Hydraulic pump

A hydraulic pump is a mechanical source of power that converts mechanical power into hydraulic energy (hydrostatic energy i.e. flow, pressure).

They generate flow with enough power to overcome pressure induced by a load at the pump outlet.

Hydrostatic pumps of various types all work on the principle of Pascal's law.

The swept volume or displacement of gear pumps for hydraulics will be between about 1 to 200 milliliters.

This is in part due to designs incorporating split gears, helical gear teeth and higher precision/quality tooth profiles that mesh and unmesh more smoothly, reducing pressure ripple and related detrimental problems.

Hydraulic gear pumps are used in various applications where there are different requirements such as lifting, lowering, opening, closing, or rotating, and they are expected to be safe and long-lasting.

In some cases these vanes can have variable length and/or be tensioned to maintain contact with the walls as the pump rotates.

Several type of "lip" designs are used, and the main objective is to provide a tight seal between the inside of the housing and the vane, and at the same time to minimize wear and metal-to-metal contact.

These pumps are used for high flows at relatively low pressure (max 100 bars (10,000 kPa)).

[clarification needed] They were used on board ships where a constant pressure hydraulic system extended through the whole ship, especially to control ball valves[clarification needed] but also to help drive the steering gear and other systems.

Although in general, the largest displacements are approximately one litre per revolution, if necessary a two-liter swept volume pump can be built.

Often variable-displacement pumps are used so that the oil flow can be adjusted carefully.

By using different compensation techniques, the variable displacement type of these pumps can continuously alter fluid discharge per revolution and system pressure based on load requirements, maximum pressure cut-off settings, horsepower/ratio control, and even fully electro proportional systems, requiring no other input than electrical signals.

This makes them potentially hugely power saving compared to other constant flow pumps in systems where prime mover/diesel/electric motor rotational speed is constant and required fluid flow is non-constant.