Oil seals are often called grease, fluid, or dirt seals. These seals close spaces between stationary and moving components in mechanical equipment. Oil seals are designed to prevent the escape of lubricant. They also block contaminants from entering machinery. This is especially important in severe environments where heat and foreign objects may be frequently present. They also prevent the mixing of different mediums like lubricating oil and water.

(7) Special attention should be paid to prevent dust from immersing in the oil seal.

As earlier said, oil seals perform some functions that ensure the functionality of mechanical equipment and extend their lifespan. And how they do this is by retaining lubricants at all cost and not making them escape no matter how high the pressure of the machine is.

2) Housing design

What should you take into account when selecting an oil seal? Different types of oil seals and various types of materials are available, each designed for specific uses. It is also important to select the right size of oil seal for the best results. For this reason, selecting the right oil seal requires adequate understanding of the application in which it will be used.

JTEKT provides special seals for use in a wide variety of machines and applications.
Table 5 lists the major special seals, their shapes, and their features.

Pour-point depressants: This additive has nothing to do the actual pouring of your oil. In fact, pour-point depressants help prevent the wax particles in the oil from hardening in cold conditions. As a result, the motor oil flows freely even in low, cold temperatures and the engine doesn’t need to work any harder to pump it.

＜Seal selection example＞
Based on the above flowcharts, the oil seal type that meets the requirements shown in Table 3 would be the type code MHSA or HMSA shown in Table 4.

Table 2: How to select the seal type

Viton® 

For more severe oil-seal service at temperatures of 160°C (320°F) or higher for extended periods, more resistant fluoroelastomer compositions are required for long service life. High-fluorine VDF/PMVE/TFE elastomers, along with TFE/olefin FEPM elastomers, are much less susceptible to attack by oil additives. TFE/P fluoroelastomers have the requisite chemical resistance, but have low fluorine content, leading to relatively high swell and to soft vulcanizates with lower wear resistance than desired.

Polyacrylate is a great compromise between cost and quality. It has a high performing temperature and chemical range, but not to the extent of the range of Viton. The temperature ranges from 31°C to 148°C (-25°F to 300°F). Polyacrylate is primarily used in automotive transmissions and hoses but also found in shaft seals, gaskets and o-rings, due to offering a high resistance to hot oil and oxidation. While Polyacrylate is a great alternative to other high temperature resistant materials that are more expensive, it does have a poor water compatibility and cold flexibility. The best situation for Polyacrylate is an environment where heat and oil resistance but cost is the major issue. And while these 4 different materials cover a wide range of applications, there are even more materials out there designed for very specific niches in mind.