How PSS Works
What Makes the PSS Shaft Seal Different & Why is it Recognised As The Best On the Market?
How Does The PSS Mechanical Shaft Seal Work?
A mechanical seal is created by the contact of a turning surface
against a stationary surface. In the case of the PSS Shaft Seal,
the stationary surface is a carbon flange held in contact against a
stainless steel rotor which turns with the shaft. The carbon flange
is attached to the boat by a nitrile bellow which, with the help of
water pressure, produces a constant contact between the carbon and
the stainless steel ring. These
type of seals are unaffected by engine motion or vibrations. The
result is a 100% watertight and totally maintenance-free seal.
All mechanical seals look very similar. There is, however, a big
difference in materials uses in the components and subsequently in
the way the seals will perform.
Materials Reference for the PSS Shaft Seal
- 1) HIGH DENSITY CARBON/GRAPHITE FLANGE
- This space age composite is machined to shape. The face is then
lapped to 4 light bands. Once installed and operational the
carbon/graphite face will actually polish the stainless steel rotor
face during the initial minutes of operation. This polishing process
ensures a perfect seal and eliminates the necessity of a spray
guard. The high density of this composite greatly increases its
impact and wear resistance. At a maximum operating temperature of
500° F, the carbon guards against any overheating situation unlike
other seals using plastic derivatives. The carbon/graphite flange
should never need replacing under normal operation conditions.
- 2) DOUBLE O-RINGS
- The nitrile O-Rings are fit inside the stainless
steel rotor to guarantee alignment and seal of the rotor to
propeller shaft. Nitrile is the material used due to its superior
resistance to petroleum products, temperature variations and
resistance to tearing. These O-rings are stationary and do not
- 3) STAINLESS STEEL ROTOR
- The one-piece stainless steel (Type 316) rotor is slid down and
secured to the propeller shaft with double set screws. Precision
tolerances are maintained by computer controlled lathes. After
machining, the rotors are passivated to military specifications for
maximum corrosion resistance. The stainless steel rotor should
never need replacing under normal operating conditions.
- 4) DOUBLE ALLEN HEAD SET SCREWS
- Allen head set screws with cupped ends (to prevent damage to
shaft) are threaded into the rotor and secured to the propeller
shaft. A second set screw is then threaded into each hole to secure
the first screw and to prevent it from possibly backing out. Set
screws are treated with a Dri-Loc 204.
- 5) DOUBLE HOSE CLAMPS
- Two stainless steel hose clamps are used to secure the bellow at
both the stern tube and flange ends.
- 6) BELLOW
- Bellow is resistance to petroleum based products and set
retention. It provides the best combination of durability, strength
and elasticity. The stern tube end of the bellow is available in
1/4" increments. Both shaft and stern tube diameters are necessary