The HUNGER TDA tandem seal for outside sealing
is used to seal pistons, plungers and accumulators. It
can be applied with mineral oils and in modified form
also with water base fluids, fire resistant fluids and
compressed air.
The TDA seal consists of 2 parts, an elastic ring of PUR
with a sealing lip and a slide ring of abrasion resistant
PTFE-Bronze-Compound with a sealing edge. Prior
to fitting, the sealing lip protrudes beyond the nominal
diameter of the seal and is pressed against the cylinder
wall after fitting. Thus effective sealing is provided even
at zero pressure.
The slide ring is surrounded by the elastomer sealing
ring and moves axially in direct contact with the inside
of the tube. With increasing pressure and compression
of the sealing ring, it is the slide ring which is predominantly
pressed against the inside of the cylinder.
The slide ring sealing edge produces an annular cavity
where any seepage oil that has passed the elastomer
lip is collected.
The seepage oil is held back by the sealing edge, such
that the emerging piston rod remains dry. During the
return stroke, the collected oil is forced back into the
cylinder.
The outer sealing surface of the TDA mainly comprises
the external slide ring which has excellent sliding
properties. When combined with a surface finish
Ra 0.1 - 0.3 μm of the cylinder tube, minimum friction
levels are achieved with highly efficient sealing and long
service life. There is no stiction, no unacceptable heat
generation and above all no stick-slip effect.