Patent ID: 7040091

Claim:
A multilevel speed regulation jack comprising: an input oil cylinder; an output oil cylinder comprising a cylinder body containing an annular space and a tube piston that fits in said annular space, said tube piston comprising a sliding sleeve movably positioned in said annular space; a fluid conduit member connecting the input and output oil cylinders; an annular in-flow oil chamber formed between an end annular surface of the tube piston and the cylinder body; and a central in-flow oil chamber formed between an inner central surface of the tube piston and the cylinder body, wherein the fluid conduit member comprises at least two parallel fluid channels connected to the central in-flow oil chamber and the annular in-flow oil chamber, respectively; and a control valve in one of the fluid channels to open and close the channel; wherein said cylinder body has two or more annular spaces and two or more tube pistons movably positioned in their respective annular space to form two or more annular in-flow oil chambers.