Gas spring device

The present invention relates a speed reducing device of a gas spring device, and it is an object of the present invention to improve the structure of a piston which is an element of the speed reducing device, thereby to improve the shielding preciseness of a gas moving passage and to easily manufacture the piston. The piston according to the present invention is slidably moved in the cylinder in the state the piston is adhered to the inner wall surface 110a of the cylinder, and a cutting recess is formed on the outer peripheral surface of the cylinder to easily move the gas in first and second chambers. A concentric gas passage is formed on the surface of the piston which makes contact with the upper washer, and includes another concentric gas passage. An inlet and outlet of the gas passage is opened towards the outer peripheral surface of the piston. A concentric gas passage is formed on the surface of the piston which makes contact with the under washer. The inlet and outlet of the gas passage is opened towards the bottom surface of an annular recess. The gas passage is connected by an axial recess which penetrates the piston. If a Teflon ring shields the cutting recess, since the gas is slowly moved in the first chamber and the second chamber, the piston rod is slowly moved. If the Teflon ring opens a cutting recess, since the gas is moved fast in the first chamber 119a and the second chamber 119b through the cutting recess 128 and the gas passage 108c and 108d, the piston rod 111 is moved fast.