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Relubrication

Y-bearing units do not need relubrication when the grease life (→ Grease life for Y-bearings) exceeds the SKF rating life of the bearing (→ Selecting bearing size).

Relubrication can extend bearing unit service life under any of the following conditions:

  • The bearings are exposed to high humidity or severe contamination.
  • The bearings accommodate normal or heavy loads.
  • The bearings operate for extended periods at high speeds or at temperatures above 55 °C (130 °F).
  • The bearings are subjected to high vibration levels.

To relubricate Y-bearing units, the following greases can be used:

  • Y-bearing units comprising either zinc-coated and stainless steel bearings
    → food-grade grease SKF LGFP 2
  • all other Y-bearing units
    → SKF LGWA 2, LGMT 2 or LGMT 3 grease

If relubrication is needed, the relubrication intervals can be estimated following the method explained under Relubrication intervals.

When relubricating, the shaft should be turned and grease should be pumped slowly until fresh grease starts to escape from the seal(s). Excessive pressure from pumping too quickly can damage the seals. When machines and equipment are used for a limited period of time, SKF recommends relubricating each bearing at the end of the operational period, i.e. immediately before being laid up.

Relubrication features

Housings

Y-bearing units with a pressed steel housing are not equipped with a grease fitting and therefore cannot be relubricated.

Relubrication features for other housings made of:

  • Cast iron
    • Grease fitting with a 1/4-28 SAE-LT thread. Exceptions are housings used for bearings with inch bore diameter larger than 1 in. and with designation suffix U, which are equipped with a grease fitting with a 1/8-27 NPT thread.
    • The hole for the grease fitting has a 1/4-28 UNF thread, which can be changed to G 1/4, using an LAPN 1/4 UNF adapter. Exceptions are housings used for bearings with inch bore diameter larger than 1 in. and with designation suffix U, which have a 1/8-27 NPT threaded hole.
    • For cast iron units comprising 5-lip seal bearings, which do not have any relubrication feature, the housing relubrication feature is plugged (designation suffix W).
  • Composite
    • Relubrication feature available on request (designation suffix N).
  • Composite for SKF Food Line
    • Relubrication feature available on request (designation suffixes N and VZ1A2 combined).
  • Stainless steel
    • Plugged hole for a grease fitting (1/4-28 UNF thread).

Bearings

SKF Y-bearings are designed to facilitate relubrication. They have two lubrication holes in the outer ring as standard, one on each side, positioned 120° apart.

Bearings without lubrication holes can be supplied on request (designation suffix W).

The following bearings do not have the standard relubrication features:
  • Stainless steel Y-bearings with grub screws have a lubrication groove in the outer ring located on the side opposite the locking device and one lubrication hole within this groove. Stainless steel bearings with designation suffix GR have these features located at the side of the locking device.
  • Y-bearings with a standard inner ring without designation suffix B and Y-bearings with 5-lip seals are lubricated for life and cannot be relubricated. They do not have any lubrication holes.
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