GB675975A - Improvements in or relating to electro-magnetically operated signalling devices - Google Patents

Abstract

675,975. Road-traffic signals on vehicles; electric indicators. KRUMM, J. L. June 29, 1949. [June 30, 1948] No. 17239/49. Classes 40 (i) and 118 (ii). [Also in Group XXXV] A signalling device suitable for use in motor vehicles of the type in which a signalling arm is longitudinally projected from a casing upon energization of a solenoid associated with a ferromagnetic core forming part of the signal arm is characterised in that the said core is substantially longer than the solenoid and has an iron cross-sectional area varying in longitudinal direction. A. non-magnetic casing 10 containing a solenoid coil 1. and a slidable hollow iron core 2 having a portion 15 provided with triangular slots is mounted inside the wall 13 of a vehicle body adjacent an opening 14 through which the core may project. Fig. 3 is a developed view of the core 2 showing the slotted portion 15 and an unslotted portion 16. A small electric lamp 4 is fitted at the slotted end of the core in a translucent housing 5 itself secured to the core. The entire lamp and core system has a thin translucent plastic cover (not shown) which with the core is movable in the casing 10. The current is fed to the lamp 4 by means of a wire 6 and spring 7, which is secured to the core at 8 and serves to return the core to the inoperative position (as shown) when the solenoid is de-energized. To reduce friction two sets of three balls are provided, one set 11 moving with the core and the other set 12 being embedded in the wall of the casing. The return line of the lamp 4 is not shown but may be housed in the space between core and casing by winding helically round the core system. To obviate false operation by centrifugal force when rounding an opposite bend the opening 14 may be obturated by locking means (not described) which are automatically removed when the solenoid is energized. Instead of using triangular slots the varying iron crosssectional area may alternatively be obtained by providing the core with a conical bore or constructing it as a spiral spring having a linearly variable pitch. Both the triangular slot and spiral spring constructions allow the lamp to illuminate the entire length of the signalling arm, and the latter construction has the added advantage of flexibility and less liability to damage when extended.