Hydrostatic bearing vs hydrodynamic bearing

What is the difference between a hydrostatic bearing and a hydrodynamic bearing?

A hydrodynamic bearing is a type of bearing in which there is minimal clearance between the bearing and the shaft. This gap is filled with lubricant. When at rest, the shaft also rests on the plain bearing.

When the shaft starts to rotate, lubricant is drawn into the constriction between the bearing and shaft and the pressure in the lubricant increases as the rotational speed increases. This forms a so-called lubrication wedge underneath the shaft, which lifts the shaft. As a result, the plain bearing and shaft no longer touch and are separated from each other by a lubricating film.

A hydrostatic bearing doesn't require a shaft to be rotating. A pump forces oil into the bearing gaps under pressure therefore these bearings require a pressure supply.

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Information on hyrdodynamic bearings

Coolant pump with plain bearings hyrdodynamic bearing — Coolant pump with hydrodynamic plain bearings

Where are hydrodynamic plain bearings used

Hydrodynamic plain bearings are often used in the automotive industry, where they are used in thermal management. They are also widely used in ships and subsea turbines, as they provide optimum performance when operating in humid environments. They also play an important role in power generation, particularly in wind turbines and hydroelectric power stations. In addition, hydrodynamic plain bearings are used in industrial machinery, such as large machine tools and pumps. Their ability to carry high loads with low friction makes them the ideal choice for these applications.

Cross section of a bearing position with a hydrostatic bearing

Functionality of hydrodynamic plain bearings

A hydrodynamic plain bearing is a type of bearing in which there is minimal clearance between the bearing and the shaft. This gap is filled with lubricant. When at rest, the shaft also rests on the plain bearing.

Information on hydrostatic bearings

Cross section of a bearing position with a hydrodynamic bearing

How hydrostatic plain bearings work

A hydrostatic plain bearing is a type of bearing in which a pump is used to pump lubricant between the shaft and the bearing. In contrast to hydrodynamic bearings, there is therefore permanent full lubrication.

Hydrostatic plain bearings are used when it is necessary for the shaft to run in the centre. However, as the oil supply or oil pressure represents a safety risk, hydrodynamic bearing points are generally favoured.

This are hydrostatic plain bearings are used?

Hydrostatic plain bearings have similar areas of application to hydrodynamic plain bearings. However, as they have a higher true-running accuracy, they are often used where high-precision operation is required. For example, in measuring equipment or machine tools. Like hydrodynamic plain bearings, they are also used in power generation. Here they are used in turbines and generators, among other things.

Our plain bearings for hydrodynamic applications

igus offers various plastic bearings that are suitable for use in hydrodynamic lubrication. These differ primarily in the various application parameters, such as e.g. temperature or chemical resistance, for which they were developed.