Quick Guide to Understanding the Design and Application of Sleeve Bearings

Sleeve bearings are bushings or journals that make linear movement between different components in a machine or application possible. They can be made from fibre-reinforced metal or plastic to reduce noise and wear. The sleeves reduce the friction between the moving components. This is possible because they have a layer of lubrication between the surface and the components that enables smooth movement of the two parts in the machine.

Applications range from usage in everyday appliances to vehicle engines and centrifugal pumps, to name only a few of them. It is essential to keep the bearings lubricated. The lubrication supply is by means of the initial oil lubrication or an external pressure system. The sleeve has a cylindrical shape, with the inside and outside having straight diameters. Important aspects for consideration of the specifications are briefly noted below.

• Length. When reading the length specification, keep in mind that it refers to the bearing’s overall length.
• Load. The maximum load is given as the weight (load) per square centimetre, millimetre, or inch, depending on the system of measurement that is being used. It is given for the maximum load as related to the load-speed application at a third of the compression limit of the bearing material.
• Speed of rotation. The type of material, the surface finish of the bearing, its hardness, the type of lubrication, and the alignment represent factors to consider regarding the unit relevant to your requirements in terms of the speed of rotation.

For agricultural applications, the surfaces of the bearings are frequently made from hardwood. For other industrial applications, the surfaces are made from metal or fibre-reinforced plastic.

The surfaces are often self-lubricating and this type does not need additional lubrication. An example is that of a bronze surface that is impregnated with oil. The idea behind the self-lubrication is that, during the first period of application, a film of lubrication is created through the transfer of part of the material from the surface layer. This is the part that comes in contact with the linearly moving parts and protects against wear. For this type, the initial lubrication is critical to ensure reliable long-term operation. If not done properly, the bearing wears out quickly, leading to machine or equipment failure.

View our product range and speak to one of our consultants for more information about the appropriate sleeve bearings for your particular applications.