Cylindrical roller bearings are generally only used to withstand radial load. Only when the inner and outer rings are with a rib of the single row bearing can withstand small directional axial load or large clearance axial load.
Relationship between bearing and load direction:
Under normal circumstances, for the use of pure radial load requirements, you can choose deep groove ball bearings or cylindrical roller bearings. If it is a thrust ball bearing, then it is only suitable for bearing the right amount of pure axial load. And one-way thrust ball bearings can only withstand the bearing load from one direction.
If there is two-way thrust ball bearings, or two-way thrust angular contact bearing, then it bears the axial load in both directions. For example, if the bearing bears a combined radial and axial load, then it is usually necessary to use angular contact ball bearings or cylindrical roller bearings. And if it is four-point contact ball bearings and two-way thrust angular contact ball bearings, then it can withstand the combined load in two directions to the advantage of bearing fou load.
However, if the bearing load in the joint load is relatively large, then the thrust bearing only uses withstand axial load. If a suitable single-row radial ball bearing or a four-point contact ball bearing is for bear axial load, then the appropriate radial clearance should maintain between the outer ring and the seat hole.
If the load action is off the center of the bearing, it may cause overturning moment. Stainless steel bearing manufacturers, and double row ball bearings can withstand the overturning moment. But recommend that you choose the matching angular contact ball, or the matching tapered roller bearing. Which available face to face type, back to back type is better. Of course, you can also choose cross-tapered roller bearings and so on.
Relationship between bearing fit and load type:
- Fixed load
The synthetic radial load acting on the ring is borne by the local area of the ring raceway. And transmitted to the relative area of the shaft or housing, and this load calls fixed load. The characteristic of the fixed load is that the combined radial load vector is relatively static with the ring. Both the ring and the composite radial load do not rotate or rotate at the same speed, then they are fix loads. Bearing the fixed load of the ring can choose a more loose fit.
- Rotating load
The synthetic radial load acting on the ring rotates along the circumference of the raceway. By various parts in turn, this load calls rotational load.
The rotational load has characters of a composite radial load vector rotating with respect to the ferrule. There are three conditions for rotating loads:
- the load direction is fixed, the ring rotation;
- load vector rotation, ring static;
- the load vector and the ferrule rotate at different speeds.
- Oscillating load and indefinite load
Sometimes the direction and magnitude of the load cannot determine exactly. For example in high-speed rotating machinery. In addition to the load bearing rotor weight is fixed in the direction, there is also the rotation load caused by the unbalanced mass. If the rotation load is much larger than the fixed load, the combined load is still the rotation load. If the rotating load is much smaller than the fixed load, the combined load is a swinging load. The magnitude and direction of the rotating or oscillating load are constantly changing. Under variable working conditions, the load on some ferrules may sometimes be a rotating load. Sometimes a fixed load, and sometimes a swinging load. This load calls indefinite load.
Swing load and indefinite load should as regarded as the same as the rotating load in the fit. Too loose fit will lead to the failure of the fit surface. Transition fit or interference fit should select for rings and shafts or seat holes rotated relative to the direction of load. The interference size is based on the principle that when the bearing is working under load. The ring does not produce “creep” on the mating surface of the shaft or the seat hole. When the load is very light, or when the ring is occasionally rotated at low speed under heavy load. The transition fit select, and the shaft surface should have a higher hardness and a smaller surface roughness.
For heavy load occasions, it should usually be tighter than in light load and normal load occasions. The heavier the load, the greater the interference should be.