Patent GB-449237-A (GB)
Title: Improvements in or connected with adjustable seats particularly suitable for use on aircraft gun mountings
IPC: B64D7/02
Filed: 1933-09-28
Abstract: 449,237. Aircraft gun mountings. VICKERS (AVIATION), Ltd., and WALLIS, B. N., Weybridge Works, Byfleet Road, Weybridge, Surrey. Sept. 28, 1933, Nos. 27431/34, (divided out of 449,234), and 27433/34. [Class 92 (i)] [See also Groups XIV, VI, XXV, XXXII, and XXXIV] An adjustable seat more particularly for use with aircraft gun mountings comprises a spring - resister, as described for example in Specification 406,753 which gives a partial counter - balancing effect to the seat, and means for supplying fluid pressure to the seat under the control of the occupant to raise the seat, the pressure being released to lower the seat or cut off to retain the seat in the adjusted position. The invention is shown in Fig. 1 applied to the vertical pillar 6 of an L-shaped turntable gun mounting which together with its driving mechanism is described in Specification 449,234. The seat 12 is connected to the pillar by parallel motion links 9, 10 interconnected at their outer ends by a seat-post 11. The seat can swivel on the post to either side of the central position shown, and is locked in adjusted position by a spring pin 16 engaging holes in the post. The upper arms 9 are hinged to the pillar through a spring resister x shown in detail in Fig. 7 and generally similar to that described in Specification 406,753. The spring resister comprises spring-pressed pistons 27, 28, controlled by cams 18, 19, the cam 19 being axially adjustable by a hand wheel 32, key 33, and screw socket 34 to alter the initial compression of the springs 31 to suit the weight of the occupant. Air pressure for raising the seat is applied to the surface of oil in a vessel 47, the oil filling also the compartment 48 of the resister between the pistons. A fine mesh screen 52 prevents air entering the space 48 when flying upside down. The air pressure is controlled by inlet and exhaust valves 58, 59 arranged on the pillar 6 as shown in plan in Fig. 11. The valves are actuated by rollers 67, 68 engaged by a sector cam 69 keyed on a shaft 71 rocked by a frame 72 on the seat-controlling handle 74. The arrangement is such that both valves are normally spring closed when the handle is central, one valve being opened and the other remaining closed when the handle is moved up or down from central position thus causing upward or downward movement of the seat. The seat is retained in adjusted position by a friction brake 100 mounted in the hollow hinge y of the arms 10 as shown in detail in Fig. 15. The brake is normally held engaged by a spring 82 acting through toggle levers 84, parallelogram-linkage 92, and longitudinal rods (not shown), on a pressure plate 98. The effect of the brake in restraining angular movements of the arms 10 is increased by the mechanical advantage supplied by epicyclic gearing comprising planetary pinions 101 on the pressure plate 98 engaging with fixed internal teeth 102 on the casing 103 and with a sun-wheel 104 moving with the brakedisc 99. The brake is automatically released, .when the handle 74 is moved from. its central position. by a Bowden wire 80 connected to the shaft 71, Fig. 11, by a bell-crank 78, links 77, and arm 76. The release mechanism of the brake is adjusted by a pin 108 engaging holes in a screwed sleeve 109. The air under pressure is conveyed to the controlling valves by a pipe 117 leading from a tube passing through the centre of the turntable and connected to a source of compressed air outside the cockpit.