Patent ID: 6823673
Filing Date: 2004-11-30
Classification: B66F,F15B

Abstract:
A lower control system regulating a flow rate of lifting jack oil comprisingan outer valve body being a hollow valve body and having a dividing portion which divides said outer valve body into a front chamber and a rear chamber; a valve hole being formed on said dividing portion and an oil lead being formed through a lateral wall of said front chamber at a selected location, a steel ball controlling the closure of said valve hole, a spring, and a throttle body having a tapered portion formed at a front end thereof; at least one throttling slot way and one lateral slot way being formed respectively on said tapered portion and a circumferential wall of said throttle body; said spring having one end holding against said steel ball and another end holding said throttle body; said rear chamber receiving said steel ball, said spring, said throttle body, and a retaining ring sequentially; said lower control system regulating the flow rate of lifting jack oil, with said steel ball holding against said valve hole, prohibiting exchange of lifting jack oil between an inner oil chamber and an outer oil chamber through said oil lead; said lower control system regulating the flow rate of lifting jack oil, with said lifting jack being loaded, restricting the flow rate of lifting jack oil from said inner oil chamber to said outer oil chamber; said restricting effect being realized by a close contact between said tapered portion of said throttle body and a corresponding inner wall of said rear chamber, and therefore oil flowing only through said throttling slot ways on said tapered portion; said close contact being achieved by said throttle body being pushed by said spring that is compressed due to the high hydraulic pressure in said inner oil chamber.