It will be seen from a study of Fig. 13 that there are four distinct elements in a Timken Roller Bearing, viz. :-(1) The inner race which, due to its conical raceway, is called the cone. (2) The outer race, termed the cup, since it fits over the cone and the rollers. (3) The rollers which roll between the two raceways. (4) The cage which keeps the rollers properly spaced and holds them in position on the cone.

The assembly of the above parts is so arranged that when put together the conical sections, represented by cup, cone, and rolls, have a common apex (see Fig. 13). The bearing thus meets the fundamental law of true rolling motion.

The small rib at the large end of the cone does not take the thrust, but merely acts as a retaining means to keep the rolls on their proper path.

It will be apparent that the Timken bearing takes thrust loads in one direction only, i.e., in the direction which tends to push the cone and rollers into the cup. It is, therefore, usually necessary to mount the bearings in pairs with the angular direction of the rollers opposed. By this means thrust in either direction is negotiated and adjustment is effected by simply tightening up the cone into the cup or the cup on to the cone.

Up to the last few years ball-bearings of the cup and cone variety were almost universally used for motor cycle hubs and steering heads, but now the Timken bearing, on account of its inherent soundness, both in design and manufacture, is becoming increasingly used in such positions, and for the reasons set out below :-

The radial load capacity of any ball-bearing is very much less than that of a roller-bearing of equivalent size, since the load is taken on only one point of the ball as against the whole length of the roller.

In the case of the cup and cone, this vertical load capacity is still further decreased as the cup and cone must be set at an angle in order to accommodate end thrust.

In the case of the Timken bearing, not only has it a much greater radial load capacity than the ballbearing (and hence longer life), but it has also a considerable capacity for end thrust on account of the taper of cone, rollers and cup.

Again, perfect adjustment is always obtained with the Timken bearing by merely pushing the rollers further into the cup, true rolling motion being always maintained, whereas when wear takes place on the race of a cup and cone ball-bearing, the correct curvature is destroyed, and adjustment does not restore the original characteristics of contact between the ball and the race.

It is therefore obvious that not only is the life of a Timken bearing much longer than that of a cup and cone ball bearing, but also its adjustment is necessary at less frequent intervals.