Patent GB-503138-A (GB)
Title: Improvements in or relating to electric motor control apparatus, particularly for motor traction coaches for electric railways
IPC: B60L3/00
Filed: 1937-09-28
Abstract: 503,138. Switchboards. WEST & CO., Ltd., A., JOHNSON, C., and MALLOCH, R. M. Sept. 28, 1937, No. 26253. [Class 38 (v)] [Also in Group XXXI] The electric control gear of an electrically driven vehicle is separated from an adjacent compartment by one or more roller blind screens. The adjacent compartment may be the driver's compartment located inmmediately in front of the control gear. As shown, there are two roller blinds 1 separating the driver's compartment from two side-by-side compartments containing respectively the main control gear and the auxiliary control gear associated with auxiliary circuits such as the controlling and lighting circuits. A single switch for isolating and earthing the control gears has three positions : an " off " position at which both control gears are isolated, an intermediate position in which the main control gear only is isolated, and an " on " position in which both control gears are operative. This switch is interlocked with the blinds in such a manner as to prevent improper operation either of the blinds or the switch. The blinds 1 are adapted to be wound up on rollers 2 and 3 having projections 2a, 3a engageable with the longer arms 4a and 5a of bell-crank levers 4 and 5. The shorter arms 4b, 5b of these levers are engageable with a slotted bar 6 connected by a pin 12 and bifurcated arm 10 with the shaft 11 of the isolating switch, the bar being slid axially in bearings 17 when the switch shaft is rotated. In the " on " position of the switch, the bar 6 is in its extreme lefthand position and prevents rocking of the bell-cranks 4 and 5 by the projections 2a and 3a on the rollers so that the blinds cannot be raised. In the intermediate position of the switch, the bar 6 is moved to the position shown, and a wide slot 7 therein just clears the arm 4b of the bell-crank 4. Roller 2 can now be turned to raise the blind of the main control gear compartment, the projection 2a rocking the bell-crank 4 so that its arm 4b enters the slot 7 and remains there as long as the blind is raised. This locks the bar and switch against return movement to the " on " position until the blind is fully lowered again. In the " off " position of the switch, bar 6 is moved to the extreme right-hand position in which a slot 8 therein clears the arm 5b of the bell-crank 5, slot 7 still clearing aim 4b. Both blinds can now be raised and, moreover, the switch cannot be moved from the " off " position until the blind of the auxiliary control gear compartment has been lowered, owing to the engagement of arm 5b in slot 8. The isolating switch is operated by a key normally oh the driver's controller from which it can only be removed when in the " off position. The controller, moreover, cannot be moved from the " off " position whilst the key is removed. The key can only be removed from the isolating switch at the " off " and intermediate positions, the latter to enable the control apparatus to be tested on air and low voltage. Initial movement of the isolating switch to the " off " position exhausts the pantograph and opens the motor generator and compressor contactors, and an air interlock ensures that the auxiliary control gear can only be isolated when the pantograph has left the line.