| 摘要 |
<p>632,840. Control of D.C. motors. GENERAL MOTORS CORPORATION. Sept. 6, 1947, No. 24573. Convention date, Nov. 20, 1946. [Class 38 (iii)] [Also in Group XXXVIII] A control device for a reversible electric motor comprises a pair of switches for controlling rotation of the motor in respective opposite directions and normally held by spring means in contact with a switch-actuator, and a manually operable member for moving either of the switches away from said actuator and thereby energizing the motor, the actuator being movable intermittently towards the moved switch for stopping the motor, under the control of motor rotation. If an arm 110 is moved in a clockwise direction from the neutral position shown, a switch-arm 90 is swung about its pivot and a plunger 94 disengages a lug 95 on a toothed member 82 so allowing contacts 92-93 to close. A spring 105 is additionally tensioned, but, since a prong 89 of a pallet 86 engages one of the teeth of the member 82, the latter is prevented from following the arm 90. Closure of contacts 92-93 energizes a relay 50 so that an electric motor 20 is supplied from a battery 101 and operates as a series machine to lift a load to which it is coupled upon energization of a clutch-coil 46. Contacts 74-75 are successively opened and closed by means of a motordriven cam 70, an electromagnet 193 being intermittently energized to oscillate the pallet 86 and allow members 82 and 91 to advance through intermittent measured steps, in accordance with a definite number of motor-revolutions, before the lug 95 engages the plunger 94 and opens contacts 92-93 to stop the motor. Reversal of the motor is obtained by moving the arm 110 to displace the switch-arm 91, the motor now operating as a shunt machine. The control device 24 may be mounted remotely from the motor 20. For example, the device 24 may be supported on a tractor and connected to the motor, which is mounted on a trailer, through cables and plug-and-socket connectors. The motor may be utilized to raise and lower a plough-share to which it is coupled through screw-and-nut mechanism and speed-reducing gearing. The application to landing-gear for aircraft is also referred to.</p> |
