Bearings play an important role in many mechanical assemblies. They are designed to assist with the movement of parts by reducing friction. When two or more parts rub together, they create friction. Excessive friction can restrain their movement and interfere with their operation. While some bearings use balls or rollers to facilitate movement and reduce friction, however, others use fluid.
What Are Fluid Bearings?
Fluid bearings are mechanical bearings that use a thin layer of fluid. Some of them use petroleum-based oil, whereas others use synthetic oil or even specialized lubricants. Regardless, all fluid bearings facilitate movement and reduce friction using a thin layer of fluid.
How Fluid Bearings Work
Most fluid bearings have two surfaces separated by a thin layer of fluid. When used in conjunction with a shaft, they allow for smooth, low-friction rotation.
As the shaft begins to rotate, it will pull fluid into the space between the bearing’s two surfaces. The fluid layer essentially becomes pressurized due to this movement, further reducing friction. The shaft will move on the fluid layer rather than the adjacent part.
Why Use Fluid Bearings
Being that there are other types of bearings available, such as ball and roller, you might be wondering why you should use fluid bearings. Fluid bearings offer several advantages over conventional bearings such as these.
Applications involving high rotational speeds produce a lot of friction. Friction, of course, means heat and stress. The balls or rollers in conventional bearings can become hot or even fail. Fluid bearings offer a solution. Rather than balls or rollers, they use fluid. Their fluid-based design makes them ideal for applications for high rotational speeds.
Fluid bearings are also effective at distributing loads across a large area. With conventional bearings, loads are focused at specific points — typically the area where the ball or rollers touch the races. Fluid bearings use an entirely different design. Instead of balls or rollers, they use a layer of fluid. This unique design allows loads to be distributed over the entire bearing surface.
Do Airplanes Use Fluid Bearings?
Airplanes use a variety of different bearings, including fluid bearings. Turbine aircraft engines feature shafts that rotate at very fast speeds. Fluid bearings, such as journal bearings, allow these shafts to rotate freely and with minimal friction.
You can also find fluid bearings in fuel pumps. Fuel pumps leverage fluid to prevent metal-on-metal contact. Fluid bearings allow the components of fuel pumps to move and, thus, transfer fuel from one area to another.