GB267576A - Improvements in electric switches - Google Patents

Abstract

267,576. Cox, F. B. Nov. 12, 1925. Controllers, actuating-mechanism for. - An arrangement of switches particularly adapted for electric motor control comprises a main switch and one or more auxiliary switches which are actuated through a common handle carrying a pawl or pawls which co-operate with coaxially mounted ratchet plates, the first reciprocation of the handle closing the main switch which is retained by a no-volt or overload device and the subsequent reciprocations imparting successive angular movements to the auxiliary switch or switches in succession while the pawl by which the main switch is operated is held clear of the main switch ratchet, so that the main switch is free to be automatically released at any point in the auxiliary switch operation. As shown in Figs. 1 and 2 the main switch A secured to a ratchet plate a<3> is pivoted coaxially with the auxiliary switch B secured to a ratchet plate b<11>. The switches are both operated by a handle A<1> carrying a pawl P extending over both ratchet plates, the main switch ratchet plate having a single tooth a<4>, Fig. 3, and the auxiliary ratchet plate having a number of teeth b<13> corresponding to the contact b<3> - - b<9> connected to sections r<1> - - r<6> of a starting resistance. The plate b<11> has one deep tooth b<12> which in the initial position shown is in line with the slot a<4> so that the pawl F steps round both ratchet plates when the handle is moved. This action moves the mainswitch A against its return spring a<5> to the closed position in which it is retained by a spring- controlled latch C under control of a no-volt magnet H and also steps round the switch B to engage the dummy contact b<2>. On the return stroke of the operating member it engages the succeeding shallow tooth b<13> so that the pawl is held clear of the plate a<3> during the stepping round of the contact arm B to cut out the resistance sections, the main switch thus being free to be automatically released on de-energization of the no-volt coil H or on operation of an overload device controlling its circuit. If a release of the main switch takes place at an intermediate position of the auxiliary switch B this switch has to be stepped round to its initial position before the main switch can be closed. The handlemay be provided with suitable means for preventing the auxiliary switch being left in an intermediate position with the main switch closed. In the modification shown in Fig. 5 a plain peripheral portion b<14> is formed behind the tooth b<12> so that after the auxiliary switch is fully stepped round further reciprocations of the operating handle produce no switch movements. In cases where the main switch requires a greater angular displacement for closing than the stepsof the auxiliary switch the cam a' is formed with a projection a<5>, Fig. 7, so that although the pawl' iu its return movement passes two of the teeth b<1> the second of these is masked, as shown in Fig. 8, by the projection a<5>. The operating movements of the main and auxiliary switches may be arranged to take place in opposite directions by the provision of suitable ratchet plates co- .operating with a double-acting pawl carried by the operating member. If the auxiliary switch is provided with a return spring its ratchet plate may be held against return movement by an auxiliary pawl which is disengaged by the tripping of the main switch. The Specification describes a drum type controller fitted with actuating mechanism for the main switch and the auxiliary resistance switch, this mechanism being arranged for operation in the manner described.