Patent ID: 8065055

Claim:
A shock absorber capable of controlling damping force characteristics, comprising: a cylinder filled with an operating fluid; a piston valve disposed inside the cylinder to divide an interior of the cylinder into a first chamber and a second chamber; a piston rod having one end extending outside the cylinder and one end coupled to the piston valve inside the cylinder; a hollow chamber formed inside the piston rod and in fluid communication with the first and second chambers; a free piston disposed within the hollow chamber configured to move axially and to divide the hollow chamber into upper and lower chambers; a variable part having a valve member positioned within the hollow chamber and configured to control the damping force characteristics by adjusting an axial range of motion of the free piston; and an actuator wherein the variable part comprises a control rod having first and second ends, the first end movably positioned in the hollow chamber to control a range of motion of the free piston, the actuator being configured to axially move the control rod.