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Duramax Marine
Rubber Lined
Propeller Shaft Bearings |
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Designed for superior performance in the most demanding environments. |
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High Quality Materials and Design:
Johnson Cutlass Sleeve and Flanged Bearings for heavy duty commercial, government and pleasure craft applications, feature a specially formulated nitrile molded rubber lining firmly bonded to a shell material. Shells for sleeve bearings are seamless naval brass and are also available with a rugged non-metallic shell.
Those for flanged bearings are one-piece centrifugally cast with integral flange. Other types of shells, such as stainless steel, monel or aluminium can be finished to order. All bearings are precision-machined to close tolerances and fully inspected.
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| Johnson Cutless bearings are engineered with a proprietary formulation of extremely tough chemical and oil resistant nitrile rubber polymer lining, molded and firmly bonded into a naval brass or non-metallic shell. Grooves run the entire length of the rubber lining allowing for maximum lubricating water flow and dissipation of frictional heat. |
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The Water Wedge Principle minimizes bearing and journal wear.
The elastic characteristic of the rubber polymer allows the landing surface to deform and create a natural pocket allowing a hydrodynamic lubricating film to completely separate the bearing surface and the shaft. At this stage the coefficient of friction is well under 0.001, reducing “system wear” to a negligible amount.
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Hydrodynamic Grit Rejection.
A seal is created at the leading and trailing ends and bearing “land” areas causing hydrodynamic grit rejection. Abrasive grit is flushed out through alternating grooves, protecting the shaft from damage.
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Why Rubber?
The tribology forces of rubber, when lubricated with water makes it one the most slippery materials. When sliding on a wet metal surface friction can be virtually eliminated, making it the perfect material to use for water-lubricated bearings.
Other reasons:
- The elastic properties of rubber allows grit and dirt to press into its surface until they are flushed out, protecting the shaft from scoring - unlike hard surface materials that can cause excessive shaft wear.
- Rubber is able to utilize any lubricants with low viscosity, such as water.
- When starved of water, rubber will not wipe or fail in a sudden catastrophic manner like hard surface materials. Rubber can crystallize but will always maintain its form.
- Each rubber landing area acts as an independent bearing surface.
- Rubber bearings always have contact area due to the elastomeric properties.
- Water-lubricated rubber has twice the specific heat of oil. An equal weight of water will absorb twice the heat of oil lubricants.
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Rubber Water-Lubricated Bearings
The Environmental Solution.
Water lubricated rubber bearings offer an alternative solution to the ever growing concerns of environmental restrictions, the high costs of maintenance and the replacement in today’s marine industry. How are rubber-lined bearings an alternative? They use water as the lubricant. This concept is very important because if water is used rather than oil, contamination seals are not required. If seals are not required, pumps and tanks may not be necessary. This leads to a simpler shaft bearing system and immediate cost savings. |
Advantages of Rubber Properties In Water-Lubricated Bearing Design.
- The proprietary rubber formulation of the lined bearing is broken up by water grooves into a number of lands or faces. These surface lands run parallel to the shaft and serve in supporting it. A tough resilient rubber compound is selected which is relatively immune to the action of grit and sand and also helps reduce noise and vibration.
- When a grit is trapped between the shaft and the rubber, it is depressed into the landing’s elastic surface and rolled into an adjacent water groove where it is immediately flushed out of the bearing.
- With proper loading, rotational speed and clearances, a water wedge is formed in the rubber landing causing the shaft to ride on a thin film that totally separates the shaft and bearing surface. This is known as hydrodynamic lubrication. At this juncture both friction and wear decrease significantly in a rubber bearing.
- Our proprietary rubber formulations have nothing more to prove. Rubber bearings are on more vessels around the world than any other material. Our Johnson Cutless Bearings have set unbelievable performance records that other bearing materials are still trying to meet.
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| Johnson Cutlass Naval Brass Sleeve Bearings |
| These Naval Brass Sleeve Bearings adapt equally well to strut and stern tube mounts, and often used effectively as rudder-stock and pintle bushings. |
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- Diameters are precision fitted to the shaft size with correct clearance for efficient water lubrication.
- Thin shelled units are available for struts of small craft.
- Over 100 different sizes in stock
- Available in inch and metric sizes
- Custom sizes available upon request
- For shaft sizes: 3/4" to 6-1/2" (19.05mm - 165.10mm)
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| Johnson Cutlass Non-Metallic Sleeve Bearings |
| These Non Metallic Sleeve Bearings feature a structure of engineered reinforced thermoset plastic. The nitrile rubber polymer liner that is bonded to shell, is non-corrosive and inherently resistant to chemicals, oil and grease, as well as being anti-electrolytic. |
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- Lightweight
- Over 100 different sizes in stock
- Available in inch and metric sizes
- Custom sizes available upon request
- For shaft sizes: 3/4" to 6" (19.05mm - 152.40mm)
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| Johnson Cutlass Strut or Sterntube Flanged Bearings |
| Flanged Bearings are centrifically cast naval brass with an integral flange for bolting to stern tube or strut housing to retain bearing and prevent rotation in housing. Shells are heavy walled providing structural strength and can be step turned if desired. Shells are furnished un-drilled unless specified. |
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- Available in solid and split design
- Over 70 different sizes in stock
- Custom sizes available upon request
- For shaft sizes: 2" to 15" (50.80mm - 381.00mm)
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| Johnson Cutlass Forward Sterntube Flanged Bearings |
| Flanged Bearings are centrifically cast naval brass featuring heavy metal wall and integral flange. Integral flange permits solid bolting of bearing to stern tube stuffing box. A machined male pilot on the integral flange mates with the female recess of the stuffing box. Shells are furnished un-drilled unless specified. |
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- Available in solid and split design
- Over 70 different sizes in stock
- Custom sizes available upon request
- For shaft sizes: 2-1/2" to 15" (63.50mm - 381.00mm)
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| Click on Images for specification sheets |
Johnson Cutless® Sleeve & Flange Bearings
Catalog |
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Duramax® is a registered trademark of Duramax Marine® LLC.
Johnson® is a registered trademark of Duramax Marine® LLC.
Cutless®is a registered trademark of Duramax Marine® LLC. |
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