GB597996A - Improvements in or relating to liquid damped telescopic shock absorber struts - Google Patents

Abstract

597,996. Hydro'- pneumatic shock - absorbers. AUTOMOTIVE PRODUCTS. CO., Ltd., and FOSTER, S. Aug. 27, 1945, No. 22031. [Class 108 (iii)] In a liquid-damped, telescopic, shock-absorber strut of the type comprising a hollow plunger 11 containing a resilient unit; and an associated cylinder 10 from which liquid is transferred on compression to the plunger 11 through a flow-restricting orifice or orifices, radial by-pass ports 26 disposed in a sleeve 21 formed on the inner side of the plunger 11 are controlled by the cylindrical surface of a piston valve 32 which is spring urged to close the ports and is subjected to a pressure differential due to flow through the orifice or orifices. In the construction shown these two orifices are formed, one 37 in a closed conical head portion 35 of the piston valve 32, and the other 42 in a closure plug 41 of the other end of the sleeve 21. The plug 41 forms an abutment for a spring 38 which urges the piston 32 to cover the ports 26 and drive the head portion 35 on to a conical seating 23. In operation, on compression at a low plunger speed, energy is absorbed by liquid-flow through the orifices 37, 42 and air is compressed above a floating piston, not shown, in the plunger 11. At an increased plunger speed due to an increased pressure differential on either side of the orifice 37, the piston 32 rises against the spring 38 and its full diameter is then exposed to the cylinder pressure. The piston then moves quickly upwards and exposes the ports 26 which are interconnected by a channel 27. On rebound, liquid can pass through passages 43 in the plunger which are controlled by a spring loaded flap valve 44. The damping orifice or orifices may alternatively be formed in the plunger.