GB287677A - Improvements relating to operating mechanisms, primarily for electric switches - Google Patents

Abstract

287.677. British Thomson-Houston Co., Ltd., Hamlyn, W. P., and Hunter, M. C. I. Feb. 5, 1927. Automatic circuit-breakers.- Operating-mechanism for holding a member 11 against a bias 20 until released by a small tripping force 40 is described as applied to a circuit-breaker. Fig. 2 shows the mechanism after release has been effected. The force 40 has caused a stop 36 to move from under a roller 35 thereby moving pivot 31 so that the joint 29 of a toggle 27, 30 has been able to pass from the lower to the upper side of its links. This has permitted the rod 26 to move upwards and therefore the joint 17 of a lap-over toggle 15, 16 (i.e. a toggle in which the link 15 was initially in compression, while the link 16 was in tension) to move clockwise, so that the pivot 12 and member 11 has moved to the right under the bias 20. The links 15, 16 are hinged to pivoted members 13, 19 of unequal length. To reset the mechanism, the handle 25 is raised to the position shown in Fig. 3, thereby moving the hinge 18 to the right and reforming the links 15, 16 into a lap-over toggle and by moving the joint 17 downwards, the tripping mechanism is reset with the roller 35 on the stop 36. Return of the handle 25 to its initial position, draws the toggle 15, 16 and hence the member 11 to the left against the bias 20 and retains it in the strained position owing to the pivot 22 passing the dead centre with reference to pivots 18 and 24. A catch may engage the handle 25 so that the stop 36 is moved from under the roller 35 should the handle be moved while the mechanism is set against the bias. Specification 183,978 is referred to.