Patent GB-233827-A (GB)
Title: Improvements in and relating to the control of electric motors
IPC: B60L15/04
Filed: 1924-03-15
Abstract: 233,827. Electro-Mechanical Brake Co., Ltd., and Pattison, M. J. March 15, 1924. Master control systems.-The system comprises a set of contactor switches A - - D, R, S, T for effecting successive control operations and a master controller M, which when rocked between two operative positions A, B completes the circuit of a contactor which has been prepared by the preceding contactor, and when released moves to its " off " position and interrupts all the contactor circuits. The invention is described with reference to a road vehicle. in which the master controller M is a three position pedal, and two direct current motors V<1>, V<2> are used with series-parallel control. A drum controller P gives normal forward and reverse running in positions I and II ,forward and reverse running with either motor V<1> or V<2> cut out in positions III and IV or V and VI. The operation is as follows, depression of pedal to position B energizes coil a to close main contactors A, and auxiliary switches a<3> to energize coil b over switches c<1>, d<1>, a<3> to establish a maintaining circuit for coil a, and a<4> to prepare circuit of coil r over switch c<2>. Coil b closes contactor B to complete the motor circuit in series position with full resistance W. Return of controller M to position A completes circuit of coil r to close resistance shorting contactors R. Switches r<2>, r<3> also close to complete maintaing circuit of coil r and prepare circuit of coil s, which is completed when controller is returned to position B, and thereupon causes closure of the next contactors S and of a maintaining circuit at switch s<2>, and prepares at switch s<3> the circuit of a coil c. Return of the controller to position A completes circuit of coil c which closes contactor C to give full series position, opens switch c<1> to break the maintaining circuits of coils b, r, and s, opens switch c<2> to prevent coil r being energized again, completes its maintaining circuit at switch c<4> over switch d' and closes switch c<5> to prepare circuit of coil d. Next movement to position B completes the circuit of coil d, through contact 8 and segment 7 on the drum P, with consequent closure of parallelling contactor D, opening of switches d<1> and d<3> to prevent contactor B closing again and to break the maintaining circuit of coil c, closure, of switch d<5> for its maintaining circuit, and closure of switch d<6> to prepare circuit of coil t. Subsequent movement to positions A and B causes closure of contactors R, S as for series operation, and final movement to position A completes the circuit of coil t over switches s<3>, d<6> to close contactors T giving full parallel operation of the motors, the circuit of coil t is maintained by the closure of a switch t<1> so any further rocking of the cont.roller M is ineffective. Return of the controller M to its " off " position at any stage of the operation breaks the maintaining circuit of coil a with consequential return of all switches and contactors to their initial position. If the drum P is in any of the positions III - - VI the circuit of coil d cannot be completed at segment 7 and contact 8 and the operation ceases with the closure of the contactor C.