What is a Trunnion? Definition, Types, and Applications

A trunnion is a type of pivot or hinge that allows a rotating shaft to be supported and constrained at both ends. It consists of a cylindrical bearing that is mounted on a flat surface, with a pin or bolt passing through the center of the bearing to connect it to the shaft. The bearing is typically made of a durable material such as bronze or steel, and is designed to absorb the loads and stresses generated by the rotation of the shaft.

Trunnions are commonly used in a variety of applications, including:

1. Axles: Trunnions are often used to support the ends of axles in vehicles, such as cars and trucks.
2. Gearboxes: Trunnions can be found in gearboxes, where they are used to support the input and output shafts.
3. Pumps: Trunnions are also used in pumps, such as centrifugal pumps and positive displacement pumps.
4. Compressors: Trunnions can be found in compressors, where they are used to support the rotating shafts that drive the compression process.
5. Turbines: Trunnions are sometimes used in turbines, where they are used to support the rotor shaft and maintain its position.

The term "trunnion" comes from the Old English word "trunian," which means "to turn." It is likely that the name refers to the fact that trunnions are designed to allow a rotating shaft to turn smoothly and consistently, without any obstruction or interference.