US2137534A - Electric motor control - Google Patents

Description

Nov. 22, 1938.

R. '-G. LOCKETT 2,137,534

ELECTRIC MOTOR CONTROL Filed May 3, 1937 W WM 26 I @(Xmmg,

Patented Nov. 22, 1938 I "PATENT OFFICE 2,137,534 ELECTRIC MOTOR. CONTROL Ralph G. Lockett, Wauwatosa, Wis., asslgnor to Cutler-Hammer, Inc., Milwaukee, Wis., a corporation of Delaware application May a, museum No. 140,362

14 Claims.

This invention relates to improvements in electric motor control. The invention relates more particularly to a control system for a reversible electric motor driving a rotatable load, such as the cylindrical containers used in laundry machines for clothes washing and/or drying, and in machines for dyeing operations.

Machines of the character aforementioned are operated in regular cycles, which may con-- sist in rotating the cylindrical container alternately in opposite directions for predetermined periods of time or for a predetermined number of revolutions, with intermediate periods wherein the cylinder coasts at diminishing speed or 15 to rest before being driven in the opposite direction, or is gradually slowed or brought to rest by the driving motor through plugging or dynamic braking of the latter. These machines are ordinarily operated with varying loads in the cy1- inder, the cylinder being rotated in a tubor casing which may or may not contain liquid. The foregoing condtions aiiect the inertia of the various moving parts of the machine and consequently vary the time required for these parts to come to rest.

It is important to be able to effect control of the driving motor for machines of the aforementioned character in a manner which will reverse the direction of operation of the cylinder as soon as it has come to rest either by coasting or plugging; the reversal being eifected in a manner which is not toopronounced -so as to smoothly take up the back lash in the driving connections and avoid destructive pounding and wear and possible breakage of the latter. It is also important to effect smooth reversal and acceleration of the cylinder to avoid Wedding and tangling of the clothes, goods, or other load therein. Various devices have heretofore been proposed in an attempt to approach in some degree the aforementioned desirable features of control. Many of these devices, as for example, various well known pilot motor operated switching devices, involve complicated and expensive equipment.

An object of the invention is to provide novel, control means for accomplishing the aforementioned desirable results. 7 50 Another object is to provide means of the aforementioned character which is simple, eflicient and inexpensive.

Anotherobject is to provide a control system of the aforementioned character having the desired features of manual and automa.tlc control,

Other objects and advantages of the invention will hereinafter appear.

Theaccompanying drawing illustrates schematically and diagrammatically an embodiment of the invention which will now be described,it being understood that the embodiment illustrated is susceptible of modification as to certain details thereof without departing from the scope of the appended claims.

I have illustrated my invention as applied to 10 I the control of a reversible electric motor driving, a cylindrical container which is rotatable upon a horizontal axis,-such as is used in the laundry industry. In a device of this character it is desired to rotate the cylinder a predeter- 15 mined equal number of times in each direction, this being particularly desirable in the operation of machines used for dyeing operations,

between reversals of the cylinder unsuitable, 30

since the occurrence of. full power reversal of the cylinder at a moment before or after that in which the cylinder attains zero speed results in shock and undue wear upon the machine.

I propose to attain the aforementioned desirable objects by employing a traveling nut double-throw limit switch operated by the rotatable cylinder itself. This provides for alternate rotation of the cylinder a predetermined equal number of times in each direction. Operation 40 of the limit switch effects interruption, respectively, of the energizing circuits of the active reversing switch and an accelerating switch, and. effects establishment of the-energizing circuit for the other reversing switch. The latter provides 4.5 for plugging the motor under reduced voltage and torqueconditions; The back lash in the driving connections is thus taken up gradually, the cylinder is smoothly and gradually brought to zero speed and immediately started slowly o in the opposite direction. Immediately upon. reversal of the driving motor and the cylinder the accelerating" switch is brought in, for which purpose I provide a switch which is responsive to the direction of operation of the equipment.

This switch may be arranged for operation either directly by the motor or by the cylinder,and while I prefer to employ a friction belt or slipclutch operating connection for the switch, it will be apparent to those skilled in the art that any of thewell known pneumatic, hydraulic or magnetic-drag devices may be employed.

More -specifically,refern'ng to the drawing, the numeral I designates acylinder or drum 1 which is rotatable, preferably upon a horizon- .tal axis, within a stationary casing or tub 2 as by means of a reversible electric motor 3. Motor 3 may be of standard squirrel cage type, and suitable speed-reducing gearing 4 is preferably interposed between the motor shaft and the shaft of cylinder I. Tub 2 is provided with an opening, the door or closure for which is shown schematically at 5, to provide for access to cylinder 2 for loading and unloading thereof through a suitable opening or openings provided in the latter. Motor 3 is adapted to be supplied with current from a suitable source of supply, represented by lines L L and L through the medium of a pair of electromagnetically oper- 25 able reversing switches 6 and I. The operating windings 6 and I'- of switches 6 and 1 are respectively subjected to control in part by the limit switches 8 and 9,--the latter being mechanically connected, as by means of the pivoted link III, to insure joint operation thereof.

The shaft of cylinder l is provided with a threaded extension II which is adapted to cooperatively engage a pair of traveling nuts I2 and I 3,a guide rod or plate It being adapted to restrain said nuts against rotation. The arrangement is such that upon a predtermined number of revolutions of cylinder I in one 'direcis initially rendered eifective for completing an energizing circuit for the winding 6 or I respectively associated therewith upon closure of the push button switch I6. Energization of the winding 5 or l is further dependent on switch I1 and inch push button switches I8 and I9.

Switch I1 is adapted to be operated by the door 5 of tub 2, said switch having up contacts I1 which are adapted to be closed when door 5 is closed, and down contacts I I which are adapted to be closed when ,door 5 is open. Inch push button switches I8, and I9 are respectively provided with normally closed up-contacts I8 and I9 and normally open down contacts I8 and I9 The system further includes an accelerating by a frictionally operated switch 2I. The equipment is preferably provided with -an electromagnetically releasable brake. 22 shown here in association with the shaft of motor 3,

Thus with the several parts in the positions thereof illustrated, the equipment may be started by closing the push button switch I6. This completes an energizing circuit for the winding I of reversing switch I, said circuit extending from line L through push button switch I6, contacts switch 20, the winding 2|I of which is controlled I I of door switch II, contacts l3 and I3, re spectively, of inch push button switches I3 and I9, by conductor 23 through limit switch 9, by conductors 24 and 25, through said winding 1*, by conductor 30 through the normally closed contacts 20 of accelerating switch 20, and by conductor 3| to line L Contacts l 1, 1 are thus closed to establish power connections through resistances R R and R, respectively, for operation of motor 3 and cylinder I at a rela-- tively slow speed in a direction such as to cause movement of nuts I2 and I3 toward the right.

, Normally open contacts 1 and I of switch 'I are also closed, contacts I providing a maintaining circuit for winding 1* paralleling the interlock contacts 20, and contacts 1 providing an electrical interlock for winding 20* of accelerating switch 20.

It is preferred that the resistances R. R, R be of a relatively high value, so that the torque of motor 3 with the resistances in circuit is limited to a pointwhich is just sufiicient to break the cylinder shaft loose in its bearing on the initial start.

In accordance with my invention there is provided the switch 2I,'previously referred to, comprising an oscillatable contactor 32 and a pair of contacts 33 and 34 to be selectively engaged thereby, depending upon the direction of operation of motor 3 and cylinder I driven thereby. For this purpose the threaded shaft II is shown as provided with an extension to which a pulley ,35 is keyed or otherwise rigidly secured. Ex-

tending around and frictionally engaged with pulley 35 is a belt 36, the opposite ends of which are rigidly attached to contactor 32 on opposite sides of the point of pivotal support of the latter. Suitable means (not shown) are provided for insuring the desired degree of tension of belt 36 against pulley 35. A switch of the general character illustrated at 2| is shown and described in detail in Patent No. 1,964,199, granted June 26, 1934, to C. T. Evans.

With motor 3 and cylinder I operating in a direction to effect movement of nuts I2 and I3 toward the right the contactor 32 of switch 2| will be engaged with contact 34,-thus providing an energizing circuit for the operating winding 20 of accelerating switch 20, which circuit extends from line L through limit switch 9, as previously traced, by conductor 24 through contact 34 and contactor 32, by conductor 31 through said winding 23, by conductor 33 through contacts I and by conductor 3i to line L Contacts 20*, 23, 20 are thus closed to shunt resistances R R R to provide for accelerated operation of motor 3 and cylinder I. Normally closed contacts 20 are opened, but as previously mentioned, the energizing circuit for winding 1 of switch 1 is adapted to be maintained through contacts 1* of switch 1.

Pending opening of push button switch I6, or opening of tub door 5 with consequent opening of contacts I1 of door switch I1, motor 3 will operate under the conditions aforedescribed until nut I3 in its movement toward the right engages and opens limit switch 3, with consequent de-energization of the windings I! and 20 of reversing switch I and accelerating switch 20, respectively. Upon opening of limit .switch 9 the limit switch 8 is closed with a snap action to establish an energizing circuit for the winding 8 of reversing switch 6, which circuit may be traced from line L through push button switch I 6, contacts I1 of door switch I1, contacts II and I9 respectively, of inch push button switches l8 and I9, by conductor 23 through limit switch 8, by conductors 39 and 40, through said winding 6*, by conductor-43 through the normally closed contacts 20 and by conductor 3| to line L Contacts 6 6, 6 are thus closed to establish power connections through resistances R R3, R respectively, for motor 3 to provide for plugging thereof under reduced voltage and torque conditions, whereupon the motor and cylinder I driven thereby are smoothly and gradually slowed to zero speed. Immediately upon attainment of zero speed motor 3 starts to slowly'drive cylinder l in a direction such as to cause movement of nuts l2 and I3 toward the left. Normally open contacts 6 and 6 are also closed upon response of switch 6,-contacts 6 providing a maintaining circuit for winding 6? paralleling the interlock contacts 20, and contacts providing an electrical interlock for winding 26 of accelerating switch 20.

At the instant reverse movement of cylinder I is initiated the contactor 32 of switch 2| will be tilted by belt 36 intoengagement with contact 33, whereupon an energizing circuit for the winding 20- of accelerating switch 20 will be established, which .circuit extends from line L through limit switch 3, as previously traced, by conductor 39 through contact 33 and contactor 32, by conductor 3] through winding 20, by conductor 38 through contacts'6 and by conductor 3| to line L. Contacts 20*, 20, 20 of switch 20 are thus closed to shunt resistances R R", R to provide for accelerated operation of motor 3 and cylinder l. Normally closed, contacts 20 and 20 are opened, but as previously mentioned, the energizing circuit for winding 6 of switch 6 is adapted to be maintained through contacts 6 of switch 6.

The aforedescribed cycle of operations is repeated automatically until it is desired to shut down the entire system. Such a shut down may be eifected at will by opening the push button switch IE or by opening the tub door 5 which results in opening the contacts I'l of door switch 11, either of which effects de-energization oi the operating windings of the active reversing-switch and the accelerating switch 20. Opening of either the push button switch I6 or contacts I! also efiects de-energization of the operating winding 22- 01' brake 22, the circuit for which may be traced from line L through push button switch l6 and contacts IT, by conductor 44 through winding 22 to line L. It will be apparent that brake 22 is adapted to be released during forward, reverse or plugging operation of motor 3, and said brake acts to stop the equipment upon deenergization of. the motor.

The control system includes manually operable means to provide for inching operation of motor 3 in opposite directions selectively while winding 22 of brake 22 to effect release thereof during inching operation of the motor. As hereinbefore described, contacts I! of door switch H are adapted to be closed when tub door 5 is opened. Thus with the push button switch i 6 closed and contacts ii closed depression of inch push button switch l8 establishes an energizing circuit for the operating winding 6" of reversing switch 6, which circuit may be traced from line L through push button switch I6, contacts I1 and contacts I8 by conductor through inch limit switch 21 and thence by conductors 42 and 40 through winding 6 to line L as previously traced. Switch 6 responds to effect slow speed operation of motor 3 as hereinbefore described.

On the other hand, depression of inch push button switch l9 establishes an energizing circuit for the operating winding I of reversing switch I, which circuit may be traced from line L through push button switch l6, contacts l'l and contacts I9 by conductor 26 through inch limit switch 28 and thence by conductors 29 and 25 through winding I to line L as previously traced. Switch I responds to effect slow speed operation of motor 3 as hereinbefore described.

Continued depression of either of the inch push button switches l8 and ill will result in energization of the operating winding 20 of accelerating switch 20,-it being apparent that the contactor 32 of switch 2| will be or will have been tilted into engagement with one or the otherof the contacts 33 or 34 upon initiation of operation of The cirwinding 20 to line L as previously traced- Switch 20 responds to effect accelerated operation of motor 3 in one direction or the other,,as hereinbefore described.

As will be readily apparent from the drawingand from the foregoing description, the motor will be de-energized and brake 22 will operate to stop the equipment upon release of the depressed inch push button switch l8 or IS.

The inch limit switches 21 and 28 are adapted to shut down the system upon movement of traveling nuts 12 and [3 into opposite limits, respectively, to provide against movement of said nuts off of threaded shaft l I during inching operations. It will be noted that the number of revolutions through which the cylinder 1- is to be operated in opposite directions during automatic operation of the equipment is determined by the spacing of nutsl2 and i3 on shaft H, and obviously such spacing would beinterferedwith if saidnuts were allowed to run off of said shaft. i V

In certain cases it may be desirabe to inch the cylinder l with low torque corresponding to that produced by motor 3 when accelerating switch 20 is open. It isobvious to those skilled inthe art that inch push button switches l8 and I9 may be respectively equipped with an-additional set of normally closed contacts; these contacts to be connected in series with each other and in series. with the operating winding 20, so that accelerating switch 20 is always open during inching.

What I claim as new and desire to secure by Letters Patent is:

1. In a control system of the character described, in combination, a reversible electric motor, a load to be driven thereby in each direction, means for completing an energizing circuit for said motor whereby said load is driven in one direction under substantially normal torque con; ditions, means including a limit switch operable automatically to'efiect interruption of said motor circuit, said means being simultaneously operable to effect establishment of an alternative energizing circuit adapted to effect plugging of said motor under relatively low torque conditions, whereby said load is gradually brought to rest and is thereafter immediately driven in the reverse direction, a switch comprising a stationary contact and an oscillatable contactor, and means including a drag connection between said load and said contactor whereby the latter is engaged with said contact immediately upon reversal of the former in the manner aforementioned, said contactor when engaged with said contact being adapted to effect completion of an energizing circuit for said motor whereby the latter is adapted to drive said load under substantially normal torque conditions in the direction last mentioned.

2. In a control system of the character described, in combination, a reversible electric motor, a load to be driven thereby in each direction, a pair of normally open electromagnetically operable directional switches, one of said switches being adapted upon energization and closure thereof to effect completion of a circuit for operation of said motor in one direction under relatively low torque conditions, a normally open electromagnetic accelerating switch operable automatically thereafter to effect completion of a circuit for operation of said motor in said direction under substantially normal torque conditions, a limit switch operable upon a given number of revolutions of said load to effect deenergization and opening of said last mentioned directional switch and said accelerating switch, said limit switch being simultaneously operable to establish an energizing circuit for the other of said directional switches to effect completion of a circuit adapted to effect plugging of said motor under relatively low torque conditions, whereby said load is gradually slowed to rest and is thereafter immediately driven in the reverse direction, means operable immediately upon reversal of said load in the manner aforementioned to establish an energizing circuit forsaid accelerating switch to effect completion of a circuit for operation of said motor under substantially normal torque conditions in the direction last mentioned, said last mentioned means including a switch having a pair of stationary contacts and a pivoted contactor movable into engagement with one or the other of said contacts, depending'upon the direction of rotation of said load, said means including a drag connection between said motor and said contactor.

3. In a control system of the character described, in combination, a cylindrical container to be rotatably driven in each direction, a reversible electric motor having a driving connection with said container, means for completing an energizing circuit for said motor whereby said container is rotated in one direction at a relatively high speed, means including a limit switch operable automatically to effect interruption of said motor circuit, means including a second limit switch operable automatically and simultaneously with said first mentioned limit switch to effect establishment of an alternative energizing circuit for said motor to effect plugging thereof under relatively low torque conditions, whereby said container is gradually slowed to rest and is thereafter immediately driven in the reverse direction at a relatively slow speed, a switch comprising a stationary contact and an oscillatable contactor, means including a frictional driving connection between said container and said contactor whereby the latter is engaged with said contact immediately upon reversal of the former in the manner aforementioned, said contactorwhen engaged with said contact being adapted to effect completion of a circuit for said motor whereby the latter is adapted to drive said container in the direction thereof last mentioned at a relatively high speed, said second mentioned limit switch being operable automatically to interrupt said last established motor circuits upon a predetermined number of revolutions of said container in the direction last mentioned.

4. In a control system of the character described,'in combination, a cylindrical container to be rotatably driven in each direction, a reversible electric motor having a driving connection with said container, means for completing an energizing circuit for said motor whereby said container is rotated in one direction at substantially normal speed, means including a limit switch operable automatically to effect interruption of said motor circuit, means including a second limit switch operable automatically and simultaneously with said first mentioned limit switch to effect establishment of an alternative energizing'circuit for said motor to effect plugging thereof under relatively low torque conditions, whereby said container is gradually brought to rest and is thereafter immediately driven in the reverse direction at a relatively slow speed, a switch comprising a stationary contact and an oscillatable contactor, means including a frictional driving connection between said container and said contactcr whereby the latter is engaged with said contact immediately upon reversal of the former in the manner aforementioned, said contactor when engaged with said contact being adapted to effect completion of a circuit for said motor whereby the latter is adapted to drive said container in the direction last mentioned at substantially normal speed, said second mentioned limit switch being operable automatically to interrupt said last established motor circuits upon apredetermined number of revolutions of said container in the direction, last mentioned, and means for positively interlocking said limit switches to insure closure of each upon opening of the other of same.

5. In a control system of the character described, in combination, a cylindrical container to be rotatably driven in each direction, a reversible electric motor having a driving connection with said container, means for completing an energizing circuit for said motor whereby said container is rotated in one direction at substantially normal speed, means including a limit switch operable automatically to effect interruption of said motor circuit, means including a second limit switch operable automatically and simultaneously with said first mentioned limit switch to effect establishment of an alternative energizing circuit for said motor to effect plugging thereof under relatively low torque conditions, whereby said container is gradually brought to rest and is thereafter immediately driven in the reverse direction at a relatively slow speed, a switch comprising a stationary contact and an oscillatable contactor, means including a frictional driving connection between said container and said contactor whereby the latter is engaged with said contact immediately upon reversal of the former in the manner aforementioned, said contactor when engaged with said contact being adapted to effect completion of a circuit for said motor whereby the latter is adapted to drive said container in the 2,187,634 direction last mentioned at substantially normal speed, said second mentioned limitswitch being operable automatically to interrupt said last established motor circuits ,upon a predetermined number of revolutions of said container in the direction last mentioned, means for positively interlocking said limit switches to insure closure of each upon opening of the other of same, and spring means associated with said limit switches to effect movements thereof with a snap action.

\ 6. In a control systemof the character described, in combination, a substantially cylindrical container rotatable upon a horizontal axis, an electric motor having a positive driving con- 5 nection with said container, a pair of normally open electromagnetically operable directional switches respectively adapted when closed to provide circuit connectionsfor forward and reverse operation of said motor under relatively low torque conditions, means for insuring closure and opening. of the respective switches in sequence to effect periodic plugging and reversal of the direction of operation of said motor, said means comprising a pair of limit switches each having a pivoted contactorand an associated stationary contact, said 'contactors being mechanically interlocked to insure against simultaneous engagement thereof with said contacts, a pair of traveling nuts associated with said container and operable to sequentially eifect opening of each of said limit switches while simultaneously efiecting closure of the ,other of same upon like amounts of rotation of said container in opposite directions respectively, a normally open accelerating switch adapted when closed to provide circuit connections for operation of said motor under substantially normal torque conditions in either direction, closure of said accelerating switch, being subject to closure of each of said directionalswitches, respectively, andna direction-responsive switch common to said limit switches, said direction-responsive switch comprising a pair of spaced stationary contacts and an oscillatable contactor associated therewith, 5 a frictional driving connection interposed between said container and said contactor whereby the latter is engageable with said stationary contacts alternately as an incident to reversal of the direction of rotation of said container, the

arrangement being such that immediately upon reversal of said container following plugging of said motor said direction-responsive switch contactor eifects engagement with one of its associated contacts whereby ,an energizing circuit is "established for said'accelerating switch to provide for operation of said motor under substantially normal torque conditions. y

7. In a device ofthe character described, in combination, a reversible electric driving motor, a load tobe rotatably driven thereby in each direction, a pair of electromagnetically operable reversing switches'ror controlling thedirection,

of operation of said motor, means operable upon a predetermined number of revolutions of said load in each direction, respectively, to efiect sequential energization of said reversing switches to provide for plugging and subsequent reversal of said motor under predetermined relatively low voltage conditions, an electromagnetically oper-" able accelerating switch. common to said reversing switches, means operable immediately upon reversal oi said motor toeil'ect energization of said accelerating switch to provideior operation of said motor under normal voltage conditions, said last mentioned means comprising an oscil-,

latable contactor, a pair of contacts to be selec-" tively engaged thereby, and means providing a friction driving connection between said load and said contactor, whereby the latter is moved alternately from each extreme position thereof to the other only upon the reversing operations of said load.

8. In a device of the character described, in combination, a reversible electric driving motor, a load to be rotatably driven thereby in each direction, a pair of electromagnetically operable reversing switches for controlling the direction of operation of said motor, means operable upon a predetermined number of revolutions of said load in each direction respectively to effect sequential energization of said reversing switches to provide for plugging and subsequent reversal of said motor under predetermined relatively low voltage conditions, means associated with said reversing switches and operable automatically in response to operation of direction-re sponsive means to provide for operation of said motor under normal voltage conditions, said dimotion-responsive means comprising an' oscillatable contactor, a pair of contacts to beselectively engaged thereby, and means to provide a drag connection between said load and said contactor, whereby the latter is moved alternate- 1y from each extreme position thereof to the other only upon the reversing operations of said load.

9. In a controller for motor operated washing machines, in combination, a reversible electric driving motor, an element to be rotatably driven thereby in each direction, means operable automatically by said element upona given amount of rotationthereby in eachdirection to initiate operation 01 said motor under relatively low torque conditions to efiect plugging thereof and subsequent rotation of said element in the reverse direction at a relatively slow speed, means operable automatically and substantially simultaneously with reversal of said element to effect acceleration of the rate of operation of said motor in each direction, said last mentioned means comprising a drag device associated with other of said reversing switches and said acceler said element and a plurality of sets of contacts ating switch in sequence to provide for rotation I of said container in one direction by said motor under normal voltage conditions, means comprising a limit switch operable upon a given number of revolutions of said container to effect deenergizat ion of said reversing switch and said accelerating switch with consequent interruption of the motor circuit, means operable substantially simultaneously with said last mentioned means to eilect energization and closure of the other of said reversing switches to provide for plugging of said motor under relatively low voltage conditions with consequent gradual stopping and subsequent reversal of the direction of rotation of said container, switching means comprising a contact element movable in opposite directions between given circuit controlling positions, means comprising a frictional driving connection between said container and said contact element, whereby said contact element is moved from one circuit controlling position thereof to the other as an incident of the reverse rotation of said container, and means adapted upon such movement of said contact element to automatically efiect energization and closure of said accelerating switch, whereby reverse operation of said driving motor under said normal voltage conditions is effected, to thereby insure completion of the accelerating circuit connections for said motor only upon initiation of relatively slow rotation of said load in said reverse direction.

11. In a controller for motor operated washing machines, in combination, a reversible electric driving motor, a substantially cylindrical, container to be rotatably driven thereby in each direction, a pair of electromagnetically operable reversing switches adapted when energized selectively to alternately provide reverse circuit connections for said motor, an electromagnetically operable accelerating switch, means including manually operable means for initially eifecting energization and closure of one or the other of said reversing switches and said acceleratin switch in sequence to provide for rotation of said container in one direction by said motor under normal voltage conditions, means comprising a limit switch operable upon a given number of revolutions of said container to effect deenergization of said reversing switch and said accelerating switch with consequent interruption of the motor circuit, means operable substantially simultaneously with said last mentioned means to eifect energization and closure of the other of said reversing switches to provide for plugging of said motor under relatively low voltage conditions with consequent gradual stopping and subsequent reversal of the direction of rotation of said container, switching means comprising a contact element movable in opposite directions between given circuit controlling positions, means comprising a frictional driving connection between said container and said contact element, whereby said contact element is moved from one circuit controlling position thereof to the other as an incident of the reverse rotation of said container, and means adaptedupon such movement of said contact element to automatically effect energization and closure of said accelerating switch, whereby reverse operation of said driving motor under said normal voltage conditions is effected, to thereby insure completion of the acceleratin circuit connections for said motor only upon initiation of relatively slow rotation of said load in said reverse direction, said limit switch also acting upon said given number of revolutions of said container in said-reverse direction to effect deenergization of the second mentioned reversing switch and said accelerating switch with consequent interruption of the motor circuit, said simultaneously operable means being effective to reenergize said first mentioned reversing switch, whereby the operating cycle aforedescribed is repeated.

12. In a controller for motor operated washing machines, in combination, a reversible electric driving motor, a substantially cylindrical container to be rotatably driven thereby in each direction, a pair of electromagnetically operable reversing switches adapted when energized selectively to alternately provide reverse circuit connections for said motor, an electromagnetically operable accelerating switch, means including manually operable means for initially eifecting energization and closure of one or the other of said reversing switches and said accelerating switch in sequence to provide for rotation of said container in one direction by said motor under normal voltage conditions, means comprising a limit switch operable upon a given number of revolutions of said container to effect deenergization of said reversing switch and said accelerating switch with consequent interruption of the motor circuit, means operable substantially simultaneously with said last mentioned means to effect energization and closure of the other of said reversing switches to provide for plugging oi. said motor under relatively low voltage conditions with consequentgradual stopping and subsequent reversal of the direction of rotation of said container, switching means comprising a contact element movable in opposite directions between given circuit controlling position, means comprising a frictional driving connection between said container and said contact element, whereby said contact element is moved from one circuit controlling position thereof to the other as an incident of the reverse rotation of said container, and means adapted upon suchmovement of said contact element to automatically efiect energization and closure of said accelerating switch, whereby reverse operation of said driving motor under said normal voltage conditions is efiected, to thereby insure completion of the accelerating circuit connections for said motor only upon initiation of relatively slow rotation of said load in said reverse direction, said limit switch also acting upon said given number of revolutions of said container in said reverse direction to eifect deenergization of the second mentioned reversing switch and said accelerating switch with consequent interruption of the motor circuit, said simultaneously operable means being effective to reenergize said first mentioned reversing switch, whereby the operating cycle aforedescribed is repeated, and means including a normally closed manually operable switch adapted upon opening thereof to effect at will a full stop of said motor and the container 0 driven thereby.

13. In a controller for motor operated washing machines, in combination, a reversible electric driving motor, a substantially cylindrical container to be rotatably driven thereby in each direction, a pair of 'electromagneticallyoperable reversing switches adapted when energized selectively to alternately provide reverse circuit connections for said motor, an electromagnetically operable accelerating switch, means including manually operable means for initially effecting energization and closure of one or the other of said reversing switches and said accelerating switch in sequence to provide for rotation of said container in one direction by said motor under normal voltage conditions, means comprising a limit switch operable upon a given number of revolutions of said container to effect deenergization or said reversing switch and said accelerating switch with consequent interruption of the motor circuit, means operable substantially simultaneously with said last mentioned means to eflfect energization Tahd closure of the other of said reversing switches to provide for plugging of said motor under relatively low voltage conditions with consequent gradual stopping and subsequent reversal of the direction of rotation oi. said container, switching means comprising a contact element movable in opposite directions between given circuit controlling positions, means comprising a frictional driving connection between said container'and said contact element, whereby said contact element is moved from one circuit controlling position thereof to the other as an incident of the reverse rotation of said container,

and means adapted upon such movement of said contact element to automatically effect energize.- tion and closure of said accelerating switch, whereby reverse operation of said driving motor under said normal voltage conditions is effected, to thereby insure completion of the accelerating circuit connections for said motor only upon initiation of relatively slow rotation of said load in said reverse direction, said limit switch also acting upon said given number of revolutions of said container in said reverse direction to effect deengization of the second mentioned reversing switch and said accelerating switch with consequent interruption of the motor circuit, said simultaneously operable means being eifective to reenergize said first mentioned reversing switch, whereby the operating cycle aforedescribed is repeated, and means including a normally closed manually operable switch adapted upon openin thereof to effect at will a full stop of said motor and the container driven thereby, and means associated with said last mentionedmeans to effect operation of said motor in one direction or the other at will.

able to subsequently initiate operation of said motor in the reverse direction at a relatively slow speed, means operable automatically to insure full power electrical connection of said motor to effect acceleration of the rate of operation thereof to substantially normal speed only upon reversal thereof, said last mentioned means comprising a drag device associated with said element, and a plurality of sets of contacts respectively controlled by said drag device in accordance with the direction of rotation of said element.

RALPH G. LOCKETT.

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