HOUSING ASSEMBLY: The outside diameter of internal seals will have a pre-determined interference allowing them to be press fitted into their housings. It is imperative that they are assembled square by exerting a firm uniform pressure.

 The ideal situation is by means of an arbor tool which should be 0.005" to 0.015" (0.125 to 0.38mm) less than the outside diameter of the seal. If you are unable to use an arbor press then make a fitting tool. DO NOT under any circumstances fit seals with a drift and hammer as irregular blows exerted by this method may loosen the metal parts, which will release the clamping of the internal components.

SHAFT ASSEMBLY: Care must always be exercised when assembling seals on to the shaft to avoid damage to the sealing edge. If a lead-in chamfer/radius has not been provided or if the seal has to pass over a keyway, then it is necessary to provide a fitting sleeve as illustrated.

Non-compliance with these instructions can lead to either the lips being turned back or cut, particularly in the case of rubber. There is also the possibility of the spring becoming dislodged, which, after the element has been returned to its normal position, will mean there is a danger of it making contact with the shaft.  This may result in damage to shaft, bearing, and any other engineering components within the system.

The application of a liberal smear of grease on the internal side of the element will greatly assist the fitting of the seal.

DIRECTION OF SEAL: Normal practice is to wipe the edge of the seal that is to face the media to be sealed, and it is in this direction that it will hold against pressure.

If however, pressure conditions do not exist then the seal can be assembled to face the other way round. This is particularly advantageous in grease lubricated applications as this will allow the discharge of any contaminated lubricant from the sealing area when the grease gun is applied. This will then ensure clean lubrication of the seal lip and reduce unnecessary wear from abrasive elements.


During maintenance/overhauling of equipment we strongly recommend that a new seal be fitted. Under no circumstances should the old seal be removed and then replaced in the same housing, the interference fit cannot be repeated.

If there is no alternative but to use the old seal then do take extra care:

  1.  Make sure that the sealing edge is not damaged in any way.


  1. Check the shaft for wear/marks. Make sure that the area on which the seal is to run is in good condition.


  1.  Apply a liberal amount of clean grease or mineral oil to the sealing edge before offering the shaft back through.



Copyright Autospin (Oil Seals) Ltd.2004.