Hydraulic telescopic shock absorber providing a damping effect which is dependent upon the position of the piston in the cylinder

Claim 1

A hydraulic telescopic shock absorber comprising a cylinder, a piston positioned to move within said cylinder, a piston rod extending through one end of the cylinder to engage said piston, the piston dividing the cylinder into two chambers, a plurality of passages through the walls of the cylinder, conduits coupled to a plurality of the passages to permit the flow of dampening fluid between the cylinder chambers, conduits coupled to a plurality of the passages to permit the flow of dampening fluid between the cylinder chambers and a dampening fluid reservoir, valve means in said conduits for effecting dampening forces during strokes of the piston, the passages being positioned in such a way that during at least a portion of an in-going stroke as well as during at least a portion of an out-going stroke of the piston at least one communication of the passages with the cylinder is closed by the piston to increase the dampening effect of the shock absorber, and including an arrangement such that during a complete in-going stroke as well as during a complete out-going stroke at least two valve means operate successively, that during the last portion of the in-going stroke valve means having the lowest resistance that is effective during said stroke is put out of action by the piston while valve means having a higher resistance is put into action and that during the first portion of the out-going stroke valve means having the lowest resistance that is effective during said stroke is kept out of action by the piston while valve means having the higher resistance is kept in action.