| 摘要 |
A lower control system serves to regulate the flow rate of lifting jack oil, and is installed between a reverse flow valve and an inner oil chamber, regulates the oil flow from the inner chamber to an outer chamber. The lower control system comprises an outer valve body, a steel ball, a spring, and a throttle body. The throttle body has a tapered portion, formed at its front end, and at least one throttling slot way and one lateral slot way, formed respectively on the tapered portion and the circumferential wall thereof. When the jack is not loaded, a reverse flow valve can lift the steel ball so that oil swiftly flows by the throttle body through the lateral slot ways to complete the reverse flow. When the jack is loaded, oil gently flows by the throttle body through the throttling slot ways, leading to a reduction of oil flow rate and a slower descending of the jack.
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