There are numerous bearing designs, of them, ball bearings and tapered roller bearings are very popular. The purpose of any bearing is to reduce friction on a rotating element as well as support a load. In the case of a conventional ball bearing this is accomplished with a series of precision hardened steel balls, encapsulated in a cage and running between a pair of parallel bearing races. One race is held stationary while the other rotates, as the race rotates so do the balls. It is this design that ensures low friction as the balls have minimal contact area compared to flat surfaces sliding against one another.
As a result of limited contact area of the balls, a typical ball bearing has a low load carrying capacity.
Tapered roller bearings:
Tapered roller bearings solve the problem of limited load carrying capacity based on physical size.
Tapered roller bearings also have four elements; inner and outer race, rolling elements and cage. The inner and outer races and the rollers carry the load; the cage maintains separation of the rollers. The cage and roller assembly is known as the “cone” and can be separated from the outer race for ease of assembly.
The rollers may appear to have parallel sides but they don’t, the rollers are tapered, hence the name “tapered roller” bearings. The rollers are larger in diameter on one end than the other, the raceways are angled to correspond exactly with the roller taper.
The angle of the rollers in relation to the bore varies, a reasonably shallow angle is used when there are heavy radial loads; a steeper angle is used when there are heavy thrust loads.
This design allows the bearing to carry radial and thrust loads, as the surface area of the tapered rollers is far bigger than the surface area of balls this bearing design has a very high load carrying capacity based on bearing size. As a tapered roller bearing can deal with radial and thrust loads and carry a heavy load, they are the ideal choice for a myriad of applications.
Typical applications include:
- Car wheel bearings
- Agricultural equipment
- Steady rest rollers, and much more
When tapered roller bearings are used in an automobile wheel hub a pair of bearings is installed back to back in the hub, in this way axial forces from either direction can be dealt with. Wheel bearings in an automobile must withstand radial and axial forces at the same time.