How does the hydraulic press work?

A hydraulic press is a device using a hydraulic cylinder to generate a compressive force. The hydraulic press depends on Pascals principle.

This example will demonstrate how the Pascals principle may be used. When force F1 acts on area S1, a pressure is given by:

The basic principle in hydraulic is Pascals law: The effect of a force acting on a stationary liquid spreads in all directions within the liquid.

Pressure acts at every point in the system, which includes surface S2. The attainable force F2 is given by:

The forces are in the same ratio as the areas. The forces F1 and F2 vary proportion to the areas of the pistons.

The displacements l1 and l2 of the piston vary inverse proportion to the areas.

Design

Hydraulic pump is driven by electric motor.

Pump sucks fluid from tank and pushes it into the lines of the hydraulic circuit through various hydraulic devices up to the hydraulic cylinder.

The direction of movement of the piston in the hydraulic cylinder is controlled via directional valve.

Hydraulic cylinder at the end of the line represents a resistance to flow. Pressure therefore increases until it is in a position to overcome this resistance, until the piston in the cylinder moves.

So that the hydraulic circuit is protected from excess pressures and hence from overloading, the maximum pressure must be limited. This is achieved using a pressure relief valve.

The flow still delivered by the pump flows via pessure relif valve directly back to the tank. The pressure at this moment is maximum.

The direction of movement of the piston in the cylinder is controlled via directional valve.