Four-point contact ball bearing is a kind of separable bearing, which can also be said to be a set of angular contact ball bearings that can withstand bidirectional axial loads. The inner and outer raceways are peach-shaped sections. When there is no load or pure radial load, the steel ball and the ferrule are in four-point contact, which is also the origin of the name.
Four-point contact ball bearing function
When only pure axial load acts, the steel ball and the ferrule become two-point contact, which can bear two-way axial load. Four-point contact ball bearings can also withstand moment loads, and have both the functions of single-row angular contact ball bearings and double-row angular contact ball bearings. Four-point contact ball bearings can only ensure normal work when they form two-point contact. Therefore, it is generally suitable for those occasions where there is two-point contact under pure axial load or synthetic load with large axial load.
1. Four-point contact ball bearing is a kind of radial single row angular contact ball bearing. The designed raceway is used to support the axial load acting in two directions. Four-point contact ball bearings can withstand radial loads up to a fraction of the axial load. Compared with double row bearings, four-point contact ball bearings occupy significantly less axial space.
SKF four-point contact ball bearings designed by QJ have a contact angle of 35° or 45°. The inner ring is a flat inner ring. This allows a larger number of balls to be installed in the bearing, which can give the bearing a higher load bearing capacity. This SKF four-point contact ball bearing is a separate design, that is, the outer ring with the ball and cage assembly can be installed separately with the two inner ring half rings.
2. The inner ring (or outer ring) of the four-point contact ball bearing is precisely assembled by two half rings, and the radius of curvature of the groove of its overall periphery (or inner ring) is very small, so that the steel ball and the inner ring have a very small radius of curvature. , The outer ring is in contact at four "points", which not only increases the radial load capacity, but also can bear a large axial load in two directions with a compact size, and has a good two-way load. This is because its axial clearance is relatively small, and its contact angle (generally taken as 35°) is relatively large.
The allowable speed of three and four-point contact ball bearings is also very high, and the operation is very stable, and its double half-rings can be removed from the entire set of bearings for installation, so four-point contact ball bearings are mostly used in engines, because it It can withstand large radial and axial loads at higher speeds.
ZhiYuan's four-point contact ball bearings have deep-bottomed shoulders (fig) on half of the two inner rings. When this four-point contact ball bearing is used with SKF cylindrical roller bearings, the oil flow is increased. In addition, these deep concave bottoms can also be used to hold the puller when disassembling the four-point contact ball bearing.
Features of four-point contact ball bearings
The four-point contact ball bearing is a separable structure, and a single bearing can replace the angular contact ball bearing combined with the front or the back.
It can bear radial load and two-way axial load, and can limit the axial displacement in two directions, but it occupies less axial space than the double row angular contact ball bearing of the current specification.
Compared with other ball bearings, four-point contact ball bearings have smaller axial clearance and higher limit speed when the radial clearance is the same.
Four-point contact ball bearings are suitable for bearing pure axial load or combined axial and radial loads mainly based on axial load. Because it is a double half inner ring (or outer ring), the number of balls is increased, and it has a larger bearing capacity.
Under normal working conditions, when this type of bearing bears an axial load in any direction, it can form a contact angle, and the steel ball contacts the inner and outer raceways at one point to avoid large sliding friction in the contact area. Therefore, the bearing should not bear mainly radial force and load.
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