Patent ID: 6347786
Filing Date: 2002-02-19
Classification: B66F

Abstract:
A hydraulic jack lifting mechanism comprising a valve seat and piston pump, a cylinder coupled to said valve seat and piston pump and filled up with a hydraulic fluid, an inner tube provided inside said cylinder and coupled to said valve seat and pump assembly, said valve seat and pump assembly comprising:said valve seat comprising a radially extended first valve hole, a forward fluid hole extended from an upper part of said first valve hole to said inner tube, a return fluid hole extended from a lower part of said first valve hole to said cylinder, a second valve hole, a low-pressure fluid hole extended from said second valve hole, a high-pressure fluid hole connected between said second valve hole and a lower part of said first valve hole, a fluid suction hole connected between said second valve hole and said cylinder, a fluid outlet connected between said second valve hole and said inner tube, a third valve hole connected to said low-pressure fluid hole, a relief hole connected between said third valve hole and said cylinder, a fourth valve hole disposed in communication with said cylinder and said inner tube; said piston pump comprising a casing coupled to coupled to the front side of the valve seat, a big piston mounted said casing and coupled to said valve seat and aimed at said high-pressure fluid hole, and a small piston mounted in said big piston and aimed at said low-pressure fluid hole; a return fluid control pin shaped as a stepped cylinder and movably mounted said first valve hole and peripherally sealed with a seal ring; a pressure regulating valve mounted in said first valve hole, said pressure regulating valve comprising stopped against said return fluid control pin, a support rod stopped at the steel ball of said pressure regulating valve against said return fluid control pin, a compression spring a screw cap with threaded into said first valve hole to close a bottom end of said first valve hole, and a compression spring supported between said screw cap and said support rod; an one-way ball valve unit mounted in said second valve hole, said one-way ball valve unit comprising a first steel ball, a second steel ball, a third steel ball, a first compression spring and a second compression spring, said first steel ball being inserted into said second valve hole to stop the passage between said fluid suction hole and said high-pressure fluid hole in one direction, said second steel ball being inserted into said second valve hole and supported on said first compression spring to close the passage from said high-pressure fluid hole to said fluid outlet, said third steel ball being inserted into said second valve hole and supported on said second compression spring to close the passage from said low-pressure fluid hole to said fluid outlet; and a return fluid valve inserted into said fourth valve hole to control the fluid passage from said fourth valve hole to said cylinder, said return fluid valve having a rear end mounted with a screw bolt disposed outside said valve seat.