Plain Bearings

SKF Extended Life Plain Bearings

SKF Explorer steel/steel spherical plain bearings are initially lubricated and sealed to eliminate the need for relubrication in applications with low to moderate levels of contamination, such as those in off-highway applications. This generates significant savings by reducing maintenance costs and grease consumption. These virtually maintenance-free1) bearings also improve reliability by eliminating failures due to missed lubrication intervals and improper lubrication practices. All of this adds up to reduce the Total Cost of Ownership (TCO).

Combining improved corrosion resistance, heavy-duty sealing and a relubrication-free design with a steel/steel sliding combination makes SKF Explorer steel/steel plain bearings more robust than ever. Plus, extensive research and testing under extreme loads has resulted in increased dynamic load ratings for SKF Explorer steel/ steel plain bearings, an increase of 50% when compared to conventional steel/steel bearings.

Maintenance-Free Radial Spherical Plain Bearings

Radial spherical plain bearings have an inner ring with a sphered convex outside diameter and an outer ring with a correspondingly sphered but concave inside surface. Their design makes them particularly suitable for bearing arrangements where alignment movements between shaft and housing have to be accommodated, or where oscillating or recurrent tilting or slewing movements must be permitted at relatively slow sliding speeds.

SKF maintenance-free spherical plain bearings incorporate special sliding layers of modern materials which have very low friction. The bearings can be operated without maintenance. They are used for applications where long bearing lives are required without maintenance, or where operating conditions are such (e.g. inadequate or total absence of lubrication) that the use of steel/steel bearing is inadvisable. The maintenance-free bearings are primarily intended for applications where loads are heavy and have a constant direction. They have only limited ability to take up alternating loads and SKF should be contacted for advice in such cases.

Angular Contact Spherical Plain Bearings

Angular contact spherical plain bearings have sphered sliding surfaces on the inner and in the outer ring which are arranged at an angle to the bearing axis. They are therefore particularly suitable for carrying combined (radial and axial) loads. A single angular contact spherical plain bearing can only accept axial loads acting in one direction. Under radial loads, a force acting in the axial direction is produced in the bearing which must always be opposed by an equal force acting in the opposite direction. Therefore, the bearings are usually adjusted against a second bearing. If two angular contact spherical plain bearings are arranged so that their sphere centres coincide, a spherical plain bearing is obtained which can accommodate heavy radial loads as well as heavy axial loads in both directions.

SKF angular contact spherical plain bearings are produced as standard with the sliding contact surface combination steel/PTFE FRP. They are primarily intended for loads of constant direction and are maintenance-free. However, to enhance protection against corrosion and to improve sealing, it is recommended in many applications, that the space surrounding the bearing be filled with a rust inhibiting lithium base grease of consistency 2 or 3 during mounting. Such an initial lubrication also extends the effective service life of the bearing.

Trust Spherical Plain Bearings

Thrust spherical plain bearings resemble angular contact spherical plain bearings in that they have sliding contact surfaces in the shaft and housing washers which are arranged at an angle to the bearing axis. However, they are primarily intended for axial loads although they can accommodate combined loads to a certain extent. The radial load component should, however, not exceed 50% of the simultaneously acting axial load.

SKF thrust spherical plain bearings are produced as standard with the sliding contact surface combination steel/FRP and are maintenance-free. To enhance protection against corrosion as well as sealing it is, however, in many applications, advisable to fill the space surrounding the bearing during mounting with a rust inhibiting lithium base grease of consistency 2 or 3. Such an initial lubrication will also extend the service life of the bearing.

Rod Ends Requiring Maintenance

Rod ends consist of an eye-shaped head with integral shank which forms a housing for a spherical plain bearing. As a rule, rod ends are available with left or right-hand female (internal) or male (external) threads according to ISO 965/1:1980. Where rod ends are needed for specific applications – primarily those where a rod end is attached to the end of a piston rod or at the base of a hydraulic cylinder – rod ends are available with slotted shank and compressible threaded section or with a “welding shank” i.e. a shank suitable for welding to another component.

SKF rod ends which require maintenance are available as standard with the sliding contact surface combinations steel/steel and steel/bronze. Both types of rod end require regular relubrication. Steel/steel rod ends have sliding contact surfaces which are hardened, phosphated and treated with a running-in lubricant. They are very resistant to wear and therefore particularly suitable for applications where heavy loads of alternating direction have to be accommodated. Steel/bronze rod ends have a hardened and chromium plated inner ring and a bronze outer ring. Their performance under conditions of lubricant starvation is therefore very good.

SKF rod ends with a left-hand thread are identified by an L in the designation prefix, otherwise the rod ends have a right-hand thread. For example, rod end SILA 40 ES has a left-hand thread whereas rod end SIA 40 ES has a right hand thread.

Maintenance-Free Rod Ends

Rod ends consist of an eye-shaped head with integral shank which forms a housing for a spherical plain bearing. As a rule, rod ends are available with left or right-hand female (internal) or male (external) threads according to ISO 965/1:1980.

SKF maintenance-free rod ends have special sliding layers of modern dry sliding materials characterised by low friction. They find application above all where long service live is required without maintenance. Primarily, however, they are intended for applications where the load acts in a constant direction.

Rod Ends for the Food Industry

Rod ends consist of an eye-shaped head with integral shank which forms a housing for a spherical plain bearing. As a rule, rod ends are available with left or right-hand female (internal) or male (external) threads according to ISO 965/1:1980.

SKF maintenance-free rod ends have special sliding layers of modern dry sliding materials characterised by low friction. They find application above all where long service live is required without maintenance. Primarily, however, they are intended for applications where the load acts in a constant direction.

Composite Bushings

Composite dry sliding bearings are primarily used for bearing arrangements where heavy loads have to be supported and where rotational or oscillating movements are relatively slow.

Filament Wound Bushings

SKF filament wound bushings are maintenance-free, corrosion resistant, high performance bushings. The backing consists of high strength glass fibres and the sliding surface is made from PTFE and polymer fibres. Both the backing and sliding surfaces are embedded in an epoxy resin matrix. These materials combine the mechanical properties of glass fibres and the outstanding tribological properties of PTFE and high-strength polymer fibres.

The SKF standard assortment ranges from a 20 to 200 mm bore diameter, each in three standard widths between 15 and 250 mm. Other dimensions are available on request.