Stave Bearings 101
There are several possible arrangements for shafts and bearings. The most common arrangement involves having a bearing with a fixed portion surrounding the majority of the shaft; the fixed portion may consist of either one or two pieces. A stave bearing is different because instead of just one or two parts that surround the shaft, it features a system of axial staves to provide support. A stave bearing typically has many such axial pieces.
Applications for Stave Bearings
Stave bearings are generally used in nautical applications and are most commonly associated with propeller shafts. This is because this type of bearing holds up well under the conditions that go along with boat propulsion: high loads and relatively low speeds. In addition, a stave bearing can easily be adapted to be used in water, which makes it a perfect match for outboard motors.
Stave bearings are also commonly used on rudder shafts. This is because motion for this component of a watercraft consists of rotation that is both reciprocating and intermittent, instead of continuous rotation in only one direction. Ball bearings tend to fail more often when used with rudders.
Materials Used in Stave Bearings
Because stave bearings historically contained some wooden components, the choice of wood used had to be one that could resist softening and swelling as well as actual rotting. In practice, tropical hardwoods were well suited for this application, but modern stave bearings frequently feature composite materials such as polyester resin in place of wood. Nitrile rubber is another popular material used in stave bearings.