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Oil seals are commonly used in engines, gearboxes, and other rotating machinery to prevent the leakage of oil from shafts and bearings. They are typically made from rubber or elastomeric materials that are resistant to oil and heat. The seal is installed in a housing or bore that is larger than the shaft, and it is pressed against the shaft to create a tight seal.
Pressure - Many oil seals can only withstand low-pressure applications, so understanding the compression set of your components is key.
In terms of size, oil seals are available in a wide range of dimensions to suit different shaft diameters and housing sizes. It is crucial to select the correct size seal to ensure a proper fit, as using an improperly sized seal can lead to leaks and premature wear.
25 40 7 oil seal

Meanwhile, rubber-cased oil seals are used under conditions where a metal-cased seal can fail (for example, because of thermal expansion). Unlike the metal-cased type, these seals do not rust. Moreover, they can seal a lightly damaged housing better than metal-covered seals since, in high temperatures, rubber can provide a more stable sealability.
A final step in preparation for assembly is to lubricate the shaft, sealing lip and bore with sufficient oil. This will allow the oil seal to slide more easily over the shaft and prevent dry running after the first rotation. Always use oil or grease that is compatible with the oil seal material. In addition, when sliding over the shaft, the oil seal comes into contact with the keyway, threads and grooves. By taping or covering the shaft at the location of these irregularities with oil-soaked paper, the oil seal can be mounted without damage to the sealing lip.

What are bearing isolators?
Rubber type
If these specific tools aren’t available, it’s entirely possible to correctly seat an oil seal in its housing using a hammer. Ideally, this hammer will be plastic or rubber due to it’s more forgiving nature. Using this and a strike plate that covers the entire seal will lend you accuracy while driving it in. The downside to this method is the inability to drive the seal any further than the strike plate will allow.
Lubricants applied between moving and stationary elements of mechanical equipment help to prevent damage. But when the equipment are under high pressure, the lubricants tend to escape, hence the need for oil seals to prevent the clashing of dry parts. Practically all mechanical equipment, including car engines, assembly machines, and PTFE machined parts use these oil seals to prevent harmful interaction that can result in damaged parts.