Patent GB-423191-A (GB)
Title: Improvements in or relating to automatic electric switches for disabling electrical sstems upon a vehicle or craft
IPC: H01H35/14
Filed: 1933-07-28
Abstract: 423,191. Gravity and inertia switches. SALMOND, H. M., Briarwood, Fareham, Hampshire. July 28, 1933, No. 21254. [Class 38 (v)] A switch for disabling electrical systems on motor - driven vehicles or crafts in the event of an accident comprises a switching member actuated by a relatively strong spring and controlled by a lever system which restrains, by relatively light yielding pressure, a pendulum by which the lever system is controlled. In one arrangement, Fig. 1, the switch comprises rigid contact elements 9, 11, leaf-spring contact members 10, 12, and an actuating spring 13 which, when released, opens the circuit of the battery 20 at the contacts 9, 10 and short-circuits the generator 21 at the contacts 11, 12. The spring 13 is normally held in its inoperative position by the toe 14 of a catch lever 15 pivoted at 17, and having a long arm carrying a member 16 which engages the head 4 of a pendulum 3 mounted by means of a ball 5 in a socket 6. When the pendulum is displaced as the result of excessive tilting or of a violent impact, the member 16 escapes from the head 4 and the spring 13 is released to operate the contact members. In a modification, Fig. 2 (not shown), the catch lever controls a knife blade switch, which is normally held out of engagement with fixed contacts against the action of a spring. In another form, Fig. 3, the contact assembly 9 ... 12 is actuated by a spring-controlled operating member 28, which is normally held in the inoperative position by the catch lever 15. The pendulum comprises a cam device 29 carried by arms 30 pivotally mounted at 31 on a collar 32, which is itself pivoted on a pin 33. In another construction, Fig. 4, an intermediate catch lever 36 is provided between the lever 15 and the switch controlling element 38. The switch comprises a spring-controlled drum 40 with a conducting segment 41 co-operating with brushes 42, and it may be arranged either to open or close a circuit on release. In another form, Fig. 5, (not shown), the pendulum is carried by pivoted arms bent to form a cam which engages the catch lever. In the construction shown in Figs. 6 and 6a the pendulum switch is provided with key-operated means for preventing unauthorized use of a vehicle. The operating spring 13 is provided with a projection 13a for operating the contact assembly 9 ... 12 on release of the catch levers 15, 35 by the pendulum. A shaft 52 is mounted beneath the switch, and has two positions determined by a cam 55 co-operating with a spring 56. In one position, an arm 53 on the shaft holds the spring 10 out of engagement with the spring 9 and completes the circuit between the springs 11, 12 ; the shaft is locked in this position by the engagement of springs 59 with slotted sockets carried by the shaft. Another arm 54 on the shaft serves to restore the spring 13 to its operative position after release by the pendulum. The springs 59 can only be released by inserting keys 60 ; the shaft 52 may then be rotated into the position shown in Fig. 6 in which the arms 53, 54 are so disposed that they do not interfere with the pendulum release. In another , construction, Figs. 7 and 7a, (not shown), the spring contact members are connected by a helical spring to prevent chattering and to overcome the effects of fatigue. The Provisional Specification describes several modifications not involving the use of a pivoted catch lever between the pendulum and the switch operating member. In one form, the switch is held in the closed position by the direct engagement of a projection on the movable contact with a cam carried by the pendulum. In other arrangements the switch is normally open and, on closure, blows a fuse or operates an electromagnetic relay to break the main supply circuit.