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FAQ

 

1. What is the bearing material used for rudders?

Thordon manufactures 2 grades of rudder bearings for different operating environments – XL and SXL. SXL offers a 15-year wearlife guarantee on newbuilds – see below. They are proprietary synthetic elastomeric polymer alloys combining the best properties of plastic with the toughness and abrasion resistance of rubber.


2. What information is required in order to obtain a 15-year SXL rudder bearing wear life guarantee from Thordon?

The 15-year rudder bearing guarantee is only available for commercial newbuild ships.  For retrofits/conversions, the guarantee is 10-years maximum or twice the life of the previous bearing—whichever is less.
Required information: Measurement data of housing, shaft, machined bearing and installed bearing bore with temperatures of all measurements; installed clearance as measured with date and copy of bearing sizing design calculations.


3. What is the maximum operating pressure for Thordon rudder bearings?

The maximum operating pressure for Thordon bearings is 10 MPa (1450 psi).


4. What is the minimum L/D ratio for Thordon rudder bearings?

This will depend upon the Classification Society, normally 1.2 or 1:1.


5. What is required at the both ends of the Thordon rudder bearing housing?

Some form of bearing retention is required. Typically, retaining rings are used and these may be referred to as a "stopper".


6. Why do we need a seal on the rudder stock bearing?

To prevent water entering the rudder trunk and causing corrosion.  It may also be needed to stop ingress to the vessel when loaded.


7. What is the advantage of using a Thordon SXL carrier bearing?

The SXL carrier bearing is lighter, can operate without high-pressure grease and reduce edge loading.