Fluid bearing

The power required by that pump contributes to system energy loss, just as bearing friction otherwise would.

In computer fan and spinning device, like a hard disk drive, heads are supported by hydrodynamic lubrication in which the fluid film is the atmosphere.

Because of mass conservation we can also assume an increase in pressure, making the body forces different.

In contrast, a conventional rolling-element bearing may require many high-precision rollers with complicated shapes.

Conventional rolling-element bearings usually have shorter life and require regular maintenance.

This helps attenuate resonances at the gyroscopic frequencies of journal bearings (sometimes called conical or rocking modes).

In contrast, fluid bearings self-correct for minor imperfections and slight deformations.

They use a gas as the working fluid, usually air, and require no external pressurisation system but need careful design to prevent wear during spin-up and spin-down when the bearing makes physical contact.

Being non-contact, air bearings avoid the traditional bearing-related problems of friction, wear, particulates, and lubricant handling, and offer distinct advantages in precision positioning, such as lacking backlash and stiction, as well as in high-speed applications.

The bearing uses a flat plane with periodic orifices which deliver air just over ambient pressure.

Michell/Kingsbury fluid dynamic tilting-pad bearings were invented independently and almost simultaneously by both British-born Australian, Anthony George Maldon Michell and American tribologist Albert Kingsbury.

The Kingsbury patent lacked this mathematical approach, and the pad's pivot point was placed in the geometric centre of the bearing.

Fluid pressure causes the pad to tilt slightly, creating a narrow constriction between the shoe and the other bearing surface.

A wedge of pressurised fluid builds behind this constriction, separating the moving parts.

Various design details ensure continued replenishment of the oil to avoid overheating and pad damage.

[7] Michell/Kingsbury fluid bearings are used in a wider variety of heavy-duty rotating equipment, including in hydroelectric plants to support turbines and generators weighing hundreds of tons.

It is likely the first tilting pad bearing in service was built in 1907 by George Weymoth (Pty) Ltd (under A.G.M.

The first British ship to be fitted out with the bearing was the cross-channel steamboat the Paris, but many naval vessels were similarly equipped during the First World War.

The practical results were spectacular – the troublesome thrust block became dramatically smaller and lighter, significantly more efficient, and remarkably free from maintenance troubles.

It was estimated that the Royal Navy saved coal to a value of £500,000 in 1918 alone as a result of fitting Michell's tilting-pad bearings.

According to the ASME (see reference link), the first Michell/Kingsbury fluid bearing in the US was installed in the Holtwood Hydroelectric Power Plant (on the Susquehanna River, near Lancaster, Pennsylvania, US) in 1912.

Until now tilting pad bearings play an essential role for rotating equipment like expanders, pumps, gas or steam turbines or compressors.