US2424119A - Clock - Google Patents

Description

F. Q. RAST July 15, 1947.

CLOCK v. n H W A l A\\\ cc n N 4 5 6 M Q 2 m July 15, 1947. F, RAST 2,424,119

CLOCK Filed May 18, 1943 3 Sheets-Sheet 2 Md ywz A TTOHNE Y.

July 15, 1947. F, RAST 2,424,119

CLOCK Filed May 18, 1943 3 Sheets-Sheet 3 INVENTOR ATTORNEY Patented July 15, 1947 UNITED STATES PATENT OFFICE CLOCK Frederick Q. East, Rochester, N. Y., assignor to International Business Machines Corporation, New York, N. Y., a corporation of New York Application May 18, 1943, Serial No. 487,439

2 Claims.

This invention relates to clocks and more particularly to a clock of the type wherein its time indicating element, or elements, is normally driven by a synchronous electric motor operated by current flow from the commercial light and power line, and wherein is provided a stand-by or auxiliary motor which operates to drive its time indicating element at the correct time rate in case the synchronous motor fails to operate effectively.

An object of this invention is to provide a clock of the above type which is of improved construc tion and arrangement of parts.

Another object is to provide a clock of the type mentioned above, which operates with a high degree of accuracy at all times, and one wherein the changeover from synchronous motor drive to stand-by motor drive, and vice versa, is accomplished in a highly effective and efficient manner and with a minimum of variation in the time keeping rate of the clock.

A further object is to provide a clock of the type indicated, wherein a spring-driven motor is used as the stand-by and wherein an improved and simple means is provided for winding the springdriven motor from the electric motor, which means utilizes minimum of power.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

In the drawings:

Fig. 1 is a top plan view showing one preferred embodiment of a clock constructed in accordance with the present invention, the outer casing of the clock being omitted.

Fig. 2 is a front elevation of the clock as shown in Fig. 1;

Fig. 3 is a vertical sectional view, th section being taken on the line 3-3 of Fig. 1;

Fig. 4 is a fragmentary vertical section taken on the line 4-4 of Fig. 1;

Fig. 5 is a fragmentary vertical section taken at right angles to Figs. 3 and 4, the section being indicated generally by the broken lin 55 in Fig. 2, and certain of the parts being broken away and shown in section in a slightly diiferent plane so as to illustrate certain structural details more clearly;

Fig. 6 is a fragmentary horizontal section, the plane of the section being indicated by the line 6--6 of Fig. 5;

Fig. 7 is an enlarged fragmentar vertical section, the plane of the section being indicated generally by the line 11 of Fig. 6;

Fig. 8 is a fragmentary vertical sectional view I showing structural details of the means for winding the power spring of the spring-driven motor, certain of the parts being partially broken away to illustrate the structure more clearly, the plane of the section being indicated by the line 8-8 cf Fig. 5; and

Fig. 9 is a fragmentary vertical section taken on the line 9-9 of Fig. 8.

From the drawings, it will be observed that the present invention has been shown as embodied in a clock of the type known as a master clock which is constructed and adapted to form a part of a clock system, which system also includes one or more secondary clocks located at points remote from the master clock. An example of a master clock and an explanation how such a clock functions in a clock system are disclosed fully in the U. S. patent to Larrabee, No. 1,878,931, granted September 20, 1932.

Generally speaking, a master clock of the type disclosed operates to send electrical impulses at regular intervals of time to all of the secondary clocks and-each secondary clock is advanced a predetermined amount upon receiving each impulse. In addition to this, the master clock at certain predetermined intervals of time automatically regulates, or effects synchronization with the master clock of any of the secondary clocks which may be fast or slow. It is noted, however, that while the present invention has been shown and described as embodied in a master clock of the type shown in the above identified Larrabee patent, it is not to be considered as being limited in all of its aspects to an application of that type, for it might also be embodied in other kinds of clocks without departing from the spirit thereof or from its intended scope,

Referring now in detail to the construction illustrated, the reference numeral indicates the front support plate and the numeral 5| the rear support plate of the master clock. The plates 50 and 5| are held in fixed spaced relation by the usual pillars 52. The clock comprises a time indicating train which consists of a driven shaft 53 supported for rotation by the two plates 50 and 5|. The driven shaft is journaled at its rear end in an axial bearing opening 54 provided in a bushing 55 which is in turn journaled for rotation in a sleeve 56, the latter being fixed to the rear support plate 5| (see Figs. 5 and 7) The driven shaft 53 is journaled at its forward end in the front support plate 50*. As will appear more fully hereinafter, the driven shaft 53 is driven at the rate of one revolution per minute. The shaft 53 can therefore, be considered as the seconds shaft of the time indicating train. A wheel 51 having thirty ratchet teeth thereon is fixed to the shaft 53. Also, a cam 29 is fixed to the forward extension of the shaft 53. As will appear more fully hereinafter, th ratchet wheel 5'! operates the rapid impulse contacts I! of the clock and the cam 29 the minutes impulse contacts 28.

In addition to the shaft 53, the time indicating train also includes a gear 60 fixed to the forward extension of the driven shaft 53 and meshing with a second gear GI of the same size as gear 60 and fixed to a sleeve 62 journaled for rotation on a bushing 63 which is, in turn, fixed at its rear end to the front support plate 59 (see Fig. 5). Also fixed to the rotatable sleeve 62 are a pair of planet arms 64 carrying, respectively, a pair of planet pinions 65, the latter being journaled for rotation on studs carried by the outer ends of their respective arms. The pinions 65 mesh with a sun gear 66 fixed to the forward end of the fixed bushing 63 and also with a second sun gear 61 fixed to a bushing 68 which is journaled for rotation on the forward extension of a support shaft 69, the latter being supported for rotation at its rear end by the plate SI and at its forward end in the fixed bushing 63 carried by the front support plate 50.

The stationary sun gear 55 is provided with sixty-one teeth and the rotatable sun gear 67 with sixt teeth. Thus, for each revolution of the driven or seconds shaft 53, in a clockwise direction, the gear BI and planet arms 64 are rotated one revolution in a counterclockwise direction and the sun gear Bl and bushing 68 are rotated one tooth or one-sixtieth of a revolution in a clockwise direction, Consequently, the sun gear 6'! and bushing 68 rotate at the rate of one revolution per hour which is the same as the minutes hand on the conventional clock.

An outer sleeve bushing is rotatably supported on the bushing 88 and a pair of cams 40 and 4| are fixed to the outer sleeve bushing 10. As will appear more fully hereinafter, the cams 40 and 4| control the opening and closing of the synchronizing contacts 38 and 39 of the clock. Also, a minutes indicating disk II is fixed, by a nut. "I2 screwed to the end of the shaft 69, to the forward edge of the outer bushing "I8 (see Figs. 1 and 5). A fixed pointer I3 carried by the plate 50 cooperates with the minutes disk II to indicate the time setting of the clock (see Fig. 2). The outer sleeve bushing I9 is connected by a friction drivewith the rotary sun gear 61 and inner bushing 68. The friction drive comprises a cupshaped spring element "I4 encircling the bushing 68 and fixed to the side of the sun gear 61 and bushing 68 so as to rotate therewith. The element I4 includes a resilient rim portion I5 which may be slit along radial lines to form spring fingers frictionally engaging a fibre washer 76 encircling the bushing 58. The rim I5 holds the washer 16 in frictional driving engagement with the-side of the cam 49. The frictional driving connection just described permits rotary adjustment of the earns 40 and AI and the minutes indicating dial II. with respect to the rotary sun gear 61 for the purpose of changing the time setting of the clock,

As explained at the outset, the clock is provided with a synchronous electric motor driving train which normally operates the time indicating train at a fixed time rate from the commercial AC power and light line, and the clock is also provided with a standby or auxiliary motor driving train which operates the time indicating train at its correct time rate upon a failure in current supply to the synchronous electric motor.

The synchronous electric motor driving train comprises a conventional form of synchronous electric motor 18 supported by suitable brackets from the rear support plate SI and having its power shaft connected by a suitable coupling 19 with a drive shaft which is journaled for rotation in spaced brackets 8I extending rearwardly from the rear support plate 5I. As indicated in Fig. 1, the motor I8 is connected by wires 82 and 83 to a convenient source of AC current. The drive shaft 80 is formed intermediate its ends with a worm 84 meshing with a worm wheel 85, the latter being rotatably supported on a fixed stud 86 carried by the rear plate 5| (see Figs. 1, 4 and 5). A spur gear 8'! is fixed to the worm wheel and meshes with a second spur gear 88 which is fixed to the rear end of bushing 55 previously described, as being rotatably supported in the sleeve 56 carried by the rear support plate 5| (see also Fig. 7).

The bushing 55 is the terminal element of the just described power transmitting gear train driven from the motor I8. The design of the electric motor I8 and of the gears 84, 85, 81 and 88 is such that when the motor is connected to the commercial AC light and power line, the bushing 55 will be operated at the fixed time rate of one revolution per minute.

The stand-by motor driving train comprises as its source of power, a spring motor 90 which comprisesa power shaft 9I rotatably supported at its ends by the support plates 50 and 5I, a spiral power spring 92, and a pair of spaced parallel disks 93 and 94, respectively (see Figs. 5, 8, and 9). The inner end of the power spring 92 is fixed to the power shaft SI and the outer end of the spring is fixed to one of a plurality of spring restraining studs 95 extending forwardly from the disk 93. The disk 93 is fixed to one end of a hub 96 journaled on the shaft 9I. A ratchet wheel 91 is fixed to the other end of the hub 96 so that the wheel 9'! and disk 93 rotate together.

In accordance with the present invention, the power spring 92 is kept wound by the operation of the synchronous electric motor I8. A worm 98 is formed on the outer end of the drive shaft 80 and meshes with a worm wheel 99 fixed to a rearward extension of a cam shaft I00, the latter being journaled for rotation in the support plates 50 and 51 and having fixed thereto a cam I01. Thus, as long as the electric motor I8 operates, the cam IN is rotated through the drive mechanism just described.

A vertically arranged pawl-carrying rock lever I03 is pivoted at its lower end on a stud I04 extending forwardly from the rear plate 5| (see Fig. 8). A rotary cam follower I05 is journaled on a stud I06 extending from the upper part of the lever I03 and engages the face of the cam I0l. A pawl I0! is pivoted at one end to the upper end of the lever I03 and is provided at its other or outer end with a hook or tooth I08 adapted to engage the teeth of the ratchet Wheel 91. A tension spring I09 connected at its upper end to a mid point on the pawl I01 and at its lower end to the lever I03, serves to hold the hook I08 in engagement with the teeth of the ratchet 91. A relatively strong tension spring H0 is connected at one end to the upper end of lever I03 and at its other end to a fixed stud III projecting forwardly from the rear plate 5|.

The spring IIO functions to hold the cam follower I05 firmly against the face of the cam IOI, and thereby acts to pull the lever I03 and pawl I01 to the left, as viewed in Fig. 8, when the cam IN is in that part of its revolution where the height of the cam face engaging the follower I05 is decreasing. With the hook I08 engaging a ratchet tooth, this movement of the lever I03 to the left, results in the rotation of the ratchet wheel 91 and disk 93 is a counter-clockwise direction to wind the power spring 92. When the height of the cam face engaging the follower I05 is increasing, the lever I03 is moved to the right, as viewed in Fig. 8, against the force of the spring I I and the hook I08 rides over the ratchet to engage a new tooth. A dog II2 pivoted to a fixed stud H3 and held in engagement with the ratchet 9'! by a tension spring I I4 serves to prevent rotation of the ratchet wheel in a clockwise or unwinding direction when the cam IOI moves the pawl I01 to the right to engage a new tooth.

From the foregoing, it is apparent that when the power spring 92 approaches a fully wound condition, it resists at a progressively increasing rate the winding force applied by the spring I I0; and, when the spring 92 is fully wound, the force of the spring I I0 is completely overcome. As the power spring 92 approaches being fully wound, a condition is reached where the spring IIO can not pull the lever I03 and pawl I0'I the full distance to the left and the cam IOI will then leave the follower I05. From the point where this condition begins, the spring IIO moves the lever I03 to the left a less distance on each succeeding revolution of the cam until the spring 92 is fully wound. When the latter occurs, there is no movement of the lever I03 to the left. As the amount of work done by the cam MI is a function of the distance it has to move the lever I03 to the right, it follows that the cam IOI does less and less work as the power spring 92 approaches being fully wound, and when the power spring is fully wound, the rotating cam performs no further work. It is believed to be apparent that because of this novel construction and arrangement, the portion of the power consumption of the electric motor which is required to wind the power spring is kept at a minimum.

The stand-by motor driving train also comprises a series or train of power transmitting gears which are continuously operated from the power shaft 9! at a definite time rate controlled by an escapement means. This gear train comprises a first gear II5 fixed to the power shaft 9| and meshing with a second gear H6 fixed to one end of a sleeve bushing I I1 rotatably mounted on the shaft 69. A third gear H8 is fixed to the other en of the bushing I I1 and meshes with a pinion I I9 fixed to a shaft I20 rotatably mounted at its ends in the support plates 50 and 5|. Also fixed to the shaft I20, is a gear I2I which meshes with a pinion I22 fixed to a sleeve I23 rotatably mounted on the driven shaft 53 of the time indicating train (see Figs. 5, 6 and '7).

The sleeve I23 is the terminal element of the power transmitting gear train just described and is continuously operated by the power spring 92, under the control of an escapement means, at the definite time rate of one revolution per minute. The controlling escapement means is of the conventional type and comprises an escapement drive wheel I25 fixed to the sleeve I23 and meshing with a pinion I26 fixed to a sleeve I21 6 journaled on a shaft I28, the latter being supported at its ends by the plates 50 and 5I. Also fixed to the sleeve I21 and pinion I26 is an escape wheel I29. Cooperating with the escape wheel is the usual verge I30 mounted for oscillation on a verge shaft I3I carrying the oscillating verge lever I32 which cooperates in the usual manner with the impulse pin I33 on the balance wheel I34. The balanc wheel I34 is mounted on the balance wheel shaft I35 supported at its ends by the front and rear support plates 50 and 5|. A more detailed description of the escapement means is considered unnecessary as it is of the conventional type and its function and operation will be readily understood by those skilled in this art.

"In accordance with the present invention, there is also provided a selective clutch mechanism, indicated generally at I40, which during normal operation connects the driven shaft 53 to the bushing 55 which is operated by the electric motor I8; and which, when ther is a failure in the current supply to the motor I8, automatically disconnects the shaft 53 from the bushing 55 and connects the driven shaft 53 to the sleeve I23, the latter being the terminal element on the stand-by motor driving train and being continuously rotated by the spring driven motor in the manner previously described.

As shown in Figs. 4, 5, 6, and 7, the clutch I40 comprises first and second clutch members MI and I42 respectively, which are arranged in spaced parallel relation and are fixed, respectively, to the front end of the bushing 55 and the rear end of the sleeve I23. The clutch members MI and I42 are shown as being in the shape of circular plates or disks and are both coaxially arranged with respect to the driven shaft 53, and each member is provided on the face thereof which is adjacent the other member, with an annular series of clutch teeth I43.

The clutch I40 also comprises a disk-lik element I44 arranged between the members MI and I42 and having a pin-ancl-slot connection with the driven shaft 53 so that the element I44 will always rotate with the shaft 53 and, at the same time, can 'be shifted axially of the shaft towards the member I4I or the member I42. Specifically, the element I44 is fixed to a sleeve bushing I45 mounted on the shaft 53 and the bushing I45 is provided with a longitudinal slot I46 receiving a pin I41 fixed to and extending radially from the shaft 53. Thus, the clutch element I44 may be shifted axially of the driven shaft a distance determined b the length of the slot I46.

Projecting from opposite sides of the periph eral ortions of the element I44, are spring clutch fingers I49 and I50, respectively, which are adapted to engage selectively the teeth I43 of member MI and member I42. In the drawings, the parts are shown in their normal operating position with the finger I49 in engagement with the teeth I43 of the first clutch member I4I which is driven in the manner previously explained by the electric motor. Thus, as shown, the shaft 53 is being driven through the element I44 and finger I 49 at its designated time rate of one revo lution per minute. At the same time, the sleeve I23 and the second clutch member I42 are being continuously operated at this same rate from the spring motor 90.

The finger I49 is held in engagement with the teeth of the first clutch member MI by a magnet I52 energized from the AC power supply wires 02 and 83 leading to the motor 18 (see Fig. 1).

Th armature |53 of the magnet forms a part of a lever H54 pivoted to move about the axis of a vertical pin I55 which is carried by spaced brack ets I56 extending forwardly from the rear support plate The lever I54 also comprises a pair of spaced bars 55'! and |58, respectively, extending horizontally from the armature I53 and receiving intermediate their ends the pivot pin I55. The outer ends of the bars are turned inwar ly toward one another to form opposed fingers |59 and H30, respectively, which are formed with slots |5| receiving the upper and lower parts of the movable clutch element M4.

From the foregoing, it is apparent that as long as the magnet |52 remains energized, the clutch element M4 is held by the lever 554 in driving engagement with the first clutch member 4|. Upon a failure in current supply, the magnet E52 is deenergized and a tension spring I62 moves the lever I54 about its pivot pin I55 and the element I44 is thereby shifted axially of the shaft 53 to disconnect the finger I49 from the member it'll and connect the finger 153 with the continuously rotating clutch member I42 so that the shaft 53 will then be driven from the spring motor 33. When the current again flows to the motor l8 and magnet I52, the latter will shift the lever I5 and clutch element hi4 against the force of the spring l32 and back to the normal operating position shown in the drawings.

lhe clock construction described above has many advantages not found in prior clocks. The clock of the present invention operates with a relatively high degree of overall accuracy. During normal operation, its time rate is controlled directly by the regulated frequency of the AC power and light line in a manner well known to those skilled in this art. The simple form of clutch 543 provides an effective means for instantaneously shifting from electric motor drive to spring motor drive and vice versa. Because the spring motor driving train is operating continuously while the electric motor is driving the clock, the time rate of the spring motor train can be regulated so that it will operate with the same degree of accuracy as any clock operated by a spring motor. Furthermore, if the spring motor were idle and started when the current failed, there would be a definite lag before the spring motor train would operate. There would also be a possibility that the spring motor would not start. Thus, there is provided a stand-by source of power for the time indicating train which is always available and dependable and which is instantaneously connected to the time indicating train by the clutch M3 the moment the electric power supply fails.

Because the clock of the present invention operates with a high degree of accuracy, it is well adapted for use as a master clock which, as stated previously, forms a part of a clock system and functions to control the operation of one or more secondary clocks in a manner fully disclosed in the U. S. patent to Larrabee, identified above. Herein, the clock system and the manner in which the secondary clocks are operated and regulated, are not disclosed as it is considered unnecessary to an understanding of the present invention. However, in the accompanying drawings, the master clock has been shown as provided with certain electrical contacts and operating means for closing and opening the contacts, so that the clock disclosed herein can function in a clock system in the same manner as the master clock of the Larrabee patent. Where it is proper, the

same reference characters are used herein to identify these contacts and their operating elements as are used to identify the corresponding parts in the Larrabee patent.

The contacts 23 are the minutes impulse contacts and are normally open. They are closed once each minute to send an electrical impulse to each of the secondary clocks of the system for advancing them. The means for operating the contacts comprises a cam follower 32 pivoted at one end to a stud 3| and engaging at its other end the face of cam 29 mounted on the driven shaft 53 which makes a complete revolution each minute (see Fig. 2). A three-arm lever 33 is pivoted at 34 on the follower 32 and one arm is provided with a contact actuating element 35 engaging the lower member of the spring contacts 28. An arm 36 engages at its outer end the face of the cam 29 and is held in contact therewith by a tension spring 3! connecting a fixed stud and the third arm of the member 33. The spring 31 also holds the follower 32 in contact with the cam 28. The arm 36 is slightly shorter than the follower 32 so that it drops off the high point of cam 29 just before the follower 32. When both arm 36 and follower 32 are engaging either the high point or the low point of the cam 29, the element 35 holds the contacts 28 open; but, when the arm 36 drops off the high point of the cam and the follower 32 is engaging the high point, the spring 31 rotates the three-arm lever clockwise as viewed in Fig. 2 so that the element 35 closes contacts 28. An instant later when follower 32 also drops off the high point, the contacts 28 are again opened by the element 35.

The synchronizing contacts 38 and 39 are actuated by the cams 40 and 4| mounted on the sleeve 10 which makes one revolution each hour. Cooperating with the cam 4| is a cam follower 43 similar to follower 32, just described. A threearm lever 44, similar to lever 33, is pivoted on the follower 43 and has an arm 41 engaging the face of the cam 40. Another arm of the lever 44 carries an insulating disk 45 which bears on the underside of the lower of the two central spring contact members of contacts 38 and 39. The two central spring members are biased downwardly so that when all restraint on the members is removed, the lower contacts 39 will close. A tension spring 46 connected a fixed stud and the third arm of lever 44, holds the arm 41 and follower 43 in contact with the faces of cams 40 and 4|.

For each revolution of the sleeve 10, the cams 40 and 4| operate to provide three operating positions of the contacts 38 and 39; viz., the closing of contacts 39, the closing of contacts 38, and a mid position where both contacts 39 and 38 are held open. In order to accomplish this, the cam 40 is provided with two steps of different heights and the cam 4| with only one step. When the follower 43 and arm 4'! engage the highest points of their respective cams 4| and 40, and when both follower 43 and arm 41 rest on the lowest points of their cams, the contacts 39 are closed. The cams 49 and 4| are so positioned on the sleeve 10, that this latter condition occurs during the period beginning with each hour and ending with about forty-nine minutes past each hour. The upper contacts 38 are closed when the follower 43 is on the highest point of cam 4| and when the arm 4'! is on the lowest point of cam 40. The latter occurs during the period beginning about thirty seconds before each hour. Neither contacts 38 nor contacts 39 are closed when the follower 43 is on the high point of cam 4| and the arm 41 is engaging the intermediate step of cam 40. The latter condition occurs from about forty-nine minutes after each hour until about thirty seconds before the next hour.

The rapid impulse contacts H, are operated once each two seconds by the thirty tooth ratchet wheel 51 fixed to the driven shaft 53. As explained in the aforementioned Larrabee patent, during the thirty second interval that the contacts 38 are closed and the contacts 39 are open, the circuit is under the control of contacts 11 and the latter then operate to send rapid electrical impulses to any of the secondary clocks which are slower than the master clock, for the purpose of advancing such slow clocks to agree with the time setting of the master clock. The upper of contacts I1 is mounted on a spring blade I10 and the lower of contacts I! is mounted on a second spring blade Ill and the blades I10 and H I engage at their outer ends the teeth of ratchet wheel 51. The relative lengths of blades H and Ill are such that they both engage the same ratchet tooth for an instant, then the blade IH drops off such tooth onto the next tooth while the blade I remains in engagement with such tooth, and then the blade I10 drops off onto the next tooth. When both blades I10 and I'll engage the same tooth, the contacts H are closed, and when the blades I10 and I'll engage different teeth, the contacts I"! are open.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied to a single modificaa tion, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art, without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims:

What is claimed is:

1. In a clock, a time indicating element; motion transmitting means for operating said element and comprising a driven shaft; selective clutch mechanism comprising first and second clutch members journaled to rotate about the axis of said driven shaft and being spaced axially from one another, and a clutch element mounted on said driven shaft between said first and second clutch members and being secured to said shaft for rotation therewith and being shiftable axially of said shaft into selective clutching engagement with said first and second clutch menibers; a first clock driving mechanism operable at a definite time rate and including a synchronous electric driving motor having a driving connection with said first clutch member; a second clock driving mechanism operating continuously and at the same rate as said first driving mechanism and including a power spring and a gear train having a driving connection with said second clutch member for continuously rotating the latter; and current responsive means operable upon a flow of electric current to said synchronous motor to shift said clutch element into clutching engagement with said first clutch member and operable upon a failure in current flow to shift said clutch element into clutching engagement with said second clutch member.

2. Apparatus according to claim 1 wherein each of said first and second clutch members comprises a clutch disk mounted for rotation on said driven shaft and provided on the face thereof which is adjacent the shiftable clutch element with a series of clutch teeth extending circumferentially about the axis of said driven shaft, and wherein said shiftable clutch element is provided on opposite sides thereof with spring fingers extending outwardly therefrom and toward both disks and being so constructed that as said element is moved toward one of said disks the fingers operatively engage the clutch teeth on said one disk and are disengaged from the other disk and so that as said element is shifted in the opposite direction toward said other disk the fingers operatively engage the clutch teeth thereon and beslgme disengaged with the teeth of said one di FREDERICK Q. RAST.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,072,609 Taliaferro Mar. 2, 1937 2,088,973 Poole Aug. 3, 1937 2,192,329 Pudelko Mar. 5, 1940 FOREIGN PATENTS Number Country Date 343,252 Great Britain Feb. 19, 1931 79,720 Sweden Feb. 2'7, 1934 790,914 France Sept. 16, 1935

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