US2106722A - Speed changing device for phonograph turntables - Google Patents

Description

Feb. 1, 1938.

E. E. coLLlsoN ET AL SPEED CHANGING DEVICE FOR PHONQGRAPH TURNTABLES FiledDec. 17, 1931 INVENTORfi. farm/r0 E. COAL/JON. ffi/L Wyn/m.

B 06M 6M WFZ ATTORNEYS.

Patented Feb. 1, 1938 UNITED STATES SPEED CHANGING DEVICE FOR PHONO- GRAPH TURNTABLES Edward E. Coliison and Emil Nyman, Fort Wayne, Ind.

Application December 17, 1931, Serial No. 581,694

2Claims.

This invention pertains to a phonograph turntable and particularly a variable speed drive therefor, for the purpose of accommodating said turntable to records to be reproduced at diiferent speeds of rotation.

Phonograph records'are produced ordinarily at a speed of 78 revolutions per minute (R. P. M.). Consequently, a phonograph turntable for proper reproduction of such record is geared to rotate at the same speed or R. P. M. It is, however, an-

ticipated that records may be produced at a slower speed in order to reproduce a program of. longer duration. Thus, for accommodating a longer program, a record may be made to rotate at a slower given speed, for instance, a speed of 33 revolutions per minute (R. P. M.).

It is the purpose of this invention to provide a simple and practical structure for a turntable drive which the operator may manipulate so that when thrown'into one position by a suitable lever or the like, the turntable will be driven at 78 R. P. M., while in another position at 33% R. P. M.,or any other corresponding speeds.

The full nature of the invention will be more clearly understood from the accompanying drawing and the following description and claims:

Fig. 1 is a central vertical section through the turntable mounting and driving mechanism showing the turntable driven at minimum speed. Fig. 2 is the same as Fig. 1 with parts removed, showing the turntable driven at maximum speed. Fig. 3 is a section on the line 33 of Fig. 1.

In the drawing there is shown a base plate It for the mechanism, above which there is mounted a rotatable turntable ll having a record centering pin l2 for receiving a disk record l3 for reproduction. The turntable is driven through suitable mechanism as hereinafter described by an electric motor l4, said mechanism and motor being supported by a framework l5 depending from the base I!) or otherwise supported in association therewith.

Suitable reproducing mechanism in the form of the usual tone arm and reproducer are mounted for contacting with and reproducing the sound from the record in the usualmanner, the same not being specifically illustrated inthe drawing. Furthermore, drive mechanism is applicable for rotation of the turntable in conjunction with an automatic record changing mechanism, not illustrated herein.

The turntable is provided with a hub it having a downwardly extending spindle I! which extends through the bearing H! on which the hub is s'upported for rotation. Said bearing is mounted in the fixed supporting platev l9 through which said spindle extends. The lower end of the spindle extends through a lower bearing 20 and is keyed to a cone-shaped driven member 2| in which are loosely mounted a plurality of ball bearings 22, 5 said ball bearings bearing against the periphery of the driving member 23. The member 23 is supported for rotation in the ball bearings 24 and has a downwardly extending drive shaft 25 supported for rotation in the bearing 26. The shaft 10 25 is operatively connected with the driving motor l4.

Slidably mounted on the spindle l1 and carrying the bearing 20, there is a cone-shaped ball race 21 adapted to engage and ride upon the 15 balls 22 about the outer surface of the driven member 2|. By means of this arrangement, the balls 22 are carried in suitable recesses in the periphery of said driven member while they engage and roll about the peripheral surface of the 20 driving member 23. On the opposite side of the driven member, said balls engage the inner peripheral surface of the ball race 21.

Slidably mounted on the spindle l1 intermediate said ball race and the supporting plate I9, 25 there is provided a clutch member 28 having a peripheral groove 29 into which the free end of the lever 30 extends, said lever being fulcrumed to the frame at 3| extending below the base plate l0 beyond the periphery of the turntable and record' I3. A suitable operating handle 32 is mounted upon a connecting rod 33 in such manner that when the handle 32 is elevated, it forces the clutch downwardly, and when said handle is pushed down, it forces the clutch upwardly. Said I clutch is provided with an upwardly extending pin 34 adapted to extend into a recess 35 formed in the supporting plate l9.

The clutch is also provided with a downwardly extending pin 36 adapted to extend into or through an opening 31 in the race 21 and into a corresponding opening 38 in the driven member 2|. When the clutch is forced upwardly, the pin 36 is drawn out of the opening 38 in the driven 45 member 2| and the pin 34 extends into the recess 35 of the supporting plate |9. Upon the clutch member being lowered, said pin 34 is released from the recess 35 while the pin 36 extends through the ball race 21 and into the driven 50 member 2|.

' In operation, the shaft 25 is so geared to the motor H as to be driven at substantially 78 R. P. M. When it is desired to rotate the record at that speed, the handle 32 is elevated so as to lower the clutch member 29. The clutch member will then be free to rotate with the spindle l1 and the pin 36 of said clutch member will int locir the ball race 2'! and driven member 2|. thus said driven member will be directly driven by the shaft 25 at 78 R. P. M. through the direct contact between the driving member and the balls 22 which are held, frictionally prevented from being rotated, by the ball race 27 which is locked to said driven member 2|. Thus, in this position, there will be a direct drive from the shaft 25 to the turntable. When it is desired to rotate the turntable at a lesser speed, or 33 R. P. M., the handle 32 is pushed downwardly so as to elevate the clutch member 28, looking the same with the stationary supporting plate l9 through the medium of the pin 34.

Thus, said clutch member will be held sta- I tionary and will also hold stationary the ball race 21 through the medium of the pin 36. The pin 36, however, will have been retracted from the driven member 2| so that said driven member and ball race will be free to rotate relative to each other. In this position, the driving member 23, instead of directly driving the driven member 2| through contact with the stationary balls, will cause said balls to rotate about the ball race 21 carrying the driven member with them, whereby the driven member will rotate at a speed intermediate the speed of the driven member and the stationary ball race. A given speed may be obtained by the proper relation and dimensions of the members and balls, and as shown herein, approximately 33% R. P. M.

From the foregoing, it will be observed that with a record adapted for reproduction at 78 R. P. M., the operator needs only to raise the handle 32 and with a record adapted to be reproduced at 33 R. P. M., the operator need only lower said handle. While specific R. P. M. have been above mentioned, it will be understood that substantially any two speeds of rotation may be obtained as desired.

The invention claimed is:

1. In a phonograph, the combination of a base plate, a turntable located above said base plate and adapted to rotate records of difi'erent reproducing speeds, and turntable rotating mechanism located below said base plate, said mechanism comprising a motor for driving said turntable, a shaft driven by said motor at a predetermined speed having a driving member on the end thereof, a spindle connected with said turntable having a driven member mounted thereon, said driven member being adapted to embrace said driving member, a stationary support for said turntable and spindle, a plurality of balls mounted for rotation in said driven member adapted to be engaged and rotated by said driving member, a ball race adapted to be locked with said balls and driven member for causing said driven member to be directly driven therethrough and unlocked therefrom to provide a ball race for said balls for obtaining a slower speed, a clutch member for locking said race with said driving member while releasing it from the support when said clutch is in one position and when in the other position locking the same with said support while releasing it from said driven member, and manually operable means extending through said base plate for selectively positioning said clutch in either of said positions.

2. A phonograph of the type including a motor board, a conventional motor thereunder, a driving spindle driven therefrom and protruding above the motor board, a turntable on that portion of said spindle which is above said motor board and adapted to be driven by said spindle at the rotary speed of the latter, a friction driven speed reducing transmission of definite ratio for driving connection between the spindle and the turntable and means extending through said motorboard for placing said transmission at will into or out of operative connection.

EDWARD E. COLLISON. EMIL NYMAN.

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