3" Shaft 5 1/2" Stern Tube

3" Shaft - 5-1/2" Stern Tube. The PSS Shaft Seal is the #1 selling marine mechanical seal worldwide and is installed as standard equipment by many of the worlds most reputable boat builders and boat yards. The PSS Shaft Seal is also recognized as the premiere retrofit (aftermarket) seal on the world market. Boat builders and boat yards recognize the advantages and value of installing the PSS as it eliminates the maintenance, constant adjustment & cost associated with traditional packing type glands. Aside from these benefits, the PSS Shaft Seal helps to eliminate water in the bilge (100% water tight) & wear to the propeller shaft.. How Does it Work?. 1. Two nitrile o-rings seal the stainless steel rotor to the shaft and will not experience wear.. 2. A primary set screw and a backup set screw (2 sets) are used to secure the stainless steel rotor to the shaft.. 3. A seal is created between the two flat surfaces of the carbon stator and the stainless steel rotor.. 4. Water is fed into the PSS Shaft Seal for cooling/lubricating the seal faces on high speed vessels.. 5. The stationary carbon stator is attached to the nitrile bellow, which is attached to the stern tube (shaft log).. Rotor. The PSS stainless steel rotor is slid down the shaft and is secured to the shaft with set screws at 90degrees for maximum holding power. Precision tolerances are maintained by computer controlled lathes. The faces have a number 9 micro finish and are perpendicular to the bore to prevent run-out as the collar rotates. The carbon graphite stator will polish the face of the rotor during the first few minutes of operation. The stainless steel rotor should not need to be replaced under normal operating conditions. The stainless steel rotor used on the PSS Type A Shaft Seal is made from 316L stainless steel.. Carbon Stator. The high density, resin impregnated carbon/graphite stator is a composite that is first mixed, molded and then formed under pressure. The blanks are then baked, machined and lapped. The face of our carbon is finished to a flatness of 4 helium light bands (measured .000044" of variation over entire lapped surface). The grade of carbon used in the PSS has an operating temperature over 500degrees Fahrenheit (+260degrees Celsius), and cannot melt if the seal runs dry, unlike a rubber lip seal or plastic face seal. The high density of the carbon greatly increases the longevity and wear resistance