US Patent 7096773 Telescopic pneumatic device

A telescopic pneumatic device comprises an outer cylinder, an inner cylinder disposed in the outer cylinder and having a cylinder wall defining an air chamber, a piston mounted in the air chamber and having a piston rod connected thereto, a flow passage provided between the cylinder wall and the outer cylinder, and a control valve operable to permit or interrupt fluid communication between the flow passage and the air chamber. The inner cylinder is made of a rigid plastic material and includes a valve mounting part for receiving the control valve, the valve mounting part being formed in one piece with the cylinder wall.