SKF - Industrial Shaft Seals

Product data – general
HMS5 seal
CRW1 seal
Fig. 4
Fig. 5
Oil retention
Lubricating oils, particularly relatively lowviscosity
oils, are much more difficult to retain
than greases. Therefore, HMS5 or CRW1
spring-loaded radial shaft seals († figs. 4 and 5)
are recommended in order to achieve the necessary
radial load and resistance to dynamic runout
and shaft-to-bore misalignment for a satisfactory
sealing performance.
Standard HMS5 seals have a straight lip while
CRW1 seals are designed with SKF Wave lips to
provide improved pumping ability, regardless
of the direction of shaft rotation († fig. 6 on
page 57). Another way of increasing a seal’s
pumping ability is to add a helix pattern, i.e.
hydrodynamic features, to the sealing lip design.
The rubber outside diameter, like the one
found on HMS5 seals, helps compensate for
small imperfections in the housing bore surface
and is therefore recommended when the required
housing bore surface is questionable.
For very tough operating conditions, where
circumferential speeds are relatively low, metal
face seals, like the HDDF seal († fig. 6), can be
used for both oil or grease retention.
V-rings († fig. 7) may also be used to retain
oil, provided they are installed on the oil side
and supported axially on the shaft.
HDDF metal face seal
Fig. 6
V-ring
Fig. 7
18