US2231603A - General purpose time switch - Google Patents

Description

Feb. 1941- G. w. SPREN GER GENERAL PURPOSE TIME SWITCH Filed'llarch 29, 1940 3 Sheets-Sheet 1 NF THIOOIR Inventor George W. Sprer cger;

His Attorney Feb. 11,- 1941. w SPRENGER 2,231,603

GENERAL PURPOSE TIME SWITCH Filed March 29, 1940 3 Sheets-Sheet 2 \d Inventor:

H W. Sprenger;

His Att orney.

1941- e.'w. SPRENGER 2, ,6

GENERAL PURPOSE mm wncr:

Filed larch 29, 1940 3 Sheets-Sheet 3 Inventor Geore W. SpI-erg His Attorney.

Patented Feb. 11, 1941 UNITED STATES PATENT OFFICE GENERAL PURPOSE TIME SWITCH George W. Sprenger, Lynn, Mass, assignor to General Electric Company, a corporation of New York Application March 29,1940, Serial No. 326.698

'lClaims.

My invention relates to time switches of the type intended to open and close electric circuits at predetermined adjustable times of day, and its object is to provide a relatively small switch of sturdy, simple construction which will be reliable in operation and reasonable in cost and adapted for various uses. An important feature of my invention pertains to an improved trigger operating mechanism for such switches.

The features of my invention which are believed tobe novel and patentable will be pointed out in theclaims appended hereto. For a better understanding of my invention reference is made in the following description to the accompanying drawings in which Fig. 1 shows a front, perspective view of my improved switch as enclosed in a casing with the casing door open; Fig. 2 shows a perspective exploded view of the triggeroperating mechanism of the switch in a simple form for oscillating a switch-operating cam between two positions; Fig. 3 shows a perspective, rear view of the operating cam of such switch; Fig. 4 shows a portion of a modified form of trigger-operating mechanism designed to accomplish the same purpose as the mechanism of Fig. 2, and in addition, to provide an intermediate switch-operating position of the cam; Figs. 5, 6 and '7 are explanatory of the operating mechanism of Fig. 4 in different operating positions; and Figs. 8, 9 and 10 represent contact arrangements for obtaining different switching sequences.

Referring to Fig. 2, the time switch is driven by a suitable timing motor l which may be a small, self-starting synchronous motor unit having a relative slow speed terminal pinion Ii. Pinion II is connected through gears l2, l3 and H to a one-way clutch, a portion of which comprises the gear H. The other portion of this clutch comprisesthe disk having forwardly bent, resilient clutch fingers I6, which fingers engage with the slots IS in gear H to form a clockwise driving connection between gear I4 and disk l5. It is to be understood that Fig. 2 is an exploded view to show all of the parts but that in practice disk 15 lies close to the rear side of gear ll so that when gear H is driven clockwise by the motor, disk i5 is driven thereby, due to the clutching engagement. Disk I5 is secured on a 0 shaft IT with a pinion l8 forming a continuation of the gear train which includes gears I9, 20 and 2i. In the form of the switch here represented, gear 2| is fastened to a hollow shaft 22 carrying a time-graduated dial 23 on its forward end. The gear relation is such that the dial 2! is driven in a clockwise direction one revolution in 24 hours and hence its graduations are those of a 24-hour time dial with a. m. and p. m. divisions, as represented. The purpose of the clutch is to permit the manual clockwise advance of dial 23 for time setting purposes. Time is indicated on dial 23 by a stationary pointer 24. The gear relation between shaft l1 and dial 2! is such that shaft H has a normal rate of one revolution per hour, and for good accuracy in setting and time reading, shaft il carries a dial 25 graduated in minutes and cooperating with a stationary reading pointer 26, both visible above dial 23, as shown in Fig. 1. The forward end of the shaft 21 on which gears l9 and" are secured is provided with a knurled surface and with a screw driver slot so that the time dials may be quickly set by turning shaft 21 by the thumb and finger, or, more accurately, by a screw driver. During such time-setting adjustments disk i5 is turned in a clockwise direction and hence the teeth It in disk [5 slip by the notches in gear H as in a ratchet device. By suitable staggering of the spacing between the ratchet teeth in disk l6 and the ratchet slots in gear H, the clock drive immediately takes up the forward drive through the clutch following a setting operation without lost motion. and hence without losing the benefit of accurate time setting.-

The dial 23 carries two or more riders 28 and 29 which are adjustable about the dial and secured in place opposite the times when certain switching operations are to be performed. Thus, in Fig. 2, rider 28 is an off rider and is secured to dial 23 opposite the 5 p. m. time-graduation thereon and hence is intended to perform an "01? switching operation at 5 p. m. Rider 29 is an on rider and is set to perform an "on" switching operation at '7 'a. m. Rider 28 has a cam surface which projects forward of dial 23 so as to engage operating lever 30 when opposite the time-indicating pointer 24 and move lever 30 downward. Rider 29 has a cam surface projecting rearwardly so as to engage operating lever 3i when opposite the pointer 24 and move lever 3| downward as the rider passes this point. As will more clearly appear later in the description, when lever ii is moved downward by rider contacts such as the pairs of switch contacts 33 and 34 arranged adjacent the cam 32. These connections include a power storage and release trigger mechanism for obtaining snap actions.

More specifically, lever is secured to the forward end of a collar shaft 35 pivoted on a stationary post 38 and has secured to it at the rear end of collar 35 a part 31 having a downward extending arm 31a to engage with a spring 38, an upward extending hooked finger 31b engaging in a slotted part 4| 2), and a rearwardly extending finger 37c for operating on the cam 32. The parts 30, 35 and 37 are rigidly secured together and operate as a trigger unit. Lever 3| is secured to the forward end of a collar 39 pivoted on a stationary post 40. The axes of rotation of the two triggers are parallel. To the rear end of collar 39 is secured a part 41 much like the part 31. Part M has a downward extending arm 41a engaging the other end of spring 33. It is seen that the spring is a tension spring tensioned by the opposing pull of the arms 37a and 4|a which urges the two triggers to rotate in opposite direc-- tions. Part 4| has a rearwardly extending arm Me for operating on cam 32, and the upwardly extending slotted arm 4|b into which the arm 31b is hooked. This latter connection is a triggering connection which restrains the tendency of the two triggers to rotate in opposite directions under the urge of spring 38. Parts 3!, 39 and 4t are secured together and operate as a trigger unit about post as a pivot. It will be noted that the arms 37c and He can strike upwardly on the lower edges of a horizontally extending projection 42 on cam 32 on opposite sides of the pivot point 43 of the cam. The elongated slot in part 41b has a step lid over which the hook 3122 must pass in moving from one end of the slot to the other in the cooperative operation of these parts.

The parts'just described, namely the parts 31 and 4! and their attachments, constitute a double trigger mechanism and perform in many respects like a toggle. Cocking of one trigger releases the other to give the switch cam 32 a sharp blow and vice versa for oscillating the cam 32 in opposite directions by strong snap actions through the angle between approximately the lines designated On and "Off drawn through the pivot 43 of cam 32 and indicating approximately the directions of the longitudinal axis of the cam 32 in its two extreme positions. This may be an angle of about 30 degrees. I

The cam 32 is made of a hard insulating material and its rear face has beveled surfaces on both upper and lower edges as shown in the rear perspective view Fig. 3. Positioned adjacent its beveled edges is one or more resilient switch contact members such as the members 44 and 45. These members are secured at their lower ends, as indicated in Fig. 2, to the rear face of the insulating terminal block 46 shown in Fig. 1 and have their upper ends positioned to be moved .to the rear by the cam action of the beveled edge of cam 32 when the cam is moved from the "on to the off position. Contact members 44 and cooperate with other relatively stationary contact members 41 and 48 also secured in the terminal block 46 (Fig. 1) spaced to the front of contacts 44 and 45 and suitably insulated therefrom. In the on position of the cam 32 contact members 44 and 45 are allowed to flex forward such that the pairs of contacts at 33 and 34 on the two sets of contact members are closed. In the off" position of the cam 32, which is the position shown in Fig. 2, members 44 and 43 are sprung to the rear slightly by the wedging action of the cam to open the contacts. In this wedging action the upper tip of the inner contact member 44 is positioned to ride over the rise indicated at 49, Fig. 3, while the tip of the outer contact member 45 will ride over that part of the rise indicated at 50.

In the on position of the cam the upper tip of contact member 44 will be opposite the low part it of the cam which helps in preventing any misalignment. The significance of the shape and disposition of the cam surfaces 49 and 50 with respect to the contact members will be further discussed in connection with the modification 1 shown in Figs. 4 to '7. It will be noted that there are four such wedging cam surfaces on cam 32 and hence the number and disposition of the sets of contacts may be varied as desired. The lines a, b, c, d, e, and f in Fig. 2 indicate approximately the various positions in which other sets of cont-act members may be placed to be operated by the oscillation of cam 32. Thus from 1 to 8 sets of contacts may be operated and certain contacts may be opened when others are closed. Thus contacts placed at e,--f, c and d would be opened when the contacts fully shown are closed. Thus a wide variety of switching arrangements are available and when less than 8 sets of contacts are required, those present may be positioned where it is most convenient from the standpoint of compact assembly and accessibility for wiring purposes. In general it is most convenient to arrange the contacts below the cam since, as shown in Fig. 1, the terminals thereof are then easily accessible and convenient to wiring entrance knockouts in the lower part of the case 51. In Fig. l the terminal block 46 is stepped. Lower back terminal 52 connects with contact member 45 while the forward upper terminal 53 connects with contact member 48. Similarly, terminals 54 and 55 connect with contact members 44 and 41, respectively. This stepped arrangement of the terminal block or blocks facilitates easy attachment and proper separation of the wiring. The dotted-line circles such as represented at 56 indicate knock-outs for the entrance of circuit wiring.

Having thus described the main structural features, I desire now more fully to describe the operation of the double trigger mechanism. For convenience I may call the parts comprising lever 30, shaft 35, parts 31, 31a, 31b, and 310, which operate as a unit, the "01! trigger because when moved by the oif" rider 28, the switches as assembled in Fig 2 are actuated to the open or off position. Parts 3|, 39, 4|, Ha, HI), and He will be referred to as the "on trigger since when moved by the on" rider 28 the switch is actuated to the closed or "on position.

In the position of the parts shown in Fig. 2 the switch cam 32 is in the off position, the off trigger is at the extreme operating position in the counterclockwise direction, the on" trigger is in the extreme clockwise operating position, spring 38 is under tension and the arms 31c and He are in contact with the under side of the hub extensions at 42 of cam 32, thus maintaining cam 32 in the position shown. This is a stable condition of the trigger parts which will not be disturbed by jarring or vibration but requires an operating force for any change in the relative position of the parts. Assuming the timing motor is running and the time of the clock set properly, the next automatic action will occur when the on rider 28 rides over the sloping upper surface of lever 8i and moves it downward at 7 a. m. Movement of lever 8i downward results in what may be termed a cocking of the "on" trigger, and a release of the "oi!" trigger together with a resulting snap action movement of the cam 82 to the o position. More specifically, the downward movement of lever it first increases the tension of spring 88, moves member lic away from the lower left surface of hub projection l2 and rotates member lib with its stepped slot clockwise until hook 87b clears the step at lid at which time the "011'? trigger snaps around in a clockwise direction until the hook 31b strikes the upper end of the slot in lib. This movement of the 011" trigger is powered by the energy stored in spring 88, and results in driving cam 82 counter-clockwise to the "on"- position where it is stopped by arm lie in its cocked position, since the on" trigger has now arrived at approximately its full oocked'position as rider 29 clears and passes by lever Ii.

This is another stable position of the parts and they remain in such position until a subsequent forced operation. The switch contacts 83 and 8l are now closed. The "01! rider next approaches lever 30; the upper cam surface of which has been raised to lie in the path of rider 28 when the off" trigger was released. Shortly before 5 p. m. rider 28 starts forcing lever 88 downward and cocks the "of!" trigger by rotating it counter-clockwise. Spring 88 is tensioned, arm 31c is retracted from contacting position with the under right side of hub l2 and at 5 p. m. hook 31b rides downward over the step lid in the slot of member lib. This results in a sudden release of the on trigger, arm lie of which drives cam 82 clockwise to the "of!" position.- At the same time lever Si is again raised into the path of rider 29 and rider 28 now clears and passes by lever 38. This completes the recurring cycle of operation which is repeated automatically in accordance with the time setting of riders 28 and 29. The switch contacts are opened and closed quickly and positively due to the quick movement of the cam 32. The mechanism may be operated manually at any time when the riders 28 and 29 are out of the way, and for this purpose the cam 32 may have a handle extension such as shown at 58 which may extend through a slot 59 in the supporting plate or housing, as shown in Fig. 1, so as to be easily accessible for manual operation. It will be evident that the trigger mechanism may be operated just as well by pressure applied through the arms 310 or lic by such manual operation of cam 32 as by pressure applied on levers or ii. Any desired number of "on" and "off riders may be used on dial 23 to repeat the "on" and off" switch operations several times in twenty-four hours, should that bedesirable. A suitable indicator or indicators to indicate the on" or off" position of the parts may be provided. Thus the position of handle 58 may serve this purpose as represented in Fig. l. A pointer 88 fixed on post 88 may indicate the on" and oiI" positions marked on lever 30 as represented. Preferably such indication and the time dial are observable through a window 8i in the cover 62 of the time switch casing when the door is closed.

It will be noted that the slot in part lib is closed and is of such dimensions as to suitably limit either trigger from rotating beyond a predetermined amount in either direction and hence the trigger parts are prevented from getting out of operative relation. The details of this may be varied without departing-from the invention. For example, it is obvious that the slot might be in the "of!" trigger and the hook in the on" trigger. The trigger parts are shown much longer in their axial direction in this exploded view than is necessary or desirable in practice.

In case a day omitting type of switch is desired, the lever 80 may be provided with the extension 88 to cooperate with a pin M in a seventoothed wheel 85. Wheel 88 is mounted to rotate on a pivot that may be secured in the forward end of post lil. Its teeth extend into the path of movement of the off rider 28 or a special rider provided for omitting purposes. As shown in Fig. 1, the seven teeth of gear wheel are marked for the days of the week, and the wheel is arranged to be rotated the distance of one tooth each day by a rider and hence makes a complete revolution in a week but stands still most of the 24 hours of each day. If pins 64 are placed in the teeth of the wheel for those days when it is desired to omit the switching on" operation and such pins are rotated opposite the upper surface of lever extension 63 which is on the off" lever, such pins will hold the lever down and the of! trigger in the cooked position and prevent it from operating on such days when the on trigger is cocked. Cocking of the on" trigger when the off trigger is thus held in the cooked position simply means that the "on" trigger will return to the uncocked position when the on" rider 29 passes by lever 3i. No on switching operation will occur until the pin iil has passed beyond the holding position with respect to extension 63. An astronomical time variation of the riders may be provided if desired, as described in United States Letters Patent No. 1,891,946, December 27, 1932, without modifying the trigger mechanism.

In Fig. 4 I have shown a modified-form of trigger mechanism to be used when more complicated switching operations are to be performed. In this form the switch cam 32 has the extreme "on and oil positions explained above and in addition has an intermediate position for effecting additional special switching sequences. For example, it may operate a pair of contact devices as in Fig. 2, both of which areopen in the "01?! position and one of which is open and the other closed in the additional intermediate position. Moreover, the arrangement is such that two switches may be closed at one time and opened at different times by the same mechanism. To bring this about, the trigger having the slot is made in two relatively movable parts to provide a second step in the slot which is effective in one direction of operation only.

Referring now to Fig. 4, the off trigger 31 is the same as in Fig. 2, except that the hook 31b thereon is shown somewhat longer for illustration purposes only. The slotted trigger is made in two parts 66b and 61. The part 61 is secured directly to the sleeve 39 which is rotated by the on rider as in Fig. 2. It has the rearwardly extending arm 81c for operating on cam 32 and it has the arm G'ia for hooking to the spring 38. In Fig. 4 the spring hooks 31a and 61a appear out of alignment but this is dueto the exploded perspective illustration and in practice they will be substantially opposite each other as the corresponding parts are in Fig. 2, and as indicated in Fig. 5. The part 61 has an upwardly extending hook-shaped finger 61d which at times performs the function of the intermediate step, reference to which has been made above. Part "b carries the slot having the step 66d therein and through which the hook 31b extends. Part 36b is free to rotate on sleeve 39 but is restrained from extended rotation thereon by reason of having a lug 56c engaging loosely in an opening 31a in part 6'! which is fast on sleeve 39. In practice parts 661) and 6! lie close together. The dial 23 has an additional short on rider 88 thereon and the switch cam block 32 is reversed end for end as compared to Fig. 2.

It will be noted that the two sides of the cam block 32 are not exactly symmetrical. The inner cam surfaces 49 on the top of the block as shown in Fig. are a greater distance apart than are the corresponding cam surfaces 49 at the bottom of the block.

The reason for this is that the cam surfaces 49 are positioned to favor best operation for the two-position operation explained in connection with Fig. 2, while the cam surfaces 49' are positioned to favor best operation for the threeposition operation mechanism of Fig. 4. This point will be clearer after Figs. 5, 6 and 7 have been explained. When the contacts are placed below the block 32 as shown in all figures the block 32 will preferably be positioned as in Fig. 2 when the trigger mechanism there shown is used and it will be turned over to bring the surfaces 45' opposite the contacts when the trigger mechanism of Fig. 4 is used.

The operation of the trigger mechanism of Fig. 4 will now be explained in connection with Figs. 5, 6 and 7 which are diagrammatic representations of the parts in difierent positions. Starting with the position of the parts represented in Fig. 5, it is noted that the on rider 29 of dial 23 has pushed lever 3| down. leaving the trigger mechanism in the position shown and the switch cam 32 in the full on position. At this time part 61 is held in the position shown, by reason of the hook 31b restraining finger 61d against the tension of spring 38. Part 66b is not under restraint. The next operation occurs when short off" rider 68 moves lever 30 about halfway down producing the condition represented in Fig. 6. Here it is seen that hook 31b has been lowered to release finger 61d and the latter has rotated counter-clockwise under action of spring 33 until stopped by the tongue 86a of part 66b, engaging the lower edge of slot 81s in part 61. Part 66b is now restrained because finger 3Tb now engages the upper stepped surface of its slot. This action has also resulted in first lowering of finger 31c and the snapping upward of finger 610 to move the switch cam 32 to the intermediate position shown in Fig. 6. It is seen that the high cam surface of block 32 has moved under the tip of contact finger 44 and hence its contacts have opened but the contacts controlled by contact finger 45 remain closed.

At some later time, depending upon the setting of the long ofi rider 28, the latter will move lever 30 all theway down to produce the conditions represented in Fig. 7. Here hook 31b has dropped over the step Bid in the slotted member 68b and the parts have arrived at the full oil position. Part 61 is still restrained by the tongue 66c engaging the lower edge of slot Sle but both parts of the "on trigger have rotated further counter-clockwise by the amount determined by the height of step 86d. Cam member 32 has thus been rotated with a snap action to the full off position represented, this occurring when hook 31b dropped over the step d. Switch contact member ll has now also been flexed to the rear and hence its contacts are now open. In the meantime lever 3! has been raised in two steps into the path of "on" rider 23.

When rider 23 next moves lever 3| down, the parts return to the condition represented in Fig. 5 in one motion. That is. there is no intermediate step in the on operation. In arriving at the conditionrepresented in Fig. 5, part 81 is first rotated clockwise alone but when the upper surface of its slot Ole engages the upper surface of tongue Ne, part "b is carried along and when finger 31b rides upward over step 36d finger Old is retracted out 01' the way so that hook 31b rides directly to the upper end of the slot in part 66!). Thus both switches operated by members l4 and 43 are closed at the same time, determined by the setting of rider 29 but are opened at difierent times selected by the positions of riders 68 and 28.

It will now be seen that a wide variety of circuit control operations can be performed by the form or the invention represented in Fig. 4 by simply repositioning the contacts used or by changing the circuit connections to different contacts and some of these will now be mentioned.

Fig. 5 shows one arrangement of the contacts for controlling two circuits which I shall designate circuits I and II. Figs. 8, 9 and represent other positions of the contacts which may be used for controlling circuits I and II. In Figs. 8, 9 and 10 the switch cam is represented in the intermediate position only but the switch conditions for the other positions can readily be visualized. For convenience I shall call the three positions of the cam 32 shown in Figs. 5, 6 and 7 as cam positions Nos. 5, 6 and 7, respectively. Then, the switching schedule for the circuits I and H for the different contact arrangements and cam positions will be according to the table given below.

It will be seen that in Fig. 5 those contacts placed to the lower right of the center of the cam block 32 are opened at different times and closed at the same time while those placed to the lower left of the center, as in Fig. 8, are closed at diil'erent times but opened at the same time. Further changing of the contacts and the connecting oi difl'erent switches in series will produce additional varieties of switching schedules, but it is believed that enough examples have been given to illustrate the possibilities in this respect.

Cam positions It will be seen that to change from the form of switch shown in Fig. 2 to that shown in Fig. 4, I merely replace the "on" trigger 4| with the two part trigger Gib-8T of Fig. 4, add the rider 68 and reverse the cam 32. Also I wish to point out that it is not essential that the cam 32 be assembled as in Fig. 2, for the successful operation of that switch since it has been shown that the switch conditions are the same in the two extreme positions of the cam 32 for both Figs. 2

memosand 4, although the cam 32 is reversed in these ngures. However, the cam surfaces used in Fig. 2 are designed to produce simultaneous opening or simultaneous closing of both contacts. and is a refinement that is not essential for many applications.

Another variation of switching may be obtained by simply leaving of! the short rider 88, Fig. 4. In such a case the cam 82 would remain in the intermediate position for a length of time determined by the slope of the cam surface on rider 28. Still another variation of switching would result by adding an on" rider like 29 between riders 28 and 68 in Fig. 4.

In installations where this switch is likely to be subjected to severe vibration, I prefer to provide a very light whisker-like toggle spring 10 seen in Fig. 7 between the part 42 of cam block 32 and one of the switch supporting plates. The purpose of such a spring is to assure stability of the cam in either of its extreme positions during that short interval of time when the arms 61c or 310, Fig. '7, are retracted from the part 42 of the cam block 32 just prior to a switching operation. For instance, in Fig. 7 the next switching operation will be preceded by the retraction of arm 610 from the lower left edge of the part 42. Hence at such times the only thingthat holds the cam 42 from counter-clockwise rotation is friction unless a toggle spring such as 10 is provided. This spring does not otherwise enter into the operation of the device and is merely a safeguard against possible premature indefinite rotary movement of cam block 32.

What I claim as new and desire to secure by,

Letters Patent of the United States is:

1. In a time switch, a pair of trigger members mounted for limited rotation on parallel axes, a spring connected between said members and tensioned to urge relative rotation of said mem bers in opposite directions,a triggering connection between said members resisting such relative rotation 'but arranged to permit triggering action between said members such that rotation of one member in a direction to increase the tension of said spring is followed by a release of the other member and its sudden rotation by a limited amount in a direction to reduce the spring tension and vice versa, the sudden rotary move ments of the two members occurring in opposite directions, time controlled means for rotating said trigger members in opposite directions to cause such triggering actions at predetermined times and a switch operating member moved inone direction by the sudden rotation of one of said trigger members and in the opposite direction by the sudden rotation of the other trigger member.

2. In a time switch, a pair of trigger members mounted for limited rotation on parallel axes, a spring connected between said members and tensioned to urge relative-rotation of said members in opposite directions, a triggering connection between said members resisting such relative rotation but arranged to permit alternate triggering action between said members such that rotation of one member in a direction to tension said spring is followed by a release of the other member and its sudden rotation by a limited amount in a direction to reduce the spring tension and vice versa, the sudden rotary movement of the two members occurring in opposite directions in single steps of approximately equal magnitude, time controlled means for alternately rotating said trigger members in opposite directions to cause such alternate triggering actions at predetermined times, and a switch operating member moved in opposite directions by and in response to the alternate sudden rotary movement of said trigger members.

3. In a time switch, a pair of trigger members mounted for limited rotation on parallel axes, a spring connected between said members and tensioned to urge relative rotation of said members in opposite directions, a triggering connection between said members resisting such relative rotation but arranged to permit triggering action between said members suchthat rotation of one member in a direction to increase the tension of said spring is followed by a release of the other member and its sudden rotation by a limited amount in a direction to reduce the spring tension and vice versa, the sudden rotary movement of the two trigger members occurring in opposite directions; one of said trigger membersbeing made in two relativelymovable parts which operate to divide the sudden rotation of said two-part trigger member into two substantially equal steps, the sum of which is substantially equal to the sudden rotary movement of the other member in the opposite direction, time controlled means for rotating said trigger members in opposite directions to cause such triggering actions to occur at predetermined times, and a switch operating member moved in one direction in two steps by the sudden rotations of said two-part trigger member and in the opposite direction in one step by the sudden rotation of the other trigger member.

4. In a time switch, a switch-operating cam member pivoted so as to rotate back and forth between first and second extreme positions, a pair of switches positioned adjacent to said cam and operated to open and closed positions thereby, one switch being operated by movement of the cam from the first extreme position to an intermediate position and the other switch being operated by movement of the cam from such intermediate position to the second extreme position, reverse movement of said cam causing the reverse operations of said switches, and timecontrolled means for moving said cam in one direction from the first extreme position to the intermediate position, at one predetermined time, for moving said. cam in the same direction from the intermediate position to the second extreme position at another predetermined time and for moving said cam in the reverse direction from the second to the first extreme position at another predetermined time in recurring sequence, said time-controlled means including an energystoring and energy-releasing trigger mechanism to cause the movements of said cam and the operations of said switches to occur quickly at such predetermined times.

5. In a time switch, an elongated switch-operating cam pivoted near its center for oscillation between extremepositions, said cam being made of insulating material and having opposite edges thereof provided with beveled or wedglng surfaces, a plurality of switches positioned adjacent one edge of said cam so as to be operated by the wedged-shaped surfaces thereof when the cam is oscillated between its extreme positions, means wherebysaid cammay be reversed in position for the purpose of operating said switches by the opposite wedge-shaped surfaces thereof, one of said edges having its wedglng surfaces arranged to operate said switches substantially simultaneously and the other edge having its wedglng surfaces arranged to operate said switches at diflerent times in the oscillatory movement of said cam.

6. A general purpose time switch comprising a pair of switches, a cam member for operating said switches, a trigger mechanism for oscillating said cam member, a rotary time dial, three riders adjustably secured on said dial for selectively operating said trigger mechanism and a timing motor for driving said time dial, said trigger mechanism including a spring in which energy may be gradually stored and suddenly released by the operation of said trigger mechanism to cause sudden movement of said cam member at times determined by the time setting of said riders on said time dial, said cam being moved from a given position in one direction at one time, moved further in the same direction at another time and returned in the opposite direction to said given position at a third time in a recurring sequence, said pair of switches being so related to the cam that one is operated during the first cam movement of said sequence, the other is operated during the second cam movement of said sequence and both are operated in the reverse direction during the third cam movement of said sequence.

7. In a time switch, a pair of triggers mounted for limited rotation on parallel axes, a spring connecting said triggers and tensioned to urge relative rotation of said triggers in opposite directions, a hook on one trigger engaging an elongated slot on the other trigger and serving to maintain tension in said spring and to form a triggering connection between said triggers, time-controlled means for rotating the slotted trigger in a direction to increase the tension of said spring, said movement causing the hooked trigger to rotate in a direction to relieve the spring tension accompanied by movement of its hook from one end of the slot to the other, a second time controlled means for rotating the hooked trigger in a direction to increase the tension of said spring, said movement causing the slotted trigger to rotate in a direction to relieve the spring tension accompanied by a return movement of the hook inthe slot, the edge of the slot contacted by said hook having a rise or step therein over which the hook must pass in moving irom one end of the slot to the other, whereby such movements occur with a sudden snap action, and a switch closed in response to one of such snap actions and opened in response to the other snap action.

GEORGE W. SPRENGER.

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