Choosing Oil Seals for Your Hydraulic System

7 different factors must be evaluated to ensure optimum seal compatibility and performance

ChoosingFaulty seals are a leading cause of problems within hydraulic machinery. Seals might be vulnerable to early failure due to poor installation or maintenance, system operation issues, or improper seal selection. Here are 7 factors that must be considered when selecting the right seals for your hydraulic system.

Shaft Speed: The maximum allowable speed at which a shaft may operate without compromising a seal depends on many factors, including the shaft finish and runout. The type of fluid being used and its level of friction tolerance can also affect the allowable shaft speed.

Temperature: As with all hydraulic parts, seals have various temperature tolerances which cannot be exceeded without risk of degradation.

Pressure: Seals do come with a limited variety of pressure capacities. Most oil seals are not designed for extreme pressure. If system pressure exceeds the seal’s tolerance, a pressure relief valve may be needed.

Shaft Hardness: In general, seals will have longer life expectancies when paired with shafts having a Rockwell hardness rating above 30. However, if abrasive contamination is likely, shafts should be rated 60 or above to see a benefit in seal life. If your shafts don’t fall in this range, expect to replace your seals more often.

Shaft Finish: Seal efficiency can be adversely affected by less than optimal shaft surface finishes. From the point of view of your seals, polished or ground shafts with concentric rather than spiral finish marks would be ideal. If you have spiral finish marks, make sure the shaft is installed so that the spiral leads toward the fluid when the machine is in operation.

Alignment: Buying a seal that promises a long life is a waste if your bore and shaft centers are misaligned. Misalignment can concentrate wear on one side of the sealing lip and lead to early failure.

Lubricant: Overlooking seal-lubricant compatibility can be a big mistake. Seals need to be constantly lubricated with a fluid that has the correct viscosity for the hydraulic system and is compatible with the seal lip elastomer material.

Need to Order New Seals?

Bernell Hydraulics has an ample selection of all kinds of hydraulic components, including seals. Our expert staff can help troubleshoot your seal issues to determine if a different seal or an adjustment to you fluid, shaft, alignment, or system operating parameters could solve your issue.