Multi-speed hydraulic jack

A multi-speed hydraulic jack, comprising:

• a. a pump block having a first cylinder and a second cylinder defined therein;
• b. a piston assembly movable within the pump block, the piston assembly having a first portion configured to sealably engage with the first cylinder and a second portion configured to sealably engage with the second cylinder;
• c. a reservoir for storing hydraulic fluid and coupled to the pump block so that when the piston assembly is moved in a first direction, hydraulic fluid in the reservoir is drawn into the first cylinder and the second cylinder;
• d. a lifting assembly having a ram chamber and a ram rod, the ram chamber fluidly coupled to the first and second cylinders;
• and
• e. a bypass check valve provided in the first cylinder, the bypass check valve configured so that as the piston assembly is moved in a second direction, when the pressure in the first cylinder is less than a threshold pressure, the first and second portions of the piston assembly push fluid into the ram chamber to extend the ram rod, and when the pressure in the first cylinder exceeds the threshold pressure, the second portion of the piston assembly pushes fluid into the ram chamber to extend the ram rod while the first portion of the piston assembly pushes fluid back to the reservoir.

A multi-speed jack, comprising:

• a. a reservoir for storing hydraulic fluid;
• b. a pump block having a larger cylinder and a smaller cylinder, the larger and smaller cylinders fluidly coupled to the reservoir;
• c. a piston assembly movable within the pump block, the piston assembly having a larger piston portion configured to sealably engage with the larger cylinder and a smaller piston portion configured to sealably engage with the smaller cylinder;
• and
• d. a lifting assembly having a ram tube and a movable ram rod provided within the ram tube;
• e. wherein the piston assembly is configured to draw fluid from the reservoir into the large cylinder and the small cylinder when the piston assembly is moved in a first direction;
• and
• f. wherein the large cylinder includes a bypass check valve configured so that as the piston assembly is moved in a second direction, when the pressure in the larger cylinder is less than a threshold pressure, the larger portion and smaller portion of the piston assembly push fluid into the ram tube to extend the ram rod, and when the pressure in the larger cylinder exceeds the threshold pressure, the smaller portion of the piston assembly pushes fluid into the ram tube to extend the ram rod while the larger portion of the piston assembly pushes fluid back to the reservoir.