Relubrication of Y-bearing units is not required if
- loads and speeds are moderate
- no vibrations occur
- operating temperature does not exceed +55 °C
- are exposed to high humidity or severe contamination
- have to carry high loads
- have to run at high speeds or at temperatures above +55 °C for longer time
When relubricating, the grease should be pressed in slowly to the running bearing until fresh grease escapes from the seal. Avoid excessive pressure as this can damage the seals.
Relubrication of standard Y-bearing unitsFor relubrication of standard Y-bearing units the use of SKF grease LGWA 2, which is fully compatible with the original grease, is recommended. The multi-purpose SKF greases LGMT 2 and LGMT 3 are also compatible with the original grease and may also be used for relubrication.
Relubrication of Y-TECH bearing unitsFor relubrication of Y-TECH bearing units in the SYKC, FYKC and FYTBKC series the use of the food compatible SKF grease LGFP 2 is recommended. Detailed information on all SKF bearing greases can be found in the catalogue SKF Maintenance and Lubrication Products.
Relubrication intervalsThe relubrication interval tf can be estimated from the diagram 1 as a function of the rotational speed n (r/min), the mean diameter of the bearing dm (table) and the operating temperature (°C).
The recommended intervals correspond to a time when 90% of the bearings are still reliably lubricated, and represent L10 grease life. When the L10 grease life is equivalent to or higher than the L10 basic rating life of the Y-bearing or Y-bearing unit, bearing or unit can be considered as being lubricated for life and relubrication is not required.
The intervals obtained from the diagram 2 are valid for Y-bearings and Y-bearing unit
- on horizontal shafts
- in stationary machines
- for operating temperatures between +40 and +55 °C
- at low loads (C/P ≥ 15).
If operating conditions differ it is necessary to reduce the relubrication intervals obtained from the diagram 3, namely
- on vertical shafts by 50%
- at higher loads, e.g. at C/P = 8 by roughly 50%
- in severe, very dirty or damp environment by up to 90.
Vibrations have an influence on the grease life too. The extent cannot be quantified exactly but it is noticeable at rising operating temperatures. Also when the operating temperatures are below +40 °C for longer periods, the grease life is shortened because the oil separation is reduced.
The values for reducing the relubrication intervals are estimated values. In cases of doubt the SKF application engineering service should be contacted.
In cases where machines and equipment are used for a limited period of time, it is recommended that they should be relubricated at the end of the operational period, i.e. immediately before being laid up.