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Title:
Torque wrench
United States Patent 2159373
Abstract:
This invention relates to wrenches, and more particularlyto a wrench for indicating the amount of force or torque applied to the handle in rotating or attempting to rotate a nut or the like engaged by the wrench. It has been found, for instance, in the tightening of nuts on cylinder heads...


Inventors:
Dunn, Allen I.
Publication Date:
05/23/1939
Assignee:
CEDAR RAPIDS ENG CO
Primary Class:
International Classes:
B25B13/46; B25B23/142; B25B23/143
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Description:

This invention relates to wrenches, and more particularlyto a wrench for indicating the amount of force or torque applied to the handle in rotating or attempting to rotate a nut or the like engaged by the wrench.

It has been found, for instance, in the tightening of nuts on cylinder heads of internal combustion engines or in assembling precision devices such as air-craft engines and the like that it is very desirable to tighten the nuts and bolts of such devices to certain known degrees.

Devices have been provided for this purpose in which hydraulic pistons have been utilized for actuating oil pressure gauges to indicate the I torque or force applied, but it has been found that such devices have been expensive to construct and maintain, are difficult to seal, and are not entirely accurate because of the friction of the parts and the inaccuracies of the production made gauges which it is necessary to employ.

It is a general object of my invention to provide a mechanical torque measuring wrench in which deformation of the parts of the wrench is employed in indicating the torque applied to the wrench.

It is also an object of my .invention to provide a wrench of the above character in which the parts are protected from mechanical injury.

Another object of my invention is to provide a torque indicating wrench of extremely simple construction and in which there is a minimum of friction.

Another object of my invention is to provide a to*que indicating wrench of increased accuracy over devices known to the prior art.

A more specific object of my invention is to proiyde a torque indicating wrench which is sufficiently accurate that it may readily be used as a scale or weight measuring device.

Another object of my invention is to provide a torque indicating wrench which is of sufficient accuracy that it may be used as a brake testing device.

Another object of my invention is to provide a 4device which is sufficiently accurate that it may be readily utilized in testing springs of all kinds.

Another object of my invention is to provide a device which may be readily adjusted to vary the stiffness of the flexible portion thereof.

Another object of my invention is to provide means for readily adjusting the indicating device so that it shall read zero when no torque is applied.

65 Another object of my invention is to provide a combination torque indicating and ratchet wrench.

Another object of my invention is to provide an Improved ratchet wrench structure.

Other and further features and objects of the invention will be more apparent to those skilled in the art upon a consideration of the accompanying drawings and following specifications, wherein is disclosed a single exemplary embodiment of the invention, with the understanding, however, that such changes may be made therein as fall within the scope of the appended claims, without departing from the spirit of the invention.

In said drawings: Figure 1 is a plan view of a wrench constructed according to one embodiment of my invention.

Figure 2 is a view in horizontal section of the wrench shown in Figure 1.

Figure 3 is a view in vertical section of the wrench shown in Figures 1 and 2.

Figure 4 is a view in vertical section of the head of the wrench shown in Figures 1, 2 and 3, but in enlarged relation to better illustrate the parts of the device. Figure 5 is a view in horizontal section of a modified form of my invention in which the torque indicating structure is combined with a ratchet wrench structure. The view is in horizontal section, and Figure 6 is a view in side elevation of the embodiment of my invention illustrated in Figure 5.

A device constructed according to a preferred embodiment of my invention is comprised of a head 10 on which is mounted an indicator II. A hollow handle 12 is received in the head 10 and fixed therein by means of a set screw 9 and the outer end of the handle is provided with a grip 13. A shaft 14 is mounted within the handle 12 and the grip 13, and the shaft is tapered at the inner end, as indicated at 15, to provide for a maximum movement of the inner end with reference to the handle 12. The inner end of the shaft 14 engages a gear rack 16 and the rack is adapted to rotate a pinion 17 which is operatively connected to the indicating needle 18 of the indicator I1.

Obviously, other forms of operative connections may be employed for transmitting movement of the shaft 14 to the needle 18. The head 10 is preferably lozenge-shaped so that the large central portion thereof serves as a protection for the mechanism inside the head and also for,the dial of the indicating instrument. The head is provided with a squared shaft 20 pressed tightly into the head 10 to prevent rotation thereof. The member 20 projects from the head to provide a squared projection for engaging the usual sockets such as that indicated at 21, (Figure 4) used for tightening and loosening bolts and nuts.

A cylindrical chamber or bore 22 extends through the head 10, and the cylindrical body portion 23 of the indicating instrument 11 is received within one end of the bore 22. The body 23 may rotate within the bore 22. Frictional resistance to rotation of the body 23 and means for holding the body within the bore is furnished by means of a spring 24 which engages a groove 25 within the body 23. The bore 22 thus affords an open chamber to permit ready assembly of the parts of the device. This chamber may be closed by means of the cap 26 which is held in place by the set-screw 27.

The body 23 is provided, at the central axis thereof, with bearings 28 for the shaft 19 of the indicator. The shaft 19 is adapted to receive the needle 18 of the indicating device and has means thereon for engaging a hair spring 29 which is anchored on the body 23 by means of a pin 31, the purpose of the hair spring 29 being to tend to rotate the shaft 19 to take up back-lash between the pinion 17 and the gear rack 16. The gear rack 16 is engaged by the split inner end of the shaft 14 and the rack is adapted to be held in the split end of the shaft by means of the cap screw 32.

The knurled rim 33 of the body 23 carries the dial 34 with it. The rim, cover, and dial may easily be rotated in the bore 22 to adjust the dial so that the needle points to zero when no stress is applied.

The outer end of the shaft 14 is preferably held within a split sleeve 41. This split sleeve 41 may '10 be moved in and out on the shaft 14 to thus shorten or lengthen the lever arm formed by the shaft in the handle 12, to thus vary the extent of movement of the inner end of the shaft with respect to the head 10. Movement of the sleeve 41 41 with respect to the shaft 14 may be accomplished by means of pins inserted through the openings 45 or by removing the cap or disk 44 and withdrawing the shaft and sleeve, adjusting and replacing them.

The split sleeve 41 is adapted to be held in place by means of a set screw 42 which engages the grip 13 on the handle 12 and also holds the split sleeve 41 in gripping relation on the shaft.

SThe shaft 14 may be moved in and out to a limited degree by means of the threaded disc 44 to bring the gear rack 16 into proper engagement with the pinion 17. The end of the shaft 14 is engaged to the disc 44 by means of a cap screw 43. The disc 44 has openings 45 therethrough and the openings 45 serve not only as a means for rotating the disc 44, but the split sleeve 41 may be moved forward and back through the holes 45 without disturbing meshing of the rack 16 and pinion 17.

In operation the squared projection 20 is engaged within a suitable socket member 21 in accordance with the usual practice and any force applied to the handle 12 or at the grip 13 or 7o along the length thereof will bend or flex the handle 12. Since the outer end of the shaft 14 is gripped in the outer end of the handle 12 the inner end of the shaft 14 will move with respect to the inner end of the handle 12 and this movement is reflected by the gear rack 16 which will rotate the pinion 17 to rotate the needle 18. The dial may be so calibrated that a pressure or force applied to the handle is indicated directly in pounds or the dial may be calibrated to indicate this force in foot pounds or inch pounds or, of course, in any other desired system of force measurement.

I may mark the grip 13 at a selected point and calibrate the dial in such manner that the reading of the dial will indicate directly the force in pounds applied at the marking. In this manner I may grip the squared portion 20 in a vise or the like and apply weight to the grip 13 at the marked portion and the needle will directly indicate the weight in pounds. I may provide a simple means for deflecting springs, to test the stiffness of the springs by means of the squared portion 20 of the torque measuring device. The device may be utilized as a brake testing device. In this case, the wheels of a motor vehicle are turned by means of the squared portion 20 and a nut on the hub of the wheel, the brake being set at selected pressures.

In a modified form of my invention illustrated in Figures 5 and 6 substantially the same struc- 25. ture is employed except that a ratchet head 10a is employed instead of the fixed head 10 illustrated in Figures 1 to 4 inclusive. The same inindicating structure II is employed, together with the same handle 12 and shaft 14 for actuating the indicating device. In this ratchet head, however, a ratchet wheel 51 forms a part of a shaft 52 having a squared extension 50 and, of couise, these parts may rotate in the head 10a. The head 0an is enlarged, as indicated at 53 and 54, in order that ratchet dogs 56 and 57 may be received in the head. These ratchet dogs are resiliently held against the teeth of the ratchet 51 by means of springs 58 and 59. The springs 58 and 59 are held in place by means of threaded plugs 61 and 62. It is to be observed that the shoulders 63 and 64 on the dogs 56 and 57, are so disposed that when one of the dogs engages one tooth the other is half-way up the slope of another tooth, therefore, the ratchet may have a relatively small number of teeth which permits the use of large strong teeth and yet the wrench may be advanced a half tooth at a time to provide for rotating the squared projection 50 even under conditions when the handle can be moved to only a very limited degree.

A torque wrench provided with a ratchet feature will work just as well as the fixed wrench shown, since the measuring instrument is actuated by flexing of the handle itself rather than depending upon a mechanism associated with the dogs.

It is apparent that I have provided an extremely simple and desirable instrument which is inexpensive to construct and maintain and which will have a high degree of accuracy. Furthermore. I have provided means for ready adjustment both of the indicating device and of the handle, and of a lever within the handle, so that the device may be readily adjusted for accurate reading. Although I. have described a specific embodiment of my invention, it is apparent that modifications thereof may be made by those skilled in the art. Such modifications may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

I claim as my invention: 1. In a torque wrench, a head, an indicating mechanism associated with the head, a flexible hollow handle fixed to the head, and shaft means within the handle for actuating the indicating instrument in accordance with the movement of flexing of the handle. , 2. In a wrench, a head, an indicating means rotatably mounted in the head, a flexible hollow handle inserted within the head, a shaft mounted within the handle and extending into the head, and a rack member secured to the end of the shaft within the head and operatively engaged to the indicating means.

3. In a wrench, a head, an indicating means rotapably mounted in the head, a flexible hollow handle inserted within the head, a shaft mounted within the handle and extending into the head, a rack member secured to the end of the shaft within the head and operatively engaged to the indicating means, and means slidably engaged on the shaft within the handle for regulating the effective flexible length of the handle. 4. The combination, in a wrench, of a hollow flexible handle, a shaft rigidly secured at one end within the handle, a head member including means for engaging a nut or bolt fixed on the handle, indicating means mounted in the head member, and means for operatively connecting the indicating means and the free end of the shaft whereby movement of the shaft is registered on the indicating means.

5. A wrench, comprising a head member, a hollow flexible handle secured in the head member, a shaft mounted in the handle and extending into the head member the end of the shaft opposite the head being rigidly secured to the handle, indicating means mounted in the head member, means operatively connecting the shaft member and the indicating means whereby movement of the shaft is registered on the indicating means, and ratchet means mounted in the head member, the said ratchet means being adapted to be operatively secured to a bolt or the like for the turning thereof.

6. In a wrench, a head, a hollow flexible handle secured in the head, a shaft rigidly secured in the handle and extending into the head, an Indicator mounted in the head, and gear and rack means operatively connecting the shaft and the indicator.

7. In a wrench, a head, a flexible hollow handle secured in the head, a shaft secured in the handle and extending into the head, a split sleeve surrounding the shaft at one end thereof and adapted to be slidingly positioned on the shaft, an indicator mounted in the head, and gear and rack means operatively connecting the shaft and the Indicator.

8. In a wrench, a head, a hollow flexible handle secured in the head, a shaft, means for rigidly securing the shaft in the handle for adjustable positioning therein, Indicating means mounted In the head, and means for operatively connecting the indicating means and the shaft whe movement of the shaft is registered on the indicating means.

9. In a wrench, a head, a socket post secured in the head, an indicating member mounted in the head, a flexible hollow handle secured In the head, a shaft extending within the handle and into the head, means for rigidly securing the shaft for adjustable positioning within the handle and the head and means for operatively connecting the free end of the shaft and the indicating means whereby movement of the shaft -is registered on the indicating means.

10. In a wrench, a head, a socket post secured in the head, an indicating member mounted in the head, a flexible hollow handle secured in the head, a shaft extending within the handle and into the head, means for securing the shaft for adjustable positioning within the handle and the head, means for operatively connecting the shaft and the indicating means whereby movement of the shaft is registered on the indicating means, a split sleeve slidably engaged'on the shaft withýin the handle, and means for positioning the sleeve on the shaft for regulating the extent of movement of the shaft when certain forces are imparted thereto.

11. In a wrench, a head, a hollow flexible handle secured to the head, a shaft within the handle and extending into the head, the shaft being coextensive with the handle and fixed within the handle at the end opposite to the head, an indicating means on the head, and meais on the free end of the shaft within the head for driving the indicating mechanism in accordance with the relative movement between the head and the free end of the shaft.

12. In a torque wrench, a head, a pipe-like bendable handle fixed to the head, a shaft within the handle and coextensive therewith held in place within the bendable member at one end thereof and the other end of the shaft projecting into the head, and an indicating means mounted in the head for indicating the degree of movement between the free end of the shaft and the bendable member. 13. In a wrench, a head, a hollow flexible handle secured in the head, a shaft rigidly secured in the handle and extending into the head, an indicator mounted in the head, and drive means operatively connecting the shaft and the indicator.

14. In a wrench, a head, a flexible hollow handle secured in the head, a shaft secured in the handle and extending into the head, a split sleeve surrounding the shaft at one end thereof adapted to be slidingly positionel on the shaft, an indicator mounted in the head, and means operatively connecting the shaft and indicator for driving the indicator from the shaft.

ALL3N I. DUNN.