US2795961A - Multi-speed drive - Google Patents

Description

June 18, 1957 w. BROWN MULTI-SPEED DRIVE 2 Sheets-Sheet 1 Filed April 15, 1954 FIG. I.

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m T N E V m WALL/AM BROWN ATTORNEY June 18, 1957 w. BROWN 2,7 5, 6

MULTI-SPEED DRIVE Filed April 15, 1954 2 Sheets-Sheet 2 FIG. 3.

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32 INVENTOR W/l. I. /AM 5190 W/V ATTORNEY United States Patent MULTI-SPEED DRIVE William Brown, Park Forest, Ill., assignor to Webcor, Inc., a corporation of Illinois Application April 15, 1954, Serial No. 423,446 7 Claims. (Cl. 74-200) This invention relates to new and useful improvements in multi-speed drives for sound recording and reproducing machines.

It is the object of the present invention to provide a drive which may be varied at will from one speed to another of one group or range of speeds, and then by a simple adjustment of the machine, permit selective variation of speeds Within a second group or range of speeds. For instance, one group or range may be 33, 45 and 78 R. P. M. at 50 cycles per second, and the second range may be 33, 45 and 78 R. P. M. at 60 cycles per second.

Thus, according to the present invention, a two or three speed phonograph drive, e. g. 33, 45, 78 R. P. M. can be readily adapted for operation on networks of different frequencies, e. g. 50 and 60 cycles per second.

When, as is preferably the case, a drive is employed in which an idler or other suitable means is movable to couple the driven element, e. g. phonograph turntable with collars or steps of various diameters on the motor shaft then, according to the present invention, the shaft is provided with two sets of steps, one set employed when one (e. g. 50 C. P. S.), and the other when a second (e. g. 60 C. P. S.) alternating current is available for driving the electric motor.

A feature of the invention provides for ready shifting from multi-speed drive at one frequency to the corresponding multi-speed drive at the second frequency. Assuming, for instance, a phonograph turntable operable at 33, 45 and 78 R. P. M., the motor shaft will be provided not only with three different diameters or steps adapted to transmit those speeds when rotated at 50 C. P. S., but with a second set of diameters or steps adapted to transmit the same speeds when the shaft is operated at 60 C. P. S. In the assumed case, the motor shaft may be provided with six successive steps of which the first, third and fifth may be employed when 50 C. P. S., and the second, fourth and sixth when 60 C. P. S. current is available.

One feature of the invention provides for steps of uniform height and ready means for altering the initial position of the speed coupling means, e. g. idler. The idler may preferably be provided with a hub longer on one side than on the other to give it a different initial position with respect to the steps of the motor shaft. One will have merely to flip over the idler to effect the change of the drive from 50 to 60 C. P. S. This permits the employment of one and the same phonograph drive on either one of two different electrical networks, avoiding the necessity of calling on skilled men to change the machines.

These and other features of the invention will more clearly appear from the claims and the detailed description of a preferred embodiment.

In the drawings,

Fig. 1 is a top plan view with part of the turntable broken away illustrating the phonograph drive adjusted for operation at 78 R. P. M.;

Patented June 18, 1957 Fig. 2 shows a portion of Fig. 1 when the drive is stopped;

Figs. 3-6 are vertical cross-sections illustrating adjustments for rotation at 78 and 33 R.'P. M. at 50 C. P. S., and at 78 and 33 R. P. M. at 60 C. P. S., respectively; and

Fig. 7 is a bottom view of the motor shaft lifting cam mechanism.

10 is the cabinet of the phonograph Within which a wedge shaped mounting board 11 is supported in rubber cushioned studs 12 on a frame 13 seated in the open end of casing 10. A turntable 14 is rotatably supported in a stub shaft 15 projecting from the board 11. The turntable has a central record supporting pin 18 and a flange 16, the latter driven by an idler wheel 17 having a rubber tire 17a engaging the inside edge of the flange 16. The idler 17 has a hub 17b which is longer on one side, as indicated at 17c, than on the other. The hub 17b fits on a pin 19 and may be held thereon by suitable means, e. g. cotter pin 17d, with the elongated hub portion pointing up (Figs. 3 and 4) arranged to select turntable speeds when the A. C. supply is at 50 C. P. S., or down (Figs. 5 and 6) arranged to select turntable speeds when the A. C. supply is at 60 C. P. S. The pin 19 projects from a Wedge shaped slide 20 provided on the mounting board 11. At its narrow end the slide has a slot 21 through which projects a pin 22 pivoted to the mounting board 11 and headed over the slide 20 as indicated at 23. A collar 24 on the pin 19 spaces the idler 17 from the slide 20 affording a seat for hub 17b. Collar 24 cooperates with the camming surfaces of a cam 25 which is pinned to the upper end of shaft 26 projecting through the mounting board 11. A leaf spring 27 presses against the side of the slide 20 and pushes the latter with collar 24 against the cam 25, and the idler 17 radially into contact with the turntable flange and the motor shaft. The spring is fastened to the mounting board at 28.

The mounting board has a cup shaped bearing 29 through which projects motor shaft 30. Below the mounting board the rotor assembly 31 of an electric motor is fastened to shaft 30. The rotor 31 is within stator laminations 32 which are energized by stator coil 32a. The

lower end of shaft 30 is seated in a bearing 33 formed in a plate 34 fastened to the lower end of bolt 35b traversing the mounting board 11, and a sleeve 35a depending therefrom. The motor shaft is free to rotate in the bearings 33 and 29, and it may be axially displaced therein. For this purpose the lower end of the shaft 35 rests on one of the steps 38, 39, 40 of a lifting cam 37. Figs. 3 and 5 show the shaft position of the idler 17 when the shaft end 35 is resting on cam surface 40, and Figs. 4 and 6 when 35 rests on 38. The cam may be slid into any one of its three operating and off positions by a mounting plate 41 suspended from the plate 34 below the electric motor. The cam is held in a clamp 42 and may be moved back-and-forth by means of a bell crank lever 43 pivotally mounted on a pin 44 projecting from an arm 45 fastened to the sleeve 46. The sleeve 46 may be rotated by means of the shaft 26 whose upper end carries cam 25 above the mounting board 11, and which projects through the mounting board and the stator laminations 32 into sleeve 46 and is pinned thereto at 47. Shaft 26 together with sleeve 46 and the bell crank arrangement for the displacement of the cam 37 may be rocked by a lever 48 projecting from an arm 49 formed on the cam 25. As the arm 49 is rocked about the pivot point formed by shaft 26, it moves the cam 37 to the right or left. The latter is positioned by a spring 50 fastened to cam 37 and engaging indentations 51 within the clamp. As will be seen from Fig. 7 there are four- 3 51c for the 78 R. P. M., 45 R. P. M. and 33 R. P. M. positions, respectively, of the device to be further elucidated below.

The upper end of the motor shaft 30 projects above the mounting board 11 within the space formed by the flange 16 of the turntable 14 into cooperative relation with the idler 17. The upper end of the motor shaft has six stepped portions, each of a different diameter; the smallest diameter upper end 52a adapted to drive the idler 33 R. P. M. at 60 C. P. S., the second portion 53a adapted to drive the idler 33 R. P. M. at 50 C. P. S., the third portion 52b adapted to drive the idler 45 R. P. M. at 60 C. P. S., the fourth portion 53b driving 45 R. P. M. at 50 C. P. S., the fifth portion 520 driving 78 R. P. M. at 60 C. P. S., the sixth portion 530 driving the idler 78 R. P. M. at 50 C. P. S.

When the arm 49 is in the off position illustrated in Fig. 2, the point 55 of cam 25 engages collar 24 to move idler 17 with slide 20 against the tension of spring 27 away from the largest diameter portion 53c of the motor shaft 30. Therefore, turntable 14 is stopped. In this position of arm 49 the motor shaft 30 is in its highest position because the shaft end 35 rests on step 40 of cam 37 which via linkage 43 has been slid to its furthest right hand position in which 35 is seated near the lefthand shoulder of step 40. The spring 50 is in notches 51 of clamp 42.

Let us assume that 50 C. P. S. alternating current is available for operating the electric motor. The idler is mounted as shown in Figs. 3 and 4 with hub 17c up. When the arm 49 is moved into the 78 R. P. M. position the slide 20 with idler 17 is allowed to rotate counterclockwise until collar 24 drops into the hollow 56 of the cam 25. In this position the lifting cam 37 will be in the position of Fig. 3 with spring 50 (Fig. 7) engaging the notches 51a. The motor shaft end 35 will be near the right-hand shoulder of step 40, and the collar or step 53c of shaft 30 will be engaged by the idler 17. It will be noted from Fig. 3 that in this position the rotor 31 is lifted slightly above the top of the stator laminations 32.

When it is desired to drive the turntable 14 at 45 R. P. M., the arm 49 is moved into the 45 position (Fig. 1). During the movement from 78 towards 45, the collar 24 rides over the cam point 57. The idler 17 will be moved laterally away from the motor shaft steps so as to permit the latter freely to move axially as cam 37 is moved to the left. During the continued movement of the cam 25, the collar 24 will be riding down from the point 57 until it comes to rest in the hollow 58 of the cam in which the tire 17a of the idler makes contact with the motor shaft step 53b to drive the turntable at 45 R. P. M. Through the bell crank linkage the cam 37 will be moved to the left with shaft end 35 riding down the slope from step 40 onto step 39 until the spring t) snaps into notches 51b. 7

When it is desired to drive the turntable at 33 R. P. M. (Fig. 4), the cam arm 49 is moved into the position 33 (Fig. 1). While moving from 45 towards 33 cam 25 will cause the collar 24 to ride up on to point 59. This will move the idler 17 away from the motor shaft and allow free axial movement of the latter. When the idler comes to rest on the portion 60 of the cam, the idler 17 will be firmly pressed into engagement with the step 53a of the motor shaft in which the turntable 14 will be driven at 33 R. P. M. In this position the rotor 31 is slightly below the level of the stator laminations 32. In response to the movement of cam lever 49, the shaft 26 will be rotated to move via 46, 45, 44 and 43, the cam 37 to the left, allowing the shaft end 35 to glide down the incline from step 39 to step 38.

It will be clear from the foregoing, that the drive can be moved back into any desired position. The fact that the idler 17 is moved radially away from the shaft 30 insures clearance of its driving steps 52 and 53, and the sloping connection between lifting cam steps 38, 39, insures smooth axial travel of the motor shaft.

If the A. C. supply is at 60 C. P. S., then one simply removes the cotter pin 17d, slips idler 17 off pin 19, flips it over so that the long hub 17c points down, pushes the hub on pin 19, and secures the idler in place by reinserting cotter pin 17d. The tire 17a of the idler will now be aligned with steps 52a, 52b, 520, depending on the positioning of shaft 30 by cam 37, to drive the turntable 14 at 33, or 78 R. P. M. selected by lever 49.

It will be clear to those skilled in the art that while the invention has been described in connection with a specific type of drive and sound reproducing device, many of its features are applicable to similar devices of widely differing types.

In order to obtain the utmost in concentricity for the drive shaft 30 of the motor drive, the steps 52 are ground into the shaft instead of applying step collars. Ideally, this may not be achieved because of the desirability of a particular size of turntable and/ or rotor drive shaft. The difiicult point is, of course, the larger diameter steps which may exceed the rotor shaft diameter. It will not cost much more to shape and/or grind six steps instead of three, as they are all ground simultaneously with one tool. The ground shaft is assembled to the motor in the place of manufacture. The concentricity of the various steps can be held to very close tolerances at the factory. If, however, a separate collar has to be removed from the rotor shaft and replaced by a different collar in the field, it is highly probable that the original high degree of concentricity will be lost. By inverting the position of the idler 17 to convert from 60 cycle operation to cycle, one does not jeopardize any of the benefits obtained by the original factory installation.

The invention may, of course, be utilized for other frequency conversions by using an additional spacer on the idler wheel bearing shaft 19. By using spacers, one can have three different positions (in height) of the idler wheel. With nine steps on the drive pulley, the motor can be used for operation on three different frequencies such as 25, 50 and cycles.

I claim:

1. In a device of the character described, an A. C. motor with a shaft adapted to be driven at any one of a plurality of certain speeds depending upon the frequency of the input current, a member adapted to be driven at any one of certain different speeds, a plurality of groups of driving surfaces of different diameters operated by said shaft, each group of driving surfaces being associated with a different frequency of input current means for coupling said member with any group of surfaces, and means for selectively driving the member by any surface of the coupled group.

2. In a sound reproducing device, an A. C. motor with a shaft adapted to be driven at any one of a plurality of certain speeds depending upon the frequency of the input current, a member adapted to be driven at any one of certain different speeds, a plurality of groups of steps of different diameters operated by said shaft, each group being associated with a different frequency of input current, means for coupling said member with a selected group of steps, and means for selectively driving the member by any step of the selected group.

3. In a device of the character described, an A. C. motor with a'shaft adapted to be driven at any one of a plurality of certain speeds depending upon the frequency of input current, a member adapted to be driven at any one of certain different speeds, a plurality of groups of successive steps of different diameters formed in said shaft, each group being associated with a diflferent frequency of the input current, means operable at will for coupling said member with one or another group of said steps, and means for selectively driving the member by an step of the coupled group.

4. In a device of the character described, an A. C. motor with a shaft adapted to be rotated at either one of two speeds depending upon one of two possible frequencies of input current, a member adapted to be driven at any one of a plurality of speeds, two groups of a plurality of successive steps of difierent diameters formed in said shaft, one group comprising odd numbered steps each adapted to drive said member at any one of said plurality of speeds when the shaft is rotated at one of said two speeds, the other group comprising even numbered steps each adapted to drive said member at one of a plurality of speeds when the shaft is rotated at the second speed, means for alternatively coupling said member with either group of steps, and means for selectively driving the member by any step of the coupled group.

5. In a device of the character described an A. C. motor with a shaft adapted to be rotated at either one of two speeds depending upon one of two possible frequencies of input current, a turntable adapted to be driven at any one of three speeds, two groups of steps totalling six steps of successively different diameters formed in said shaft, the odd numbered steps comprising one group and the even numbered steps comprising the other, an idler wheel adapted in one position to couple the turntable with to any one of said steps of one group, and in another position adapted to couple the turntable with any one of three steps of the other group, and means for effecting said coupling.

6. In a phonograph having a flanged turntable, an

A. 0. motor wheel with a shaft adapted to be rotated at either one of two speeds depending upon one of two possible frequencies of the input current, an idler wheel mountable in one of two positions and cooper-able with the turntable flange, six successive steps of ditferent diameters comprising two groups of three steps each formed in said shaft, a mounting for said idler normally aligning it with either one of three steps of either group, and means for selectively moving said idler into engagement with the other steps.

7. In a phonograph having a flanged turntable, an A. C. motor with a shaft adapted to be rotated at either one of two speeds depending upon one of two possible frequencies of the input current, six successive steps of difierent diameters comprising two groups of three steps each formed in the end of said shaft, an idler wheel mountable in two positions and cooperable with the turntable flange, said idler having a hub longer on one side than on the other side, a mounting including a pin projecting through said hub and normally aligning the idler with one step of one group when the long side of the hub points up, and with another step of the other group when the long side points down, and means including a cam for selectively moving said idler into engagement with any step.

References Cited in the file of this patent UNITED STATES PATENTS 2,118,347 Hardenberg May 24, 1938 2,308,090 Macfarren Jan. 12, 1943 2,631,458 Metzner Mar. 17, 1953

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