US2688857A - Safety coupling for flexible shafting - Google Patents

Description

Sept. 14, 1954 w, JONES 7 2,688,857

SAFETY COUPLING FOR FLEXIBLE SHAFTING Filed July 29. 1953 I N V E N TOR. 4/562? #4 Jan/5.9

Patented Sept. 14, 1954 SAFETY COUPLING FOR FLEXIBLE SHAFTIN G Joseph W. Jones, New York, N. Y., assignor to Jones Motrola Corporation, Stamford, Conn., a corporation of Connecticut Application July 29, 1953, Serial No. 371,081

1 Claim. 1

The invention herein disclosed relates to flexible shaft drives for tachometers and instruments of like character.

Particularly, the invention is concerned with the drive of tachometers used with diesel engines and certain types of quick starting electric motors.

These machines start so suddenly and at such instant high speed as to tend to break the flexible shafting and drive connections to the tachometer.

In the case of the diesel engine, if the sudden start does not break or injure the drive connections or the instrument operated thereby, the effect may be to momentarily overspeed the tachometer which, in the case of automatic cutoff actuated by the tachometer, would have the effect of stopping the engine even before it was properly started.

Special objects of this invention are to provide simple and practical means, readily adaptable to present installations, which will prevent such overspeeding and which, in general, will protect the entire line of drive connections and serve as a safe, effioient drive for the tachometer, or other such instrument.

Further special objects of the invention are to incorporate the safety features mentioned in a small, lightweight form of slip clutch, adaptable to the end of the flexible shafting and directly engageable with the squared end shaft of the conventional tachometer.

Other desirable objects and the novel features through which the purposes of the invention are attained are set forth and will appear in the course of the following specification.

The drawing accompanying and forming part of the specification illustrates a present practical embodiment of the invention but structure may be modified and changed within the true intent and scope of the invention as hereinafter defined and claimed.

Fig. 1 in the drawing is a broken part-sectional side elevation of the invention as applied to a flexible drive cable and connected with a tachometer of usual or standard design.

Figs. 2 and 3 are enlarged broken details of the coupling applied to the end of the flexible drive shaft; Fig. 2 indicating this coupling as engaged with the squared stem of the tachometer shaft and Fig. 3 showing these parts in separated relation.

Fig. 4 is a cross-sectional view on substantially the plane of line 4-4 of Fig. 2.

Fig. 5 is a similar view but showing the parts in the slip-drive relation.

The instrument indicated at I in Fig. 1 may be considered a tachometer of conventional design, having a drive shaft 8 terminating in a squared portion 9 engageable by a clutch or coupling element on the end of the flexible drive shaft II).

In the present invention, this coupling is in the form of a sleeve or tubular body portion H swaged or otherwise secured on the end of the flexible shaft and having a circular socket 12 in the end of the same large enough to rotatably receive the angular end portion 9 of the instrument shaft.

At opposite sides the socket forming portion l2 has transverse recesses 13 which are cut through and open into the socket.

A washer or collar i4 is loosely engaged over the terminal sleeve H and this collar has angularly extended spring fingers It at opposite edges of the same, provided with inwardly indented end portions [6 which project inwardly into the openings at IS in the sides of the socket and far enough to engage the fiat sides of the tachometer stern. This relation is shown in Fig. 4.

The spring coupling described may be made of a single piece of spring sheet metal, pierced at the center to pass over the sleeve l l and having the extensions [5 projecting from opposite edges and bent up at an angle and extended inwardly to enter the notches at the opposite sides of the socket I2.

This spring element can thus be mounted and be yieldingly secured in place by simply slipping it over the sleeve into position where the inwardly extended ends of the spring fingers will enter the openings in the sides of the socket. In this relation the ends of the spring fingers will engage opposite flat sides of the tachometer shaft to form a drive connection for all normal operations.

In case of any suddenly applied torque, however, the spring fingers will open up or yield outwardly, as in Fig. 5, to release the grip on the squared shaft and to permit the coupling to turn until such time as they again pick up and carry the tachometer shaft along with it.

The invention provides a spring safety coupling which, as shown in Fig. 1, may 'be applied to an ordinary flexible shaft drive and used with a tachometer, or like instrument, of conventional design, the spring collar being light enough and small enough to go on the end of the shaft and to be received within and operate in the usual neck portion ll of the instrument.

What is claimed is:

A safety slip coupling for the flexible shaft 3 drive of a tachometer or the like, comprising a sleeve attachable to a flexible shaft, said sleeve having a circular socket in the end of the same, of a size to freely receive the squared shaft end of a conventional tachometer, said socket having openings in opposite sides of the same and a collar of spring metal engaged over said sleeve and having angularly extended spring fingers at opposite edges of the same, terminating in inwardly bent ends entered into said openings far enough to engage the fiat sides of the squared shaft end and to retain said collar in position on the sleeve.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,503,189 Blba, Jr Apr. 4, 1950 2,537,122 Desmond Jan. 9, 1951 2,656,185 Bach Oct. 20, 1953

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