GB595112A - Improvements relating to electrical switching apparatus - Google Patents

Abstract

595,112. Motor controllers. ENGLISH ELECTRIC CO., Ltd., MARDIS, P. L., SMITH, S. A., and WILSON, F. July 6, 1945, No. 17260. [Class 38(iii)] A controller comprises switch arms independently pivoted about a common axis and spring biassed towards fixed contacts, and a rigid structure pivoted on the same axis and carrying a bar parallel to the axis so that movement of the structure may cause the bar successively to engage the switch arms and open the switch contacts successively. The structure may carry a second bar co-operating similarly with a second set of switch-arms spring biassed in an opposite sense so as to close their switch contacts successively as the others open. Each switch-arm 13, moulded in insulating material, turns freely on the shaft 14. A bar 24, when turned clockwise about the shaft by the crank 26 pinned to the shaft, engages in succession adjustable screws 25, to turn each arm clockwise against the force of spring 22 anchored either to the frame or to a further rod carried by a further crank on shaft 14. Each arm carries a bridging contact member 16 arranged to engage contacts 11 and 12 with a wiping action. To provide some contacts which open while others close, reversed arms each identical with arm 13 may be mounted on shaft 14 and operated by an additional bar nearly diametrically opposite bar 24. The angular movement between successive contact separations or engagements may be only a few degrees and the total movement of shaft 14 for operating say a dozen switch arms may be about 30 degrees. A trolley-bus controller may have, in addition to a reversing switch, two shafts such as 14 with contact arms - one controlling power and the other electric braking. The power control shaft is biassed to the " off " position by a spring strong enough to overcome springs 22 and is connected to a power control pedal by a crank, a partly insulating linkage and ball joints. The brake control shaft, which has a spring biassing it to the " on " position and a stronger opposing spring, is similarly connected to a brake control pedal but with lost motion; as the brake pedal is depressed the brake control shaft is allowed to move towards the " on " position where it is arrested by a stop while the pedal can be further depressed to apply mechanical braking.