US3449699A

US3449699A - Programmer for controlling switches of washing machines and the like

Info

Publication number: US3449699A
Application number: US604416A
Authority: US
Inventors: Jean Jullien Davin
Original assignee: Crouzet SA
Current assignee: Thales Avionics SAS; Crouzet SpA
Priority date: 1965-12-24
Filing date: 1966-12-23
Publication date: 1969-06-10
Anticipated expiration: 1986-06-10
Also published as: BE691024A; NL154041B; NL6617453A; CH465696A; GB1144514A; FR1510196A

Description

June 10, 1969 J. .1. DAVIN 3,449,699

. PROGRAMMER FOR CONTROLLING SWITCHES OF WASHING MACHINES AND THE LIKE Filed Dec. 25, 1966 Sheet of 3 INVENTOR. J'Pd KMLLIEN Imvm BY 44% dum June 10, 1969 .DAV. 3,449,699

J. J PROGRAMMER FOR CONTROLLI SWITC OF WASHING MACHINES AND THE LIK' 2 Filed Dec. 25, 1966 Sheet of 3 "919) L f k I INVENTOR. TEA/U JuLUG/U DAWN BY GM June 10, 19,69 J. J. DAVIN PROGRAMMER FOR CONTROLLING SWITCHES OF WASHING MACHINES AND THE LIKE Sheet Filed Dec. 23, 1966 Fig/6 jAB H8 7 INVENTOR. TERA! TLLLLI/d DAV HG em United States Patent 3,449,699 PROGRAMMER FOR CONTROLLING SWITCHES OF WASHING MACHINES AND THE LIKE Jean Jullien Davin, Valence-sur-Rhone, France, assignor to Crouzet S.r.l., Milan, Italy Filed Dec. 23, 1966, Ser. No. 604,416 Claims priority, application Italy, Dec. 24, 1965, 28,604/ 65 Int. Cl. H01h 51/08 US. Cl. 335-138 11 Claims ABSTRACT OF THE DISCLOSURE A programmer which includes a rotary cam means which is continuously rotated for actuating at least one switch, this rotary cam means being supported for rotary movement by a fixed shaft which also supports for rotary movement a rotary cam block having a hollow interior adapted to receive additional components of the assembly. A releasable coupling means is provided for releasably coupling the rotary cam means and the cam block to each other, and this releasable coupling means is capable of being periodically energized so as to provide a step-bystep advance of the cam block, a positioning means being provided for determining the angular positions of the cam block during the intervals between the turning thereof periodically when the coupling means is energized. The cam block itself controls additional switches of the assembly.

It is known to use programmers to control machines automatically, in particular clothes washing machines, dishwashing machines and the like, in which cams actuate contacts according to a predetermined program. When the duration of the cycle exceeds a certain time, the continuous rotation of the cams is too slow to actuate electrical contacts satisfactorily. To obviate this, it has been proposed to rotate the cams step-by-step at regular intervals, each rotation of one step being sufficiently rapid for the contacts to operate satisfactorily. Numerous step-by-step control devices are known and currently applied, in which the duration of the inoperative time between two steps is determined by the shortest of the operations to be carried out, while longer operations require several such successive intervals.

A complete revolution comprises as many steps of shortest operation as are contained in the total duration of the cycle. This has the advantage of providing the smallest possible number of steps for the complete cycle, a feature which permits wide tolerances in the formation and angular positioning of the cams and hence reliable operation, easy construction and moderate cost.

It is also known to stop the step-by-step advance of the cams during some operations, the duration of which does not depend on the program. This is done, for example, during the heating or filling, a thermostat, float or pressurestat controlling the resumption of the step-by-step movement when the operation is concluded. In these cases these operations use only one step, while their normal duration would have required several.

It frequently happens that it is necessary to feed the synchronous motor of the programmer, during a part of the program, by means of a particular contact, and then through another contact, the transition from one contact to the other taking place during one step. If the motor has only a small inertia or comprises a permanent magnet, it may happen, if the first contact is opened before the second contact is closed, that the motor stops and remains in a position in which it cannot be restarted. To avoid this risk, it is then necessary to use, during the 3,449,699 Patented June 10, 1969 transition, 21 third safety contact actuated by means of a cam connected to a reversing cam which continuously rotates, The problem is to provide a programmer meeting the requirements, under the best conditions of price and compactness, and with the required quality. To have at the same time high quality and low cost, selection is made of a certain number of means, the combinations of which will produce all the versions required with the maximum number of common members, with ease of assembly and reliability in operation, said means and combinations of means also rendering unnecessary certain previously employed expensive devices.

The object of the present invention is a new combination of means to obtain a new programmer, with cams specially adapted to the automatic control of washing machines and the like, whereby by means of a simple change in the assembly of some of the combinations of means, the programmer may be constructed in several forms to satisfy the requirements of different washing machine manufacturers, these dilferent forms comprising the maxi mum number of common members.

A programmer according to the present invention comprises means which form a base, said means being constituted by two plates connected together by means of columns hooked or riveted at their ends, one of the ends of the columns being provided with a bore to permit assembly by a self threading screw, or a rivet secured by friction locking if, for repairing, it is necessary to destroy the hook connection by drilling. Since such repair may be expected on less than one percent of the apparatus, the elimination of the connecting screws constitutes a saving in the new apparatus.

There are also means to provide some operations in a continuous cycle, in particular, the reversing control of the direction of rotation of the drum of the washing machine, said means consisting of a stepping or advancing cam which actuates at least one contact and which is driven by a rapid continuous movement of a synchronous reduction motor.

Means are provided to insure the control of various functions of the washing machine according to a predetermined program, said means consisting of a cam block rotating with a step-by-step movement and controlled by contacts. This cam block is cast in one piece for the purpose of reducing the cost and increasing precision. This cam block, since it is formed as a single piece, has a large central hollow interior which may be used for accommodating other members.

There are also means for controlling the step-by-step rotation of the cam block to cause the cam block to skip several successive steps in a continuous movement for the purpose of curtaining some phases of the program, or

for stopping the step-by-step advance for the duration of 1 an operation, for example, heating or filling, until a thermostat, pressurestat or float initiates the resumption of the step-by-stcp rotation, these means consisting of an electromagnetic coupling device permitting:

(a) The periodic connection of the cam block to a rotary cam means or stepping cam for the step-by-step advance when controlled by brief pulses of a contact actuated by the stepping cam;

(b) The rotation of the cam block with a continuous movement through 'an angle covering several steps, when controlled by some phases of the program by means of a contact actuated by a memory cam, interchangeable or forming part of the cam block;

(c) The advance of the programmer when controlled by a manual contact, which may be remote, a feature which makes it possible to suppress, if desired, the manual operating button; and

(d) The suspension of the step-by-step advances, when, during some operations, such as heating or filling, a cam of the block causes the interruption of the step-by-step impulse circuit, until the operation of heating or filling being completed, a thermostat, float or pressurestat, by means of a contact, directly initiates the advance of a step and re-establishes the periodic impulse circuit.

The stopping of the step-by-step movement is made directly by means of an interruption of the step-by-step impulses and not by means of an interruption in the feed of the synchronous reduction motor which remains continuously energized, thus rendering unnecessary the use of a special contact which was indispensible in many of the known programmers.

Also, the stopping of the step-by-step drive is effected without the necessity of using any special device. An important feature of the coupling means, according to the present invention, resides in the fact that they are entirely located in the hollow space of the cam block, which permits a simple construction which is very reliable in operation and is very compact, said means consisting in an electromagnet coil mounted on a fixed shaft of nonmagnetic metal drilled for the passage of the coil leads, and controlling a tubular core which encloses the drilled shaft and is longitudinally displaceable thereon, returned by an opposing spring and fitted, by being inserted by casting, in a grooved male mandrel rotated by projections of the reversing cam and the grooves of which, when the coil is energized, cooperate with the grooves of a female portion formed by casting in the interior of the cam block.

There are means to insure the fixed angular position and direction of movement of the cam block during the interval between two impulses and to prevent, if the programmer is of the type comprising a manual control, rotation in the opposite direction which would harm the contact plates, said means consisting of two toothed crown wheels of plastic material having as many ratchet teeth as there are steps provided for one complete revolution of the cam block and in which one of said wheels is fixedly located against one of the base plates by means of centering feet obtained by casting and the other is connected to and rotates with the cam block by engagement with projections of the cab block. It is kept resiliently against the block by a spring in such a manner that the teeth provide rotation of the cam block in only one direction, the centering feet and the driving projections being provided to avoid any chance of reversal of the angular position of the assembly of toothed crown wheels.

A further feature of the programmer is that for giving step-by-step impulses, one or two diametrically opposed contacts may be actuated by the stepping cam. One stepby-step frequency or the double frequency is manually selected.

In a variation, the programmer comprises means for temporarily obtaining different values of duration of the interval between successive steps, these means consisting either in at least one additional cam actuating at least one contact and driven by a continuous rotational motion from the synchronous reduction motor in a ratio different from that of the stepping cam, and in at least one interchangeable memory cam or similar part of the cam block, actuating at least one contact to insure appropriate coupling between the contact or contacts actuated by the additional cam and the contact or contacts actuated by the reversing cam to control the coupling members.

In a further frequently required form, the programmer has the feature of employing alternative means to produce the various operations, said means comprising one or more cams, connected to rotate with the cam block, and capable of being axially displaced, to pull or push the manually controlled push button, the actuators of the contacts being controlled by these cams which have such shapes that the operation obtained when the button is pushed is different from that obtained when the button is pulled.

All these features and others will be more clearly apparent from the following description, with reference to the accompanying drawings, in which:

FIG. 1 shows a programmer according to the present invention the base or frame of which is shown in section with the cams centered on a line passing through the axis of the device, the members of the electromagnetic coupling being shown in half-section to illustrate certain details;

FIGS. 2, 3 and 4 show three variants of the angular arrangement of the displaceable toothed crown wheel for connection to the cam block, shown in section on the line AA of FIG. 1;

FIG. 5 shows a form of centering and angular fixing of the fixed toothed crown wheel to be attached to a plate; I

FIG. 6 shows details of the teeth of the toothed crown wheels;

FIG. 7 shows a programmer with an additional cam;

FIG. 8 shows a programmer with some cams axially displaceable;

FIG. 9 is a detail of FIG. 8 taken at section line CC of FIG. 8;

FIGS. 10, 11, 12, 13 and 14 show details of the mounting columns;

FIG. 15 is a simplified circuit diagram showing how the step-by-step advance, normally controlled by the stepping cam, may be temporarily replaced by a continuous advance or interrupted or initiated by a thermostat or pressurestat or by a manually operated push button which actuates a contact;

FIG. 16 is a circuit diagram including a reversing cam and an additional cam for a different speed; and

FIG. 17 is a diagram which represents different step impulse frequencies derivable from the circuit of FIG. 16, assuming that the stepping cam makes a revolution in two minutes and the additional cam a revolution in six minutes.

FIG. 1 is a section of a programmer according to the present invention. The rear plate 1 and the small front plate 2 connected by two columns or spacers 3 constitute the base or frame of the apparatus. The rear plate 1 supports one end of the tubular drilled shaft 4 of nonmagnetic material, kept in a fixed, nonrotating position by its rear shoulder 4a. Loosely mounted on the shaft 4 is a rotary cam means in the form of a stepping or advancing cam 5 comprising at least one cam track 5a, the profile of which controls at least one contact, not shown, and teeth 5b which make it possible to drive the cam with a continuous rotary movement by means of the gear 6 connected to the output shaft 7 of a synchronous reduction motor (not shown). Also loosely mounted on the shaft 4, by means of a bore 8a, is a cam block 8 obtained by stamping from a single piece. The construction of the cam block in a single piece of plastic permits a high degree of precision in the relative angular locking of the cams, economy in members and time of assembly and saving in material. The cam block has a large hollow space in its interior, utilized to receive an electromagnetic coupling means between the cam 5 and the cam block 8.

The cam block 8 comprises several tracks or camming flanges 8b, each track actuating at least one, but preferably two or more contacts 9 which may be of known type, single make or multiple.

The cam block 8 comprises a journal which rotates in a bore of the plate 2 and in which a shaft 10, of hexagonal section, is secured by insertion and casting. The shaft 10 is intended to receive a push button (not shown) for manual control, if such control is provided, or a simple indicator frame (not shown) if remote manual control is provided by means of an auxiliary manually controlled contact.

The electromagnetic coupling means comprise a fixed electromagnet formed by a magnetic core 11, mounted by locking on the shaft 4, on which is riveted a cylindrical casing of soft iron 12 containing a coil 13, the

windings of which are protected externally by means of a covering of injected plastic material by a process used for the protection of the windings of the synchronous motor. The output wires of the casing, contained in an insulating sheath 14, issue from an opening 12a and enter the drilled shaft 4 through a lateral opening 4b. They are conducted to the exterior of the apparatus, the casing 12 being closed by a cover of soft iron completing the magnetic circuit. The said cover has a number of radial tabs 15a mounted within notches formed in the edge of the casing 12 the ends of which ensure the centering of the cam block. The coupling means further comprises displaceable fittings formed of a tubular armature or core 16 connected, by insertion and casting, to a toothed transmission member 17. The fittings slide longitudinally on the hollow shaft 4, being urged in one direction by a return spring 18 and capable of being moved in the other direction when the coil 13 of the electromagnet is energized. The said displaceable fittings are also continuously rotated by projections 50 of the cam 5 cooperating with apertures 17a. The teeth of the member 17 engage, when the coil 13 is energized, with the corresponding grooves 8g obtained by stamping within the cam block, thus forming a splined transmission.

Finally, FIG. 1 shows thepositioning means for retaining the cam block in predetermined angular positions, said means consisting in a displaceable crown wheel 19 with ratchet teeth connected to rotate with the cam block 8 by means of projection 8d cooperating with apertures 19a of the toothed wheel 19, the latter being also resiliently biased by the spring to engage with the opposed teeth of a crown wheel 21 fixed by feet 21a which engage in holes in the plate 2.

FIG. 2 shows how the projections 8d may be arranged if the number of teeth of the

crown wheels

19 and 21 is a whole multiple of the number-of projections 8d; if not,

it is necessary to provide means to insure only one assembling position, as for example, by an auxiliary projection 8d which fits into a bore 19b (FIG. 3). Alternatively, one of the projections 8d is made of greater width than the other (FIG. 4), or again an asymmetrical distribution of the said projections may be used. For the same reason one of the feet 21a (FIG. 5) of the crown wheel 21 is different from the other feet 21a.

FIG. 6 shows in detail the magnified shape of the teeth of the

crown wheels

19 and 21. One of the sides of each tooth has a small incline distributed over approximately of the step controlling the rotation in one direction with compression of the spring 20. The other side of each tooth has a sharp incline distributed over a quarter of the step p which prevents rotation in the other direction, drive by means of the coupled connection being effected over approximately Vs of each step. The tips of the teeth of the displaceable crown wheel 19 ride over the tips of the teeth of the wheel 21. Hence, discontinuing the energization of the coil 13, the rotation of one step is completed through the action of the spring 20 which tends to guide the tips of the teeth of one of the wheels to the roots of the teeth in the other Wheel. During this last fraction of the step, the torque transmittedby the coupled connection is reduced, the effect of whichis to reduce the friction forces against the grooves 8g and to facilitate the disengagement of the transmission member under the action of the spring 18. If spring 18 is sufliciently weak, a short impulse is sufficient to control the engagement which, due to the aforementioned friction, remains during the first portion of the step (approximately of the step).

An important feature of the programmer resides in the fact that the various members do not comprise any special fixing means and remain displaceably inposition between the

plates

1 and 2 connected together by the riveting of the columns 3, thus making assembly extremely easy and cheap. Since the ends of the projections 8d are very close to the plate 2 and an interior shoulder 8e of the cam block 8 is very close to the front end of the case 12, the cam block 8 is longitudinally or axially posi tioned with but slight axial play.

Case 12 and the tubular shaft 4, connected together, are retained axially by the plate 1, due to the fixed shoulder 4a. An end 8 of the cam block 8, located close to the cam 5, positions the latter longitudinally with slight play. Transmission member 17 is held by the spring 18 against the cam 5. The toothed wheel 21 is held against the plate 2 by the thrust of the wheel 19 under the action of the spring 20. At least one insulating support 22, carrying the contacts 9, is supported in position between the

plates

1 and 2, with end tabs 22a, 22b, obtained by casting, of difierent shape to avoid any inaccuracy in assembly.

FIG. 7 shows an embodiment of the programmer comprising at least one additional cam 23. v

The stepping cam 5 comprises a cylindrical hub 5d on which the additional cam 23 loosely rotates, comprising at least one track or camming flange 23a, provided with teeth 23b which mesh with a pinion 24 coaxially fixed to the gear 6 of the shaft 7 of the synchronous reduction motor (not shown). Elements having the same functions as those of FIG. 1 are indicated by the same reference numerals.

FIG. 8 shows an embodiment of a programmer comprising one or more axially displaceable cams for actuating contacts the feelers of which an: shaped to permit ditferent operations according to whether a manual control knob is pulled or pushed. The members which effect operations identical to those described above bear the same reference characters, and the members having the same shape as that of FIG. 1 have no reference characters.

The cam block 8 freely turns on the hollow fixed shaft 4 by a bore 8a. The projections 8d comprise a shoulder 8p on which the spring 20 rests. A cam 25 freely mounted by a bore 25a on the shaft 4 comprises at least one camming flange or track such as 25b and a journal 250, rotating in a bore of the plate 2 and in which there is secured, by insertion and casting, a shaft 10 which may have a hexagonal section and is adapted to receive a manually controlled push button (not shown). Since said shaft 10 works with end pressure, it has a groove 10a receiving a projection of journal 25c to prevent axial movement of element 10 in element 25. The journal 250 has a shoulder 25d which engages the plate 2 when the cam is in one axially displaced position, and a channel 25:: receives a small coiled spring 26 (FIG. 9) cooperating with two circular grooves 4c, obtained by turning or pressing in the hollow shaft 4, to keep the cam 25 either in position pressed against the cam block 8, or in a withdrawn position. The rotary drive and the angular movement of the cam 25 are insured by the projections 8d which pass through the cam 25 in the apertures 25f.

Each track 25b of the cam 25 actuates at least one, but preferably two or more, contacts 27 which may be one way or multiple, the displaceable members of which are provided with feelers 28 of suitable shape to cooperate with the cam 25 in such manner that the operation of said contacts varies according to whether the cam 25 is in one position or another.

FIG. 10 shows how the column 3, provided with a bore 3a and spun over in the plate 1, as shown by the full line, may be made dismountable for repair by boring out the cone face 3b, shown in broken lines.

FIG. 11 shows how, after repair, the column 3 may be remounted on the plate 1 by means of the self-threading screw 29 of known type, which is an advantage since experience shows that serious repairs are necessary in less than 1% of manufactured programmers.

FIG. 12 shows another method of remounting the column 3 on the plate 1, after repairs, consisting in forcing a rivet 30 into the bore 3a and friction-locking it.

FIG. 13 shows a solution which may perhaps be even more economical. The column 3 on the new apparatus has a simple enlargement 3c intended to permit spinning over on the plate 1 according to the full line. For dismantling, the bore 3a and the cone 3b are made in one operation by a drill 31 which serves as a pivot for a conical cutter 32 mounted on the drill 31 by a lock screw 33, as shown in FIG. 14.

- FIG. 15 schematically shows how, when the cam 5 is permanently rotating, the electromagnetic coupling device actuated by the coil 13, makes it possible to drive the cam block 8 in different ways.

When the contact C is closed, the cam 5, closing the Contact C once during every rotation, sends a short impulse to the coil 13 and the cam block 8 is driven with a step-by-step movement.

When, independently of the contacts C and C the manual contact C is closed, the cam block 8 is driven with a continuous movement.

When, during step-by-step advance, an interchangeable memory cam or such, forming part of the cam block 8, closes the contact C the cam block 8 is driven with a continuous movement during the whole time for which the closure of the said contact lasts.

When the step-by-step advance drives the cam block 8 in a position corresponding to the filling operation of a washing machine, at the same time a contact (not shown) controls the filling valve and the contact C is open, thus interrupting the impulses of C while the contact C is closed, energizing the pressurestat P. At the same time, a contact C is closed so that when, at the end of the filling, the pressurestat has established a connection by means of C the coil will receive current which, at the end of a step, will be interrupted with the opening of C while the cam block has reached the heating position.

In the heating position, in which the contact C is closed and the contact feeds that one of the thermostats T or T which has been previously selected by one of the manual push buttons B or B and when the temperature reaches the value to which the selected thermostat has been preadjusted, the contact T or T closes, the coil 13 receives a current which is interrupted when the cam block, having advanced by one step, has caused the contacts C and C to open simultaneously. Contact C closing again reestablishes the circuit of the step-bystep impulses controlled by C When the cam block reaches the position empty during the cycle, the contact C is again opened and the contact C closed while the contact C is closed. When the emptying is concluded, the pressurestat closes the contact C the coil 13 receives current which is interrupted when the cam block 8, having taken one step, has opened contact C If this is the last emptying after the last heating, the contact C is merely interrupted, reestablishing the impulse circuit by means of C Otherwise, C remains closed and C closes for emptying again.

It will be apparent that all the operations have been affected without interrupting the current to the motor. Operaion is therefore reliable without it being necessary to provide a safety contact, as is the case with many previous programmers in which it is necessary, to effect similar operations, to insure the feed of the motor successively through different contacts, the aforementioned safety contact being intended to avoid any risk of the motor stopping as a result of a defect in the action of the switch mechanism.

An important feature of the present programmer resides in the fact that the use of the electromagnetic coupling device renders unnecessary, both a special device for step-by-step driving and any device making it possible to interrupt temporarily the step-by-step feed.

FIG. 16 shows how it is possible to use the additional cam 23 shown in FIG. 7 to obtain diflerent intervals by interconnecting contacts. If connection AB is made and the contact D is closed simultaneously, there is an impulse with ever-y half-revolution of the cam 5.

If there is a ratio l/R between the speed of rotation of the cam 5 and the speed of rotation of the cam 23 and, if, at the same time, connection AC is made and the contacts E and D are closed, there is an impulse for all the R half-turns of the cam 5.

If there is only the connection AC, there is an impulse for all the whole R turns of the cam 5.

The basic time t of the impulse is in each case defined by the cam 5.

FIG. 17 is a diagram showing the timing, based on the assumption that the cam 5 makes one revolution in two minutes and the cam 23 one revolution in 6 minutes, i.e

According to requirements, the connections AB, AC, D and E may be selected by hand by way of a keyboard with keys or controlled by the cams of the programmers.

I claim:

1. In a programmer for a washing machine and the like, in combination:

(a) a shaft;

(b) cam means rotatable on said shaft;

(c) drive means for continuously rotating said cam means;

(d) a rotary cam block rotatable on said shaft;

(e) coupling means for periodically coupling said cam means to said cam block for joint angular displacement, whereby said cam block may turn periodically; and

(f) switches positioned for actuation of one of said switches by said cam means and for actuation of a plurality of said switches by said cam block during angular displacement of said cam means and of said cam block respectively,

(1) said cam block being a unitary hollow body of electrically nonconductive material.

2. The combination of claim 1, wherein said coupling means include a releasable splined connection between said cam block and said rotary cam means, said connection including a group of grooves and a group of teeth received in said grooves when said cam block is coupled to said rotary cam means, one of said groups being operatively connected to said rotary cam means for rotary movement therewith, the other group being integral with said cam block, one of said groups being axially shiftable into and out of engagement with the other group.

3. The combination of claim 1, further comprising positioning means connected to said rotary cam block for determining successive angular positions thereof during intervals between periodic turning of said cam block.

4. The combination of claim 3, wherein said positioning means includes projections of said cam block which are integral therewith and which extend parallel to said shaft.

5. The combination of claim 4- wherein a component in the hollow interior of said cam block is fixed to said shaft, said cam block having a shoulder adjacent the component to limit axial movement of said cam block in one direction along said shaft, and a frame carrying said shaft and having a wall situated adjacent a free end of at least one of said projections of said cam block for limiting axial movement thereof in an opposite direction, so that the axial position of said cam block on said shaft is determined.

6. The combination of claim 1 and wherein said cam block has an end situated adjacent said rotary cam means for preventing any substantial axial movement thereof on said shaft. k

7. The combination of claim 2, wherein said hollow cam block encloses an electromagnet, said shaft, as well as said rotary cam means and said cam block being made of a nonmagnetic material, and said electromagnet when energized displacing said group which is operatively connected with said rotary cam means into engagement with said group which is integral with said cam block for establishing a transmission from said rotary cam means to said cam block, said electromagnet being fixed to said shaft and said shaft being hollow and receiving conductors of said electromagnet, the operative connection between said shiftable group of the splined connection and said rotary cam means being in the form of projections of the latter extending parallel to said shaft and apertures in said shiftable group receiving said projections, and a spring surrounding said shaft and urging said shiftable group away from said group which is integral with said cam block to eliminate the connection between said rotary cam means and said cam block.

8. The combination of claim 7 wherein an electrical circuit means is formed in part by said one switch and is operatively connected with said electromagnet for periodically energizing the latter to provide a step-by-step advance of said cam block.

9. ,The combination of claim 8', further comprising positioning means for determining the angular position of said cam block during intervals between the turning thereof by said rotary cam means, said positioning means including a pair of ratchet wheels one of which is stationary and the other of which is operatively connected with said cam block for rotary movement therewith and a spring urging said other wheel into engagement with said stationary wheel.

10. The combination of claim 1 and wherein at least one additional cam is supported for free rotary movement by said rotary cam means for controlling at least one additional switch.

11. The combination of claim 1 and wherein a further cam is operatively connected with said cam block for rotary movement therewith as well as for axial shifting movement relative thereto, manually operable means coacting with the latter cam for shifting the latter between a pair of axial positions with respect to said cam block, a pair of switches one of which is controlled by said axially shiftable cam in one position thereof and the other of which is controlled by the latter cam in the other position thereof, and resilient detent means coacting with said axially shiftablelcam for maintaining the latter in one or the other of said positions thereof, said detent means including a pair of circular grooves formed in said fixed shaft and a springy member carried by said axially shift able cam and received in one or the other of said grooves.

References Cited UNITED STATES PATENTS 7/1929 Jackson 335 2/1968 Rose 335-74 FOREIGN PATENTS 973,814 10/1964 Great Britain.

U.S. Cl. X.R. 20038