Patent GB-463293-A (GB)
Title: Improvements in or relating to electric switch mechanism for controlling electric motors
IPC: H01H25/04
Filed: 1936-05-05
Abstract: 463,293. Controllers ; interlocked switches. IGRANIC ELECTRIC CO., Ltd., and WRIGHT, S. R. May 5, 1936, No. 12675. [Classes 38 (iii) and 38 (v)] A multi-pole main switch comprising rows of fixed contacts and co-operating bridging contacts mounted on a contact carrier movable to effect the bridging of different combinations of pairs of fixed contacts and give different speeds of a multispeed induction motor, is combined with a reversing switch and a mechanical interlock which prevents operation of the reversing switch except when the main switch is at the " off " position. The invention is described as applied to the switch described with reference to Figs. 1-4 of Specification 403,801. The reversing switch comprises two rows of fixed contacts 13, Fig. 1, co-operating with a row of bridging contacts 14 which are mounted on a plate 15 pivoted at 16 and biassed by a spring 17 to the " off " position. The contacts 13 are operated by a push-button 8 having an extension 18 and a reduced portion 12. A sliding plate 10, mounted on a plate 9 having an H-shaped slot 6, Fig. 2, in which the operating lever 5 for the main switch contacts 1, 2 operates, is provided with a slot parallel with the centre part of the H-shaped slot, and a hole 11 from which two semicircular smaller holes projecting on opposite sides. The arrangement is such that when the operating lever 5 is in an operative position the engagement of the lever 5 with the slot in the plate 10 slides the plate into such a position that the reduced portion 12 of the press-button 8 engages one of the semicircular projecting holes and the pushbutton cannot be depressed. When the operating lever is in its off position, however, the plate 105 is so positioned that the hole 11 is in line with the push-button and the latter can be depressed. As applied to the switch described with reference to Figs. 5 to 7 of Specification 403,801 in which a stop push-button 23, Fig. 5, is provided, the push-button 8 operating the reversing switch has its lower end reduced at 30, and the stop button 23 has an intermediate reduced portion 32 connected by a conical cam portion 33 to the portion of the shank beneath it. A sliding plate 24 is provided, having holes 28, 29 formed with opposite smaller semicircular portions. Normally the push-button 23 is in its upper position and the lower portion of its shank is in the hole 29 thereby locking the plate 24 in a position to the right so that the reduced portion of the push-button 8 engages one of the semicircular projecting holes and the pushbutton 8 cannot be depressed. When the pushbutton 23 is depressed, however, to open the main switch, the push-button 8 may be depressed to slide the plate 24 to the left where it is fixed so that the push-button 23 cannot return to its normal position. When the push-button 8 is released, the push-button 23 may slide the plate 24 to the right in returning to its normal position. The invention may be applied to the switch described with reference to Figs. 11 and 13 of Specification 403,801 by providing a pin on the operating shaft of that switch and employing that shaft in place of the lever 5 of the switch shown in the present Fig. 1 to effect movement of a plate controlling movements of the reverse push-button 8.