Patent GB-202797-A (GB)
Title: Improvements in and connected with change-over switches for electric lighting and other installations for railway carriages and other vehicles
IPC: H01H51/08
Filed: 1922-06-28
Abstract: 202,797. Stone & Co., Ltd., J., and Darker, A. R. June 28, 1922. Electromagnetic switches; ratchet actuation; tappet actuation.- In a two-battery train-lighting system employing an automatic change-over switch, in order to prevent unequal charging of the batteries when the train is operating on shuttle workings, the operating means and the switch parts are so co-ordinated that changing over takes place irregularly i.e. any sequence of operative actions is interrupted by an inoperative action. Fig. 1 shows a diagram of a two-battery system with dynamos d, cut-in switch C. and a load e connected through the main switch M to terminal L, the change-over switch being so arranged that the terminal D may be connected to the terminal B or B<2> corresponding to battery No. 1 or No. 2 on charge, in either case the other battery floating or regulating, by being connected through a resistance R to the dynamo. In the form of change-over-switch shown in Figs. 2 - - 8 a solenoid j, which is energized each time the dynamo is cut-in or cut-out, by attracting a core h carrying a pawl a steps round a ratchet plate e bearing two semi-circular contacts a, b on which bear four brushes L, D, B<1>, B<2>. The plate e has an odd number of teeth, for example five so that in a sequence of five successive operations, one is inoperative to change over the batteries, the switch in passing between the positions corresponding to Figs. 4 and 5 producing no change in the battery connections. In a similar modification a toothed ratchet plate is locsely mounted on a shaft carrying an H armature to which is attached a stepping pawl, the armature being rotated by the energization of the field poles, and after moving the ratchet plate through one step is returned by a clock spring. In this form, a second set of teeth may be arranged between the first set on the ratchet plate, and by moving round the plate until this set is engaged by the stepping pawl, a further change in the sequence of the changing over of the batteries is produced. The fixed brushes may also be unsymmetrically spaced around the contacts a, b for this purpose. As applied to a change-over switch employing an oscillating switching bar (Figs. 13-15) the core h carries a member t having hooked projections cooperating with pivoted pawls u, v on the pivoted switch bar s. On initial energization of the electromagnet (Fig. 13) the lower right-hand projection x engages the pawl v moving the bar to the horizontal position, Fig. 14, in which the moving contacts a<1>, b<1> still bridge the extended inner contacts L, D and the outer contacts B<1>, B<2> respectively, no change-over having been effected. On further energization of the coil J the pawl v is engaged by the projection y and the bar s is moved to the position shown in Fig. 15, so changing over the batteries. A third operation restores the bar s to its initial position shown in Fig. 13, the pawl u being engaged by the projection w. In a further similar modification an anchor likemember attached to the core h co-operates with pins on a pivoted switch bar to produce a similar sequence of switching operations. Specification 7469/10 is referred to.