US2128858A - Coin time switch - Google Patents

Description

Aug. 30, 1938. J STARK 2,128,858

COIN TIME SWITCH Filed Jan. 25. 1935 2 Sheets-Sheet l Figl.

l2 6 5o 5! 1 v 29 '3 5 wgg Inventor":

Julian H. SLar'K,

s Annorneg.

Aug. 30, 1938. J H STARK 2,128,858

COIN TIME SWITCH Fi led Jan. 25, 19:55 '2 Sheets-Sheet 2 Inventor- Julian H. StarK,

His Attorney.

Patented Aug. 30, 1938 PATENT OFFICE 2.12am; com mus stmcn Julian H. Stark, Fort Wayne, Ind., asaignor to General Electric Company, a corporation of New York Application January 25, 1935, Serial No. 3,479

9 Claims.

My invention relates to check or coin controlled devices of the type through which some form'of service is made available for a predetermined length of time upon the deposit of a coin of the proper value. For example, the device may control the closing and opening of a service switch in the circuit of an electric refrigerator, washing machine, radio, or the like. Often times, such coin time switches are used in a method of collecting payments on the device controlled thereby. For example, a customer may contract to purchase an electric refrigerator on a deferred payment plan which permits the use of the refrigerator while it is being paid for, provided the agreed payments are made on schedule. For this purpose, a coin time switch connected in the circuit of the refrigerator permits of the continuous use of the refrigerator provided a twenty-five cent piece is deposited in the coin time switch once per day. The device may be of the type which permits of the deposit of a number of coins -,at any one time to correspondingly prolong the number of days the switch is kept closed.

In the usual form of coin time switch which is used in this way, service is made available as soon as one coin is deposited regardless of the fact that the customer may have been delinquent in making payments for one or more days previous thereto. Thus, the only inconvenience suffered by the customer due to such delinquency in making payments is the loss of refrigerating service for the delinquency period and the customer is not required to make up the delinquent payments before he may again obtain service. To the extent that the customer fails to make use of the refrigerator, the usual form of win time switch as thus used fails to accomplish its intended purpose of requiring payments to be made regularly and on time.

It is the primary object of my invention to provide a coin time switch which will keep track of the extent of-such delinquency up to a reasonable magnitude and will require that the back payments be made up by the deposit of a corre- 45 sponding number of coins before service is again made available.

A further object of my invention is to provide such a coin time switch with an indicator which shows at all times the delinquent or credit con- 50 dition of the device and gives a warning signal of the approach of a delinquent condition.

A further object of my invention is to provide a coin switch of this character which is adjustable for different delinquency and credit pay- 55 ments.

The features of my invention which are believed to be novel and patentable will be pointed out in the claims appended hereto. For a better understanding of my invention, reference is made in the following description to the accompanying 5 drawings, Fig. 1 of which shows an exploded perspective view of a time coin switch mechanism embodying 'my invention together with circuit connections ordinarily associated therewith; Figs.

2 and 3 represent different adjustments of 10 switch-operating cam parts used in the device; Fig. 4 represents an indicator dial for a coin switch having the delinquency feature; Fig. 5 represents a non-adjustable cam for such a switch; and Fig. 6 represents a general view of 15 the switch as inclosed in a casing.

Referring now to Fig. 1, in general, the apparatus comprises a coin credit part III and a time debit part II connected together through a diflerential H. The central member of the dif- 20 ferential assumes different positions depending upon the relation between the debit and credit conditions of the device and operates a circuit controller I: and an indicator H, which show the credit balance or delinquency, as the cas= may be.

The time debit part of the mechanism include a timing motor l5, which may be a self-starting synchronous motor permanently connected to an alternating source of supply l6. Between the differential l2 and the motor l5; there is a time interval mechanism for changing the constant rotation of the motor into a periodic intermittent motion. This mechanism includes a gear driven from motor I5 through shaft l8 and the 35 necessary gearing illustrated. Gear has a bearing on a shaft |9 and is secured to one end of a spring 2|). The spring is coiled about shaft l9 and has its other end secured to a disc 2| fixed on shaft I9. Disc 2| and the shaft I! to 40 which the disc is secured are normally held from rotation by a stop finger 22 pivoted on disc 2| at 23 and resting on a stop plate 24. Gear I1 is continuously driven in the direction indicated by the arrow thereon by the timing motor I5 and continuously winds spring 20 which urges disc 2| to rotate with gear However, disc 2| is held from rotation by stop finger 22 until such time as a finger 25 extending from gear rotates into contact with finger 22 and pushes it ofl from stop plate 24. This occurs once per revolution of gear H and it will be assumed that the gear l'l makes one complete revolution in twenty-four hours. When disc 2| is thus released. the tension stored in spring 20 causes the disc 2| and shaft l9 to make a complete revolution in a very short period of time, for example, in less than a second. The finger 22 is caught again by the stop plate 24 as it completes its revolution where it rests until finger 25 has made another revolution in the next twenty-four hour period. A light spring shown to the rear of disc 2| may be used to bias stop finger 22 about its pivot 23 to the position where it will come against stop plate 24. When shaft i9 thus rotates, it drives a pinion 26 thereon, a large gear 21 meshing with pinion 26, a hollow shaft 28 to which gear 21 is secured, and one side 29 of the differential, 29 being a smaller gear also secured to hollow shaft 26. From the above, it will appear that the time debit mechanism causes the side 29 of the differential to be quickly rotated a predetermined small amount in a counterclockwise direction once every twenty-four hours.

Thecoin credit mechanism i9 here represented includes a supporting structure 30 containing a coin chute 3i into which coins may be inserted at the top. Such coins then drop to the position indicated by the coin 32. A hand operated plunger 33 has a sliding fit in the support and is normally held in its upper position shown by a spring 34 secured between the support and a pin 35 extending through a slot in the support to the lower end portion of plunger 33. Pin 35 limits the upward movement of the plunger. When the plunger is forced down, it contacts with the coin 32 and forces it downward into a suitable coin receptacle, not shown. As the coin is forced down, it rotates an L-shaped member 36 about its pivot 31 on the supporting structure and momentarily lifts a pin 36 projecting from the side of a pawl 39. Pawl 39 and its pin 39 are supported for limited vertical movement and r are normally held down by a spring 49. When moved upward by the forcing of a coin past member 36, the pawl acts upon and rotates a ratchet wheel 4| one notch in a clockwise direction. The ratchet wheel is secured to a gear wheel 42, which comprises the other side of the differential. Thus the deposit of a coin through the coin chute causes rotation of the side 42 of the differential a predetermined small distance in a clockwise direction.

The central member of the differential includes the cam plate 43 in which is rotatively mounted a shaft 44 having pinions 45 and 46 at opposite ends. Pinion 46 meshes with gear 42 of the coin controlled credit mechanism and pinion 45 connects through the idler gear 41 supported from cam plate 43 to the gear -29 of the time controlled or debit mechanism. The cam plate 43 is secured to a shaft 49 which extends through hollow shaft 29 to the indicating disc l4. In the adjustable form of the device, the shaft 49 also carries additional cam plates 59 and 5i and all of these cam plates are adjustable about the shaft 49 to which they are secured. Cam plates 50 and 5| have arc-shaped openings through which shaft 44 extends, allowing a considerable range of adjustment of these cams about shaft 49 with respect to cam plate 43. Shaft 49 and gear 42 are on the same axis of rotation. Cam plates 43 and Si have raised and depressed cam surfaces of the same radius and constitute parts of a single adjustable cam operating on a cam follower 62. Thus, if cam plate 5| is loosened on its shaft and turned in a clockwise direction one-fourth revolution and again fastened to the shaft. the raised peripheral portion of the cam 2,12s,ssa

comprising plates 43 and Si will be extended by a like amount and the depressed peripheral portion of this cam will be correspondingly reduced. Thus cam plates "and Si are merely adjustable parts of the sime cam member which will normally be located much closer together on shaft 49 but have here been separated for the sake of a clear illustration. Cam plate 59 has a reduced peripheral portion of the same radius as the reduced periphery of cam plates-43 and 6i and has a raised peripheral portion having a radius somewhat less than the radius of the raised peripheral portions of cam plates 43 and 5i so that the cam follower 52, which is pivoted at 53 and biased against the came assembly by a spring 54, has three positions. It is shown in its intermediate position resting against the raised portion of cam plate 50. Rotation of the cam member assembly in a clockwise direction will depress the cam follower 52 as the raised portion of cam plate 43 or 5i comes opposite thereto and rotation of the cam assembly in a counterclockwise direction will allow the cam follower 52 to rise as the reduced portion of cam 59 is moved opposite thereto.

The cam assembly included in the central member of the differential i2 operates through the cam follower upon the movable member of the circuit controller i3. The circuit controller has an insulating bar 55 to which the pivoted cam follower is resiliently connected. At 56, the bar 55 carries a conducting strap arranged to bridge two stationary contacts 51. The switch thus formed is connected in the circuit of some electrical apparatus 53, which may be an electric refrigerator, the operation of which is permitted when the switch is closed. In the intermediate position of the cam follower shown, determined by cam plate 59, the strap 56 bridges contacts 51 and closes the 59. The cam follower is lower insulating member 59 which has an arm resting against the upper side of a contact bar 60 which is normally biased upward by spring pressure to bridge two stationary contacts H. The contacts 6| and the conducting strip 69 constitutes a switch in the circuit of a signal lamp 62, which switch and circuit are also closed when the cam follower is in the intermediate position shown.

The conducting strip 60 and the terminals 6i have aligned openings at their extremities through which stationary insulating posts 63 extend. These posts support compression springs which are coiled about the posts beneath the conducting strlp 60 and serve to retain the conducting strip 69 in proper position but allow the strip 60 to be moved downward on the posts against the compression of the springs to open the signal circuit when part 59 is moved downward. The insulating posts 63 also extend upward beneath insulating bar 55 and assist in properly positioning said bar in the operation of the circuit controller.

The downwardly extending arm 64 of the cam follower is rigidly connected to the insulating part 59 through the post 65. However, the insulating bar 55 is resiliently connected with the cam follower in that it is loosely mounted on a pin having a head 66, which pin extends upward from post 65 through a somewhat larger opening in the central portion of bar 55. A compression spring 66a about the pin between the head 66 and the bar 55 tends to press the bar downward in contact with that portion of arm 64 which is also connected to a circuit to the device,

secured to post I. These parts are also shown in a much less compact assembly relation than exists in practice-in order to better illustrate and explain their operation.

As has already been stated, when the cam follower is in the intermediate position, determined by the raised portion of cam plate III, both switches of the controller I! are closed and this is; the position illustrated. when the cam :01- lower moves downward as determined by the highest portion of the cam assembly in the coin crediting rangeof the device, the lamp circuit is opened due to the fact that conducting part 60 is pressed downward. However, the refrigerator circuit controlled by contact bar 55 remains closed. When the cam follower moves upward from the postion' shown as determined by the lowest portion of the cam assembly over the coin delinquency range of the device, bar II is moved upward to open the refrigerator circuit at the contactor I. The signal circuit to lamp I2, however, remains closed. The details of construction of the switch may be varied considerably but a construction should be used which positively opens and closes the diiferent circuits in the selective manner described. The quick step by step movement of the cam both in response to the time controlled and coin controlled actuatin means assures that the switch will open and close quickly.

In the device illustrated, the ratchet wheel II has seventeen teeth and is rotated the distance of one tooth for each coin used or deposited. The central member I! of the differential is rotated in a clockwise or service switch closing direction one-half the distance or $6 of a revolution for each coin deposited. The device will, therefore,

require the deposit of thirty-four coins in order to revolve the central member of the differential in step a complete revolution, assuming that the other end 29 remains stationary in the meantime.

The time debit end of the differential is rotated in steps of $4 of a revolution each time the timing interval mechanism associated with gear ll operates, the gear ratios used being such as to accomplish this result in the particular device described. Each such operation moves the'central member i2 of the differential of a revolution in a counterclockwise or service switch opening direction and, consequently, it will require thirty-four days for the timing mechanism to rotate the central part of the differential a complete revolution assuming, of course, that no coins are deposited in the meantime. The central member of the differential and-the other parts connected thereto will, therefore, have thirty-four different rotary positions and the indicator Il may have a corresponding number of graduations.

By using a differential arrangement such that the switch-operating cams and the indicator ll rotate at one-half the rate of the coin credit and time debit parts, the range of the device is made just twice as great as one in which no differential is used. The coin switch described can be used in the ordinary way without the delinquency feature if that is desired and will then have a coin capacity of thirty-three atoms, that is, thirtythree coins may be deposited at one time and the device-will operate for thirtythree days and then open the switch to the refrigerator. For such use, the cam plate 5| will be rotated with respect to cam plate 43 so as to extend the raised periphery of the cam over of the periphery and cam 58, if it is used, will be adjusted so that the step therein lies midway between the adjacent step in the cam formed by plates 43 and II. Such adjustment of the cams is represented in Fig. 2.

In Fig. 2, I have also represented schematically the condition of the signal and refrigerator switches when the cam follower is on the high part of the cam and the cam is in a position corresponding to a credit of two coins. The refrlgerator circuit is closed and the customer is, therefore, obtaining service. The lamp or signal switch is open. During the next'time interval of the device, assuming no more coins are deposited, the cams will rotate 5 of a revolution in a counterclockwise direction and cam follower 52 will move to the high part of cam 50. The refrigerator switch will still remain closed and the signal lamp switch will close advising the customer that, within the next twenty-four hours, refrigerator service will be discontinued unless an additional coin or coins are deposited. If no coin is deposited during the net twenty-four hours, the timing interval mechanism will rotate the cams ,5 revolution counterclockwise and the cam follower "will move to the low part of the cams, cutting off the refrigerator service by opening the switch contacts 56-41. The signal lamp will remain closed advising the customer that additional coins are required. Should no coin be detion of ratchet wheel ll in a clockwise direction under the condition just mentioned whereby it is not blocked by pawl 39 or a stop pawl if one is used. Damageto the mechanism is thus prevented should this condition arise. The steps in the cams which face in a clockwise direction are suiliciently sloped so that the cam follower can be readily forced outwardly by operation of the manually operated coin credit mechanism operating on the differential through ratchet wheel 4 I It will be evident that, with the cams in the position represented in Fig. 2, up to thirty-one additional coins may be deposited at once and credit received therefor by rotation of the cams in a clockwise direction of a revolution. Over this coin credit range of movement the service switch is retained closed. If desired, a stop pin 81 may be inserted in the tail of cam plate I to prevent a complete rotation of the cam assembly by operation of the cam credit mechanism beyond the range of the device. While such a complete rotation of the central member of the differential in a clockwise direction, causing the cam follower to drop off the back end of cam 5|, would do no damage to the mechanism, it would return the cams to the no-credit condition with a corresponding loss in credit of thirty-four coins. A suitably positioned stop, such as the stop 61 on some part of the central member of the differential will simply block the coin credit mechanism from further operation until cleared by the operation of the time debit mechanism in response to the passage of time. For operation of the mechanism as above described, the indicating dial used at H should preferably be one graduated from 0 to 33 in a coun-' terclockwise direction and should have its zero indication opposlte'the reading point I! when period is not counted.

the cam assembly is in position to open the refrigerator circuit.

It will now be explained that the cams may be readily adjusted to provide the delinquent feature hereinbefore mentioned. Let us assume, for example, that the cams are adjusted as represented in Fig. 1. The raised portions of cam plates 4! and Bi extend over approximately 180 degrees and are so positioned that these portions are in alignment. Cam plate 50 is adjusted with respect to cam plate 43, as in Fig. 2, and serves the same purpose. The position of the cams with respect to the cam follower, as represented in Fig. 1, corresponds to a credit condition of one coin, that is, the refrigerator switch is closed and the signal lamp is energized, advising the customer that additional coins should be deposited. He can, of course, tell by looking at the indicator H whether his credit has been used up or is about to be used up, but this is not so noticeable as the electric signal. He may now deposit up to sixteen coins and receive credit therefor or sixteen days continuous operation of the refrigerator. However, if he fails to deposit any more coins, his service will be discontinued within the next twenty-four hours.

After the service has been discontinued by the cam followers dropping from the intermediate portion to the lowportion of the cams in the intermediate range of movement where the service switch is operated, the timing motor and timing interval mechanism continue to operate and, at the end of each twenty-four hour period, rotate the cams in a counterclockwise direction in steps of 3& revolution per day. This continues, assuming no coins are deposited, for seventeen days until the steep step in the cam plates comes to rest against the cam follower 52. This is the limit of the delinquency range of the device as above described and adjusted, and over this range the service switch is retained in the open position. Any additional delinquency beyond this However, before the customer may again obtain service from the refrigerator, he must rotate the cams back over the delinquency range by first depositing seventeen coins and then at least one additional coin to bring the apparatus back to the condition represented in Fig. 1. Thus, the customer gains nothing by becoming delinquent for two weeks. c

He not only cannot use the refrigerator but he must make up the delinquent payments before he can again obtain service within the delinquency range of the device which is sufflcient to make the refrigerator practically useless unless the payments are made on time.

In case the device as thus adjusted appears to penalize a particular type of customer too severely, it may be adjusted to shorten the delinquency range and length the credit range by adjustment of cam plate 5i and, in Fig. 3, I have represented the cams adjusted for a delinquency range of eight coins or eight days in the device described. The credit range now corresponds to twenty-five days. As thus adjusted, the customer who allows his payments to fall behind must make them up for at least eight days, if he is behind that much, before he can use the refrigerator and then keep them up to obtain continuous service.

The indicator used at ll will preferably be one which is graduated with credit and debit portions corresponding to the credit and debit adjustment of the cams. The indicator shown in Fig. 4 is intended to be used when the device is adjusted for a delinquency period of eight days. The graduations to the right of the "zero mark are credit graduations and may be in black and the graduations to the left of the zero mark are debit graduations and may be in red color, or be printed on a removable sector colored in red. Differently graduated interchangeable indicator discs or debit sectors may be provided with the adjustable form of the device.

It will be apparent that the lamp-signaling cam 50 can be adjusted to different positions so as to give a longer signaling period before service is disconnected if that is desired or it can be adjusted to light the signal lamp only when the service is disconnected; In the latter case, the step in cam 50 would be adjusted even with the longer step in cam 43 or cam 50 omitted entirely. If no signal is desired, both the cam 50 and the signal lamp and its switch may be omitted without interfering with the remainder of the device. Also, if a fixed delinquency period and signal period are satisfactory, the switch may be simplified by omitting both of the extra cam parts 50 and ii and using instead'a single cam part, such as is shown in Fig. 5, to take the place of cam part 43. It will be evident from the previous description that the cam of Fig. 5 will give a one-day signal of the approach of a delinquency condition before credit expires and a delinquency range of nearly half .of the credit range. Thus, coin switch devices to meet a large variety of conditions are made available simply by varying the cam arrangement or its adjustment and selecting the proper indicating disc.

Attention is directed to the following desirable arrangement of the apparatus as a whole:

It will be noted that the service switch is normally biased to an open position by the spring 54 so that little energy is required from the timing interval mechanism to operate the central member of the differential in a service switch opening direction. The main energy requirement of the device is in forcing cam follower 52 downward over the rise in the cams and this is always supplied manually through the coin-controlled, manuallyoperated ratchet 39-4l at the time coins are deposited. The energy requirements of the automatic time controlled end of the differential are therefore small and this is important if the device is to be made reliable and at the same time small and inexpensive in construction and economical in operation.

A further advantage of this arrangement lies in the fact that the energy required to drive the ratchet wheel ll through the gears l2, I6, 45 and 41 from the time controlled end of the differential is greater than that required to rotate the central member of the differential from the time controlled end thereof under normal conditions. The ratchet wheel ll, therefore, does not need to be blocked to guard against its being erroneously driven in this way, but its rotation in this way is nevertheless permitted when the cam member is blocked at the limit of its travel in a service switch opening direction. Rotation of ratchet wheel I thus serves as a safety release feature to prevent damage to the apparatus when this last mentioned condition exists.

It will be understood that the device will be housed in a suitable casing, such as is represented in Fig. 6. This shows the coin chute 3i, coin plunger 33, and signal lamp 62 extending from the top thereof. A window 68 for viewing the coin credit or debit condition of the device is contained in a removable front cover 10 which is suitably secured in place by a lock 1 i. A conduit for accommodating the required electrical circuit connections is represented at 12.

In accordance with the provisions of the patent statutes, I have describedthe principle of operation of my invention together with the apparatus which I now consider to represent the best embodiment thereof but I desire to have it under stood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A time switch comprising a switch, a reversely movable member for opening and closing said switch, said member having a number of stationary positions where said switch is open, a number of stationary positions where said switch is closed, and an intermediate range of movement where the switch is caused to move from an open to a closed position or vice versa depending upon the direction of movement of said member, a device for moving said member from one stationary position to the next in a switch-closing direction, and a time-controlled device for moving said member from one position to the next in a switchopening direction at predetermined spaced intervals of time.

2. A time switch comprising a switch, a reversely movable member for opening and closing said switch, said member having a plurality of stationary positions overits range of movement, in

some of which positions the switch is retained closed, in some of which positions said switch is retained open, there being an intermediate range of movement between said two sets of switch-retaining positions where said switch is caused to open or close depending upon the direction of movement of said member, actuating means for moving said member from one position to the next in a switch-closing direction, time-controlled means for moving said member from one position to the next in a switch-opening direction at predetermined intervals of time, and means for adjusting the relative number of switch-retaining positions of said member on opposite sides of its switch-operating range of movement.

3. A time switch comprising, a switch, a reversable movable member for opening and closing said switch, said member having a plurality of stationary positions over its range of movement, some where said switch is open, others where said switch is closed, and an intermediate range of movement where the switch is caused to move from closed to open position and vice versa depending on the direction of movement of said member, an actuating device for progressively moving said member between diiferent consecutive positions in a switch-closing direction, a timecontrolled device for progressively and quickly moving said member between its difierent consecutive positions in a switch-opening direction at predetermined time intervals, and means operated in response to the movement of said member for indicating the condition of said switch and the position of said member in terms of the number of progressive movements required to return it to said intermediate switch-operating range of movement.

4. A time switch comprising, a service switch, a movable member for opening and closing said switch, said member being movable in opposite directions in a series of equal steps over a range of movement including an intermediate step where the switch is moved from open to closed position or vice versa depending on the direction of movement of said member, actuating means for moving said member in a switch-closing direction one step at a time, and time-controlled means for moving said member in the opposite direction in steps at predetermined spaced intervals of time.

5. A time switch comprising, a service switch, a movable member for opening and closing said switch, said member being movable in opposite directions by a series of equal steps over a range of movement which includes an intermediate step where the switch is moved from open to closed position and vice versa depending upon the direction of movement, actuating means for moving said member in a switch-closing direction one step at a time, a timing device for moving said member in a switch-opening direction in steps at predetermined spaced intervals of time, and means moved by said member for indicating the number of switch-closing steps required at any given time in order to close said service switch when it is open and to further indicate the number of time-controlled steps required to open said service switch when it is closed.

6. A time switch comprising, a service switch, a differential, the central member of which includes a cam member for opening and closing said switch as the cam is turned in opposite directions, actuating means which when actuated drives one side of said differential in steps, a time-controlled device for intermittently driving the other side of said difierential, said two drives serving to turn said cam in switch-closing and switch-opening directions, respectively, in response to the actuation of said means and the operation of said time-controlled device, said cam having a multiple step range of movement where the switch remains closed and a multiple step range of movement where the switch remains open on opposite sides of the switch-operating position'thereof, and indicating means driven from the central member of said differential for indicating the number of steps required to open or close said switch.

7. A time switch comprising, a service switch, a cam for opening and closing said switch when moved in opposite directions and having a range of movement in one direction from its switchoperating position where the switch remains closed and a range of movement in the opposite direction from its switch-operating position where the switch remains open, a difierential for operating said cam, manually operated and timecontrolled devices for driving the opposite sides of said difierential, the manually operated device serving to drive said cam in a switch-closing direction in equal steps, each step corresponding to a fraction of the range of movement of said cam, and said time-controlled device serving to drive said cam in a switch-opening direction in similar steps at predetermined intervals of time, means preventing the movement of said cam beyond its range of movements, and means for indicating the position of said cam with respect to its switch-operating position in terms of the number of steps required to close or open said switch as the case may be.

8. A time switch comprising, a service switch, a cam for opening and closing said switch by movement of the cam in opposite directions, said cam having a range of movement beyond the switch-closing position with the switch closed and a range of movement beyond the switch-opening position with the switch open, means for adjusting the relative magnitudes of said ranges of movement, a differential for moving said cam through its switch-operating position and said ranges of movement, a manual actuating device and a time-controlled actuating device for respectively driving the two sides of said differential, said manual actuating device serving to move the cam in a switch-closing direction in steps, each step corresponding to a fractional part of the range oi movement of the cam, and said timecontrolled device serving to move the cam in a switch-opening direction in similar steps at predetermined intervals of time.

9. A time switch comprising, a service switch biased to open position, a differential, a member operated from the central member of said differential for forcing the opening and allowing the closing of said switch in response to opposite amaass directions of movement of said member, a stepby-step device for driving one side of said differ-- ential in a switch-closing direction, a manuallyactuated ratchet for operating said ratchet wheel, timing means for driving the opposite side of said diiferential in a switch-opening direction, and means for blocking the movement of said switchoperating member when it reaches the limit of its movement in a switch-opening direction, whereby further operation of said timing means on said differential causes said ratchet wheel to be driven therethrough by the timing means in the same direction in which said ratchet wheel is rotated by the manually actuated means and whereby damage to said device due to this condition is prevented.

JULIAN H. STARK.

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