GB166098A - Improvements in or relating to pneumatic cushioning or shock absorbing devices - Google Patents

Abstract

166,098. Holmes, B. B. July 3, 1920, [Convention date]. Pneumatic springs.-Consists of a pneumatic shock-absorbing device, particularly for motor road vehicles, which comprises two mechanically related cushioning units having different ratio of pressure variation for simultaneous movements under shocks, and means for enabling fluid to pass between said units during operation. A casting formed with an enlargement 8 and a guideway 9 is mounted on a vehicle side-bar, while an inner sliding member 12 is mounted through a sliding roller connection on a radius-rod 6. The member 13 has a port 14 and is closed at its lower end by a threaded plug 15 having an arm 17 extending beneath the rod 6. The member 13 has a head 21, an opening in which receives a doubly tapered extension 22 of a hollow member 12 attached to the screwed cap 10 of the casting, which cap is adapted to receive the end of the member 13 and is flared to facilitate the entry. The lower end of the member 12 carries a piston 24, the central portion of which is a spider 48 and the outer parts of which have arcuate ports 36 controlled by a flap valve 37, retained by a double bevelled ring 38, to allow of fluid passing upwards only. The ring 38 forms a seat for a spring 39. Cup leathers 41 spread by rings 42 and held by retaining rings 43 prevent leakage. A ported passage between chambers 26, 27 in the member 12 is controlled by a valve 30 adapted to be unseated by contact of its stem 33 with the plug 15. Air is pumped in through a valve in the chamber 8, and oil is introduced by removing a plug 35. A dust guard 36 works between flanges 47. The air pressure is such as to hold the device in its normal position, as shown, under full load. The low-pressure space below the piston 24 will have more violent pressure fluctuations under road shocks, and the pressure therein will momentarily rise above that in chambers 8, 27, which are connected by a port 34 producing flow of fluid through ports 36. Repeated shocks will lower the piston, unseat the valve 33, and allow of slow return of fluid until normal riding position is reached. Oil may be forced through ports 36 owing to reduction of low-pressure space due to leakage of oil past the piston ring 25. The spring 39 resists undue elongation of the device, and otherwise acts to check rebound. Sudden elongation is also restrained by dash-pot action of the taper 22 and ring 21 on oil forced therethrough, and under heavy loads of the ring 21 into the cap 10 is heavily checked. Specification 165,431 is referred to.