Hydraulic shock damper assembly for use in vehicles

A hydraulic shock-damper assembly for use in vehicles and particularly for the rear wheel of a motorcycle such as a rally-cross motorcycle, the shock-damper assembly comprising a hydraulic cylinder accomodating a hydraulic damping fluid and a piston provided with one or more apertures and dividing the cylinder internally to provide upper and lower chambers, and a dashpot closed at one end and a displaceable partitioning element accomodated in the dashpot and in which a first space enclosed between the partitioning element and the closed end of the dashpot is filled with a fluid under pressure and a second space located on the other side of the partitioning element is connected to the upper chamber of the hydraulic cylinder via a transmission channel for the damping fluid, characterised in that there is provided a second cylinder being spaced concentrically around the said hydraulic cylinder, an open connection close to the lower end of the hydraulic cylinder and running between the lower chamber of the cylinder and the intermediate space between both cylinders, two branch lines connected to the transmission channel for the damping fluid flow and emerging into a single line which again emerges into the said intermediate space, an externally controllable closure means and a non-return valve being arranged in each one of the said branch lines, both of which non-return valves open in opposing flow directions of the hydraulic fluid.