Oil Seals

Oil Seals

Oil Seal Chart

Oil seals prevent internal system fluids from leaking and keep external contamination from entering the system. Leakage and/ or contaminants paths occur between the shaft and the seal lip and between the seal and the housing. Oil seals need to seal both dynamically (on the shaft) and statically (on the outer diameter of the seal).

An oil seal normally consists of three basic components: the rubber sealing element, the metal insert (case) and the garter spring. The purpose of the sealing element is to stop the fluid from leaking between the shaft and housing. The metal insert will give rigidity and strength to the seal while it is being held in the bore or recessed groove. The garter spring will help make the rubber sealing element more effective.

Where hydrodynamic aids have been provided it should be remembered that a pressure deficit can be produced in the space between primary and secondary lips which will increase the radial force. This situation can be alleviated by providing breathing holes in the secondary lip. It should also be remembered that contaminants which have penetrated past the secondary lip will eventually cause damage in the couterface region. A build-up of heat can also occur between the two lips; this promotes premature wear.

Oil Seals Groove Dimensions & Tolerances PDF

Order reference chart for Oil Seals

Oil Seal ChartUse the oil seal reference chart when ordering.

Seal O.D. Tolerance - Metric


Press-fit Allowance
Bore Diameter (mm)Metal CaseRubber Covered CasePermissible Eccentricity
Up to 50+0.10 - +0.20+0.15 - +0.300.250
Over 50 to 80+0.13- +0.23+0.20- +0.350.350
Over 80 to 120+0.15- +0.25+0.20- +0.350.500
Over 120 to 180+0.18- +0.28+0.25- +0.450.650
Over 180 to 300+0.20- +0.30+0.25- +0.450.800
Over 300 to 500+0.23- +0.35+0.30- +0.551.000

Housing & Shaft Tolerance - Metric

House ToleranceShaft Tolerance
Bore Diameter (mm)Bore ToleranceShaft Diameter (mm)Tolerance
Over 6 to 10+0.022/-0.000Over 3 to 60/-0.075
Over 10 to 18+0.027/-0.000Over 6 to 100/-0.090
Over 18 to 30+0.033/-0.000Over 10 to 180/-0.110
Over 30 to 50+0.039/-0.000Over 18 to 300/-0.130
Over 50 to 80+0.046/-0.000Over 30 to 500/-0.160
Over 80 to 120+0.054/-0.000Over 50 to 800/-0.190
Over 120 to 180+0.063/-0.000Over 80 to 1200/-0.220
Over 180 to 250+0.072/-0.000Over 120 to 1800/-0.250
Over 250 to 315+0.081/-0.000Over 180 to 2500/-0.290
Over 315 to 400+0.089/-0.000Over 250 to 3150/-0.320
Over 400 to 500+0.097/-0.000Over 315 to 4000/-0.360

Housing Tolerances - Inch

Diameter (in)Tolerance
Up to and including 4.000+/-0.003
4.001 to 6.000+/-0.004
6.001 to 10.000+/-0.005
10.0001 and larger+/-0.006

Seal O.D. Tolerance - Inch


Press-fit AllowanceBore Tolerance
Bore Diameter (in)Metal CaseRubber CaseMetal CaseRubber Case
Up to 1.000+0.004+0.006+/-0.002+/-0.003
1.001 to 2.000+0.004+0.007+/-0.002+/-0.003
2.001 to 3.000+0.004+0.008+/-0.002+/-0.003
3.001 to 4.000+0.005+0.010+/-0.002+/-0.004
4.001 to 6.000+0.005+0.010+0.003/-0.002+/-0.004
6.001 to 8.000+0.006+0.010+0.003/-0.002+/-0.004
8.001 to 10.000+0.008+0.010+0.004/-0.002+/-0.004
10.001 to 20.000+0.008+0.010+0.006/-0.002+/-0.004
20.001 to 40.000+0.008+0.010+0.008/-0.002+/-0.004