Abstract: A pressure controlled valve for controlling the actions of a piston within a cylinder including a base, the ends thereof having their outer edges protruding outwardly to form respective seal portions which press tightly against the inner walls of an housing of the cylinder and an open end of the cylinder respectively, a T-shaped shaft with a waist portion capable of displacing axially within the base, the ends of the base further having their inner edges extending inwardly to form respective annular seal portions for pressing tightly against the shaft. The base may consist of a base body and a sleeve accommodated within the base, both of which may have their respective ends extending outwardly or inwardly to form seal portions. The waist portion of the shaft always aligns with a radial hole of the base.