There are different ways to reduce friction. One way to reduce friction and increase the efficiency of devices such as generators, motors, and fans is to use bearings. Bearings are devices that allow surfaces to slide or roll across each other while reducing the force of friction.
Many different types of bearings can be used under different circumstances, like plain bearings, fluid bearings, and magnetic bearings. Now, let’s see how these bearings help to reduce the frictional force & increase the efficiency of devices and machines.
Plain bearing to reduce friction
A plain bearing involves sliding two surfaces across each other while they are lubricated with oil or graphite. A rolling-element bearing uses balls or rollers to reduce friction (Figure 1). The balls or rollers are usually lubricated with oil. Both of these types of bearings have been used for years and can have very low coefficients of friction.
Fluid Bearings & reduction of frictional force
Fluid Bearings: Some newer types of bearings can reduce friction to negligible levels in some cases. For example, fluid bearings use a film of fluid, such as air or oil, to separate two surfaces (Figure 2).
The fluid film reduces the force of friction drastically in a similar way that a thin layer of water separates a skate blade on ice. Fluid bearings require a seal to keep the fluid in place and a pump to replace the fluid when it leaks. These bearings can be made cheaply, and they create less noise when operating than rolling element bearings.
However, they can fail suddenly without warning if the seal breaks. These types of bearings also use energy to keep the lubricant in place. A typical use for fluid bearings is in the hard drive of a computer.
Magnetic Bearings & magnetic levitation to minimize friction
Magnetic bearings: Magnetic bearings use magnetic fields, instead of fluids, to keep two surfaces separated. The two surfaces do not make direct contact with each other, so this technology is often called magnetic levitation.
Magnetic bearings often require a backup bearing system in case they fail. Electricity is required to operate the electromagnets that keep the surfaces separated. So energy is required to keep the bearings working.
However, the bearings need no maintenance and have no known upper limit on speed. Typical uses of magnetic bearings are in motors, turbines, generators, Maglev trains, and household meters.