Shock absorber including plural control means

Claim 1

A shock absorber comprising a working cylinder, a pressurized gas-liquid mixture within said working cylinder, a piston rod slidably extending into said working cylinder, a main piston mounted on the inner end of said piston rod for slidable movement in said working cylinder, a subsidiary cylinder disposed within said working cylinder behind said main piston, the open end thereof facing said main piston, a subsidiary piston mounted on said piston rod and slidably movable within and out of said subsidiary cylinder means for restrictively controlling flow of said gas-liquid mixture From the front side of said main piston to the other side thereof and into said subsidiary cylinder, means for restrictively controlling flow of said gas-liquid mixture from the front side of said subsidiary piston to the other side thereof upon the inward movement of the piston rod in said working cylinder while the subsidiary piston remains in said subsidiary cylinder, said subsidiary piston being provided with a circumferential recess thereabout and passage means radially spaced from said recess, and in communication therewith, and an O-ring movably seated in said recess and cooperating with said passage means to prevent flow of said gas-liquid mixture past said subsidiary piston through said passage means during inward movement of said piston rod and to permit rapid flow of said gasliquid mixture past said subsidiary piston through said passage means during return movement of said piston rod, said gas-liquid mixture being free to flow into said subsidiary cylinder when said subsidiary piston has moved out of said subsidiary cylinder into said working cylinder during the operation of said piston rod, whereby said subsidiary piston and said subsidiary cylinder provide an initial resistance to movement of said piston rod when it starts its inward movement into said working cylinder.