Patent GB-467642-A (GB)
Title: Improvements relating to electric traction braking equipment
IPC: B60T13/74
Filed: 1935-12-20
Abstract: 467,642. Control of D.C. motors. BAKER, W. S. GRAFF-, and LONDON PASSENGER TRANSPORT BOARD. Dec. 20, 1935, No. 35292. [Class 38 (iii)] [Also in Group XXXIV] In a braking equipment for electrically propelled vehicles, the driver's brake valve in addition to controlling mechanical braking pneumatically and /or electropneumatically is also provided with electric contacts by which electric regenerative or rheostatic braking is adapted to be controlled independently of the mechanical braking, electric braking being effected in positions of the brake valve between holding and application positions for pneumatic braking. The electric braking control circuits may include contacts on the master controller so that electric braking can be effected only with this controller in the " off " position. The equipment shown comprises a reverse controller 3 with contacts 8-9, a master controller 1 with contacts 32-28 and contacts 2 on the " dead man's handle and contacts 4 on the driver's brake valve. The motor circuits are controlled by switches operated by energizing conductors F, R, M, 17, 18, B and electropneumatic braking by conductors A, H, Int, connected respectively to contacts 39-31 and to application and holding valves and an interlock valve which prevents release of the brakes unless the cocks and valves are correctly set. The circuits controlled by the brake valve are energized through conductor 14. Assuming the controller 1 is in the " off " position O and the brake valve in the " running " position I, the conductor Int is energized through contacts 13, 30. To effect electric braking the valve is moved to position III in which (a) conductor B is energized through contacts 13, 12, 11 to effect the change-over from motoring to braking conditions, (b) the reverse controller 3 being in forward position " For," conductor F is energized for forward running through contacts 13, 18, conductor 20, contacts 21, 23, conductor 24, contacts 25, 8, (c) conductor 17 is energized through conductor 20, contacts 21, 22 to give a first degree of braking corresponding to the first motoring step. In position IV conductor 18 also is energized through contacts 13, 26 conductor 27, contacts 28 to modify the braking effect corresponding to the second motoring step. In position V the holding valve is deenergized and application valves are respectively energized and de-energized to give a pneumatic brake application. The valve may be returned to position II to terminate the electric braking while holding the pneumatic application. In position VI also, conductors A, H are respectively de-energized and energized to maintain the electropneumatic application ; this position is also a " lap " position for maintaining a pneumatic application effected in position VII by variation of the train-pipe pressure. In position VIII pneumatic and electropneumatic applications are simultaneously effected. The electric braking is maintained in positions V to VIII, but the contacts may be modified so that it is terminated in some or all of these positions. Electric braking may be reduced or terminated when the pneumatic braking reaches a predetermined value by opening of contacts 32 by a spring-urged position 33 subject to brakecylinder pressure. The pneumatic brake may be applied upon failure of electric braking by an electrically operated valve in the motor circuits. The pneumatic brake may be either pressure or vacuum operated and the electric braking may be either regenerative or rheostatic. For motoring, the motor circuits are controlled by current supplied from a conductor 5 through the dead man " contacts 2 which are opened in the off " position O of the master controller. When the controller is moved from the position, the conductor F or R is energized through contacts 6, 8 or 6, 9 according to the position of the reverse controller 3. When the controller is put in position I conductor M is energized through contacts 7, 10 to set the motor equipment for motoring. Acceleration of the motor is effected in two steps by moving the controller through position I to position II in which conductors 17, 18 are consecutively energized through contacts 7, 15 and 7, 16 respectively.