SKF Timing Belt Kits - SKF.com

Engine drive systems
Aggressive oils
The additives used with engine oils have changed in
order to cope with increasing temperatures and the
extension of oil change intervals. This has led to oils
attacking some conventional fluorpolyamide (rubber)
materials. PTFE is inert, so the changes to material
properties, and hence reduced sealing capability, have
been eliminated.
Robust design
The design of a PTFE seal means that the sealing lip
contacts the shaft over a width of 0.079-0.118 in/2–3
mm. This compares with a width of 0.004-0.008 in/
.1–.2 mm for a conventional rubber seal. If there is
a small defect in the shaft’s sealing lip, then with a
conventional seal, this would probably lead to leakage.
With the much wider sealing track of the PTFE, the
probability that the same defect will lead to leakage is
much reduced.
Reduced wear
Shaft wear is an important issue. With PTFE, because of
the wide contact area, the depth of wear grooves in the
shaft is significantly reduced.
6
Valve stem seal
line contact surface contact
Shaft contact with rubber seal.
Shaft wear conventional rubber materials.
Shaft wear with PTFE.
Shaft contact with PTFE seal.
Static plug Spark plug tube seal Sensor seal
Oil pan drain plug Valve cover seal Rear retainer assembly / Rotostat
shaft
shaft