GB590144A - Improvements in and relating to inertia switches - Google Patents

Abstract

590,144. Inertia switches; switches held set and freed mechanically. BIRD, F. W. R. April 14, 1945, No. 9373. [Class 38 (v)] An inertia switch for mounting in an aircraft &c. is actuated by movement in one direction only of a resiliently restrained steel ball 16. The ball 16 is enclosed between the side covers of a casing 10 and is trapped against the casing 10 and a hardened steel plate 45 therein by a spring-loaded plunger 17 and a stud 19 or a pivoted detent 21. When the aircraft is subjected to a severe deceleration, e.g., in excess of 2¢g., the ball 16 moves the plunger 17 and allows the detent 21 to release a striker 23, an insulated striker pin 25 then closing contacts 27, 28. To recock the switch, the striker 23 is retracted by withdrawing a knob 31 actuating a catch 29, while the ball 16 is held free of the detent 21 by inserting a key 52 through a hole 46. A pointed projection 44 of the striker 23 provides a visible and tactile indication of the switch position. A pin 33 may be inserted through a hole 46<1>' in the casing to hold the catch 29 when the latter is withdrawn, thereby locking the striker 23 inoperative. Spring-biassed pivoted plates 47, 47<1> cover the holes 46, 46<1>. The plunger 17 moves in a cylinder 18 forming an air dash-pot, with a bleed hole 53, the loading of spring 41 being adjustable by a screw 42 which may then be locked by centre-popping and sealing compound. The screw 42 becomes inaccessible when the casing is mounted by lugs 11. The side covers may be of suitable transparent material and - pegs may be inserted in the base to prevent the ball from rolling out when the side covers are removed. Internal leads from the contacts 27, 28 terminate in a box 40.