Patent ID: 7194857

Claim:
A ventilation valve of a hydraulic jack dedicated to be mounted at an outer wall of an oil storage tank of a hydraulic jack; the hydraulic jack including a valve seat, a valve ball, a cap; characterized in that: the valve seat is a hollow seat; the valve seat is locked to an outer wall of an oil storage tank of a hydraulic jack and is communicated to the oil storage tank; the valve body is received in the valve seat; the valve body is a hollow body and is received in the valve seat; an upper end of the valve body is formed with a valve hole having a valve ball therein; a lower end of the valve body is formed with a stopper for hindering the valve ball to fall out; the valve ball is installed within the valve body; by the raising and descending of the valve body, the valve hole of the valve body is controlled to be closed or to be opened; the cap is tightly combined with another end of the valve seat; a vent communicated with outer space is formed at a predetermined position of the cap; wherein in above mentioned ventilation valve, when the jack is not operated, the valve hole is opened; the vent of the cap is communicated with the oil storage tank of the jack so as to maintain the equilibrium of the pressure of the oil storage tank; thereby the piston of the pump can suck oil successfully so that the oil is absorbed into the oil chamber of the pump to be saturated therein.