the shank portion 3 in the direction B. As shown in FIGURE 1, arm portion 10 crosses shank 3 between junction 4 and fastener engaging portion 2.

A handle portion 13 of the bar stock extends coaxially with the arm portion 10 from the junction zone 12. Thus, the handle portion 13, i.e. the point of application of manual force to the torque wrench 1, is disposed on a side of the shank 3 opposite to the side where the helical loop portion is located with reference to the direction A. As shown, loop 8 is displaced and thus extends, laterally of loop zone 8, in the directions A and B.

A wooden handle cover 14 may be telescoped over the handle extremity 13 of the wrench 1, as shown in FIG- URES l and 2, and secured in place by conventional techniques.

4 OPERATING CHARACTERISTICS A force applied to the handle 13, perpendicular to the common axis of the handle 13 and junction zone 12 and concurrently perpendicular to the common plane of the axis of the shank 3 and first arm portion 6, will tend to rotate the arm portion 10 toward the shank 3 and tighten the helical loop portion 8.

For all practical purposes, the extent of torque thus applied to the shank 3, by manually manipulating the handle 13, will be a direct linear function of the distance between the shank 3 and arm portion 10 as measured along the direction B.

Significantly this torque will be determined almost exclusively 'by tightening of the helical portion 8, although it may be effected to some nominal extent by beam-type deflection of the handle 10. However, it will be recognized that the prime influence over torque will be provided by the single torque control loop 8. No complexities are introduced by bend zones between the arm portions 6 or 10 and the loop 8, or between arm portion 10 and handle 13.

With the elongate loop structure, defined by the arms 6 and 10 and the helical loop portion 8, moving progressively downwardly along the axis of the shank 3, it is ensured that the arm portion 10 will contact the straight shank 3 and not the junction 4. This is uniquely advantageous in that it insures a positive and consistent degree of loop deflection required to bring the arm portion 10 into abutting engagement with the shank 3. If the arm portion 10 was engageable with the junction 4, very slight deflection of the arm portion 10 along the shank of the axis 3 would vary the extent of loop closing required to bring the arm portion 10 into contact with the junction 4. In other words, less loop deflection would be required to bring the shank into contact with the junction zone 4a than would be required to bring it into contact with the junction zone 4b.

Thus, with FIGURES 1 and 2 structure, an operator may effectively and consistently control the application of torque force so as to be certain that in bringing the arm portion 10 into engagement with the shank 3, a predetermined and consistent level of torque is applied to the shank 3. It is not necessary to attempt to guess as to the direction to which force should be applied to the handle 13, i.e. an operator need only consisently apply force perpendicular to the handle 13 and the common plane of the arm portion 6 in shank 3. With the arm portion 10 always engaged with the axially straight shank 3, an operator is assured of a consistent degree of loop closing thereby indicating a consistent level of applied torque.

Further, the displacement of arm portion 10 downwardly along the shank 3 provides an operator engageable, shank stabilizing zone 4. An operator may engage this zone with one hand, while applying torque to handle 13, and thereby stabilize the shank 3.

TORQUE INDICATING STRUCTURE FIGURES 3 and 4 illustrate one form of a torque indicating device preferably associated with torque wrench 1.

This torque indicating device 15 is fabricated from resilient sheet metal and includes a U-shaped body portion 15a having two legs 15b and 15c, each terminating in a cliplike, fastening portion 16. Clip ortions 16 may each be fabricated in a hexagonal shape so as to conf rm to the cross section of the handle portion 10 as shown in FIGURE 4. The resilience of each clip portion 16 is such as to resiliently secure the torque indicating device on the arm portion 10.

Sheet metal body portion 15a of the indicating device 15 projects laterally outwardly of the fastening means 16 in the general direction B, i.e., toward the shank 3. A sheet metal abutment 18, connecting legs 15b and 150, is

carried by the sheet metal body portion a on a side f the shank 3 opposite to the side crossed by the second arm portion 10.

Thus, when force is applied to the handle 13, tending to unscrew a fastener, i.e., open up the helical loop portion 8, the abutment 18 will engage the shank 3 and prevent distortion or undue opening up of the loop portion 8.

A torque indicating edge 19 of the t rque indicating means 15 is provided on leg 15c and includes a series of evenly spaced indicia extending across the gap between the shank 3 and the arm portion 10 in the general direction B. As the loop 8 is tightened, the shank 3 will move progressively across these markings or indicia. These indicia are evenly spaced and correlate with the torque applied to shank 3, which is a substantially linear function of the gap between arm portion 10 and shank 3. As will be apparent, the markings closest to the arm portion 10 will be indicative of a greater level of applied torque, when aligned with the shank 3, than will the markings disposed laterally outwardly near the abutment 18 when they are aligned with the shank. By bringing spaced abutment 3 ones or surfaces 10a and 3a of arm portion 10 and shank 3, respectively, into contact, an operator will have exerted a predetermined, maximum allowable torque on the shank 3.

Thus, depending upon the position of the shank 3 relative to the indicia 19, an operator will be able to determine the level of torque being applied to the fastener engaging portion 2.

A modified and still further advantageous form of the FIGURE 3 torque indicating device is shown in FIG- URE 5. As shown in FIGURE 5, the modified torque indicating unit or device 20 includes a tubular base portion 21, slidably mounted on the arm 10. Base portion 21 may include a central recess 22 conforming in cross section to the cross section of the arm portion 10 and frictionally engageable with the outer periphery of the arm portion 10. A hooklike abutment 23 carried by the torque indicating device 20 serves to limit opening up of the loop 8 in exactly the same way that the abutment 18 serves this function.

A series of cylindrical abutments of different diameters are spaced longitudinally along the axis of the arm portion 10 and encircle the opening 22. Two such abutments 24 and 25 are illustrated in FIGURE 5.

As will be apparent, with the loop 8 closed so as to bring the arm portion 10 into engagement with the shank 3, the maximum level of applied torque will be indicated. This degree of closing is possible with the indicating device 20 positioned as shown 11 FIGURE 5.

By moving the indicating device slidably along the axis of the arm portion 10, so as to make the smaller diameter abutment 24 engageable with the shank 3 in response to loop closing, a different and lower level of torque indication is provided.

By sliding the indicating device 20 still further along the axis of the arm portion 10, toward the loop 8, a still lower level of applied torque may be indicated. This lower level of torque would result from the positioning of the abutment 25 so as to make it engageable with the shank 3 in response to closing or tightening of the loop 8.

FIGURE 6 illustrates a simplified and somewhat rcversed arrangement of the torque indicating device 20.

The FIGURE 6 torque indicating structure 26 includes a resilient clip portion 27 substantially the same as the previously described clip portion 16. Torque indicating unit 26 includes a first abutment 28 and a second abutment 29. The second abutment 29, which is disposed between the abutment 28 and the loop 8, is positioned laterally outwardly of the axis of the arm portion 10 at a greater distance than is the abutment 28.

Thus, with the torque indicating device 26 positioned as shown in FIGURE 6, the loop 8 may be closed so as to bring the shank 3 into engagement with the abutment zone 10a, thereby indicating a relatively high level of applied torque. By sliding the torque indicating device 26 somewhat away from the loop 8, the abutment 28 may be disposed so as to be engageable with the shank 3 in response to loop closing. Such engagement would reflect an intermediate level of applied torque.

By sliding the torque indicating device 26 still further away from the loop 8, the abutment 29 may be disposed so as to be engageable with the shank 3 in response to loop closing. Such engagement would, of course, reflect a relatively lower level of applied torque.

MODIFIED FORMS OF WRENCH It will be apparent that structural variations may be effected within the scope of the inventive concept herein presented. For example, as shown in FIGURE 8, a torque wrench 30 may be fabricated of round bar stock while maintaining a hexagonal fastener engaging end 2. Obviously fastener engaging end 2 may be modified so as to provide a female or male type fastener engaging portion conforming to the structural characteristics of a wide variety of conventional fasteners.

Further and somewhat unobviously, the handle portion 13 of the wrench 30 may be provided with a conventional brace and bit-type extension 31. This extension would include a shank 32 extending parallel to the shank portion 3. A handle extension portion 33 extends from shank portion 32, perpendicular to portion 32. Another handle extension portion 34 may be disposed so as to be coaxially aligned with the shank 3 and perpendicular to the handle extension portion 33.

As shown, wrench 30 includes components 2, 3, 6, 8 and 10, corresponding to the same numbered components of wrench 1.

A conventional knob 35 may be journaled on the handle extension portion 34. With this arrangement an operator would grasp the handle 35 with one hand, with the fastener engaging portion 2 engaged with the fastener to be torqued. With the other hand, the operator would apply force substantially perpendicular to the arm 10 and the common plane of the shank 3 and arm portion 6.

SUMMARY OF ADVANTAGES AND SCOPE OF INVENTION As will be apparent, a prime advantage of the invention resides in ensuring that torque is effectively and predominantly controlled by the single, helical loop portion 8. With this arrangement it is possible for an operator to apply force to the wrench handle in an easily defined direction, i.e. perpendicular to the handle and the common plane of the shank and first arm portion, and know that a consistent level of applied torque will result. The helical loops and tangential loop arms confine torque control to a predictable, simple, helix portion having readily ascertainable torque resistant properties.

The operator will also know that the arm portion 10 will always engage the straight shank portion 3, thereby further ensuring certainty in the level of applied torque. Further, the operator may readily grasp junction 4, so as to stabilize shank 3, without having his fingers pinched by the convergence of shank 3 and arm portion 10.

With the multiple, torque level, indicating device employed, an operator may easily and readily ascertain a series of applied torque levels. The variously dimensioned torque indicating abutments enable torque level to be determined without having to visually observe a scale.

The loop movement limiting abutments of the torque indicating device effectively avoids tool damage by ensuring that the loop is not opened up and stressed while attempting to unscrew fasteners.

By limiting the width of the rod stock defined portions of the tool to the width of the loop portion 8, the bulk of the tool is maintained at an absolute minimum level, thereby facilitating its utilization and storage.

As will be apparent, alternative terminology has been occasionally employed in describing certain components of the invention, consistent with the variations in terminology employed in the art. For example, element 10 has been referred to, synonymously as a straight arm, a handle portion, an arm portion, a handle, a second arm portion, a second arm, and an arm. Similiraly, it has been indicated that the stock material from which the wrench is fabricated extends to a stock zone or junction zone 12. This zone of the bar stock constitutes the junction between the naked portion of the bar stock and the portion 13 of the bar stock which is recevied within the handle cover 14. The zone 10a of arm 10, which is adapted to abuttingly engage the zone 3a of the shank 3, has been referred to synonymously as an abutment surface. The metal tab 1511 has been identified synonymously as a metal portion. The indicating unit has been synonymously identified as an indicating device.

In describing the invention reference has been made to a preferred embodiment. However, those skilled in the art may well recognize additions, deletions, substitutions or other modifications which would fall within the purview of the invention as defined in the appended claims.

In the claims:

1. A torque Wrench comprising:

a fastener engaging portion;

a straight shank portion extending from said fastener engaging portion;

a curved junction extending at one end thereof, tangentially from said straight shank portion;

a first, straight arm portion extending tangentially of another end of said curved junction and generally laterally of said shank portion;

a helical loop portion extending tangentially of said first arm portion and spaced laterally outwardly of said shank portion;

said helical loop portion curving outwardly of said shank portion and generally toward a plane intersecting said fastener engaging portion;

a second, straight arm portion extending tangentially from a junction with said helical loop portion genarally toward said shank portion;

the junction between said second, straight arm portion and said helical loop portion being substantially devoid of deflection generally parallel to said shank portion and directed toward said fastener engaging portion;

said second arm portion being axially straight and exceeding the length of said first arm portion so as to cross and extend beyond said shank portion and be laterally spaced therefrom; and

a handle extending coaxially with said second arm portion, with said handle and helical loop portion being disposed on opposite sides of said shank portion;

said second arm portion being displaced from said first arm portion and curved junction along the axis of said shank portion and engageable with said shank portion in response to a force exerted on said handle perpendicular to a plane coextensive with said shank portion and first arm portion and concurrently perpendicular to said handle.

2. A torque wrench as described in claim 1:

wherein said first arm portion is inclined relative to said shank portion so as to extend generally toward said plane intersection said fastener engaging end, which plane extends perpendicular to said shank portion; and

wherein said second arm portion is disposed coextensive with a plane extending perpendicular to said shank portion.

3. A torque Wrench comprising:

a fastener engaging portion;

a straight shank portion extending from said fastener engaging portion;

a curved junction extending at one end thereof, tangentially from said straight shank portion;

a first, straight arm portion extending tangentially of another end of said curved junction and generally laterally of said shank portion;

a helical loop portion extending tangentially of said first arm portion and spaced laterally outwardly of said shank portion;

a second, straight arm portion extending tangentially from said helical loop portion generally toward said shank portion;

said second arm portion being axially straight and exceeding the length of said first arm portion so as to cross and extend beyond said shank portion and be laterally spaced therefrom;

a handle extending coaxially with said second arm portion, with said handle and helical loop portion being disposed on opposite sides of said shank portion;

said second arm portion being displaced from said first arm portion and curved junction along the axis of said shank portion and engageable with said shank portion in response to a force exerted on said handle perpendicular to a plane coextensive with said shank portion and first arm portion and concurrently perpendicular to said handle;

fastening means mounted on said second arm portion;

and

torque variations indicating means extending transversely of said fastener means and generally toward said shank portion, said torque variations indicating means being operable in response to convergence of said shank portion and second arm portion to successively indicate a plurality of torque levels applied by said handle to said shank portion.

4. A torque wrench as described in claim 3 wherein said torque indicating means further includes shank portion engaging, abutment means positioned on a side of said shank portion opposite to the side of said shank portion crossed by said second arm portion and operable to prevent separation of said shank portion and second arm portion.

5. A torque wrench as described in claim 3:

wherein said fastening means is slidably mounted on said second arm portion for axially slidable movement therealong; and

wherein said torque variation indicating means comprises a plurality of shank engaging abutment means displaced axially of said second arm portion, engageable with the side of said shank portion crossed by said second arm portion, and displaced laterally outwardly of the axis of said second arm portion at progressively greater distances, successively along the axis of said second arm portion.

6. In a torque wrench comprising a unitary, metallic, resilient rod of polygonal cross sections, said rod includa fastener engaging portion;

a straight shank portion extending from said fastener engaging portion;

a curved junction extending at one end thereof, tangentially from said straight shank portion;

a first, straight arm portion extending tangentially of another end of said curved junction and generally laterally of said shank portion;

a helical loop portion extending tangentially of said first arm portion and spaced laterally outwardly of said shank portion;

a second, straight arm portion extending tangentially from said helical loop portion generally toward said shank portion;

said second arm portion being axially straight and exceeding the length of said first arm portion so as to cross and extend beyond said shank portion and be laterally spaced therefrom;

a handle extending coaxially with said second arm portion, with said handle and helical loop portion being disposed on opposite sides of said shank portion;

said second arm portion being displaced from said first arm portion and curved junction, along the axis of said shank portion, and engageable with said shank portion in response to a force exerted on said handle perpendicular to a plane coextensive with said shank portion and first arm portion and concurrently perpendicular to said handle;

said second arm portion being engageable with said shank portion between said fastener engaging portion and an operator engageable, shank stabilizing means defined by said curved junction;

fastening means mounted on said second arm portion;

torque variation indicating means extending transversely of said fastener means and generally toward said shank portion, said torque variation indicating means being operable in response to convergence of said shank portion and second arm portion to successively indicate a plurality of torque levels applied by said handle to said shank portion; and

shank portion engaging, abutment means carried by said second arm portion and positioned on a side of said shank portion opposite to the side of said shank portion crossed by said second arm portion and operable to prevent separation of said shank portion and second arm portion.

7. A torue wrench compirsing:

article engaging means;

handle means operable to apply torque to said article engaging means;

spaced abutment means operable to converge in response to torque exerted by said handle means on said article engaging means;

means yieldably resisting convergence of said spaced abutment means;

a plurality of interconnected spacing means, each operable to be interposed between said abutment means, and when engaged with each of said abutment means, to indicate a predetermined torque applied by said handle means to said article engaging means; and

means supporting said plurality of spacing means for sequential disposition between said abutment means, with adjacent spacing means being operable to indicate different levels of torque applied by said handle means to said article engaging means.

References Cited UNITED STATES PATENTS 1,310,641 7/1919 Welch 81-477 X 1,392,728 10/1921 Westman et al 81-119 2,936,661 5/1960 Hostetter 81--52,4 3,274,827 9/1966 Sturtevant 81-52.4 X 3,283,620 11/1966 Bailey 81-52.4 3,355,970 12/1967 Knudsen et al. 81--52.4

FOREIGN PATENTS 60,530 l/ 1943 Denmark. 675,755 5/1939 Germany.

JAMES L. JONES JR., Primary Examiner Po-wfin UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 485, 117 Dated December 23, 1969 Inventofls) V. c. TYRRELL ET AL It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In Column 2, line 62, change "outwarrly" to outwardly In Column 3, line 14, change "egnageable" to engageable In Column 3, line 34, omit the period after "2" and insert a comma In Column 3, line 42, change 'intersection" to intersecting In Column 3, line 69, after 'portion" add 8 In Column 4, line 39, after "with" add the In Column 4, line 50, after closing" add a comma In Column 5, line 23, after "abutment" change "3 ones" to zones II II In Column 5, line 51, after"shown" change n to in In Column 7, line 66, change "intersection" to intersecting In Column 8, line 28, change "variations" to variation In Column 8, line 30, change "variations" to variation SIGNED NND SEALED JUN 3 01970 Anew Edward M. Fletcher, Ir. WILLIAM E- 'SGINYIIER, J

Anesfing Officer Gomissioner of Pat-ants

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