02-512-714 PSS "Type B" Shaft Seal - Shaft Diam: 5-1/2", Stern Tube Diam: 7-1/4" to 7-3/8"

02-512-714 PSS "Type B" Shaft Seal - Shaft Diam: 5-1/2", Stern Tube Diam: 7-1/4" to 7-3/8"

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02-512-714 PSS "Type B" Shaft Seal - Shaft Diam: 5-1/2", Stern Tube Diam: 7-1/4" to 7-3/8"

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02-512-714 PSS "Type B" Shaft Seal by PYI - #1 selling marine mechanical seal worldwide. Designed for boats with Shafts diameters of 4 inches and up. 

Shaft Diam: 5-1/2". 
Stern Tube Diam: 7-1/4" to 7-3/8"

PSS Pro Shaft Seal

In Stock: 10


Reg Price: $6,000.00
CPlus Price: $5,700.00 Question mark icon

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02-512-714 PSS "Type B" Shaft Seal - Shaft Diameter: 5-1/2", Stern Tube Diameter: 7-1/4" to 7-3/8"

The Type B PSS Shaft Seal is a mechanical face seal. The sealing surface is created between the flat surfaces of the rotating stainless-steel rotor and the stationary carbon flange. The stationary carbon flange is attached to the front side of the bellow with hose clamps, and the back end of the bellow fits over the Stern tube and is secured with hose clamps. The stainless-steel rotor is fit on the shaft in front of the carbon flange. The stainless-steel rotor is used to compress the bellow before the rotor is secured to the shaft with set-screws. This compression (pre-load) maintains constant contact between the two flat faces of the stainless-steel rotor and carbon flange, allowing the PSS to compensate for the variable fore and aft movement due to propeller thrust. The carbon flange is over-bored to the shaft diameter allowing it to “float” around the shaft and thus compensate for most misalignment and vibration problems. The stainless-steel rotor is sealed to the shaft by two O-rings that are recessed into the bore of the collar. These O-rings rotate with the shaft and stainless-steel rotor and do not experience wear during operation.


Part #: 02-512-714
Shaft Dia. (A): 5-1/2"
Stern Tube Dia. (B): 7-1/4" to 7-3/8"
Approx. Length (C): 13.42"
Rotor Diameter (D): 7.875"
Stern Cuff Length (E): 2.5"
Approx. Compressed Length: 1" to 1-1/4"

How Does It Work?

 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 mating faces of the carbon stator and the stainless steel rotor.

4. Raw water is fed to the PSS Shaft Seal for cooling / lubricating the seal faces on high speed vessels.

5. The stationary carbon stator is attached to the bellow, which is secured 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 90° 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 B Shaft Seal are made from Nitronic 50 stainless steel.

Carbon-graphite is a versatile seal face material used with mating rings of harder material. The PSS carbon has superior wear characteristics and broad chemical resistance.

The face of the carbon is finished to a flatness of 4 helium light bands (measured .000044" of variation over entire lapped surface). The high grade of carbon used in the PSS has an operating temperature over 500°F (+260°C), and cannot melt if the seal runs dry, unlike a rubber lip seal or plastic face seal.

The high density of the carbon increases the longevity and wear resistance. Over 40,000 hours (over 4.5 years of continuous operation) has been recorded on the same original component. The carbon graphite stator should not need to be replaced under normal operating conditions.

BELOW -The PSS Bellows offer the best combination of durability, strength & elasticity, and in addition to carrying standard sizing, can be engineered in a number of configurations to meet various application requirements. The most common configuration is composed of two ends (connectors) and a convolution region where the ends provide the assembly interface and the convolution (bellows) region provides for the design application travel / required flexibility.

The silicone bellow material meets and exceeds the properties listed in SAE J20 Class A and provides superior low and high temperature resistance. The Fluorosilicone Cover creates an oil and fuel resistant barrier protecting the exterior surface from the possibility of damage from splash or spill.

HOSE BARBFor high speed vessels it is required that a positive water supply be plumbed to the PSS Shaft Seal for the purpose of lubricating and cooling the seal faces. There are many sources of water supply, review the PSS Shaft Seal Installation Instructions for more information and note all plumbing must follow the standards and practices of proper boat plumbing. In most cases a slow speed boat that does not have a bearing the shaft log does not require positive water feed and can simply be "vented". Ideally the vent line will be run at least 2-3 feet above the water line and is close to the center line as possible to ensure the vent hose is never below the water line, even if the boat heels. Review the PSS Shaft Seal Installation Instructions for more details on venting the seal.
BELOW RINGS - The PSS Type B Shaft Seal uses metal rings around the bellow for added strength due to the high pressures that the seal may encounter.

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