Seals and radial shaft seals

The radial shaft seal is the cheapest part of the assembly and the one that determines whether the rest lasts. If dust or water gets into the housing, the bearing will fail within weeks no matter how good it is.

A radial shaft seal is ordered by three dimensions, always in this order: shaft inner diameter, housing outer diameter and height. A 50 x 72 x 8 is a seal for a 50 shaft, 72 housing and 8 millimeters thick. The catalog has over six thousand, and more than four thousand already have those three dimensions loaded, so you can find them by size even if you don't have the part number.

The design type is the second thing to define. It changes whether the seal has a spring or not, whether it has a dust lip in addition to the main lip, and whether the case is metal or rubber. That's where most replacements go wrong: the size matches but the design doesn't, and two months later it leaks again.

For split plummer block housings, sealing is a world apart. The same SNL body accepts felt seals, labyrinth seals, V-ring type or double lip seals, and the choice depends on the environment. Felt in a clean workshop, labyrinth in a place with fine dust, double lip where there is pressurized water. It's the decision that most influences bearing service life and the one least considered when buying.

If you have the size but not the part number, or the old seal on hand to measure it, that's enough to request a quote.