All About Oil Seals

 

 Oil seals go by many names, such as shaft seals, dirt seals, grease seals, lip seals, and many other variations of these. They are essentially simple devices used in rotary shaft equipment to prevent lubricant from escaping and for excluding contaminants such as dust, dirt and water. An oil seal’s most important function, however, is that it protects every type of ball, sleeve and roller bearing in the rotating shafts. The seals also prevent the integration of two different fluids that shouldn’t mix, such as oil and water.

 

How do oil seals work?

The basic principle of an oil seal is fairly straightforward. It is installed adjacent to the bearing, with the flexible lip against the rotating shaft and the casing pressed into the housing to hold the seal in place. It’s important that the sealing lip is lubricated to prevent it from overheating as a result of any generated friction. It’s also crucial to understand which type of seal is appropriate for your particular machinery. Before selecting your seal, consider the environment, temperature, pressure and shaft speed of your machine, as well as the type of medium the seal will come into contact with during operation. These considerations will all determine the size, colour, and type of lip material or sealing element to choose, and whether it can be sealed in or sealed out.

What material are oil seals made from?

Oil seals are made from multiple compounds and materials. Some of the oldest, still in use today, are leather and felt compounds. The trend in mass production, however, has seen a move towards synthetic rubber or elastomers. Nitrile is by far the most popular material but developments in PTFE have created a surge of interest in buyers needing seals for high-speed shaft rotation applications. Viton is taking over from the polyacrylic and silicone, as it works better in high-temperature applications and has a high-resistance to abrasion and harmful chemicals.

 

There are various sizes of industrial and ordinary oil seals, ranging from 0 to 33cm (13in). These varieties are also designed for different temperatures. As long as your seal matches the original equipment it’s intended for, you can be sure your machine will perform at its best. For further guidance and information regarding oil seals, don’t hesitate to contact our knowledgeable team. We are always available to assist you with your bearing, seal and gasket needs.

 

The causes of oil seal failures in the field have been itemized by the authors of these papers. In the case of Beer, who deals with the case of a Model C Tournapull, which is a 20 ton machine on the 200 + class with a tourmatic drive consisting of a six speed transmission with a single stage torque converter, and on which there are fifteen shaft type oil seals, he states as follows :—Providing transmission shafts are correct hardness and finish and bore concentricities and shaft run‐outs meet the minimum requirements, the seals failed because (1) Incorrect spring tension held the sealing lip too tightly against the shaft causing increased frictional heat which hardened the material and with existing shaft run‐out did not permit the seal to follow the shaft resulting in leakage. The grooves in the shafts could also be associated with tight springs. (2) High operating temperatures exceeded the temperature limits of the seal material thus causing it to harden and lose its sealing effectiveness.

Rick;
I have to both agree with you and disagree with you.
Spliting the tractor will allow for more room when trying to remove or install the rear main seal. With the trans input shaft out the way you could remove the main bearing caps allowing the crank to drop that every so slight bit. This makes it a little easier to install the upper rear main seal.
Does the fact that you need a hoist to do this because you can not block the engine up under the oil pan for the split because you need access to remove the pan; make this idea unpractical???
I would think so.

To do it right the crank is suppose to be removed completly. The only way of doing that is to also remove the front of the engine.

To tell you the truth..... unless the leak is real bad I would just leave it alone. Even after changing the seal out for a new one you may still have a leak. Check the archives from this site and you will see that.