US2917942A - Rotary locking device - Google Patents

Description

1959 J. w. JARRETT ETAL 2,917,942

ROTARY LOCKING DEVICE Filed Jan. 31, 1958 INVENT JOHN w. .1422 :vmsrr a. RICE ATWRMEYJ United States Patent ROTARY LOCKING DEVICE John W. Jarrett, Fortville, and Everett L. Rice, Indianapolis, Ind., assignors to the United States of America as represented by the Secretary of the Navy Application January '31, 1958, Serial No. 712,594

'3 Claims. (Cl. 74-504) (Granted under Title 35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to a locking device and more particularly to a locking device that can be applied to an electrical component such as a rotary switch, potentiometer, or the like, to prevent accidental rotation thereof.

Control panels, such as those used in aircraft, often have large numbers of electrical components such as switches and potentiometers, and because of space limitation these components are often mounted closely together. Consequently, it is very likely that a component may be unintentionally rotated when it should not be, thus creating an insafe condition. The locking device disclosed herein actually serves a dual purpose in that it locks a rotary device against accidental rotation and also has a detent arrangement for setting a rotary device in adesired position.

The locking device disclosed herein is adaptable for mounting to many heretofore available components and requires only a very minor modification of the component to be operable thereon. A shaft is axially slidably attached to the existing shaft of an electrical component, and the attached shaft has at least one lug that is engageable with a plurality of slots in a shaft bushing. The attached shaft is resiliently biased outwardly to retain the lugs within one of the slots and, when in this position, the attached shaft is locked from rotation. When it is desired to rotate the attached shaft, it is first necessary to move it inwardly until the lug is disengaged from the slot. The shaft is then free to be rotated.

It is therefore a general object of the present invention to provide a device that will prevent accidental shaft rotation of an electrieal device,

Another objeet of the invention disclosed herein is to provide a device for locking the shaft of an electrical component in a plurality of positions.

Qther objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein;

Figure 1 is a plan view showing the shaft end of an embodiment of the present invention;

Figure 2 is a partial sectional View taken on line 2-2 of Fig e Figure 3 is a partial sectional view taken on line 3-3 of Figure 1 and showing the attached shaft moved inwardly;

Figure 4 is a plan view showing a shaft and bushing arrangement; and

Figure 5 is a plan view similar to the view shown in Figure 4 but showing the shaft rotated.

Referring now to the drawing, there is shown in Figures 1-3, a locking device 11 that is attached to an elec- 2,917,942 Patented Dec. 22, 1959 trical component 12, such as a rotary switch or potentiometer. The electrical component 12 is of the type adaptable for panel mounting and has a threaded por= tion 13 through which extends a rotatable shaft 14.

The threaded portion 13 of component 12 is passed through a bore 15 in the end of a cylindrical housing 16 and a nut 17 is provided to hold the housing in position. A washer 18 having a lug 19 thereon is positioned around the threaded portion 13, and the lug 19 engages a hole 21 in the end of the cylindrical housing 16 to prevent rotation of the housing relative to the component 12.

A bushing 22 is attached to the end portion of housing 16 by means of screws 23, and a shaft 24 is rotatably mounted within the bore of bushing 22. The shaft 24 has a large diameter portion and a small diameter portion, the small diameter portion having a flat 25 thereon for facilitating the fastening of a knob (not shown). The large diameter portion of shaft 24 is slightly smaller than the bore of bushing 22 and the shaft is axially slidable within the bushing and also capable of rotation. As shown in Figure 4 of the drawing, shaft 24 has a plurality of lugs 26 radiating from the large diameter portion thereof, and these lugs are engageable with a plurality of slots 27 in the inner end of bushing 22. Although three lugs 26 and three slots 27 are shown for purposes of illustration, it should be understood that either a lesser or greater number could be used equally well.

Shaft 24 has a bore 28 and a slot 29 in the large diameter portion that permits the coupling of shaft 24 to the shaft 14 of component 12. A pin 31 is press-fitted into shaft 14 and slot 29 is slidably engageable with pin 31. As shown in Figure 2 of the drawing, slot 29 has sufficient depth to allow shaft 24 to move axially inwardly until lug 26 on shaft 24 is cleared from slot 27, at which time the shaft 24 is unlocked and free to be rotated.

As shown in Figures 2 and 3 of the drawing, a coil spring 32 is provided within the cylindrical housing 16 between the inner face of the housing and the inner face of shaft 24 to bias the shaft 24 outwardly. Thus when lugs 26 are engaged in slots 27, spring 32 retains the shaft 24 in a stationary position and therefore the shaft 24 is maintained in a locked position,

In operation, the shaft 24 is normally maintained in a locked position due to the lugs 26 being engaged in slots 27. When it is desired to rotate the shaft 14 of component 12, it is first necessary to move shaft 24 inwardly until the lugs 26 are cleared from slots 27. Figure 3 of the drawing shows this condition, with the spring 32 being compressed and the lug 26 moved inwardly to clear slot 27. While still applying an inward pressure, the shaft 24 is then rotated in a desired direction and a rotating force is transferred from shaft 24 to pin 31 in shaft 14, to drive shaft 14, which is the component shaft. As shown in Figure 5 of the drawing, after lugs 26 are rotated from being in alignment with slots 27, it is no longer necessary to apply inward pressure on shaft 24, and shaft 24 can be rotated until the lugs are forced into the next adjacent slots by the spring 32.

It can thus be seen that the device herein diselosed provides a convenient locking arrangement for a component shaft in that it is first necessary to apply an in, wardly directed force and then, while applying this force, apply a rotating force. Thus aecidental rotation of a shaft is not likely to occur,

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that the in- 3 vention may be practiced otherwise than as specifically described.

What is claimed is:

'1. A locking devicefor an electrical component comprising, a cylindrical housing member having an open end and an inside face and removably attached to the shaft end of an electrical component having a rotatable shaft, a bushing fixedly attached to said housing member and having a plurality of radial slots, and attached shaft having an inside face and mounted for rotary movement and axially slidable movement in said bushing with SZliL. side face on said shaft being opposite said inside face on said cylindrical housing, saidattached shaft having a large diameter portion having :a diametral slot on the end thereof and having means for engaging said plurality of slots in said bushing, means on said rotatable shaft of said component in slidable engaging relation with said diametral slot in said attached shaft, and means positioned within said housing member for biasing said attached shaft in a direction outwardly from said electrical component.

2. A locking device as set forth in claim 1 wherein said means for biasing said attached shaft comprises a compression spring mounted between the inside face of said housing member and the inside face of said attached shaft.

3. A locking device for an electrical component comprising, a cylindrical housing member having an open end and an inside face and removably attached to the shaft end of an electrical component having a rotatable shaft, a bushing fixedly attached to said housing member and having a plurality of radial slots, an attached shaft having an inside face and mounted for rotary movement and axially slidable movement in said bushing with said inside face on said shaft being opposite said inside face on said cylindrical housing, said attached shaft having a large diameter portion having a diametral slot on the end thereof and at least one lug extending perpendicular to the longitudinal axis of said attached shaft for engaging said radial slots, a pin fixedly attached to said rotatable shaft of said component and in slidable engagement with said diametrar slot in said attached shaft, and a compression spring mounted between the inside face of said housing member and the inside face of said attached shaft for biasing said attached shaft in a direction outwardly from said electrical component.

References Cited in the file of this patent UNITED STATES PATENTS 1,274,471 Todd Aug. 6, 1918 2,438,045 Gerhardt et al Mar. 16, 1948 2,561,482 Schostak July 24, 1951 2,631,203 Mekelburg Nov. 10, 1953 2,651,281 Nathan Sept. 8, 1953 2,704,466 Way Mar. 22, 1955 2,849,891 Mills Sept. 2, 1958 FOREIGN PATENTS 797,938 France Feb. 24, 1936

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