As single row cylindrical precision roller bearings, the rollers are in linear contact with the raceways. They have higher radial load capacity compared with the point-contact ball bearings and are suitable for high speeds.
Double Row Roller bearings
TPI roller bearing company's double row cylindrical roller bearings are, because of their second row of rollers, suitable for very heavy radial loads and provide increased radial stiffness. With a tapered bore design, NN precision roller bearings can reach even much higher rigidity. There are three integral flanges on the inner ring and no flanges on the outer ring, which makes the bearing are separable under a static state.
Precision roller bearings have two types of cages are available and categorized by the material with characteristics as below,
T2 cage, an engineered plastic molded cage. Although it has a favourable combination of strength and elasticity, an ageing process mostly influenced by temperature, time and lubricant should be taken care.
Machined brass cage, are mostly machined from cast or wrought brass. Unlike T2 cages, they are unaffected by most common bearing lubricants, temperature at the sacrisface of flexibility and light weight.
Bearing life is usually expressed as the number of hours an individual bearing will operate before material fatigue develops on either the raceways or the rolling element. The usual life rating for industrial applications is called “L10” life. The L10 life is the number of hours which that 90% of bearings will survive； or, conversely, 10% of bearings will have failed in the L10 number of service hours. One thing to be noticed that, roller bearing has different factor when it comes to bearing life calculation.
Cylindrical roller bearings with tapered bores are usually used to allow easier adjustment of internal clearance. When the radial internal clearance becomes negative, the cylindrical roller bearings are preloaded. Generally, cylindrical roller bearings for the front end (fixed end) of the spindle are preloaded during operating. Bearing for the rear end (free end) are adjusted to produce a slight clearance during operating. The amount of radial internal clearance after mounted is based on several factors such as rotating speed, load, bearing size, required rigidity, etc.