US2329447A - Timing mechanism - Google Patents

Description

Sept. 14, 1943. c, so 2,329,447

TIMING MECHANISM Filed Sept. 9, 1940 5 Sheets-Sheet l &

INVENTOR. C. L. ANDERSON wvmh W W;

ATTORNEY Sept. 14, 1943. c. 1.. 'ANDERS ON 2,329,447

TIMING MECHANISM Filed Sept. 9, 1940 5 Sheets-Sheet 2 Sept. 14, 1943.

Filed Sept. 9, 1940 5 Sheets-Sheet 5 ?0 slab I 89 as U IN VEN TOR. c. L. ANDERSON ATTORNEY Sept. 14, 1943. c. L. ANDERSON 2,329,447

TIMING MECHANISM Filed Sept. 9, 1940 5 Sheets-Sheet 4 INVENTOR. 6. A ANDEAfiO/V ATTORNEY p 1943. c. 1.; ANDERSON 2,329,447

TIMING MECHANISM Filed Sept. 9, 1940 5 Sheets-Sheet 5 INVENTOR. c. L ANDERSON ATTORNEY Patented Sept. 14, 1943 UNITED STATES PATENT OFFICE TIMING MECHANISM Carl Ludwig Anderson, Moline, Ill., assignor to Eagle Signal Corporation, ,Moline, 111., a corporation of Massachusetts Application September 9, 1940, Serial No. 356,005

9 Claims.

This invention relates to timing mechanisms and has special reference to mechanisms particularly suited to the timed operation of switches, though it should be understood that within the broad purview thereof other mechanisms besides switches may be controlled by the timing mechanisms hereof.

In the construction of timers, rotary timing members have advantages over other types of construction due to the relatively low cost of fabrication thereof and due to the compactness attainable with rotary types. The disadvantages of rotary types of low cost have been, first, the lack of accuracy when employing simple compact types of rotary members and'the resultant necessity of large timing members, and, second, the impossibility of using indicating means to show the elapsed time within the cycle. Thus, one timer which others have unsuccessfully attempted to sell recently was provided with an elaborate device to insure accurate setting of the timing member but the deviation in time of actuation at any particular setting was so great that the extreme accuracy of the setting was needless expenditure.

It is a principal object of this invention to provide a timing mechanism which, with a simple arrangement of parts, increases the accuracy of operation many fold. It is a further object to provide a simple, low-cost, accurate timing mechanism having means for indicating at all times the period in the cycle of operation.

In the accompanying drawings, I have shown illustrative embodiments of this invention as applied to the timed actuation of switches. In the drawings,

Fig. 1 is a front elevation of a timer in accord with this invention;

Fig. 2 is a left end elevation with a portion of the framework broken away, better to show the construction and arrangement of the operative parts;

Fig. 3 is a plan of the timer shown in Fig. 1;

Fig. 4 is a vertical section substantially on the line 4-4 in Fig. 3 but with the switches and the terminal block omitted;

Fig. 5 is apartial section substantially on the line 5-5 in Fig. 4;

Fig. 6 is a diagrammatic illustration best described as a section substantially on the plane of the line B--6.in Fig. 5;

Fig. 6a. is an edge view of a part of the structure illustrated-in Fig. 6, showing certain ancillary control mechanism;

Fig. 6b is a. front elevation of the structure shown in Fig. 6a with part of the structure removed for clearness; I

Figs. '7, 8, 9 are details of the switches and switch-operating means in reset, timing, and timed out position, respectively;

Fig. 10 is a wiring diagram of the timer showing three bridges in place between certain of the terminals, and with a starting switch connected thereto;

Figs. 11 and 12 are wiring diagrams of simplified character illustrating operation of the timer when connected as in Fig. 10;

Figs. 13, 14, and 15 are simplified wiring diagrams of the timer connected for another of its applications, showing the operating cycle thereof;

Fig. 16 is a diagrammatic section similar to Fig. 6 but showing a modified form of the timer; and

Figs. 17 and 18 are detailededge and face views of one element of the structure shown in Fig. 6a.

As shown in Figs. 2 and 4, a front frame plate I5 is secured in spaced relation to rear frame plate i5 by side frame plates I! and I8. An intermediate bearing plate I9 is secured between the plates [5 and 16 parallel thereto by being secured at its right hand end to side frame plate 18 and at its left hand end to front frame plate [5 by frame members 20 and 2|. A synchronous motor 22 is secured to the rear surface of the plate 19,

and is provided with a driving stub shaft 23 which extends through an opening in the plate l9 into driving engagement with the clutch member 24. This clutchmember 24 comprises a shaft 25, a clutch plate 26, and a shaft 21, extending forwardly from the plate 26 into bearing engagement with the frame plate IS. The shaft has an opening in the rear end thereof for insertion of stub shaft 23 whereby the rear end of member 24 is held against lateral thrust. A second clutch member 28, comprising a clutch plate 28, gear 30, sleeve 3 I, and operating collar 32, is slidably supported on the shaft 21, with the plate 29 facing the plate 26. positioned between the movable clutch member 28 and the frame plate l5. Clutch operator 34, described hereinafter, bears against the rear side of operating collar to cooperate with the spring 33 in moving the clutch under electromagnetic control into. engaged and disengaged positions.

An intermediate driving member 35 comprises a shaft 36,, which supports non-rotatably thereon a gear 31 in driven engagement with gear 3-0, and a gear 38, the forward side of which is concave.

An operating spring'33 is The member 35 is rotatably supported by the plates I and IS. A pin 39 is carried by a plate 48, adjustable about shaft 36, and extends into the concavity of the gear 38 remote from the center thereof for engagement with a stop 4| in the gear. A helical rewind spring 42 is secured at its ends to plate 49 and shaft 36 in conventional manner for turning stop 4| into engagement with pin 39. This plate 48 is pivotally mounted on the shaft 36 and is provided with a set bolt 43 (see Fig. 5) to clamp the plate in adjusted position about the shaft. Adjustment of plate 4| adjusts the normal or reset position of driving member 35. i

The main timing and indicating assembl 44 involves a frictionally held rotatably adjustable member 45 for determining the length of the timed period, a timing unit 46, mounted for rotation thereon and cooperation therewith in measuring the timed interval, and an indicating member 41, also mounted for rotation on member 45, being rotatable with timing element 46 to indicate visually the position thereof. The adjustable member 45 involves a shaft 48, supported for rotation in frame plates l5 and I9, a timing disc 49 secured to the shaft, an indicating pointer 58 secured to the shaft between the plate l5 and transparency 5|, and an adjusting knob 52 secured to the shaft. A friction brake 53 is clamped on the shaft 48, and a pin 54 carried by plate |9 engages therewith, to prevent turning thereof, whereby a drag is placed upon the shaft to hold it in adjusted position.

The indicating member 41 comprises a sleeve 55 which is rotatable upon the shaft 48. This sleeve extends from the timing disc 49 forwardly through the plate l5 and has a pointer 56 secured to its forward end between the plate I5 and the pointer 58. The sleeve 55 is provided with a shoulder in engagement with the rear surface of the plate I5, whereby this shoulder and the rear end of shaft 48 prevent endwise movement of the entire timing assembly. The sleeve 55 is further provided with a gear 51 secured thereto in engagement with the gear 38, whereby to indicate the position of the gear 38 at. all times during operation.

The timing unit 46 involves a sleeve 68, carried by the sleeve 55, between the gear 51 and the timing disc 49, slidable therealong. Member 46 is provided with a gear 59, in engagement with the gear 38, which is sufficiently wide that the two mesh in all axial positions of member 46. A timing disc 68 is secured to the rearward end of the sleeve 58, for cooperation with timing disc 49 in measuring the desired time interval for which the timer is adjusted.

When the timer is in reset position, the timing unit 46 is in forward position and the clutch is open, whereupon the spring 42 will move the gear train to a position in which the pin 39 engages the boss 4|. In this position. pointer 56 is in line with the zero marking on the scale. The pointer 58 is positioned with respect to the timing disc 49 so that when the pointers are in alignment the boss 6| on timing disc 68 is in line with opening 62 on disc 49. The knob 52 may then be adjusted to any desired time as indicated by the scale. Upon timing, as will be explained herebelow, the clutch is closed, the motor driven, and the timing unit 46 spring-pressed rearwardly. since in reset position, with the knob set for a time interval other than zero, the boss 6| is out of line with opening 62, the boss 6| will therefore ride upon the disc 49 until it is in line with the opening, whereupon under spring pressure the timing unit 46 will move rearwardly causing actuation of the switching means. As the pointer 41 is driven by the same gear as the timing unit, this pointer will indicate the movement of the timing unit and will read directly in the time elapsed since timing started.

A plurality of switch elements 63, 64, 65, 66, and 61 is pivoted on a rod 68 carried by the side plates I1, l8, each switch element comprisin .an insulated pivoted arm, to the forward end of which is secured a contact member to which electrical connection is made. Each switch element is provided with a spring 69, which bears against :the rear edge of cradle 18, and engages the rear end of the respective switch element, whereby the forward end of each element is biased downwardly. A switch controller 1| is pivoted in theplates 1, I8 below the forward ends of the switch elements to control the relative positioning of the elements when allowed by the cradle 18 to be moved under action of springs 69. In order to move the switch controller from one of its controlling positions to another of its positions, as below explained in connection with switch actuation, a pair of identical arms 12 is pivoted on a pin 13 carried by frame member 2| above timing unit 46 (see Fig. 4). A pair of springs 14, supported by arm 15 carried by frame member 2|, biases the arm 12 clockwise, as seen in Fig. 4. A spring 16 mounted on the pin 13 biases the controller 1| counterclockwise, as seen in Fig. 4, though the spring 16 is considerably weaker than the springs 14, whereby the arms 12 will move the controller 1| against the action of spring 16. The lower ends of the arms 12 are provided with enlargements which engage the timing unit 46 to move therewith, whereby upon translation of the timing unit rearwardly the arms turn clockwise. Upon such movement, the upper ends of the arms, which engage the switch controller 1|, will move the controller from rear supporting position of the switch elements to the forward supporting position.

A solenoid 11 is provided for controlling the positioning of the cradle 18. The solenoid is provided with a fixed core section 18, and with a movable core section 19 pivoted thereto by pin 88. The movable core section is connected to rod 8| through a lever arm 82 fixed to the rod 8|, and through a link 83 pivotally connected to the ends of the movable core section and the lever arm 82. A spring 84, engaging the fixed core section and the link 83, biases the rod 8| clockwise, as seen in Fig. 2. At its farther end, as seen in Fig. 4, the rod 8| is provided with a twoended lever 85, the ends of which are provided with pins 86, 81 adapted to pivotally support one end of the link 88. The upper end of link 88 is pivotally connected by a pin 98a to the rear end of lever 89 which is secured to rod 98 pivotally supported on its axis by the frame plate l8 and the internal frame member 28. A second lever 9| is secured to rod 93 and is positioned so that in raised position of link 88 it turns the arms 12 counterclockwise, as viewed in Fig. 4, moving the timing disc 68 out of cooperative engagement with 49. In lowered position of link 88, the lever 9| is moved to a position allowing the boss 6| to enter the opening 62. A third lever 34 is likewise secured to rod 98 and cooperates with a collar 32, as heretofore described, in operating the clutch. In position such that the timing discs are out of cooperative engagement, lever 34 moves the clutch out of engagement. Upon actuation of rod 80 by the electrically controlled means, involving solenoid T1 and spring M, to

move the timing discs into operative engagement, the clutch also moves into engagement. Therefore, with the knob turned to a position ofl of the zero reading so that the boss '8! is out of line with opening", the timing operation is initiated by turning of rod 8! to engage the clutch and allow the boss 6'! to engage the. surface of 49. The disc '80 is driven at constant, speed by the motor until the'boss isfin line with the opening in the disc, whereupon the spring M will instantly snap the control member H from one of its positions to the other.

A rod 92, also pivoted to the lever 88, effects a third function upon initiation of timing. The upper end of rod 92 is slidably received. in the cradle and is provided with a shoulder 93 to engage the cradle and tilt it: counterclockwise against action of spring 94, vass-icon in Fig. 4, when the rod is raised. In this raised position of the cradlc, the positions of the switch arms are controlled by the cradle. Upon lowering of the rod 32 upon initiation of the timingcyc-le, the cradle turn under action of spring 94, whereupon the switch arms rest upon the controller member "H, whereby their positioning isdctermlned. At the end of the timed cycle, the member H is moved,

as described previously, whereby the positioning of the switch arms may be shifted to a third relationship, in which positioning they are under control f member 1 I.

To buffer the action of the electrical control means, involving spring 84 and-solenoid 11, an arm 94a is secured to the left end of rod 8| and is pivoted to plungcr 95. arranged for sliding movement in dash pct. 96. which ispivotally carricd on pivot 91 secured to frame plate H.

An illustrativeset of switch arms is shown in Fig. 3, but it should be. understood. that extreme variation is possible in the. switching arrangement. "The switch arms 83 and 64 comprise a single pole single throw switch, which maybe employed incontrclling circuits within the times. Accordingly, very flexible controloi this switch is provided, whereby to adapt the timer to diverse types of service. The contact member on switch arm 64 extends over that on. switch arm 63. A

I notch 98 is provided in the forward edge of cradle 7i! below arm 64, whereby, when the cradle-is in I controlling. position, this switch may be closed (see Fig. '7). The cradle is also provided with an opening below arm 64' in which a pin, 93 may be inserted, whereby this switch may be held open when the cradle is in. controlling position (see Fig. '7). When the forward edge. of cradle 10 is lowered out of controlling. position, and the switch arms are responsive to member H in-rearward position (see Fig. 8), the arm 53 rests upon upward extension Ill 0 on member'Tl, whereby the arm 64 is supported by arm '63 clear oi. both cradle l6 and member H. In forward or timed out position of member I I, to which it is moved at the termination of the timed period (see Fig. '9) the may be omitted whereby the switch is closed in the reset position of Fig. 7.

The remaining switch arms are in general cmployail for controlling external timed circuits, though or some services these switches may be employed for simultaneously controlling both internal and external circuits. As shown, the arms W, B, and 61, together with their associated. contact members, constitute a single pole double throw switch. Removable pins I02, I03 may be provided in the cradlelfl under each of the arms 55 and 61, whereby in reset position each of these arms is supported. The contact member assoelated with arm 66 will then be in contact with that supported by arm 65 and out of contact with arm 61.. An upward extension I04 is profvided on member II whereby in timing position (see 8) arm 56 rests thereupon while arms 64am 6! are free to move downward, thereby openingthe circuit between arms 65 and 66 and closing that between arms 66 and 61. Rcarwa-rd maybe substituted for the single polo double throw switch, as, for instance, two single pole single throw switches.

A terminal block I'M of insulating material is supported at the lower edge of frame plate 15. Conventional electrical conduits H1, 8 conof" the motor 22'.

terminals 108- and I [2 with solenoid TI. Conduits 1H and I22 connect the contact elements on arms 63 and 64 with terminals I09 and H3, and conduits I 23, 1.24,. and I25 connect the contact elements on arms 55, 66 and 61 with the terminals H5, no, and H5.

When the timer is arranged-as shown in Fig. m, with bridges on the pairs of terminals W'HO; I I2H3,'.and H3H4, and with the pins 98, 1162., and 10! in position and link 88 connected to pin Be, the circuit diagram of Fig. 11 illu'stratcs the. circuit conditioning in reset position. To initiate timing, external starting switch I26 is closed, whereupon power is communicated through the solenoid which, through connections, the operation'of which has heretofore'becn described, moves the cradle out of controlling position, closing switch 53-64, and shifting contact arm 66 from arm to arm 61, as shown in Fig. 12. Power is simultaneously communicated to motor 22 through switch 6364, the solenoid 11 becoming a holding coil for switch 63-84, wherefore the starting switch I26 may be released. Upon the member H moving to timed out position, the circuit conditioning returns to that shown in Fig. 11. In this arrangement, the timer automatically resets, involving turning of the cradle into controlling position at the termination of the timed period.

Another application, illustrating the versatility of this timer, involves the use of bridges between terminals l09l l0; and 3-! Hi, the position ing of link 88 on pin 81, and the use of pins 99 and I83. In this arrangement, the switch I26 is normally open, and in timed out position the switches 63- 64 and 56-61 are open and the switch 6566 is closed (see Fig. 13). To reset the timer, the switch I26 is closed, whereupon all the switch arms are responsive to the cradle and all switches are open (see Fig. 14). Upon deenergization of the solenoid by opening switch 126, spring 84 moves the remainder of the control mechanism to engage the clutch. Atthe same time, the switches 63-64 and 66-61 are closed, switch 6566 remaining open, as shown in Fig. 1.5. Termination of the timed cycle changes the circuit conditioning to that shown in Fig. 13.

In the embodiment of the invention shown in Fig. 16, the motor and clutch assembly 24-28 is identical to that shown in Fig. 6. The gear 30 engages and drives the gear 31 on shaft 36, upon which is secured a gear 38' to rotate with gear 31. The shaft 43 extends from the plate I8, in which it is mounted for rotation, through the front plate, and is provided with a knob 52 and pointer 53 to indicate its position. The indicating member 61, as in the form shown in Fig. 6, comprises a pointer 56 and gear 51 secured together with the gear in mesh with gear 36'. The indicating member engages a shoulder on shaft 48' to prevent forward movement of the shaft. The timing unit 4-5 is the same as shown in Fig. 6 except that it rotates and translates directly on shaft 38' instead of on a sleeve secured to the indicating member. The timing disc 48', which cooperates with timing disc 60, is rigidly mounted upon a frame member I21, thereby making the timed out position fixed instead of adjustable. The gear 31 meshes with a. gear I28 supported by a sleeve I29 immediately forward of the brake construction. A pin I30 extends forwardly from the front face of gear I28 and engages a pin I3I fixed in and rotatable with shaft 48.

Accordingly, in this form, the reset position is adjustable by the knob 52. A spring I32, secured to pin I3! and gear I28, returns the movable clutch member shaft 36, and gear I28 to reset position upon disengagement of the clutch.

With the clutch disengaged, and the timing discs out of cooperative engagement, the knob 52 is adjusted to the desired position as indicated by the scale. As the gear I28 is free to move under action of spring I32, the pins I30 and I! remain in engagement and, therefore, through the gears 31 and 33, the timing and indicating units move with the knob. Accordingly, in reset position,

the two pointers will be in alignment. Upon actuation which engages the clutch and which moves the timing unit rearwardly to slide upon timing disc 49, the three gears 51, 59, and I23 rotate synchronously. Rotation will continue until the pointer 56 is in line with the zero on the scale, whereupon the timing unit will translate upon shaft 48, as previously described.

While in both forms of the invention, the reset and timed out positions are relatively rotatively adjusted by the knob. in the first form it is the timed out position which is adjusted and in the second the reset position. In the first form, the indicating pointer 56 reads on the scale directly in the time of the cycle elapsed, while in the second the pointer reads in the time yet to elapse. It is thus to be seen that, in the first form, the pointer starts timing from zero, in the second form, from a position in line with pointer 50, and that the motor must rotate oppositely in the two forms.

As shown in Figs. 6a and 61), this mechanism may be, and preferably is, provided with means for insuring release of the clutch when the timing unit 46 moves longitudinally of sleeve 55 carrying the boss 6| into the opening 62 of disc 43. This comprises a support I35 carried by a rigid part of the structure, having a pivot I36, on which is pivotally mounted a lever I31, of which the end I38 engages the collar 32, and the end I39 engages a fiat face of gear 58. Therefore, as the arms 12 move the unit 46 longitudinally along the sleeve 56 toward disc 49, the lever I31 is rocked about its pivot I36, and end I38 pushes collar 32 forwardly, pulling clutch plate 29 out of engagement with plate 26. This frees the clutch 24 and permits rotation of clutch member 29 independently of motor 22. Consequently, the knob 52 may be turned to set the hand 58 without rotating the rotor of the motor.

As shown in Figs. 6, 1'1, and 18, the opening 62 is preferably not uniform in dimensions, being provided with a step 62a which permits the boss 6| to enter opening 62 part way and then pause before entering all the way. When boss 6| aligns with opening 62, then, through the pressure of springs 14 and arms 12, unit 46 will be moved until boss 6I engages step 62a. Also, arms 12 push support 1I forward slightly, releasing switch support 66 ahead of 63 because of the notch 660 out in the end of 66. This permits the switch 65, 66 to close momentarily before 63 is released from 64 by the continued rotation of element 46, the former being held up by the rest I60 until the boss 6| enters all the way into the opening 62. When this happens, the levers 12 turn about their pivot 13 as far as unit 46 will permit them to turn. This pushes member 1| forward, releasing switch element 63 and permitting it to withdraw from switch element 64. This breaks the circuit to the timing motor 22 and causes reset.

When the above description is considered in the light of prior constructions, it is to be seen that this invention is limited to neither of the specific forms disclosed; wherefore, it should be understood that the scope of this invention is defined only by the subjolned claims.

Having now described my invention, I claim:

1. A snap action timing mechanism, comprising cooperating timing means, one of which is rotatable and normally spring biased in one rotative direction, one of said timing means being mounted for reciprocation, said timing means cooperating to allow reciprocation thereof in one rotative position of the rotatable timing means and to prevent reciprocation in other relative positions thereof, spring means to effect reciprocation when said elements are in said position allowing reciprocation, means for limiting spring biased movement of said spring biased timin means, said limiting means and the timing means other than said spring biased means being relatively adjustable to vary the degree of movement of the spring biased means from the limited position to the position allowing reciprocation, and chronometric driving means for rotating said r0- tatable means against the bias thereof whereby to measure predetermined time periods.

2. A snap action timing mechanism, comprising cooperating timing means, a shaft upon which one of said timing means is mounted for rotation thereabout and reciprocation therealong, spring means normally to bias said rotative means in one rotative direction, spring means to bias said rotative means in one reciprocative direction, a pair of limiting means, one of which cooperates with said rotative means to limit spring biased rotation thereof, and the other of which in one rotative position of said timing means allows spring biased reciprocation thereof and in other rotative positions thereof prevents such spring biased reciprocation, one of said limiting means being normally fixed and the other cooperating with said shaft upon rotation of said shaft to vary the degree .of movement of said rotative means between the limiting positions, and means for effecting rotation of said rotative means between said limiting positions in the opposite direction from that produced by the spring means.

3. A timer comprising a shaft, a timing element mounted for rotation on and reciprocation along said shaft, a spring for biasing said timing element for rotation in one direction, means for limiting spring bias rotation of said timing element in one direction, a timing motor operatively connected to rotate said timing element in the opposite direction, a second means for limiting rotation of said timing element when driven by said motor, said timing element and said second limiting means cooperating to allow reciprocation of the timing element in a position thereof limited by said limiting means, means for indicating the rotative position of the element in all positions thereof along the shaft, means to synchronize rotation of the element and of the indicatin means, and means to rotate the element.

4. A timer comprising a shaft fixed against longitudinal movement, a timing element mounted for rotation about and reciprocation along said shaft, said timing element being rotatable between limiting positions for determining desired time in tervals, means for reciprocating said timin element relatively to said shaft when in one of its limiting positions, means mounted in fixed position along said shaft for rotation with said shaft for indicating the rotative position of said timing element at all times, and means synchronously to rotate said timing element and said indicating means.

5. A timer comprising a manually adjustable rotatable shaft, a timing element mounted for relative rotation on and for reciprocation along said shaft, said timing element being rotatable between limiting positions for determining desired time intervals, means for reciprocating said timing element in one of its limiting positions, said shaft and said timing element cooperating to effect relative adjustment of the limiting positions upon manual adjustment of said shaft to vary the time interval, means mounted for rotation on said shaft for indicating the rotative position of said timing element at all times, and mean synchronously to rotate said timing element and said mean for indicating.

6. A timer comprising a shaft, a timing element mounted for rotation on said.- shaft and for reciprocation therealong, limiting means cooperating with said timing means for limiting rotation thereof in opposite directions, indicating means mounted for rotation on said shaft for indicating the relation rotative position of said element in all positions thereof along said shaft, said timing element and said indicating means each comprising a gear, and drive means for rotating said timing element comprising a shaft, a gear secured to said shaft which engages the timing element gear in all positions of the element along the shaft, and a gear secured to the shaft which engages the gear of the indicating means, whereby the timing ele ment and the indicating means are synchronously rotated upon rotation of said drive means.

7. In a snap action timer, the combination comprising a shaft, a pair of timing elements carried by the shaft, one of which is secured thereto and the other of which is rotatable with respect thereto, one of said pair being reciprocable therealong, one of said pair having a face perpendicular to the shaft and having an opening therein, and the other having a projection extending toward aid face, spring means to bias the reciprocable element toward the other element, said projection normally riding on said face to prevent movement together of the elements, and said projection cooperating with said opening to allow reciprocation of said reciprocable element toward the other element, means for rotating the rotatable element in opposite directions, coaction of said projection and opening limiting rotation in one direction, and means for limiting movement in the opposite direction, said shaft being rotatable whereby to adjust the relative positioning of the element secured to the shaft and the limiting means.

8. A switching mechanism comprising cooperating switch elements, controlling means for controlling the relative positioning of said elements, and upon actuation to effect change of the relative positioning of said switch elements, holding'means to hold said elements non-responsive to said controlling means and to control the relative positioning of said elements when so held, a pair of timing elements, one of which is rotatable from an initial limiting position to a time determining position, means for reciprocating one of said elements when said rotatable element i in determining position, means operatively connecting the reciprocable element and said controlling means for actuating the latter upon reciprocation of the former, and means for reciprocating said one of said elements in the opposite direction and for simultaneously moving said holding means to holding position.

9. In a timer, the combination comprising a shaft, a timing means rotatable on and translatable along the shaft, spring means and chronometric means for rotatively driving said timing means in opposite directions between limiting positions, a gear secured to said timing means, a face plate, indicating means positioned on the side of said face plate opposite said timing means, a gear secured to said indicating means to rotate therewith, and unitary gear means in mesh with each of said gears.

CARL LUDWIG ANDERSON.

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