Rotary Seals - Dilanda.it

Radial Oil Seal
n Rotary and axial seal combination
General Description
In many applications rotary shaft lip seals are used to seal
against various mediums.
An important failure mechanism for lip seals is the
destruction of the lubricant film, resulting in rapid wear,
due to the ingress of dirt, dust, moisture etc. The use of
shaft seaIs having one or more auxiliary sealing lips (dust
lips) provides a limited improvement, is not always
sufficient. In order to meet the constantly increasing
requirements as to sealability - not the least considering
the environmental protection -and long service life the
STEFA COMBI - seal is a simple solution, which has proved
to be particularly well suited even in critical applications
with heavy contamination. The COMBI-seal consists of a
GAMMA seal and a rotary shaft lip seaI working together.
The lip seal provides the counterface for the GAMMA seal
being fixed to the shaft by press fit. See Figure 29 and 30.
Years of successful experiences show that another
frequently used alternative consists in the combination of
aV—Ring seal with a standard seal selected inside the type
list: TRC/BB; TRD/BC; TRB/DB; TRF/DC.
The rotary shaft seal should be ordered “Without
Markings“ on the air side.
Radial Oil Seal + GAMMA seal
Figure 30
GAMMA seal fitted on the shaft boss
Radial Oil Seal + V—Ring
The function of the rotary axial seal is to prevent by
centrifugation the intrusion of particles and water drops.
In other words, adds it’s original protection capacity to the
radial seal functionality. The necessary condition to allow
the application is the space availability on the shaft to host
the axial seal width. (See Figure 31).
b
B1
b
Figure 31
V—Ring fitted on the shaft end
Figure 29
GAMMA seal fitted on the shaft end
Housing and shaft design
The radial lip seal needs to be assembled in the housing
according to usual fitting instructions. Both V—Ring and
GAMMA seal is assembled later on the shaft. The shaft
design requires to be adapted by an elongation
corresponding at least to B1 (b) dimension. In case of
very high peripheral speeds, the V—Ring body should be
radially supported. See also the instructions reported in the
specific catalogue chapter.
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Edition April 2006
111