Roller bearings
Roller bearings use rollers as the rolling element and are available in different types depending on the shape of the rollers, including cylindrical roller bearings, needle roller bearings, tapered roller bearings and spherical roller bearings.
Cylindrical roller bearings
The cylindrical roller bearings consists of straight geometry for outer ring, inner ring and roller. The rollers are guided by the ribs of the inner or outer ring. The cage can be polyamide, steel or brass. . The inner and outer rings can be separated to facilitate assembly, and both can be fitted tightly.These bearings can accommodate high radial load as the roller make line contact with the raceway. The bearings are available in a number of designs and sizes. Different types of ball bearings are designated as NU, NJ, NUP, N, NF and NH for single-row bearings and NNU & NN for double-row bearings.
On types with no ribs, either the inner or the outer ring can move freely in the axial direction, making cylindrical roller bearings ideal for use in free side bearings that absorb shaft expansion.
On types with ribs, the bearing can bear a slight axial load between the roller end surfaces and the ribs.
BOW cylindrical roller bearings are available in two types single row and double row.
Needle roller bearings
These bearings use small needle rollers, 6mm or less in diameter with a width 3 to 10 times diameter, as rolling elements. They feature a smaller cross-section, higher load-carrying capacity, greater rigidity, and lower inertia forces that facilitate size and weight reductions in machinery. They’re designed to withstand oscillation, perform under severe conditions, and interchange with sliding bearings.
Tapered roller bearings
Tapered roller bearings are designed so the inner and outer ring raceway and the apex of the tapered rollers intersect at one point on the bearing centerline. For this reason, the rollers are pushed against the inner ring rib and roll guided by the rib, receiving the loads from the inner ring raceway surface and the outer ring raceway surface as a combined load on the raceway surface.
The inner ring with rollers and outer ring separate, facilitating mounting with clearance or preload. However, assembled clearance is hard to manage and calls for attention.
Tapered roller bearings are capable of supporting large loads, both axial and radial.
BOW tapered roller bearings are available in single row, double row, and four-row configurations.
Spherical roller bearings
These bearings have an outer ring with a spherical track surface, and an inner ring that encloses two rows of barrel-shaped rolling elements.
Various types exist that differ by internal design, including bearings with a tapered bore inner caliber. The bearings are easily mounted on the shaft with an adapter or un-mounting sleeve, and are used in many industrial machines for their high load capacity. Potential troubles include one row bearing no load when axial load is large, calling for attention to usage conditions.
Cylindrical roller thrust bearings
These bearings use cylindrical rollers and have single-row, double-row, and three-row types for larger load capacities.
They support axial loads only, are suited to high loads, and have high axial rigidity.
Tapered roller thrust bearings
These are thrust bearings using tapered rollers. The single-type bearings include those with and without ribs on the housing raceway washers, as well as the full complement roller type. Double-type bearings are mainly used to support axial loads such as those on rolling mill roll necks.
Spherical roller thrust bearings
Spherical roller thrust bearings have asymmetrically sphered rollers., with a spherical surface on which the raceway surface of the housing raceway washer (outer ring) is centered on the guide sleeve. They can bear high axial loads.
As there are many sliding surfaces such as the roller end surfaces and the cage, oil lubrication must be used even in low-speed operation.
