Patent GB-166256-A (GB)
Title: Improvements in and relating to switch gear for controlling electric motors
IPC: H02P1/06
Filed: 1919-09-12
Abstract: 166,256. Hirst, J. A., and Brook. P. S. Sept. 12, 1919. Controllers, mechanical actuating-mechanisms for. -Relates to switchoperating rear of the kind described in Specification 155,614, in which an oscillating movement of the switch handle about one axis results in a step-by-step cutting- out of resistance, whilst a secondary movement of the switch handle about another axis actuates an auxiliary switch closing the main circuit. The invention consists in means for actuating the two elements of the switch and in means for locking the gear when in the full-on pooition. The fixed part A, Figs. 1 and 2, of the switch is bolted to the main switch case at a', whilst the rotary part B carrying the handle H is attached to the fixed part by means of segmented flanges a', b' axial displacement being prevented by means of a detachable flange a<2> which is screwed into the part A after the two parts have been interchanged. In the form shown in Fig. 1, the handle H is bowed, the two arms being carried by a transverse axle h<2> on which is mounted a cam h<3> which forces the axially-movable spindle D forward against a coiled spring (not shown) to close the main circuit. The handle H is held in the position shown in Fig. 1 against the pressure of a coiled spring h<5> on the axle h<2>; when released the handle swings outwards and downwards through 180‹, and the spindle D is retracted into the position shown in dotted lines. A sleeve C carries claws c<1> which engage with and actuate the starter (not shown) in a step-bystep manner. This is effected by oscillating the handle H, when in the position shown, causing the whole movable part B to rotate relatively to the fixed part A. An intermittent rotary movement is thereby conveyed to the sleeve C and claws C<1> through the ratchet gearing shown in Fig. 2. A pawl b<3> carried by the moving part drives the ratchet-wheel c<2> keyed to the sleeve C on each forward stroke of the handle, overrunning being prevented by means of a detent a' which is forced by means of a pin b<6> against the teeth of a reversed-set ratchet C'. In order to lock the gear against further movement by the handle H, when the full-on position has been reached, a locking-piece d<2> is mounted on the axially-movable spindle D, and is at the same time connected by a sliding pin d<a>, Fig. 1, with the sleeve C. When the sleeve has been rotated to the full-on position, the nose of the locking-piece d<2> engages with the end of a locking-lever a<5> mounted co-axially with the detent a<3> and so presents any further movement of the handle. The gear can then only be released by allowing the handle H to swing outwards to retract the spindle D and thereby carry the locking-piece d<2> forward out of engagement with the locking-lever a'. An alternative mode of locking the gear is shown in Fig. 7. In this construction the driving-pawl b<1>3 carries a pin b<12>, which in the full-on position is engaged by a locking-lever a<8> mounted on the detachable flange a<1>2. The lever a<3> is normally held by an axially coiled spring (not shown) out of the path of the pin b<12>, but is forced into the operative locking position by the nose of a locking-lever d<1>2 which, as before, is mounted on the spindle D and is retracted, so as to free the gear, when the handle H is allowed to swing outwards. In a modified form the handle H, instead of being swung outwards to retract the spindle D, is rotated about its own axis against a coiled spring. The driving-pawl b<3> may be loaded with a weight b<10>, Fig. 2, so that if the handle is moved too quickly the pawl is swung outwards by centrifugal force and is thereby rendered inoperative. A shutter c<4>, Fig. 1, fixed to the sleeve C, indicates when the fulloa position has been reached. The arrangement may be used in step-by-step switching-gear not having an auxiliary switch operated by the transverse movement of the spindle.