Patent GB-693481-A (GB)
Title: Improvements in or relating to electrical switches
Inventor: BROWN ANDREW
IPC: B61L19/14
Filed: 1948-01-22
Abstract: 693,481. Stencil switches. STANDARD TELEPHONES & CABLES, Ltd. Jan. 21, 1949 [Jan. 22, 1948], No. 2002/48. Class 38 (v) [Also in Group XXX] An electric switch arrangement for setting up any required combination (which may be only one) of contacts out of all the available contacts by a preparatory first action without actually disturbing the contacts and then by an operating action putting the required contacts into effective position comprises for each required contact combination a code bar 13 appropriately slotted as shown in Fig. 5 to provide upstanding teeth for actuating the required contacts 15 and for each code bar an associated selecting bar 25, the preparatory first action (selection) setting the particular selecting bar into such position that the subsequent operating action moves only this particular selecting bar thereby moving its associated code bar to actuate the required contacts. The switch arrangement is applicable for the setting up of routes in a railway track lay-out. The selecting bars as shown in Fig. 6 are notched at 29 for engagement by cams 30 each operated by a selecting magnet allotted to a particular required combination, the notches 29 being so arranged that only the particular selecting bar will be positioned in readiness to be raised by the operating lever 23, the other selecting bars presenting an open bottom slot 28 to allow only the particular selecting bar to rise since only this selecting bar will present an open top slot 35 to allow movement across the lock bar 34. The operating lever 23 is raised by an eccentric 24 the shaft of which carries contact discs used in the control circuit Fig. 8 for the setting up of a route in a railway track lay-out. Thus to set up route A a key for this route is actuated to apply current to the magnet SMA which actuates that cam 30 which positions the selector bar 25 appropriate to route A so that its slot 28 is moved out of line with the lifting lever 23; this circuit includes a contact of disc D closing the circuit only in the normal position of the eccentric-carrying shaft by which the operating lever 23 is actuated. When the magnet SMA has responded (and so set the selector bar) a front contact sma thereof energizes a magnet Z for the drive of the eccentric-carrying shaft; as this circuit includes a contact of disc G closed only at normal the circuit is broken as soon as the shaft starts to turn but a contact of disc H closed except at full normal and full reverse ensures the magnet Z being energized till the full stroke is effected and the contact springs thereby actuated; one of the contact springs for route A namely ac 1 energizes a relay ZCR over a contact of disc D at reverse. The relay ZCR controls the signal for the route so that this signal can be put to the "stop" aspect by opening the route key to cut off the current. Before another route can be set up a release circuit for the set up route A has current applied thereto so that a cancelling magnet ZNR is energized over another one ac 2 of the contact springs for route A; the magnet ZNR at front contact znr 2 and a contact of disc G at reverse energizes the magnet Z to return the eccentric-carrying shaft to normal this magnet continuing to be energized over the contact of disc H till the full normal position is reached. Figs. 9 and 10A show the operating lever 23 as actuated by a magnet 37 and there being upper and lower contact sets, 15, 38 the lower set of which 38 is held in operation by the operating lever 23 being latched up at an intermediate position by a stepwise-slotted latch 39 until released by a back lock magnet 44 being energized. The Provisional Specification also discloses the form of apparatus shown in Figs. 1-3 comprising a set of spring contacts 15 actuated in various combinations according to the "cut" of code bars 13 mounted on a drum 1 which is moved to a position corresponding to the required route under the control of contact discs 3 - 8 carrying appropriately gapped contact strips by which a clutch 9 is energized to drive the drum 1 from a shaft 20. Thus to set up a route A an appropriate key is actuated to apply current from keypoint A, Fig. 3, to a wiper brush on disc 6 and so to a relay ZR which at contact zr 1 energizes the clutch 9. The clutch continues in action until the wiper reaches the "gap" of the contact disc 6 thereby to stop the drum at the A position. At this position the contact disc 3 has a "finger" in register with its wiper whereby a relay ZCR is energized which at its contact zcr 1 energizes a magnet 12 to lift the drum whereby that code bar 13 which is provided for route A actuates the required combination of spring contacts 15 for setting up route A. Specification 496,495, [Group XXX], is referred to.