Bearings and rod ends requiring maintenance

Bearings and rod ends requiring maintenance should be greased prior to being put into operation. With the exception of a few applications, they should be relubricated periodically.

SKF steel/steel radial spherical plain bearings are made of bearing steel and are through-hardened. The high-strength sliding contact surfaces are phosphated and treated with a special running-in lubricant. These bearings are used primarily in applications where there are:

  • heavy static loads
  • heavy alternating loads
  • shock loads

They are also relatively insensitive to contaminants and high temperatures.

To facilitate relubrication, lubrication holes and grooves are provided in both the inner and outer rings of all steel/steel radial spherical plain bearings – with the exception of a few small sizes. SKF steel/bronze rod ends also require relubrication. However, requirements are less stringent than for steel/steel rod ends, as the emergency running properties of bronze are more forgiving than steel.

The SKF multi-groove system

Standard steel/steel radial spherical plain bearings that must accommodate minor alignment movements under very heavy, constant direction loads are prone to lubricant starvation. Lubricant starvation is a common cause of peremature bearing failure in applications where minor movements are made under heavy, constant direction loads. To improve and maximize the effects of the lubricant under these conditions, SKF has developed the multi-groove system. Metric bearings have the multi-groove system on the sliding surface of the outer ring (fig. 1) and inch bearings have it on the sliding surface of the inner ring (fig. 2). Bearings with the multi-groove system are identified by the designation suffix ESL.

The lubrication grooves provide the following benefits:

  • improved lubricant supply to the loaded zone (fig. 3)
  • enlarged lubricant reservoir in the bearing (fig. 4)
  • enable relubrication under load
  • extended relubrication intervals
  • space for wear particles and contaminants
  • extended grease life

The main benefit of the multi-groove system is that it improves lubricant distribution in the heavily loaded zone to extend service life and/or maintenance intervals.

SKF logo