US2159373A - Torque wrench - Google Patents

Description

May23,1939; A L DUNN 2,159,373

Tonarm WRENCH Filed April 10, 1937 3 Sheets-Sheet 3 INVENTOR. ALL EN DUN/V BY @W7 ATTORNEY.

Patented May 23, 1939 'roaQUE WRENCH Allen I. Dunn, Cedar Rapids, Iowa, assignor to.

Cedar Rapids Engineering' Company, Cedar Rapids, Iowa, a corporation of Iowa Application April 10, 1937, Serial No. 136,048

14 Claims.

This invention relates to wrenches, and more particularlyto a wrench for indicating the amount vof 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 ld 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 3U torque or force applied, but it has been found` that such devices have been expensive to constructand maintain, are diflicult 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 myinvention -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 isnalso an object of my .invention toprovide a wrench'of the above character in Awhich the parts are protected from mechanical injury.

Another object of my invention is to provide a 30 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 torque indicating wrench of increased accuracy 35 over devices known to the prior art.

A more speciiic object of my invention is to proyide a torque indicating wrench which is sum- Aciently accurate that it may readily be used as a I scale or weight measuring device. A 40 Another obiect'oi' my invention is to provide a torque indicating wrench which is of sumclent accuracy that it may beused as a brake testing device.

Another object of my invention is to provide a device which is sumciently accurate that it may be readily utilized in testing springs o't all kinds.

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

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

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 5 invention will be more apparent to those skilled in the artl upon a consideration of the vaccom- "pan'ying drawings and following specications. wherein is disclosed a single exemplary embodiment of the invention, with the understanding, 10 however, that such changes may bemade therein Aas fall within the scope of the appended claims. without departing from the spirit of the invention. Y

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 oi the wrench shown in Figure 1` Figure 3 is a view in vertical section of the 20 wrench shown in Figures 1 and 2.

-Figure 4 is aview invertical section of lthe head of the wrench shown in Figures 1, 2 and 3, but in enlarged relation to better illustrate the parts of the device.

. 25 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 lratchet wrench structure. The view is in horizontal section, and

Figure 611s 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 Hl on which is mounted an indicator i l. A hollow handlel2 is received in thehead i0 and xed therein Aby means of a set screw 9 and the outer end of the handle is provided with a grip I3. A shaft I4 is mounted within the handle i2 and the grip I3, and the vshaft is tapered at the inner end, as indicated at i5, to provide for a maximum movement of the inner end with reference to the handle i2. The inner end of the shaft Il engages a gear rack I6 and the rack is adapted to rotate a pinion l1 which is operatively 45 connected to the indicating needle i8 of the indi# cator il. Obviously, other forms of operative connections may be employed for transmitting movement of the shaft I l to the needle i8.

'The head I0 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 55 tation thereof. The member 20 projects from the ing bolts and nuts.

A cylindrical chamber or bore 22 extends through the head I0, and the cylindrical body portion 23 of the indicating instrument II is re'- ceived within one end of the bore 22. The body 23 may rotate within the bore 22. Frictional resistance to rotation of the body 23 land 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.' 'I'he 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 21.

Thev body 23 is provided, at the central axis thereof, with bearings 28 for the shaft I9 of the indicator. The shaft I9v is adapted to receive the needle I8 of the indicating device and has means thereon for engaging a hair spring 29 which is anchored on the body 23 by means of apin 3|, the purpose of the hair spring 29 being to tend to rotate the shaft I9 to take up back-lash between the pinion I1 and the gear rack I6. The gear rack I 6 is engaged by the split inner end of the shaft I4 and the rack is adapted to be held in the s lit end vof the shaft by means of the cap screw 3 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 g is applied.

The outer end of the shaft I4 is preferably held within a split sleeve 4I. This split sleeve 4I may be moved in and out on the shaft I4 to thus shorten or lengthen the lever arm formed by the shaft in the handle I2, to thus vary the extent of movement of the inner end of the shaft with respect to the head I0. Movement of the sleeve 4I with respect to the shaft I4 may be accomplshed 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 4I is adapted to be held in place by means of a set screw 42 which engages the grip I3 on the handle I2 and also holds the split sleeve 4I in gripping relation on the shaft. The shaft I4 may be moved in and out to a limited degree by means of the threaded disc 44 to bring the gear rack I6 into proper engagement with the pinion I1. The end of the shaft I4 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 4I may be moved forward and back through the holes 45 without disturbing meshing of the rack I6 and pinion I1.

In operation the squared projection 20 is engaged within a suitable socket member 2I in accordance with the usual practice and any force applied to the handle I2 or at the grip I3 or along the length thereof will bend or flex the handle I2. Since the outer end of the shaft I4 is gripped in the outer end of the handle I2 the inner end of the shaft I4 will move with respect to the inner end of the handle I2 and this movement is reiiected by the gear rack I6 which will '20 pressed tightly into the head III to'prevent rorotate th pinion I1 to rotate the needle I8. 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 `marl: the grip I3 at a selected point and calibrate the dial in such manner that the reading of the dial will indicate directly the force inpounds 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 I3 at the marked portion and the needle will directly indicate the weight in pounds.

I may provide a simple means for defiecting 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 meanslof the squared portion 20 and a nut on the hub of the wheel, the brake lbeing-set at selected pressures.

In a modified form of my invention illustrated in Figures 5 and 6 substantially the same structure is employed except that a ratchet head Ia is employed instead of the xed head I0 illustrated in Figures 1 to 4 inclusive. 'I'he same inindicating structure I I is employed, together with the same handle I2 and shaft I4 for actuating the indicating device. In this ratchet head, however, a ratchet wheel 5I forms a pari of a shaft 52 having a squared extension 5i! and, of course, these parts may rotate in the head Illa. The head Illa is enlarged, as indicated at 53 and 54, in order that ratchet dogs 56 and 5l may be received in the head. These ratchet dogs are resiliently held against the teeth of the ratchet 5I by means of springs 58 and 59. The springs 58 and 59 are held in place by means of threaded plugs 6I and 62. It is to be observed that the shoulders 63 amd64 on the dogs 56 and 5l, 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 l 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 rwell as the fixed wrench shown, since the measuring instrument is actuated by ilexing of the handle itself rather t'han 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 mair 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: y

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 .han

within the hanne for actuating the indicating' instrument in accordance with the movement off flexing of the handle.

2. In a wrench, a head, an indicating means rotatably mounted inthe 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 operativelyv engaged to the indicating means.

3. In a wrench, a head, an indicating means rotaably mounted in the head, a flexible hollow le 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 forregulating the effective flexible length of the handle.

l 4; The combination, in a wrench,of a hollo ilexible handle, a shaft rigidly secured at one 'end within the'handie, 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 shaftopposite the head being rigidly secured to the handle, indicating means mounted in -the head member, means operatively connectinthe 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 exible 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 thev 7. In a wrench, a head, a exible 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 tobe 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 operativeb connecting the indicating means and the shaft movement of the shaft is registered on the indicating means.- I. 9. In a wrench, a head, a socket post secured in the head, an indicating member mounted inthe head, a flexible hollow handle secured in the head, ashaft 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. .L

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 seeming the shaft for adjustable positioning wit-hin 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 with- \in 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 ilxed within the handle at the end opposite to the head, an indicating means on the head, and means on the free end of the shaft within the head for driving the indicating -mechanism Ain 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 xed 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 exible handie 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 msm :.DUNN.

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