Main types of roller bearings
Roller bearings may be differentiated according to the configuration of the rolling elements and the orientation of the load they support.
1. Cylindrical roller bearings Description:
The rolling element is of a cylindrical shape, and the rollers make linear contact with a particular raceway. Structural characteristics: The inner and outer rings are generally separable, facilitating simple mounting and dismounting. Depending on the design of the flange on the outer ring, it is classified into several types.
NU type: the inner ring has no flange, and the outer ring has a double flange. Allows axial displacement to occur in both directions and is ideal for floating end bearings.
N-type: the outer ring has no flange, and the inner ring has a double flange. Bidirectional axial displacement is also allowed.
NJ type: The inner ring has a double flange, and the outer ring has a single flange. It can withstand unidirectional axial loads and can be used as a locating end bearing.
NUP type: the inner ring has a double edge plus a flat ring, and the outer ring has a single side. Capable of bearing bidirectional axial loads and serving as a fixed end.
Features: Extremely high radial bearing capacity, good rigidity, low friction coefficient, suitable for high speed (second only to ball bearings). However, it basically does not bear pure axial load (except for NJ and NUP types, which can withstand a certain axial force).
Applications: Motors, generators, gearboxes, rolling mills, large pumps, compressors.
2.Describe Tapered Roller Bearings
The rolling element is conical shaped and the inner and outer raceways are also conical shaped and the apex of each cone surface intersects at a singular point along the axis.
Structural features: separable type, the outer ring (outer ring) can be installed separately from the inner ring (inner ring with roller and cage assembly).
Features: Capable of bearing large radial loads and unidirectional axial loads at the same time. The axial bearing capacity increases with the increase of the contact angle (determined by the roller angle). It is usually used in pairs (face to face or back to back) to withstand bidirectional axial forces.
Application: Automobile hub, gearbox, reducer, rolling mill, crane, machine tool spindle.
3. Describe Spherical Roller Bearings
The rolling element is shaped like a cylinder but in a drum form and the raceway of the outer ring is a sphere.
Structural features: It has an automatic aligning function, allowing the inner ring to have a large angular deviation from the outer ring (usually 1-2.5°).
Features: Extremely high radial bearing capacity and can bear bidirectional axial loads at the same time. It has strong vibration and shock resistance and can compensate for shaft deflection and installation errors.
Application: Mining machinery, vibrating screen, paper making machinery, wind turbine spindle, heavy-duty conveyor, high-power reducer.
4. Describe Thrust Roller Bearings
These are the roller bearings that have been specially constructed and designed to withstand axial loads and include thrust cylindrical roller bearings, thrust tapered roller bearings and thrust spherical roller bearings.
Structural Features: Usually composed of a shaft ring, housing ring, and rolling element cage assembly.
Characteristics: Extremely high axial load capacity. Thrust spherical roller bearings also have a self-aligning function and can withstand certain radial forces.
Applications: Heavy-duty vertical motors, large hydroturbines, marine propellers, oil drilling rigs.
5. Needle Bearings
Description: Rolling elements are slender cylindrical rollers (needles), with a small diameter and long length.
Structural Features: Very low radial section height, very compact structure. Can be used without an inner or outer ring, allowing the hardened shaft to serve directly as the raceway.
Characteristics: Extremely high radial load capacity but generally do not bear axial loads. Low limiting speed and sensitive to angular misalignment.
Uses: Gearboxes, connecting rods, universal couplings, rocker arms, rotating systems with limited space.
