GB758798A - Improvements in or relating to hydraulic shock absorbers - Google Patents

Abstract

758,798. Hydraulic shock absorbers. DAHL. G. H. Sept. 28, 1954 [Sept. 30, 1953; Sept. 17, 1954], No. 27999/54. Class 108 (3). The invention relates to hydraulic shock absorbers of the type comprising a piston 10 having passages 13, 14, closed by valves 15, 16, operating for opposite respective directions of piston displacement, and a cylinder 20, surrounded by a reservoir 1, communicating with the upper and lower portions of the cylinder. According to the invention, an annular part 8 which closes the cylinder 20 carries a cylindrical skirt 22, and has at least one calibrated aperture 23 forming a communication between the cylinder 20 and the annular space between the reservoir 1 and the skirt 22. In Fig. 1, the skirt 22 extends over the whole length of the reservoir. There are two calibrated apertures 23, 24 to provide the flow path between the cylinder 20 and the reservoir 1. The cylinder 20 and reservoir 1 are connected at their lower ends by a valve assembly 21 which includes a calibrated compression valve 26 and a lightly-loaded rebound valve 28. The valve 26 is more heavily loaded than the valve 16 on the piston. The easing of the reservoir 1 is provided with metal cooling fins 25. In operation, on compression, liquid flows upwardly through the piston passages 14 and is displaced out of the cylinder via the apertures 24, 23, into the reservoir 1. The skirt 22 maintains the liquid in the proximity of the casing which is cooled by the fins 25. On harder compression, liquid is also displaced through the valve 26. On rebound, liquid is forced by the piston through the apertures 24, 23, and on more severe rebound the valve 15 on the piston is lifted. The cylinder is replenished via the valve 28. In Fig. 7, the skirt 32 is shorter, and is outwardly turned at its lower end to deflect liquid on to the cylinder wall. The apertures 23, 24 are replaced by a single passage 24<SP>1</SP>. A flexible magnetized washer 35 secured to the cylinder 20 and disposed in the reservoir 1, collects steel particles present in the liquid and prevents emulsion. There are no cooling fins 25, but a dust cover 33 is arranged to pump air over the casing of the reservoir 1.