What type of bearings are commonly used on crankshafts and camshafts?

Friction bearings, often referred to as plain bearings, are commonly used on crankshafts and camshafts due to their ability to handle high loads and provide a smooth surface for the rotating parts in an engine. These bearings consist of a smooth surface that is typically made from metal or plastic which directly supports the crankshaft and camshaft.

The design of friction bearings allows for a thin film of lubrication to minimize direct contact between the bearing surfaces, thus reducing wear and heat generation during the operation of the engine. Since crankshafts and camshafts endure significant rotational motion and pressure, friction bearings are well-suited for these applications, as they can distribute loads evenly and accommodate thermal expansion.

Other types of bearings, such as ball bearings or needle bearings, are typically used in different contexts where higher precision or lower friction is needed, but they are not as common in the specific applications of crankshafts and camshafts where the simplicity and durability of friction bearings are advantageous.