Bearings and Bushings
Vesconite is ideal for many marine applications. It is suited to both dry and immersed applications - in fact water is an excellent lubricant.
Vesconite is extensively used for rudder and stern tube bearings. Vesconite's internal lubricants make it eminently suited to upper rudder bearing applications where there are long periods between greasing or no greasing at all, or where water lubrication cannot be ensured when operating with light ballasts.
The hundreds of vessels equipped with Vesconite during the last 15 years - ranging from pleasure boats to tankers - testify to the desirability of long life, low maintenance Vesconite in marine applications.
Why use Vesconite?
Vesconite is extremely versatile. It outperforms in most plain bearing applications, whether unlubricated, grease and oil lubricated, or water lubricated.
Vesconite keeps size - no water swell
Excessive clearances must be avoided for three reasons.
Firstly, they allow increased vibration.
Secondly, when machining an excessive clearance, one is machining away part of the wear life of the bearing - before installation!
Thirdly, and most negatively, the rate of wear of a sleeve bearing increases in proportion to the clearance.
The greater the clearance, the faster the bearing wears, which greatly shortens bearing life.
Vesconite remains hard
In the long term, humidity in the general environment leads to water absorption. Softening caused by humidity and immersed conditions has two major disadvantages for these materials.
Firstly, the drop in compression strength leads to creep. If the bearing is reasonably loaded, it will squeeze out, and no longer hold the shaft in its proper location.
Secondly, because the bearing surface is softer, its rate of wear increases dramatically, leading to a shorter bearing life.
This is why Vesconite is the marine bearing material of choice - it remains hard in moist and immersed conditions, keeps its compression strength and maintains its excellent long life wear characteristics.
does not delaminate
Avoid delamination problems by switching to Vesconite.
has low friction, even in actual working conditions
Many products are claimed to have a low friction, but often only in the laboratory when tested under lightly loaded conditions, and before the effects of softening caused by water. Vesconite keeps its low static and dynamic friction whether dry or wet, or lightly or heavily loaded.
Why is this important? Low friction for a rudder bearing means less bearing wear, as well as smoother operation and less wear to the whole steering gear.
The low static friction of Vesconite is especially beneficial to the low amplitude oscillating movements of rudders. With Vesconite every change of direction occurs smoothly, with a minimal power requirement and without any jerking.
Test this for yourself with Vesconite - its the best way to prove it. You will be delighted with the performance improvement compared to conventional materials.
The case study of the propeller shaft bearings of the Jackson pilot boat is an example of the low shaft wear rate.
If shaft wear is your problem, or you would like to extend your shaft life, contact us about options.
does not corrode
of Vesconite bearings
Vesconite does not contain any reinforcement, and old Vesconite bearings are easily removed. This is often not the case for laminated bearings: workers often struggle for hours trying to cut, hammer or burn laminated bearings out of their housings.
Safety and health
Vesconite has passed a series of stringent health tests. It is fully approved for applications in direct contact with drinking water, both in cold and hot water.
Easy to machine
With Vesconite the size you machine is the size you get, unlike elastomers which stress relieve and change size during machining.
There are no dust or health problems when machining Vesconite, whereas these can be problems with laminates as a result of the fibre reinforcement.
Low friction Vesconite keeps lathe tooling sharp hour after hour. This is another example of the long life, low wear properties of Vesconite. If machining a bearing blunts your tooling, think what it does to your shafts.
versus white metal
If you need a bearing for a problem chemical application, contact us - we can advise whether Vesconite is suitable, or whether we can offer another of our speciality bearing materials.
American Bureau of Shipping
Trials of Vesconite Stern Tube Bushes
The RP Jackson sails in and off Durban harbour in waters with high concentrations of abrasive, suspended sand particles arising from propeller wash.
Superior wear figures of 1.5 to 3.0 mm (0.06 -
0.118") were obtained after each 5 year period of service. These wear figures
were remarkably low given the sandy harbour waters the Jackson operates in.
See also the Vesconite Production List
Vesconite is stocked in a wide range of
sizes and shapes, and is machined at short notice to toleranced drawings.
Straight Bushings (Tubes) are stocked for shafts from 20 to 660 mm (0.8" to 26") diameter (housing diameters up to 750 mm (29.5")). To save costs, bushings with diameters greater than 250 mm (10") can be supplied to the exact length required.
Ready-to-Fit stern tube and rudder bushes with water grooves are stocked for shafts from 25 to 60 mm (1" to 2.4") diameters for housings from 40 to 80 mm (1.5" to 3.2"). Outside diameters can be supplied to the nearest imperial size.
Staves are produced in lengths up to 3 metres (10'). Linings and machining of housings can be undertaken.
Flanged Bushes and Thrust Washers can be produced up to 715 mm (28") outside diameter. Solid Rods from 20 to 160 mm (0.8" to 6.3") are stocked in 1 metre lengths. Plates and Wear Strips are available in accurately machined thicknesses from 2 to 50 mm (0.08" to 2").
A wide range of new bushing sizes up to 750 mm (29.5") has been put into stock.