US1940928A - Electrical apparatus - Google Patents
Electrical apparatus Download PDFInfo
- Publication number
- US1940928A US1940928A US487307A US48730730A US1940928A US 1940928 A US1940928 A US 1940928A US 487307 A US487307 A US 487307A US 48730730 A US48730730 A US 48730730A US 1940928 A US1940928 A US 1940928A
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- Prior art keywords
- switch
- reverse switch
- reverse
- locking
- motor
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P7/00—Arrangements for regulating or controlling the speed or torque of electric DC motors
- H02P7/03—Arrangements for regulating or controlling the speed or torque of electric DC motors for controlling the direction of rotation of DC motors
Definitions
- My invention relates to electrical apparatus, and more particularly to electric controlling apparatus for reversible motors.
- An object of my invention is to provide an improved controlling mechanism. Another object of my invention is to provide improved starting and reversing mechanism for an electric motor. A further object of my invention is to provide an improved starting and reversing mechanism for an electric motor in which starting is impossible except in predetermined positions of the reverse switch and in which during running, movement of the reverse switch is precluded both when current is being supplied to the motor and after the interruption of current supply to the motor from an external source when the motor is rotating at a suflicient speed so that there is any material current flowing in its armature. Other objects and advantages of my invention will hereinafter more fully appear.
- FIG. 1 is a front view of the exterior of the improved controlling mechanism.
- Fig. 2 is a view with the cover plate removed, taken approximately on the line 22 of' Fig. 3.
- I Fig. 3 is a section on the line 3-3 of Fig. 2.
- Fig. 4 is a section on the line 4-4 of Fig. 2.
- Fig. 5 is a diagrammatic view showing an illustrative form of circuit of which the controlling mechanism of the invention may form a part.
- 1 is a casing with- 5 in which the illustrative embodiment of the invention is enclosed.
- This casing has a front cover plate 2 through which an operating shaft 3 for the reversing mechanism later described projects, and the shaft 3 is provided with an operating handle 4.
- a pair of push buttons 5 and 6 also project through and are guided in the cover plate 2, the push button 5 being a start button and the button 6 a stop button.
- Within the casing 1 is a housing member '7 in which a switch 8 (see Fig. 5) is disposed for movement to circuit closing position by pressure upon the button 5 and to cir cuit opening position by the stop button 6.
- This switch 8 may be either a switch for controlling a pilot circuit, as illustrated in said wiring diagram, or may be, under some circumstances, a switch controlling the main linedirectly. Switch 8 may therefore be termed a primary switch.
- the push button 5 has an operating rod 10 connected to it, and this rod has a collar 11 formed 50 upon it for a purpose which will shortly appear.
- the reverse switch operating shaft 3 carries at its inner end and within the space enclosed within the cover plate 2 a T-shaped head portion 12 which cooperates with a transverse slot 13 on a reverse switch contact carrying member 14 to rotate the latter to its operative circuit making positions.
- the member 14 carries segmental contactor plates 15 which are adapted to cooperate with stationary contacts 16 two of which are shown in Fig. 4, there being four of these contacts, arranged one in each quadrant, and in one circuit making position of the reverse switch the plates 15 connect for example, the contact members 16 in the first and fourth and second and third quadrants respectively, while in another circuit making position the first and second quadrant contacts and the third and fourth quadrant contacts would be connected.
- Rotating with the shaft 3 is a plate 18 which has in its periphery three notches 19, two of these being disposed diametrically opposite each other, and the third midway between the other two.
- the form of these notches 19 and their disposition permits certain of them to receive the collar 11 associated with the push button 5 when the latter is de- 90 pressed, provided thenotches are in proper position with respect to the push button. Unless the notches are, however, in juxtaposition to the collar 11 the unnotched portions of the disc 18 preclude depression of the push starting or circuit closing position.
- Fig. 2 shows one of the notches 19 in such relation to the push button 5 that depression of this push button may effect starting of the motor
- an electrically controlled locking device including a plunger or lock member 20 which, in the position of the parts in Fig. 2, may engage the left hand notch 19; and in the position of the parts when the handle 4 is moved from the position of Fig. l to its other operative position, the plunger or lock member would engage the central one of the notches 19.
- the member 20 is actuated by an armature 21 which is moved, upon current supply to the solenoid 22, to cause the member20 to project into a notch 19.
- the solenoid 22 is connected acrossthe armature of the motor to be controlled so that whenever current is flowing in the armature the solenoid 22 will be energized and the plunger or stop member 20 maintained in looking position. Stops 25 and 26 are arranged to cooperate with the hand lever 4 to facilitate proper position of the reverse switch in its different operative positions.
- the motor M comprises an armature 27, a series 'field 28, and a shunt fleld 29.
- the reversing switch generally designated R is arranged to reverse the direction of current flow through the armature.
- a resistance cut out device, which may be either of the manually operated or automatically operated type is diagrammatically illustrated at 30.
- a main line switch 31 is controlled by a solenoid 32in a pilot circuit 33, the latter controlled by the switch 8.
- a reverse switch a switch adapted to control the initiation of current fiow through the reverse switch, a plate, operating means for said reverse switch on the face of said plate, means also on the .face of said plate movable to effect closure of said second switch, and interlocking connections precluding movement of the reverse switch when the second switch-is in circuit making position including a member movable with the reverse switch and a cooperating member movable at an angle to the plane of movement of the first member and movable with the second switch member.
- a rotatable reverse switch a member movable with the reverse switch and having three spaced locking portions
- cooperating locking element engageable alternatively with two of said locking portions to hold said reverse switch in its reverse circuit establishing positions, controlling means for said locking element, a second locking element also engageable alternatively with two of said locking portions to hold said reverse switch in its reverse circuit establishing positions, and controlling means for said second mentioned locking element; one of said locking portions being engageable only by one of said locking elements, another of said locking portions being engageable only by the other of said locking elements, and the third of said looking portions being engageable by one or other oi said locking elements, depending upon which of its reverse circuit establishing positions said reverse switch occupies.
- a reverse switch In an electric controlling apparatus, a reverse switch, a plate movable therewith, a look-- ing element adapted to be automatically moved to and maintained in looking position during substantial current flow through the reverse switch, a switch adapted to institute and interrupt current flow through the reverse switch, a second locking element moved to locking position on closure of said second mentioned'switch, and a plurality of notches in said plate engageable by said locking elements, one of said notches being engageable by different locking elements in different positions of the reverse switch.
- a rotatable reverse switch a member movable with the reverse switch and having three spaced locking portions, a cooperating locking element engageable alternatively with two of said locking portions to hold said reverse, switch in its reverse circuit establishing positions, controlling means for said locking element, a second locking element also engageable alternatively with two of said locking portions to hold said reverse switch in its reverse circuit establishing positions, and controlling means for saidgsecond mentioned locking element; one of 12 said locking portions being engageable only by one of said locking elements, another of said locking portions being engageable only by the other of said locking elements, and the third of said locking portions being engageable by one or the other of said locking elements, depending upon which of its reverse circuit establishing positions said reverse switch occupies, and one of said locking element controlling means being manually operable and the other electrically operable, the latter having operating means adapted to effect its operation automatically on movement of the former to locking positions and to remain effective after opposite movement 01' the first mentioned locking element if substantial 186/ current is flowing in the reverse switch.
- a motor having a shunt field and an armature, a reverse switch, a switch movable to effect initiation and interruption of current flow through the reverse switch, and means for controlling movements 01'
- said reverse switch including a locking device for the latter controlled by said second switch and operative, on movement of said second switch to effect initiation of current flow, to lock said reverse switch against movement, and subsidiary locking means controlled by current flowing through said armature for preventing movement of said reverse switch while said motor is rotating at a substantial speed.
- a rotatable reverse switch In a motor controlling mechanism, a rotatable reverse switch, a disc rotatable with said reverse switch and having three notches, a looking element reciprocable parallel to the axis of rotation of said reverse switch and engageable alternatively with two of said notches, controlling means for said locking element adapted to be governed by current flow in the circuit con trolled by said reverse switch, and a second looking element reciprocable parallel to the axis of rotation of said reverse switch engageable alternatively with one of said two notches last mentioned and with the third notch and adapted to be moved to locking position on initiation of current supply to said reverse switch.
- a reverse switch and manual and electrical devices for locking the same in diflerent operative positions including a member occupying one predetermined position in one operative position of said reverse switch and another predetermined position in a difierent operative position of said reverse switch and operative when held stationary to fix said reverse switch against circuit-altering movement, said member cooperating at a certain locus thereon with one of said locking devices in one operative position of the reverse switch and cooperating at the same locus thereon with the other of said locking devices in another operative position of the reverse switch.
- a motor having a shunt field and an armature, a reverse switch, a switch movable to effect initiation and interruption of current flow through the reverse switch, said reverse switch having operating means for efiecting movement thereof, while said second mentioned switch is in open-circuit position', to one of its opposite circuit making positions, and means for further controlling movement of said reverse switch including a locking device for the latter controlled by the second switch, and subsidiary locking means controlled ,by current flowing through said armature for preventing movement of said reverse switch while said motor is rotating at a substantial speed.
- a motor having a shunt field and an armature, a reverse switch, a switch movable to effect initiation and interruption of current flow through the reverse switch, means for efiecting movement of said reverse switch, means for efiecting movement of said second switch, a locking device for the reverse switch controlled by the operating means for said second switch, and subsidiary locking means for said reverse switch controlled by current flowing through said armature for preventing movement of said reverse switch while said motor is rotating at a substantial speed.
- a reverse switch a member movable with said reverse switch and provided with a plurality of notches, and locking means adapted to cooperate with said notches to hold said reverse switch in circuit closing positions including locking elements respectively manually and electrically moved into said notches, said electrically moved means having controlling means adapted to maintain it in notch engaging position as long as a motor controlled thereby operates at a substantial speed.
- a reverse switch a member movable therewith, a locking element arranged to cooperate with said member, a primary switch, a second locking element movable with said primary switch and arranged to cooperate with said member to lock the latter on closure of said primary switch, and a plurality of recesses in said member engageable by said locking elements, one of said recesses being engageable by different locking elements in different positions of the reverse switch.
- a rotatable reverse switch a disc rotatable with said reverse switch and having three notches, a locking element reciprocable parallel to the axis of rotation of said re- .erse switch and engaging alternatively with two of said notches, controlling means for said locking element, a second locking element reciprocable parallel to the axis of rotation of said reverse switch and engageable alternatively with one of said two notches last mentioned and with the third notch.
- a reverse switch In combination, a reverse switch, a primary switch, a plate, operating means for said reverse switch on the face of said plate, means also on the face of said plate movable from the front of the latter to efiect closure of said second switch, interlocking connections precluding movement of the reverse switch when the primary switch is closed including a member movable with the reverse switch and a cooperating member movable at an angle to the plane of movement of the first member and movable with the primary switch.
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Stopping Of Electric Motors (AREA)
Description
Dec. 26, 1933. I c. w. WYMAN ELECTRICAL APPARATUS Filed Oct. 8. 1950 2 Shee ts-Sheet 1 [WE/from CAI/7R1. 5 WWI rim. /A W Patented Dec. 26, 1933 ELECTRICAL APPARATUS Charles W. Wyman, Claremont, N. IL, assign'or to Sullivan Machinery Company, a corporation of Massachusetts Application October 8, 1930. Serial No. 487,307
13 Claims. (01. 172-179) My invention relates to electrical apparatus, and more particularly to electric controlling apparatus for reversible motors.
An object of my invention is to provide an improved controlling mechanism. Another object of my invention is to provide improved starting and reversing mechanism for an electric motor. A further object of my invention is to provide an improved starting and reversing mechanism for an electric motor in which starting is impossible except in predetermined positions of the reverse switch and in which during running, movement of the reverse switch is precluded both when current is being supplied to the motor and after the interruption of current supply to the motor from an external source when the motor is rotating at a suflicient speed so that there is any material current flowing in its armature. Other objects and advantages of my invention will hereinafter more fully appear.
In the accompanying drawings I have shown for purposes of illustration one form which the invention may assume in practice, and in these drawings 7 5 Fig. 1 is a front view of the exterior of the improved controlling mechanism.
Fig. 2 is a view with the cover plate removed, taken approximately on the line 22 of' Fig. 3. I Fig. 3 is a section on the line 3-3 of Fig. 2. Fig. 4 is a section on the line 4-4 of Fig. 2.
Fig. 5 is a diagrammatic view showing an illustrative form of circuit of which the controlling mechanism of the invention may form a part.
Referring to the drawings, 1 is a casing with- 5 in which the illustrative embodiment of the invention is enclosed. This casing has a front cover plate 2 through which an operating shaft 3 for the reversing mechanism later described projects, and the shaft 3 is provided with an operating handle 4. A pair of push buttons 5 and 6 also project through and are guided in the cover plate 2, the push button 5 being a start button and the button 6 a stop button. Within the casing 1 is a housing member '7 in which a switch 8 (see Fig. 5) is disposed for movement to circuit closing position by pressure upon the button 5 and to cir cuit opening position by the stop button 6. This switch 8 may be either a switch for controlling a pilot circuit, as illustrated in said wiring diagram, or may be, under some circumstances, a switch controlling the main linedirectly. Switch 8 may therefore be termed a primary switch. The push button 5 has an operating rod 10 connected to it, and this rod has a collar 11 formed 50 upon it for a purpose which will shortly appear.
The reverse switch operating shaft 3 carries at its inner end and within the space enclosed within the cover plate 2 a T-shaped head portion 12 which cooperates with a transverse slot 13 on a reverse switch contact carrying member 14 to rotate the latter to its operative circuit making positions. The member 14 carries segmental contactor plates 15 which are adapted to cooperate with stationary contacts 16 two of which are shown in Fig. 4, there being four of these contacts, arranged one in each quadrant, and in one circuit making position of the reverse switch the plates 15 connect for example, the contact members 16 in the first and fourth and second and third quadrants respectively, while in another circuit making position the first and second quadrant contacts and the third and fourth quadrant contacts would be connected. Rotating with the shaft 3 is a plate 18 which has in its periphery three notches 19, two of these being disposed diametrically opposite each other, and the third midway between the other two. The form of these notches 19 and their disposition permits certain of them to receive the collar 11 associated with the push button 5 when the latter is de- 90 pressed, provided thenotches are in proper position with respect to the push button. Unless the notches are, however, in juxtaposition to the collar 11 the unnotched portions of the disc 18 preclude depression of the push starting or circuit closing position.
Fig. 2 shows one of the notches 19 in such relation to the push button 5 that depression of this push button may effect starting of the motor,
Also adapted to cooperate with the disc 18 is an electrically controlled locking device, including a plunger or lock member 20 which, in the position of the parts in Fig. 2, may engage the left hand notch 19; and in the position of the parts when the handle 4 is moved from the position of Fig. l to its other operative position, the plunger or lock member would engage the central one of the notches 19. The member 20 is actuated by an armature 21 which is moved, upon current supply to the solenoid 22, to cause the member20 to project into a notch 19. The solenoid 22 is connected acrossthe armature of the motor to be controlled so that whenever current is flowing in the armature the solenoid 22 will be energized and the plunger or stop member 20 maintained in looking position. Stops 25 and 26 are arranged to cooperate with the hand lever 4 to facilitate proper position of the reverse switch in its different operative positions.
Referring to Fig. 5, the motor M comprises an armature 27, a series 'field 28, and a shunt fleld 29. The reversing switch generally designated R is arranged to reverse the direction of current flow through the armature. A resistance cut out device, which may be either of the manually operated or automatically operated type is diagrammatically illustrated at 30. A main line switch 31 is controlled by a solenoid 32in a pilot circuit 33, the latter controlled by the switch 8.
Unless the reverse switch is in one of its circuit making positions, that is in the position of Fig. 1, or in a position clockwise from that position, the flange of disk 18 will prevent the collar or flange 11 on the push button rod 10 moving inwardly, and thus hold switch 8 open. When the reverse switch is in proper position to effect running in one direction, the push button --5 may be pushed in to close the pilot circuit and thereupon the main line switch 31 will be closed. Immediately the solenoid 22 will be energized and the lock member 22 moved to position to interfit with one of the notches 19. Thereafter, so long as any material current flows in the armature, the reverse switch is held immovable. When, however,-
the motor has been stopped due to opening of the line switch the lock member 20 will be retracted automatically and the reverse switch can be moved to its other position if desired.
From the foregoing description it will be apparent that I have provided a very simple and yet certain mechanism for insuring against success in unwarranted attempts to reverse the motor while the same is running. The parts are inexpensive, very compactly arranged, and positive in action, and insure the proper positioning of the reverse switch before any circuit can be closed as well as prevent movement of the reverse switch from one circuit establishing position to open circuit position or to a different circuit establishing position as long as the motor is connected across the line or any substantial current is generated after connection with the line is broken within the motor armature.
While there is in this application specifically described one form which the invention may assume in practice, it will be understood that this form of the same is shown for purposes of illustration and that the invention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.
What I claim as new and Letters Patent is:
1. In a motor controlling mechanism, a reverse switch, a switch adapted to control the initiation of current fiow through the reverse switch, a plate, operating means for said reverse switch on the face of said plate, means also on the .face of said plate movable to effect closure of said second switch, and interlocking connections precluding movement of the reverse switch when the second switch-is in circuit making position including a member movable with the reverse switch and a cooperating member movable at an angle to the plane of movement of the first member and movable with the second switch member.
desire to secure by 2. In combination, a rotatable reverse switch, a member movable with the reverse switch and having three spaced locking portions, 9. cooperating locking element engageable alternatively with two of said locking portions to hold said reverse switch in its reverse circuit establishing positions, controlling means for said locking element, a second locking element also engageable alternatively with two of said locking portions to hold said reverse switch in its reverse circuit establishing positions, and controlling means for said second mentioned locking element; one of said locking portions being engageable only by one of said locking elements, another of said locking portions being engageable only by the other of said locking elements, and the third of said looking portions being engageable by one or other oi said locking elements, depending upon which of its reverse circuit establishing positions said reverse switch occupies.
3. In an electric controlling apparatus, a reverse switch, a plate movable therewith, a look-- ing element adapted to be automatically moved to and maintained in looking position during substantial current flow through the reverse switch, a switch adapted to institute and interrupt current flow through the reverse switch, a second locking element moved to locking position on closure of said second mentioned'switch, and a plurality of notches in said plate engageable by said locking elements, one of said notches being engageable by different locking elements in different positions of the reverse switch.
4. In combination, a rotatable reverse switch, a member movable with the reverse switch and having three spaced locking portions, a cooperating locking element engageable alternatively with two of said locking portions to hold said reverse, switch in its reverse circuit establishing positions, controlling means for said locking element, a second locking element also engageable alternatively with two of said locking portions to hold said reverse switch in its reverse circuit establishing positions, and controlling means for saidgsecond mentioned locking element; one of 12 said locking portions being engageable only by one of said locking elements, another of said locking portions being engageable only by the other of said locking elements, and the third of said locking portions being engageable by one or the other of said locking elements, depending upon which of its reverse circuit establishing positions said reverse switch occupies, and one of said locking element controlling means being manually operable and the other electrically operable, the latter having operating means adapted to effect its operation automatically on movement of the former to locking positions and to remain effective after opposite movement 01' the first mentioned locking element if substantial 186/ current is flowing in the reverse switch.
5. In a motor controlling mechanism, a motor having a shunt field and an armature, a reverse switch, a switch movable to effect initiation and interruption of current flow through the reverse switch, and means for controlling movements 01' said reverse switch including a locking device for the latter controlled by said second switch and operative, on movement of said second switch to effect initiation of current flow, to lock said reverse switch against movement, and subsidiary locking means controlled by current flowing through said armature for preventing movement of said reverse switch while said motor is rotating at a substantial speed.
6. In a motor controlling mechanism, a rotatable reverse switch, a disc rotatable with said reverse switch and having three notches, a looking element reciprocable parallel to the axis of rotation of said reverse switch and engageable alternatively with two of said notches, controlling means for said locking element adapted to be governed by current flow in the circuit con trolled by said reverse switch, and a second looking element reciprocable parallel to the axis of rotation of said reverse switch engageable alternatively with one of said two notches last mentioned and with the third notch and adapted to be moved to locking position on initiation of current supply to said reverse switch.
7. In a motor controlling apparatus, a reverse switch and manual and electrical devices for locking the same in diflerent operative positions including a member occupying one predetermined position in one operative position of said reverse switch and another predetermined position in a difierent operative position of said reverse switch and operative when held stationary to fix said reverse switch against circuit-altering movement, said member cooperating at a certain locus thereon with one of said locking devices in one operative position of the reverse switch and cooperating at the same locus thereon with the other of said locking devices in another operative position of the reverse switch.
8. In a motor controlling mechanism, a motor having a shunt field and an armature, a reverse switch, a switch movable to effect initiation and interruption of current flow through the reverse switch, said reverse switch having operating means for efiecting movement thereof, while said second mentioned switch is in open-circuit position', to one of its opposite circuit making positions, and means for further controlling movement of said reverse switch including a locking device for the latter controlled by the second switch, and subsidiary locking means controlled ,by current flowing through said armature for preventing movement of said reverse switch while said motor is rotating at a substantial speed.
9. In a motor controlling mechanism, a motor having a shunt field and an armature, a reverse switch, a switch movable to effect initiation and interruption of current flow through the reverse switch, means for efiecting movement of said reverse switch, means for efiecting movement of said second switch, a locking device for the reverse switch controlled by the operating means for said second switch, and subsidiary locking means for said reverse switch controlled by current flowing through said armature for preventing movement of said reverse switch while said motor is rotating at a substantial speed.
10. In an electric controlling apparatus for a motor, a reverse switch, a member movable with said reverse switch and provided with a plurality of notches, and locking means adapted to cooperate with said notches to hold said reverse switch in circuit closing positions including locking elements respectively manually and electrically moved into said notches, said electrically moved means having controlling means adapted to maintain it in notch engaging position as long as a motor controlled thereby operates at a substantial speed.
11. In combination, a reverse switch, a member movable therewith, a locking element arranged to cooperate with said member, a primary switch, a second locking element movable with said primary switch and arranged to cooperate with said member to lock the latter on closure of said primary switch, and a plurality of recesses in said member engageable by said locking elements, one of said recesses being engageable by different locking elements in different positions of the reverse switch.
12. In combination, a rotatable reverse switch, a disc rotatable with said reverse switch and having three notches, a locking element reciprocable parallel to the axis of rotation of said re- .erse switch and engaging alternatively with two of said notches, controlling means for said locking element, a second locking element reciprocable parallel to the axis of rotation of said reverse switch and engageable alternatively with one of said two notches last mentioned and with the third notch.
13. In combination, a reverse switch, a primary switch, a plate, operating means for said reverse switch on the face of said plate, means also on the face of said plate movable from the front of the latter to efiect closure of said second switch, interlocking connections precluding movement of the reverse switch when the primary switch is closed including a member movable with the reverse switch and a cooperating member movable at an angle to the plane of movement of the first member and movable with the primary switch.
CHARLES w. WYMAN.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US487307A US1940928A (en) | 1930-10-08 | 1930-10-08 | Electrical apparatus |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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US487307A US1940928A (en) | 1930-10-08 | 1930-10-08 | Electrical apparatus |
Publications (1)
Publication Number | Publication Date |
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US1940928A true US1940928A (en) | 1933-12-26 |
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ID=23935206
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Application Number | Title | Priority Date | Filing Date |
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US487307A Expired - Lifetime US1940928A (en) | 1930-10-08 | 1930-10-08 | Electrical apparatus |
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Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2608624A (en) * | 1948-09-18 | 1952-08-26 | Joy Mfg Co | Manually operated switch with magnetically latched position |
US2658962A (en) * | 1949-02-07 | 1953-11-10 | Rotax Ltd | Electric switch |
US3319144A (en) * | 1964-05-04 | 1967-05-09 | Gen Motors Corp | Timer control mechanism with indexing means |
-
1930
- 1930-10-08 US US487307A patent/US1940928A/en not_active Expired - Lifetime
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2608624A (en) * | 1948-09-18 | 1952-08-26 | Joy Mfg Co | Manually operated switch with magnetically latched position |
US2658962A (en) * | 1949-02-07 | 1953-11-10 | Rotax Ltd | Electric switch |
US3319144A (en) * | 1964-05-04 | 1967-05-09 | Gen Motors Corp | Timer control mechanism with indexing means |
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