In terms of an oil seal, there are a lot of different types. Depending on how they are constructed, U-ring oil seals as well as block vee rings can be used as a rod seal, a piston seal or even a symmetric seal. U-rings and block vee rings are called single acting seals, also known as unidirectional seals, and have to be mounted back to back in cylinder applications that are double acting.
A Block Vee seal is really more compact and performs better under high pressure conditions than a U ring does. V ring seals are made of all rubber and are primarily used to get rid of dirt and other types of contaminants. V rings are stretched over a shaft and sealed against the side of housing or another type of machine component. Besides, more oil seals are introduced as there are several different kinds of clearance seals, also known as labyrinth seals. The one feature they all share with each other is that they all work on a principle of positive clearance. This means that there isn’t any rubbing that occurs against the shaft or the housing.
A lot of labyrinth seals are made up of a rotor, which rotates, and a stator, which is static, piece with a radial gap between the two pieces. The gap has to be bigger than the radial clearance of the bearing that is being sealed. Also, the operating speeds as well as the temperature have to be considered when utilizing a labyrinth seal. These kinds of seals typically don’t perform very well at lower operating speeds.
Another type of labyrinth seal is a laminar sealing ring, which utilizes a series of flat metal rings, similar to washers, of different diameters to make a labyrinth seal. Bearing isolators are a dynamic kind of seal that is designed to keep bearings protected from outside elements. They are also made up of a rotor, a rotating piece, and a stator, or static member. Some bearing isolators are made out of labyrinth construction but others use O rings or other kinds of positive seals.
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