US Patent 8991571 Hydraulic shock absorber

In a hydraulic shock absorber, a damping force generating device provided between a piston side oil chamber of a cylinder and a rod side oil chamber is provided with a through-hole which communicates the piston side oil chamber of the cylinder with the rod side oil chamber of the cylinder via an outer flow path of the cylinder. A leading end portion of a piston rod is provided with a needle which can come in and out of the through-hole of the damping force generating device, and an opening degree of the through-hole can be varied by the needle according to a forward and backward position of the piston rod with respect to the oil chamber of the cylinder.