GB671742A - - Google Patents

Abstract

671,742. Theft and like alarms. JOKSCH, R., and GRUNBERG, F. March 18, 1950. No. 6808/50. Class 118 (i). [Also in Group XXVII] An alarm arrangement for a motor vehicle comprises a pair of leads 13, 15 connecting the horn 14 in parallel with the primary ignition circuit. The contacts of a relay 19, the coil of which is energized from the engine-driven generator 11 are connected in the lead 15, so that the alarm circuit is broken when the engine is running. A hand-operated ignition switch is provided having two pairs of contacts ; with the switch in the "running" position closure of the pair 7 completes the ignition circuit, while in the "open" position the line 15 is connected to earth over the pair 8. When the switch is "off" any attempt to close the ignition circuit by bridging the contacts 7 or to operate the starter switch, which is provided with an additional contact 44 completing the ignition circuit, results in closing of the alarm circuit also ; the alarm circuit is similarly completed by a spring-loaded switch 47 if the clutch lever is depressed. A tertiary winding 43 on the ignition coil is connected in parallel with the alarm system, being in opposition to the primary winding so that, in addition to the sounding of the alarm the secondary voltage of the ignition coil is reduced sufficiently to prevent ignition. Also provided are door switches 23, 24 which close when the corresponding doors are opened, the alarm being sounded if a door remains open when the ignition switch is in the "running" position ; when the vehicle is in motion and the alarm circuit consequently broken by the relay 19, the doors mav be checked by closure of a manual switch 29 which short-circuits the relay contacts. A manual switch 26 is also provided for operating the horn in the normal manner.