US2143401A

US2143401A - Interchangeable shaft for electrical devices

Info

Publication number: US2143401A
Application number: US167716A
Authority: US
Inventors: Marion J Arvin
Original assignee: PR Mallory and Co Inc
Current assignee: Duracell Inc USA
Priority date: 1937-10-07
Filing date: 1937-10-07
Publication date: 1939-01-10
Anticipated expiration: 1956-01-10

Description

Jan. 10, i939.

` M. J. ARVIN INTERCHANGEABLE SHAFT FOR ELECTRICAL DEVICES Filed Oct. 7, 1937 INVENTOR ATTORNEY Patented Jan. 10, 1939 UNITED STATES PATENT OFFICE INTER-CHANGEABLE SHAFT FOR ELECTRI- CAL DEVICES Application October 7, 1937, Serial No. 167,716

6 Claims.

This invention relates to control shafts for electrical devices such as variable resistances for use in radio sets.

An object of the invention is to improve the 5 arrangement of such shafts and particularly to render said shafts replaceable or interchangeable.

Other objects of the invention will be apparent from the following description and accompanying drawing taken in connection with the appended claims.

The invention comprises the features of construction, combination of elements, arrangement of parts, and methods of manufacture and operation referred to above or which will be brought out and exemplified in the disclosure hereinafter set forth, including the illustrations in the drawing.

In the drawing:

Figure 1 is a side view of a replaceable control shaft according to the invention;

Figure 2 is a sectional View of a variable resistance device adapted to receive said shaft;

Figure 3 shows the shaft and resistance device assembled and provided with an actuating knob;

Figure 4 is asection on the line 4-4 of Figure 3; and

Figure 5 shows the end of a modified form of shaft.

'I'he radio receiving sets manufactured today vary in their parts requirements. For instance, one set will require a variable resistance device of one resistance value and terminal arrangement while another set has very different requirements. Likewise many different lengths of control shafts 35 are required and these also vary in construction according to the kind of knob attachment desired. One shaft may be desired with a round end and another with a fiat end and so forth. There are at least ten kinds of variable resisters needed to fulfill all the requirements and each type must be furnished with perhaps ten varieties of shafts.

Heretofore the shafts have been made an integral part of the resistance device and hence, to meet all the needs of manufacturers and radio service men about one hundred different models had to be carried in stock.

I have invented an interchangeable shaft arrangement whereby any desired shaft may be attached to any type of variable resistance. This makes it possible to meet all requirements by carrying in stock only about ten kinds of shafts and ten kinds of resistance devices.

While a preferred embodiment of the invention is described herein, it is contemplated that c'onsiderable variation may be made in the method of procedure and the construction of parts without departing from the spirit of the invention. In the following description and in the claims, parts will be identified by specific names for convenience, but they are intended to be as generic in their application to similar parts as the art will permit.

Referring to the drawing, the preferred shaft I comprises a cylindrical piece of metal with parts cut away at one end to leave a flat tongue II having a pair of notches I2 in opposite edges. The knob end of the shaft may be formed in any desired Way to accommodate a knob 23, for instance by providing a flat face I3 against which a set screw may bear.

The resistance device may comprise a case I4 containing an arcuate resistance element I and a rotatable contact arm I6 adapted to travel around said element in contact therewith to vary the amount of resistance in a circuit in a well known manner. Arm I6 is suitably secured to the inner end of a stub shaft II which extends through a bushing 20 affixed in the wall of case I4.

Stub shaft Il extends just beyond the open end of bushing 20 and is provided with an annular groove 29 around the projecting portion within which a clinch ring I9 is fitted to prevent stub shaft Il from sliding into the bushing.

The end of stub shaft I1 is slotted to a depth corresponding to tongue II on shaft I0, the slot I8 thereby extending back within the bushing for a considerable distance. The slot I8 is of such dimension as to fit over tongue II when the two shafts are brought together. It is preferred that the two end prongs of stub shaft Il be bent together slightly so as to provide a spring-like clamping of tongue II when it is inserted in slot I8.

The length of tongue I I, and hence the depth of slot I8, should be greater than the diameter of shafts I0 and I 'I to secure good bearing within the bushing and eliminate play and looseness.

Clinch ring I9 is provided in elliptical form (as shown most clearly in Figure 4) so that it Will hold stub shaft I'I in place but the long diameter of ring I9 is suflicient to allow tongue II to be inserted in slot I 8. When the two shafts are fully assembled, as shown in Figure 3, the notches I2 in tongue II will be aligned with groove 29 in stub shaft I'I so that clinch ring I9 locks them together. It will be evident that the shafts could only again be separated if the ring I9 were centered with its long axis parallel to the tongue Il,

a most unlikely occurrence especially when the shafts are mounted horizontally, as is usual.

If desired, of course, the ring I9 may be clinched after assembly.

Figure 5 shows a modied shaft 2li having a trifurcated

tongue

25, 26, 2l With the center prong 2E offset from the others to provide a springlike bearing area upon insertion into the slot in the stub shaft. A notch 28 is provided to receive the lock ring i9.

The improved shaft arrangement is applicable to shaft controlled electrical devices generally, such as variable resistance devices, rheostats, volume controls, potentiometers, switches, variable condensers, and the like.

The shafts may be manually or automatically controllable, long, short, flexible, rigid and formed of metal or other'material.

The arrangement provides an interchangeable, attachable, detachable shaft assembly which, when assembled will give positive action, free from backlash and excessive play, and which is positively locked together.

While the present invention, as to its objects and advantages, has been described herein as carried out in specific embodiments thereof, it is not desired to be limited thereby but it is intended to cover the invention broadly Within the spirit and scope of the appended claims.

What is claimed is:

1. A control shaft coupling for adjustable electrical devices comprising a pair of circular shaft sections of substantially the same diameter having interlocking portions for connecting them together end-to-end, one of said portions having a slot extending back from its end and having a groove extending around said slotted region, the other of said portions comprising a tongue fitting into said slot, said tongue having edge notches in register with said groove When said shafts are in interlocked relation, and a clinch ring in said registering groove and notches locking said shafts together.

2. A control shaft coupling for adjustable electrical devices comprising a pair of circular shaft sections of substantially the same diameter having interlocking portions for connecting them together end-to-end, one of said portions having a slot extending back from its end and having a groove extending around said slotted region, the other of said portions comprising a tongue fitting into said slot, said tongue having edge notches register with said groove when said shafts are in interlocked relation, and a clinch ring in said registering groove and notches locking said shafts together, and a tubular bushing surrounding said slotted shaft section adjacent said clinch ring, said clinch ring comprising a ange preventing walls of said slot to take axial movement of said slotted section into said bushing.

3. A control shaft coupling for adjustable electrical devices comprising a pair of circular shaft sections of substantially the same diameter having interlocking portions for conecting them together end-to-end, one of said portions having a a slot extending back from its end and having a groove extending around said slotted region, the other of said portions comprising a tongue fitting into said solt, said tongue having edge notches in register with said groove when said shafts are in interlocked relation, and a clinch ring in said registering groove and notches locking said shafts together, said tongue comprising a plurality of prongs affording spring bias against the in said coupling.

4. A control shaft coupling for adjustable electrical devices comprising a pair of circular shaft sections of substantially the same diameter having interlocking portions for connecting them together end-to-end, one of said portions having a slot extending back from its end and having a groove extending around said slotted region, the other of said portions comprising a tongue tting into said slot, said tongue having edge notches in register With said groove when said shafts are in interlocked relation, and a clinch ring in said registering groove and notches locking said shafts together, said clinch ring being elliptical in shape to permit coupling of said shafts. V5. A control shaft coupling for adjustable electrical devices comprising a pair of shaft sections having interlocking portions for connecting them together end to end, said portions comprising non-circular interiitting parts tting together to form a substantially circular joint, said interfitting parts being correspondingly groved to provide a circumferential groove in said joint, and a clinch ring in said groove locking said sections together.

6. A control shaft coupling for adjustable electrical devices comprising a pair of shaft sections having interlocking portions for conecting them I together end to end, said portions comp-rising non-circular intertting parts tting together to forrn a substantially circular joint, said intertting parts being correspondingly grooved to provide a circumferential grove in said joint, and

a clinch ring in said groove locking said sections together, and a tubular bushing surrounding said joint adjacent one side of said clinch ring, said bushing serving to maintain said shafts properly aligned and concealing a portion of said joint, said clinch ring providing a flange preventing axial movement of said joint further into said bushing.

MARION J. ARVIN.

up play and backlash 4