Lubricated bearings are characterized by frictional linear contact and a large friction coefficient. They are generally used on low-speed, heavy-duty machinery. Bearing oil
First, the choice of lubricants for sliding bearings
When selecting a lubricant for a sliding bearing, the main factors that should be considered are speed, temperature, load, etc., and the viscosity of the selected lubricating oil or the consistency of the grease should be determined accordingly.
When lubricating plain bearings, the difference in radius (clearance) between the main shaft and the sleeve is the main parameter. The clearance depends on the operating temperature, load, minimum oil film thickness, friction loss, and eccentricity of the main shaft and sleeve. When selecting a lubricant, the gap is also an important parameter. For sliding bearings with relatively small gaps, we must pay more attention to the correspondence between the gap and the viscosity of the oil or the consistency of the fat.
The selection of sliding bearing lubricants is mainly based on operating conditions and lubrication methods. As for the use of lubricating oil or grease, it is usually determined by the average load factor K of the bearing.
Advantages of grease for plain bearings:
(1) In a dusty environment, it is easy to keep the bearings clean and prevent impurities from entering;
(2) Conducive to sealing without leaking oil;
(3) Does not cause environmental pollution;
(4) Conducive to use in places where it is inconvenient to refuel;
(5) The lubrication system is simple and durable;
Notes on selecting grease for sliding bearings
(1) When the bearing load is large and the rotation speed is low, the consistency of the selected grease should be greater, and at the same time, the viscosity of the base oil of the grease should be greater; otherwise, the product with a larger penetration should be selected;
(2) The dropping point of the grease is, in general, higher than the working temperature by 20 ~ 30 ° C;
(3) Grease should have good adhesion properties;
(4) If the sliding bearing works in water or wet environment, calcium-based grease should be used, and lithium-based grease should be used under high ambient temperature conditions;
(5) For special operating conditions, such as: railway locomotive shafts (high peripheral speeds and high loads), paper dryers and baking dryers, etc., such as using sliding bearings and grease lubrication, Use special grease.