Hydraulic shock absorber

Claim 1

A hydraulic shock absorber for a vehicle comprising: a vertically mounted hydraulic cylinder with a double action piston which divides the interior of said hydraulic cylinder into an upper chamber or compartment and a lower chamber or compartment; a damping chamber in form of a hydraulic cylinder with a piston supported by a first spring and a first tube to connect with said upper chamber and a second tube to connect with said lower chamber; and a return chamber, in form of a hydraulic cylinder with a piston supported by a second spring and a third tube to connect with said upper chamber and a fourth tube to connect with said lower chamber; said fourth tube being provided with a one-way valve which only opens to the direction toward said hydraulic cylinder; characterized by that a control valve and a shock sensor are provided; said control valve being provided in a position of said first tube to prevent the oil in said damping chamber from flowing into said upper compartment and controlled by a signal from said shock sensor; said shock sensor being provided on a position of said vehicle to detect the shock to which said vehicle is subject and being responsive to a shock exceeding a predetermined level to give said signal to said control valve.