Patent GB-231096-A (GB)
Title: Improvements in electrical switches and operating mechanism therefor
IPC: H01H19/24
Filed: 1923-12-21
Abstract: 231,096. Cox, F. B. Dec. 21, 1923. Controllers, actuating-mechanism for.-Relates to quick-action mechanism for step-by-step switches, controllers &c. in which a handle is moved in either direction to store up energy in a spring, so that when the switch which is held against the action of the spring by a retaining pawl, is released by further movement of the handle, it is moved to the next position with a snap action. The part which is actuated by the strained spring is provided with two reverselyset retaining pawls which as they move forward with the switch after being disengaged by the spring-energized part are freed from this part so that their movement into engagement with the next tooth is unrestrained, one tooth being provided per pair of pawls for each different switch position. Alternatively two pairs of retaining pawls may be employed. As shown in Figs. 1 and 3, if the handle F which is loose upon the switch shaft A is moved in the direction of the. arrow in Fig. 1 a projection f<1> on the handle boss engages a projection d<1> integral with the spring straining lever D<1> sn straining a spring E<1> which connects it to an arm b<3> of a pawl carrier B secured on the switch shaft. A. Two other arms b<1>, b<2> of the carrier B support pivoted pawls C<1>, C<2>, pressed apart by a blade spring c<3> the outer ends of which carry rollers c<2> engaging the internal teeth of a fixed ratchet G. The switch shaft is thus held during the straining of the spring E<1> until the arm D<1> engages the tail c<5> of the pawl C<1> so moving its roller c<2> clear of a ratchet tooth as shown in Fig. 2 so that the carrier B together with the shaft A is moved quickly across to the position shown in Fig. 3. A similar action is produced if the handle is turned in the opposite direction to step round the switch shaft anticlockwise. In the modified form shown in Fig. 15 one spring E<3> only is employed connecting the ends of spring-straining levers D<3>, D<4>. The carrier B in this form has a triangular projection b' which is engaged by these levers. In Fig. 25 an externally toothed ratchet G<2> is employed the pawl carrier B<2> supporting pivoted pawls C<13> pressed inwards bv a spring C<10>. The switch shaft A<2> (Fig. 29) is surrounded by a coil spring E<4> the ends e<10>, e<11> of which are brought out to bear on opposite sides of an arm B<4> of the pawl carrier. The handle F<2> is secured to a loose sleeve D<5> carrying a spring straining projection D<6> now lifts the upper pawl c<13> from the ratchet and a quick switching action ensues. A construction of multiple contact switch to which the switch actuating mechanism already described may be applied is shown in Figs. 33 and 34 the rotatable bar A carrying two part spring contacts which engage with sets of fixed contacts K adjustably mounted in carriers M on bars J arranged parallel to the switch axis. The moving contacts (Fig. 37) consist of phosphor bronze blades 0 clamped in holders Q and bearing at their outer ends copper contact pieces P which engage similar contacts K (Fig. 38) mounted on phosphor bronze blades k<1> clamped in recesses in the holders M. A modified form of actuating mechanism for rectilinearly moving switches is shown in Fig. 30 the shaft A<4> carrying a hollow tubular cam carrier B<10> containing springs E<10>, E<11> which are interposed between its ends and a collar integral with the shaft. The carrier B<10> supports two pairs of pivoted pawls c<5>, c<6> the ends of which are pressed against fixed ratchet plates G<10> by springs connecting their tail pieces. When the operating shaft A<4> is moved upwardly the spring E<11> is strained but the carrier B<10> connected to the switch contacts is nrevented from moving until arm t<1> attached to the shaft A<4> engages the tails C<21> of the lower pair of pawls so disengaging them from the ratchet and permitting a quick-action switching motion to occur. Positive action if the spring fails is produced in all forms of the switch described by inter-engagement of the parts on continued movement of the handle. Applications of the switches described to the control of motor starting resistances are described in the Specification.