PSS Shaft Seals


The Packless Sealing System (PSS) Shaft Seal is a mechanical face seal that is created between a rotating stainless steel collar (rotor) and a stationary carbon flange (stator). The carbon flange is attached to a convoluted rubber (EPDM) bellow and the back of the bellow is attached to the shaft log (sterntube) of the boat with hose clamps.

During installation, the stainless steel collar is used to compress the convoluted bellow.  The collar is then secured to the shaft with set screws. The compression of the bellow allows the seal faces to remain in constant contact and compensate for the fore-and-aft movement of the shaft caused by the propellers thrust pushing on the engine mounts. The carbon flange is bored larger than the shaft diameter, allowing it to float around the shaft and compensate for most misalignment and vibration problems.  The stainless steel collar is sealed to the shaft with two o-rings that are recessed into the bore of the collar. These o-rings rotate with the shaft and collar and do not experience wear during operation. This static o-ring seal enables the PSS Shaft Seal to be fit on shafts that have some wear or pitting, unlike lip seal designs that require a clean area for the lip seal to ride.