How Does a Hydraulic Press Work?

A hydraulic press uses a fluid to exert a compressive force to accomplish work. It is typically used in applications requiring a large force to be applied over a short distance. The operation of a hydraulic press is based on Pascal’s principle, which was developed in the early 17th century.

Overview

Pascal’s principle states that a fluid exerts constant pressure in a closed container. This pressure acts at a right angle to the wall of the container. A hydraulic press contains two pistons of differing sizes. A small piston acts as a pump and generates only a modest mechanical force. The large piston in a hydraulic system is in a press cylinder, which uses the force from the small piston to generate a much larger force. The pump in a hydraulic press is typically separated from the press cylinder. This allows the press to use tubing with a small diameter, which has a higher tolerance for pressure.

Operation

The hydraulic fluid is typically some type of oil, which creates less friction when it moves through the system. The pump moves a large distance to pressurize the fluid to a specific level, which is regulated by a relief valve. This pressure moves the fluid into the press cylinder, which moves the main piston a short distance. The pressure is released, which moves the hydraulic fluid into a reservoir until the next operation of the hydraulic press. The hydraulic press requires a second mechanical action of some type to return the main piston to its original position.