US2253929A - Timing mechanism - Google Patents

Description

1941- 2 A. B. CAMPBELL 2,253,929

TIMING MECHANISM Filed May 27, 1938 5 Sheets-Sheet l INVENTOR.

Arthur B. Campbell AITTORNEY.

v A. B. CAMPBELL 2,253,929

TIMING MECHANISM Filed May 27, 1938 5 Sheets-Sheet 2 INVENTOR. Arthur B. Cimpball FIG. 4- I 'ATTORNEY.

Aug. 26, 1941. A. B. CAMPBELL 2,253,929

I TIMING MECHANISM Filed May 27, 1958 5 Sheets-Sheet s INVENTORV Arthur B. Campbdl ATTORNEY.

TIMING MECHANISM Filed May 27, 1938 5 Sheets- Sheet 4 INVENTOR.

Arihur- B. Campbell 'ATTORN Aug. 26, 1941. A. B. CAMPBELL TIMING MECHANISM Filed May 27, 1938 5 Shegts-Sheet 5 INVENTOR.

Arthur B. Campbdl ATTORNEY.

Patented Aug. 26, 1941 TIMmG MECHANISM Arthur B. Campbell, Thomaston, Conn., assignor to General Time Instruments Corporation, New York, N. Y., a corporation of Delaware Application May 27, 1938, Serial No. 210,363

15 Claims.

This invention relates to timing mechanisms, and more particularly to a mechanism which includes both an automatically operated electric switch and an alarm or audible signal indicating a predetermined time interval.

Certain embodiments of my invention may be used as range timers, or as a timing switch which will close and open an electric circuit at predetermined times. When used as a range oven timer, it is often desirable to have incorporated therein means for timing other kitchen operations, such as cooking on other circuits thanthe oven circuit, or for indicating a time at which the current in the oven circuit should be changed, to increase or decrease the oven heat. Provision also is made in the above embodiments of my invention for the manual operation of the timing switch at any desired time.

In previous devices of this sort, where the switch is controlled by a pivoted member which can be displaced in one direction from an intermediate position to operatively interconnect the timing mechanism to the switch, and which can be displaced inthe other direction to directly or manually operate the switch, it is not possible to manually move the pivoted control member from the first mentioned position through the intermediate position to the second mentioned position without resetting the timing mechanism. In other words if the timing mechanism has been set to operate the switch at some future time, one cannot directly or manually operate the switch. This invention overcomes such objection by enabling the operator to open or close the circuit directly at any time, regardless of the position of the control member at that time, without resetting the timer.

I have, furthermore, provided a timing switch which can be used to regulate current consuming devices, such as ranges, which are adapted to operate on polyphase current. Most ranges are wired for 230 volt heating elements, and with single phase three-wire distribution, a single pole timing switch is suflicient. However, some districts are supplied with three-phase Y-connected distribution where only 199 volts are obtainable between two wires. Since both systems deliver 115 volts from one line to neutral. range manufacturers, to standardize their production, have designed 230 volt units with a mid-point ta for neutral which can be used on either distribution system. When a mid-point tap is used, a single pole switch is not operative. I have provided a double pole switch which is phase system. An ordinary 115 volt synchronous motor can be used to control the switch, irrespective of the voltage across the lead-in wires.

An object of this invention is to provide an improved timing mechanism which combines the advantages of a time switch and an alarm.

A further object is to provide an improved construction of timing mechanism which can be readily operated and set by relatively few controls projecting from the face thereof.

Another object is to provide an improved time switch which can be directly and manually operated at any time with facility.

A still further object is to provide a compact and inexpensive timing unit which may be incorporated into an electrical apparatus to control the operation thereof.

.A further object is to provide a timing mechanism which includes an automatically operated double pole switch.

A further object is to provide a timing device which can be incorporated into a polyphase circuit for the regulation of a current consuming device.

Other objects, features and advantages of my invention will appear as the description proceeds. Reference is hereby made to the accompanying drawings illustrating a preferred embodiment of my invention in which like reference numerals indicate like parts.

Figure 1 is an elevation of one embodiment of my invention.

Figure 2 is a top plan view thereof, showing only generally the assembly of the parts.

Figure 3 is a detailed plan view of the switch and control assembly.

Figure 4 is a front elevation of the same, part of the dial being broken away.

Figure 5 is an elevation similar to Figure 4, the switch control member being in the off position.

Figure 6 is an elevation similar to Figure 4, the switch control. member being in 'the set" position.

Figure 7 is a rear elevation showing in detail the switch.

Figure 8 is a detailed top plan view of the alarm or interval timer.

Figure 9 is a rear elevation of Figure 8, part of the gong being broken away.

Figure 10 is a circuit diagram of an embodiment of my invention.

operative with a mid-point tap for use in a three- Referring now to Figures 1 and 2, it will be seen that mounted on front and rear plates l0 and II respectively are a synchronous motor, or

other source of mechanical power, l2, a switch and switch control assembly, and an interval timer with a gong I3. In addition to driving the switch control assembly and the interval timer, the synchronous motor also drives a train of clock work, not shown, which operates the hands I4 in the usual manner.

The front and rear plates are rigidly positioned with respect to each other by spacing members l5, which may be located at the corners of the plates and at suitable intermediate points.

A clock dial I6 is spaced from front plate ID by suitable means to cooperate with hands l4. A dial I1 is similarly spaced from the front plate and has two circular apertures therein in each of which is adapted to be positioned a rotating disc or dial, l8 and IS. A third aperture, 23, is provided in stationary dial I! to expose to the view of the operator indicia appearing on a rotatable dial 2| mounted between dial l1 and front plate III.

A third dial 22, the interval timing dial, is provided at the right hand portion of the unit, similarly spaced from the front plate, and adapted to co-operate with rotating hand 23.

On the rear plate II is mounted a' sheet of insulating material 24 and two insulating blocks 25 and 26 to each of which is solidly anchored a terminal post, 21 and 23, including a clip 29 and 30. Conductors leading from a source of power may be connected to the clips. To each terminal post is afiixed an elongate resilient conducting member 3| and 32 carrying a contact 33 and 34 at the remote end thereof adapted to co-operate with a similar contact 35 and 35 anchored on and spaced from the insulating block, 25 and 26, at a point remote from and insulated from the terminal post. A conducting clip 31 and 3|! is provided adjacent to and in series with stationary contact 35 and 35 to which conduc tors may be affixed leading to the electrical apparatus to be regulated, such as a range.

The insulating blocks are arran ed para lel to each other with the resilient conducting members 3| and 32 lying between the blocks. The contacts 33 and 34 are carried on the inside of the conducting members, as shown in Figure 'l, which are sprung inwardly so that the contacts are urged tightly against the stationary contacts 35 and 36 which serve to limit any inward motion of the resilient conducting members. A double acting cam 39 is rotatably positioned between the conducting members, the surface of which is so shaped that as the cam is rotated both conducting members are sprung outward y and both circuits opened simultaneously. The solid lines in Figure 7 indicate the opened circuit, while the broken lines indicate the members in closed circuit position. The cam is made of some suitable insulating material such as Bakelite."

The cam 33 is keyed to a shaft 40 which extends through insulating sheet 24 and is Journaled in the front and rear plates and terminates in a knurled knob 4|. To this shaft is affixed between the plates control member 42. A spring 43 is coiled around the camshaft, one end of which engages the control member, and the other end of which may be anchored to the rear plate by any suitable means, such as a pin, so as to urge the control member in a counter-clockwise direction as viewed in Figure 4: At the end of the control member is pivoted a finger 44, extending outwardly in the same direction as the control member and adapted to rotate about its pivot in substantially the same plane as the control member rotates. The finger has a projection 45 extending from one edge thereof and bent over to engage the side edge of the control member so as to limit the rotation of the finger in a clockwise direction as viewed in Figure 4. A spring 45 engaging another projection 41 on the finger, urges the finger to the limit of its rotation in a clockwise direction. The other end of the spring may be wrapped around the camshaft and be anchored on the control member. The finger consequently acts as a latch, allowing the control member to move in a clockwise direction beyond suitably positioned stops, but engaging such stops and limiting rotation in a counter-clockwise direction, as viewed in Figure 4.

The positionof the switch actuating cam is determined by certain stops comprising pins and rotatable shafts which limit the rotation of the control member. Pins 48, 49 and 50 are suitably mounted on the front plate I0. Pins 48 and 43 are so positioned to engage the body portion of the control member and to define the extreme limits of rotation thereof. Rotatable shafts 5| and 52 are journaled in the front and rear plates. The shafts 5| and 52 and pin 50 are positioned equidistant from the camshaft 40 and at such a distance therefrom that any one shaft or pin can engage the tip of finger 44 on the rotating control member and serve asa stop to interrupt the counter-clockwise rotation of the control member and the camshaft. That section of each shaft 5|, 52 which engages the finger in its normal plane of rotation is provided with a notched or flattened portion 53, 54 on its cylindrical surface which acts as an escapement during the rotation of the shaft and enables the shaft to release the spring tensioned control member when the notched portion comes into registry with the tip of the finger. Rotation of the control member in the reverse or clockwise direction can be effected irrespective of the position of the notches due to the latching effect of the finger at the end of the control member. The circumferential groove 55, 56 on each shaft 5|, 52 is formed adjacent the notch portion and is of sufficient depth and breadth to permit the tip of finger 44 to pass therethrough without engagement therewith when the camshaft 40 and the control member are displaced axially so that the finger of the rotating control member will rotate in the same plane in which the circumferential grooves are positioned. Pin 50 is of such a length that the axially displaced rotating control member will entirely clear the end ofpin 50 after passing through grooves 55 and 58 in the shafts 5| and 52 in its counterclockwise rotation.

The gear 51, 58 is keyed on each shaft 5|, 52 near the rear plate, and a hand 59, 60 is keyed to the shaft at the front end to indicate the position of the notch with respect to the control member. Shafts GI, 62 are journaled in the front and rear plates and carry gears 63. 64 adapted to mesh the gears 51 and 58, respectively, thereby rotating shafts 5| and 52. Each shaft is doubly grooved as at 85, either of which groove may be engaged by a V-shaped member 66 carried at the end of a spring 61 which spring in turn is anchored to the front plate. Each shaft 5|, 62 is shiftable axially to either of two positions, each position being defined by the co-operation of the V-shaped member 66 with one of said grooves. In one of said positions gears 63 and 64 mesh with gears 51 and 53, as above mentioned, so that rotation of either shaft 6|, 82 will change the position of the notch in shaft 52. In the second position of shaft 6 I, that is the position in which the shaft is drawn toward the operator, the gear 63 meshes with the clock work, not shown, so that rotation of the shaft will set the clock.

Gear 88 is driven through the clock work by synchronous motor I2 and in turn drives gear 69 which is loosely mounted on shaft 5I. A similar gear 18 loosely mounted on shaft 52 is driven by gear 89 through the intermediately positioned pinion II which is mounted on plate I8. Gears 69 and I8 are adapted to rotate shafts 5| and 52 by suitable friction means such as springs I3 and 14 in the form of spiders which bear against and are confined between suitable shoulders on shafts 5| and 52 and the sides of gears 69 and I8 respectively. Dials I8 and I9 are suitably affixed to collars I5 and 76, which collars are preferably made integrally with gears 69 and I8. It will be seen that the clock work drives the dials I8 and I9, shafts 5I, 52 and the hands 59 and 88, but the position of the hands with respect to the dials may be changed by the rotation of shafts 6| and 62 caused by manual operation of knobs I1 and I8 secured to, the ends thereof.

In the embodiment herein shown the dials are marked into twelve subdivisions, each subdivision corresponding to on hour, and rotate with the hour hand I4 although in the opposite direction. Rot'atable dial 2I is affixed to shaft 48 and has marked thereon suitable indicia to indicate the position ofv the switch actuating cam 39, such as set, on," off, and a portion of different color indicated on Figure 4 as a black portion.

With reference to Figure 1 it will be seen that a suitable pinion 88, a part of the clock work, drives the spur gear 8I which is aflixed to shaft 82 running from one end of the unit to the other and at its remote end terminating in a like spur gear 83. The gear wheel 84, Figures 8 and 9, is mounted upon an axially shiftable staff 85 and meshes with spur gear 83. Pinion 86 is also mounted on staff 85. Second wheel 81 is driven by pinion 88 and is loosely mounted on shaft 88 which carries at one end hand 23. Friction disk 89 is affixed to second wheel 81 and through a spring 98, which may be in the form of a spider having a central portion affixed to shaft 88 and arm portions engaging disk 89, frictionally drives the shaft. Shaft 88 extending beyond rear plate II terminates in cam 9|, having a slot 92 therein. Positioned between cam 9I and rear plate II is a second cam 93 loosely mounted on shaft 88. Rigidly associated with cam 93 is a pinion 94. Pin 95 is affixed to loose cam 93 and extends thru slot 92 in cam 9| defining limits of rotation of cam 93 with respect to cam 9|, beyond which limits one cam drives the other. A second pin 96 is positioned on cam 9I and a coil spring 91 connects pins 95 and 96 to bias loose cam 93 in such a position that it does not overlap the notched portion of cam 9i, as will be hereinafter explained. The pinion 94 and its associated cam 93 are driven by a gear 98 which is mounted on rear plate H.

Shaft 62 has a pinion 99 mountedthereupon (Figure 3), which when said shaft is in its forward position, that is, drawn toward the operator, will engage gear I88 which is rigidly secured to staff I8I. This staff is journaled in the front and rear plates and has aflixed thereto a pinion I82 which meshes with and drives gear 98 and cam 93.

Pin I83 is mounted on rear plate I I about which is pivoted lever I84, one end of which carries a gong hammer I85. The other end terminates in a hook I86 to which is affixed coil spring I01. The other end of spring IN is anchored to pin I88 which is positioned in the rear plate. A third L-shaped arm I89 extending from the central portion of lever I84 has at its remote end a cam surface II8, which when rotated in counter-clockwise direction from the position in which it is shown in Figure 9 will engage the end of axially shiftable staff 85 and displace the same forwardly in such a manner .as to disengage gear wheel 84 from spur gear 83. Spring III bears against the forward end of shaft 85 and tends to keep gears 84 and 83 in engagement with each other when lever I84 is in set position as shown in Figure 9.

. cam rider in the form of a pin II2 so situated thereon that it can engage cam surface II3 of cam 9|, which determines the set position of the lever. Cam surface II3 defines an arc of about 338 about the center of cam 9| the remaining portion of the periphery of the cam being notched, in which notch pin I I2 is adapted to rest when the lever I84 is in inoperative position. One edge II4 of said notch is relatively sharp; that is, when the lever I84 is in set" position and pin 2 engages cam surface II3, as shown in Figure 9, rotation of cam 9| in counterclockwise direction, by means of the clock work driving friction disk 89 which transmits rotation through spring 98 to shaft 88 and cam 9I, will bring the cam to a position wherein the pin will slip off cam surface H3 and move along edge II4 into the notch. This edge is so formed that it is substantially tangential to the are described by the pin at this stage to give a quick action to the hammer I which strikes the gong I3, supported by member II5 projecting from the rear plate. Pin II2 has a cut away portion II8 producing a sharp edge thereon which cooperates with edge I I4 to give quick action. As the gong is sounded, the movement of lever I84 into inoperative position disengages gear wheel 84 from spur 83, rendering the interval timing portion of the unit inoperative until it is again set,

As the knob I8 is withdrawn towards the operator and rotated in clockwise direction (Figure 1), loose cam 93 will be rotated in a clockwise direction (Figure 9) in opposition to the bias of spring 91, and cam surface III-of cam 93 will lift pin I I 2 out of the notched portion of cam 9 I, allowing the latter cam to rotate when pin reaches the end of the slot 92 and rotation is transmitted by the former cam to the latter. It will be seen, consequently, that lever I84 is displaced into the set position by the action of loose cam 93, and held in that position by cam 9I until the clock work drives cam 9| to that position where the lever is released. As the lever I84 is displaced cam surface H8 is disengaged from the rear end of staff 85, allowing spring III to axially displace the same and operatively interconnect the clock work with cam 9I.

The angular displacement of cam 9|, as it is driven by cam 93 from the release or inoperative position, is indicated by hand 23 on dial 22 in terms of the time interval required for the clock work to rotate cam 9I back to the release position.

Referring now to Figure 10 wherein the electrical circuit of the above described embodiment of my invention is diagrammatically illustrated, reference numerals I58 and I5I represent two power lines of a Y -connected three-wire threephase distribution system having the neutral or mid-point grounded. The potential between lines I50 and |5| is approximately 199 volts, when the potential between either line I50 or |5| and the ground is 115 volts.

The timing unit, generally indicated as T comprises resilient contact members SI and 32 actuated by cam 39, the position of which cam is controlled by a 115 volt synchronous motor, I2, in a manner more fully described above.

The current consuming device, such as a range, which is regulated by timing unit T is generally indicated as R, and comprises a heating element I55 having a mid-point connection I56 between its terminals I50 and IN.

It will be seen that the heating element is connected at its terminals I60 and |5| between power lines I50 and I5I, the contact members 3| and 32 being in series therewith so that when the contacts are closed, a circuit is established through line I50, contact 3|, conductor I53, heating element I55, conductor I54, contact 32, and line I5I. The mid-point I56 is connected to ground I59 through conductor |5l so that the voltage drop will be 115 volts in each half of heating ele ment I55, thereby permitting the use of a standard 230 volt element rather than a 199 volt element.

The synchronous motor I2 is connected between line I5I and ground I59 by conductors I52 and I58, thereby permitting the use of a standard 115 volt motor.

It is only by the use of a two pole switch that control of a heating element so connected may be obtained, but if preferred, the two contacts rather than being in series with the two power lines, respectively, could be in series with one power line and the ground wire, respectively.

Regarding the operation it will be seen that a source of power can be connected to the clips 23 and 30, and conductors may be connected to clips 31 and 38 leading to the oven heating element. A conductor I52 L provided leading from one of the terminal posts to the clock motor. The other conductor leading from the clock motor may either be grounded or connected to the neutral wire.

The position of the switch is indicated by the indicia appearing on dial 2|, in which the words set and oil" indicate an open circuit and in which the word on and the colored portion, when it appears to the operators view through aperture 20, indicate a closed circuit.

The angular displacement of shafts 5| and 52 from the position in which the notches 53 and 54 will release the control member is indicated by hands 59 and 60 and dials I8 and I9 respectively in terms of the hour or fraction thereof at which the clock work will have rotated the respective shaft to a position at which the spring propelled control member will be released to actuate the switch.

After the device has been connected in circuit as above indicated and the clock set to the correct time in the usual fashion, let it be assumed that it is three o'clock and the operator desires to set the timing device so that it will turn the range on at five oclock and turn it of! at seven. It will be noted that dial I8 is indicated as the 0115" dial and dial I9 is indicated as the on" dial. By pushing in knob 10 and rotating it the hand 60 may be set at five o'clock, and by pushing in and rotating the knob 11 the hand 59 may be set at seven o'clock. The knob 4| is then rotated in a clockwise position until -tated to such an extent to allow resilient conductors 3| and 32 to spring against the contacts 35 and 35 and close the circuit. The switch control mechanism at this stage is illustrated in Figure 4 in which it will be seen that shaft 52 has rotated just suillciently to release the control member, which is now engaged by shaft 5|. At seven oclock shaft 5| will have rotated sutflciently to release the control member which will then be rotated further in a counter-clockwise direction until it engages stop 50. This stage is shown in Figure 5 and at this point the word of! is exposed to the operator's view on the dial 2|. This further rotation will have rotated the cam 38 to the open circuit position as illustrated in Figure '7.

At this stage if it is desired to manually turn on the oven, knob 4| may be pushed in which will allow the control member to clear the end .0! stop 50 and spring to the manual position or position wherein the colored portion of dial 2| is exposed to the operator. 1!, however, at three o'clock just as the apparatus had been set as above described and the operator desired to use the oven for a short period without resetting the hands I0 and I5, the knob 4| may be pushed in which will displace the control member from its normal plane 01 rotation and allow the spring to propel it to the manual position, the finger 44 passing through the circumferential grooves 53 and 50 without being engaged by the shafts 5| and 52. If desired, the interval during which the oven is to be used may be timed by the interval timer.

II it is desired to measure an interval, say fliteen minutes, knob 10 is drawn toward the operator and rotated in a clockwise direction until hand 23 points to the desired interval. As the knob is rotated lever I04 is displaced to the set position allowing spring I to force the gear wheel 84 into engagement with spur 83, thereby connecting the clock work with the interval timer.

At the end 01' the desired interval the cam 9| will release the lever I04 which will snap back quickly into inoperative position striking the gong I3 as it does so. This indicates expiration of the desired interval and the oven can be shut oil at this time by rotating knob 4| to the 0113" position. If desired the timing mechanism may be reset to the position where it will turn on automatically at five and turn of! at seven by merely rotating knob 4| to the set position.

If desired, of course, a spring-driven clock work with the usual escapement may be substituted for the synchronous motor which drives this timing device. Also this mechanism may be constructed with a one pole switch rather than i a two pole switch in instances where single phase current is used in the apparatus to be regulated.

Although I have described but one embodiment of my invention, it will be understood that various modifications and changes in the above construction may be effected without departing from the spirit of my invention. Consequently this invention is to be limited not by the above description but only by the following claims.

I claim:

1. In a combination time switch and interval timer, the combination with timing mechanism, of a cam for actuating said switch, a control member for controlling the motion of said cam, stop means associated with said timing mechanism and adapted to engage said control member and to release the same at a predetermined time, rotatable means in said interval timer, means operative upon rotation thereof for operatively connecting said interval timer with said timing mechanism, an axially displaceable shaft capable of assuming two positions, and means on said axially displaceable shaft for engaging said stop means to set the same when said shaft is in one of said positions and for engaging said rotatable means to connect said interval timer with said timing mechanism and to set the same when said shaft is in the other of said positions.

2. In a combination time switch and interval timer, the combination with timing mechanism, of a cam for actuating said switch, a control member for controlling the motion of said cam, a rotatable shaft adapted to engage and to release said control member, rotatable means in said interval timer, means operative upon rotation thereof for operatively connecting said interval timer with said timing mechanism, an axially displaceable shaft capable of assuming either of two positions, means controlled by said axially displaceable shaft in one 'position thereof for rotating said rotatable shaft, and means controlled by said axially displaceable shaft in the other position thereof for engaging said rotatable means to operatively connect said interval timer with said timing mechanism.

3. In a timing unit including time indicating means, a time switch, and an interval timer, the

combination with timing mechanism, of a con-j trol member for controlling said switch, two stop means adapted to engage said control member and assoc ated with said timing mechanism to release said control member at predetermined times, an axially displaceable setting shaft adapted to assume either of two positions, means controlled by said axially displaceable shaft when in one of said positions for setting the time of release of one ,of said stop means, means controlled by said shaft when in the other of said positions for setting said interval timer and operatively connecting same with said timing mechanism, a second axially displaceable shaft adapted to assume either of two positions, means controlled by said second axially displaceable shaft when in one of said positions for setting the time of release of the other of said stop means, and means controlled by said shaft when in the other of said positions for setting said timing indicating means.

4. In a timing unit including time indicating means, a time switch and an interval timer, the combination with timing mechanism of a cam for actuating said time switch, a control member for controlling the motion of said cam, two rotatable shafts adapted to engage and release said control member, a rotatable means in said interval timer, means operative upon rotation thereof for operatively connecting said interval timer with said timing mechanism, an axially displaceable shaft having a gear thereon and adapted to assume either of two positions, in one of which positions said gear engages one of said rotatable shafts to rotate the same and in the other of said positions engages said rotatable means, and a second axially displaceable shaft having a gear thereon and adapted to assume either of two positions, in one of which positions said gear engages the other said rotatable shaft and in the other of said positions engages said time indicating means.

5. A timing unit including timing mechanism, time indicating means driven thereby, two stop members actuated thereby, an interval timer driven thereby, a spring actuated switch, a r0- tatable control member associated with said switch and adapted to engage said stop members,

means whereby said stop member may release said control member at predetermined times, a first axially displaceable means for setting one of said stop members when said displaceable means is in normal position, and for setting said time indicating means when said displaceable means is in displaced position, a second axially displaceable means for setting the other of said stop members when said second displaceable means is in normal position, and for setting said interval timer when said second displaceable means is in displaced position, and means in said interval timer to operatively connect said interval timer with said timing mechanism upon operation of said second displaceable means in its displaced position.

6. A timing unit including timing mechanism, a time indicating means frictionally driven thereby, two rotatable shafts frictionally driven thereby, an interval timer adapted to be frictionally driven thereby but normally disengaged therefrom, a spring actuated switch, a rotatable control member associated with said switch and in the rotation thereof adapted to engage said rotatable shafts, means associated with said rotatable shafts for releasing said control member, an axially displaceable means for rotating one of said shafts when said displaceable means is in normal position, and for positively driving said t me indicating means when said displaceable means is in displaced position, a second axially displaceable means for rotating the other of said rotatable shafts when said second displaceable means is in normal position, and for positively driving said interval timer when said second displaceable means is in displaced position, and means in said interval timer to operatively connect said interval timer with said timing mechanism upon rotation of said second displaceable means in displaced position.

7. In a time switch, timing mechanism, a spring biased rotatable switch cam, a control member to determine the position of said switch a cam, stop means to interrupt the rotation of said control means, means associated with said timing mechanism whereby said stop means may release said control member for rotation, and manually operative means to disengage said control means from said stop means.

8. In a time switch, timing mechanism, a spring biased rotatable switch, a control member for said switch adapted for rotation in either of two planes, rotatable means to interrupt said control member in its normal plane of operation and adapted to be rotated by said timing mechanism into a position wherein said control means will be.released for further rotation, and means to move said control member into said second plane to effect release between said control member andsaid rotatable means.

9. In a time switch, the combination of timing mechanism, a switch, a spring biased control member for governing the Position of said switch, said control member being adapted for motion in either of two planes, stop means to interrupt said control member in its normal plane of motion to define set," on," off," and "manual" positions thereof, said stop means which define said "set" and said "on positions being associated with said timing mechanism to release said control member for further motion at predetermined times, and means to displace said control member into said second plane to effect release between said control member and said stop means which define said "set," on, and "off positions, whereby said switch may be operated manually at any time. A

10. A timing mechanism comprising a frame, a clock motor and a clock train supported thereby, a two pole switch, a switch actuating cam, a rotatable member associated with said cam to control the rotation thereof, a stationary member and two rotatable shafts adapted to engage said rotatable member to define the position thereof, a spring biasing said rotatable member and urging said rotatable member into engagement with said stationary member and said rotatable shafts, a notch in each of said shafts permitting release of said spring biased rotatable member in its normal plane of rotation, and an annular groove in each of said two shafts adjacent to said notch permitting rotation of said member in the plane displaced from said normal plane of rotation, said stationary member being of a length to engage said rotatable member only in its normal plane of rotation.

11. A timing mechanism comprising a frame, a clock motor and a clock train supported thereby, a two pole switch, a switch actuating cam, a rotatable member associated with said cam to control the rotation thereof, two stationary members adapted to engage said rotatable member and to define the extreme positions thereof, a third stationary member and two rotatable shafts intermediately positioned with respect to said first two stationary members and adapted to engage said rotatable member to define intermediate positions thereof, a spring biasing said rotatable member and urging said rotatable member into engagement with said third stationary member and said rotatable shafts, a latch positioned at the end of said rotatable member to permit manually propelled rotation thereof in opposition to said spring and beyond said third stationary member and said rotatable shafts, a notch in each of said shafts permitting release of said spring biased rotatable member in its normal plane of rotation, an annular groove in each of said two shafts adjacent to said notch permitting rotation of said member in a plane displaced from said normal plane of rotation, said third stationary means being of a length to engage said rotatable member only in its normal plane of rotation, and a spring biasing said rotatable member into its normal plane of rotation.

12. A single stroke alarm, including a spring biased striking member, timing mechanism, means to displace said striking member, means associated with said timing mechanism to release laid striking member after a predetermined time interval, and means co-operating with said striking member upon displacement thereof to operatively interconnect said timing mechanism with said releasing means.

13. A single stroke alarm. including a spring biased striking member, timing mechanism, means to displace said striking member, means associated with said timing mechanism to release said striking member after a predetermined time interval, engaging means co-operating with said striking member upon displacement thereof to operatively interconnect said timing mechanism with said releasing means, said releasing means including a rotatable cam, the angular displacement of which cam from release position is a function of the time interval required for restoration thereof to the release position by said timing mechanism, and a visible indicating means associated with said cam to show the angular displacement thereof.

14. An alarm comprising a rotatable shaft, an interval indicating device on said rotatable shaft, timing mechanism for driving said shaft, a pivoted member carrying an alarm hammer at one end thereof, said pivoted member being spring biased into normal position, a fixed cam on said shaft, a cam rider on said pivoted mem- :ber, a second cam loosely mounted on said shaft and adapted to drive said first cam, means to allow'limited rotary movement of said second cm with respect to said fixed cam, means to rotate said second cam to displace said cam rider and to hold said cam rider in displaced position until such time as said fixed cam engages said rider,

biased means to operatively connect said shaft.

to said timing mechanism whereby said fixed cam is rotated to release said spring biased pivoted member to normal position, and a cam surface on said pivoted member adapted to disengage said shaft from said timing mechanism when said pivoted member is in normal position.

15. An alarm comprising a rotatable shaft, an interval indicating device on said rotatatable shaft, timing mechanism for driving said shaft, a pivoted member carrying an alarm hammer at one end thereof, said pivoted member being spring biased into normal position, a fixed cam on said shaft, a cam rider on said pivoted member, said cam having a portion of its surface substantially parallel to the movement of said cam rider, a second cam loosely mounted on said shaft and adapted to drive said first cam, means to allow limited rotary movement of said second cam with respect to said first cam, means to rotate said second cam to lift said cam rider over that portion of the surface of said fixed cam which is substantially parallel to the movement of the cam rider and to hold said cam rider in displaced position until such time as said first cam engages said rider, biased means to operatively connect said shaft to said timing mechanism whereby said fixed cam is rotated to release said spring biased pivoted member to normal position, and a cam surface on said pivoted member adapted to disengage said shaft from said timing mechanism when said first cam releases said pivoted member to normal position.

ARTHUR. B. CAMPBELL.

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