Can a seal be selected from dimensions alone?

Only for simple rings such as GR. Seals for housings and combined bearings are shaped to the seat, and the designation names the family — EDH for SES housings, for instance. Ordered by diameter alone it will not enter the groove or will not seat against the flange.

How often should a seal be replaced?

Whenever the arrangement is opened, even if it looks intact. The lip loses elasticity long before wear becomes visible: heat and contact with grease harden the rubber, so it presses less firmly despite an undamaged edge.

Does a seal increase bearing friction?

A contact lip does — it raises friction torque by a few percent. A non-contact shield practically does not, but it will not hold moisture out. Hence shields at high speeds, and a contact lip where the environment is dirty.

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Seals

Sealing rings and covers

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193–205 z 205

About this category

Type: sealing elements for bearings, housings and linear guides
Families: GR and EDH rings, bolt-on BTAC seals, DRS carriers, KA closing plugs
Selection: by seat family, not by shaft diameter alone
Service life: a wear part — replace whenever the arrangement is opened

These are not universal shaft seals but elements matched to a specific arrangement: a plummer block housing, a combined bearing, a linear guide carriage. That is why the designation carries the seat family — EDH for SES housings, BTAC for SNS housings, DRS for ZARF bearings — and not just dimensions.

The seal is a wear part, and it decides how long the whole arrangement lasts. Dust let through acts as grinding paste inside the bearing, and escaping grease leaves the raceway without a lubricant film. In both cases the damage later looks like material fatigue, although the cause was a sealing lip worth a few euros.

What to look at when selecting

01Select by housing or bearing family, not by diameter: the same size exists with several lip designs.
02One lip (GR) is enough in a clean environment; for dust and moisture choose two (EDH).
03Check the circumferential speed at the lip — above the limit the material overheats and hardens, and the seal stops making contact.
04On assembly, coat the lip with the same grease that runs in the bearing: the first dry revolution can tear it.

Common questions

Can a seal be selected from dimensions alone?: Only for simple rings such as GR. Seals for housings and combined bearings are shaped to the seat, and the designation names the family — EDH for SES housings, for instance. Ordered by diameter alone it will not enter the groove or will not seat against the flange.
How often should a seal be replaced?: Whenever the arrangement is opened, even if it looks intact. The lip loses elasticity long before wear becomes visible: heat and contact with grease harden the rubber, so it presses less firmly despite an undamaged edge.
Does a seal increase bearing friction?: A contact lip does — it raises friction torque by a few percent. A non-contact shield practically does not, but it will not hold moisture out. Hence shields at high speeds, and a contact lip where the environment is dirty.