Information on Hydraulic Lifts

Hydraulic lifts are often set right into the floor or ground.

A hydraulic lift (also called a hydraulic jack) is an important tool in both the automotive repair and home repair industries. Hydraulic lifts are used to lift cars, heavy machine parts, and even parts of buildings.

Parts of a Hydraulic Lift

A hydraulic lift consists of six basic parts. The hydraulic fluid is held in the reservoir. A suction pump is connected to it by a check valve. The main cylinder, which contains the ram piston (or lift piston) is also connected to the pump. A release valve connects the main cylinder to the reservoir.

Theory of Operation

The hydraulic lift works because of Pascal's Principle. This states that any change in the pressure of an enclosed fluid is distributed equally everywhere. Because the ram piston is wider than the pump piston, it exerts a greater force to distribute the pressure evenly. (Though it moves a shorter distance to make up for the increased force.)

How Hydraulic Lifts Work

The pump draws hydraulic fluid into itself from the reservoir on the upstroke of the pump piston. The check valve closes on the downstroke, pushing the fluid into the main cylinder. This pushes the ram piston up. The long weak downstroke of the pump piston is converted into a short powerful upstroke of the main piston.

References

• CarTech Auto Parts: Hydraulic Jacks
• Hydraulic Jacks Home Page: Jack Bascis Page

Resources

• Georgia State University Hyperphysics: Pascal's Principle