What is a plain wheel bearing?

A plain wheel bearing, also known as a plain bearing or bush bearing, is a type of bearing used in the wheel assemblies of vehicles. It serves as a support and friction-reducing mechanism between the wheel hub and the axle spindle, allowing smooth rotation of the wheel. Plain wheel bearings are commonly found in older vehicles and certain types of trailers.

These bearings consist of several components:

1. Outer Race: The outer race is the stationary part of the bearing that typically sits within the wheel hub.

2. Inner Race: The inner race is the rotating part that attaches to the axle spindle.

3. Rolling Element or Lubricated Surface: Instead of using rolling elements like balls or rollers found in more traditional ball or roller bearings, plain wheel bearings often utilize a lubricated surface or bushing made from materials like bronze, steel, or other alloys. This surface reduces friction between the inner and outer races, allowing smooth movement.

4. Lubrication: Proper lubrication is crucial for the functioning of plain wheel bearings. They might use grease or oil to reduce friction and wear.

Plain wheel bearings have been widely replaced by more modern designs such as sealed cartridge bearings or hub units in many newer vehicles. These newer designs often require less maintenance and provide better durability and performance in various conditions.

Maintaining and ensuring the proper functioning of plain wheel bearings involves regular lubrication and inspection for wear and tear. If a plain wheel bearing is damaged, it can lead to issues such as wheel vibration, noise, and compromised handling, which may necessitate replacement or repair.