There are two types of bores: straight bores and counter bores. Straight bores have no built-in shoulder to help seat the seal, making installation trickier. With straight bores, the installation tool needs a flange to position the seal at the proper location. Alternatively, the seal itself might be designed with a flanged case to facilitate proper positioning. Figure 139 shows a non-flanged seal being installed into a straight bore. Figure 140 shows a flanged seal installed.

Counter-bores have a shoulder against which the seal seats, making installation less difficult. By effectively stopping the seal at a particular point relative to the shaft, a counter bore controls the placement of the primary sealing lip on the shaft surface. Shaft seals with a rubber nose also allow the formation of a face seal at the counter bore. Figure 141 shows an example of a nose gasket installed into a counter bore.

THE BORE MAIN PAGE