Abstract: A pressure-receiving chamber in an actuator and an air chamber of an air spring for displacing a shutter in a piston rod communicate with other through an air passage provided in the piston rod. The air passage includes a small-diameter hole of a rod insertion hole in the piston rod and an air hole formed in a side wall of the piston rod. By this arrangement, an external pipe such as used in a conventional air suspension apparatus for enabling communication between the actuator and the air spring becomes unnecessary, and the pressure in the air chamber is introduced into the pressure-receiving chamber in the actuator through the air passage in the piston rod. Therefore, a problem such as leakage of air can be avoided, leading to a reduction in the number of necessary parts.

Abstract: A hydraulic shock absorber of the adjustable damping force type includes a piston rod which is projected out of a cylinder and provided with a damping factor adjusting actuator includes a casing. The actuator accommodating a rotor for rotation with an adjusting rod, an ultrasonic vibratory element and a vibration transmitting member. A high frequency voltage is applied to the ultrasonic vibratory element from outside to generate surface waves of a high frequency on the surface of the vibration transmitting member to rotationally drive the rotor. The rotor thus rotates the adjusting rod to adjust the damping force of the hydraulic shock absorber.