Patent ID: 7637479

Claim:
A hydraulic jack, comprising: a frame; and a pump connected to said frame, said pump including: a rod having a cross-sectional area; a housing having an end through which said rod slides; a piston associated with said rod, said piston establishing a rod side chamber and a piston side chamber within said housing, said piston having a cross-sectional area; and a plurality of valves each being fluidly connected to at least one of said rod side chamber and said piston side chamber, said piston, said rod and said valves being arranged to provide a first hydraulic fluid flow associated with said cross-sectional area of said piston until a predetermined pressure is reached and a second hydraulic fluid flow associated with said cross-sectional area of said rod after said predetermined pressure is reached, said piston being slidingly disposed inside of said hosing and said rod being slidingly retained by said piston, said rod being configured to pressurize hydraulic fluid as it slides through the piston thereby causing said second hydraulic fluid flow.