Q: Can any bearing type be used in a strut or stern tube?
A: A large variety of bearings are used today from Phenolic, White metal, Polyester, Brass shell Rubber to Thordon.
Q: What is Thordon?
A: Thordon is a propriety elastomeric polymer, originally developed in Canada during the late 1960’s for use as a journal bearing for vertical pump applications. Thordon performs exceptionally well in the following conditions:
(a) Exposed to or submerged in water.
(b) Extremely dirty environmental environments.
(c) Where shock loading is a factor.
Q: Are all bearings designed specifically for small or large vessels?
A: NO, most bearing types have limitations in available sizes. Thordon covers from ¾" shafts to over 40" diameter shafts in both Marine and Hydro environments.
Q: Is there any bearing material that is specifically designed for dirty water?
A: YES – Thordon SXL run larger clearances than standard rubber type so the larger particles are continually flushed thru rather than remaining in the center of the bearing as a grinding paste.
Q: Which is better for high sediment water, hard or soft bearings?
A: SXL bearings are better in that they tend to roll out particles without scoring the shaft or liner.
Q: Will Thordon bearing lock on to the shaft if failure occurs?
A: NO – Thordon bearings are designed to keep supporting the shaft at low rpm for a period of time. They will not lock the rotating shaft up. Polyester type tends to seize, bind or crack due to any heat build up.
Q: Is it better to have a tight shaft / bearing tolerance or larger clearances.
A: There is no doubt that a elastomeric polymer bearing that is designed to run on larger clearances increases water flow thru the bearing – flushing and rolling particles out of the bearing before they have the opportunity to act as a grinding paste on the shaft or liner.
Q: Is there a predictable life expectancy from any of the available bearing options?
A: NO – however it is expected that Thordon bearing material should provide double the life of a standard Rubber cutlass, Phenolic or Polyester bearing in the same environment.
Q: Can Thordon bearing material save you money in the long run?
A: YES – in most cases the actual cost of the bearings reflect less than 10% of the cost in removing, stripping, replacing and refitting the shaft assembly / pump unit. If you can achieve double the life then it is possible to effectively reduce your maintenance costs by 50%.
Q: If the housing I.D. is corroded what is the best bearing option?
A: KIWI liners are designed specifically as a retro fit in acorroded housing. KIWI composite outer liner and a Thordon inner bearing is designed specifically for full emersion without altering tolerances. In this instant a KIWI liner with Thordon bearing is simply glued into the housing with Marine grade Epi Glue (epoxy). NOTE: In normal circumstances the KIWI shell liner will not need to be removed when replacing the Thordon liner in the future.
Q: Is the Thordon bearing difficult to replace?
A: NO – it is a very simple process of applying low heat to the internal Thordon bearing material and removing it with a drift and small hammer. The replacement Thordon bearing material is simply freeze fitted back into the original housing. No further mechanical fastening is required.
Q: Are all bearings the same length?
A: NO – Most bearings including Rubber brass shell type are manufactured / designed to work at 4 x the shaft diameter. Thordon offer two designed length options: XL @ 4 x shaft diameter or Compac @ 2 x shaft diameter. The options with Thordon bearing material allow for the most effective solution to suit the application and budget.
Q: Do all Thordon bearings come in standard sizes?
A: NO – Thordon bearings can be supplied as custom units, machined to requirements based on housing data supplied by the customer which is then entered into the Thordon sizing program to arrive at the correct machining tolerances. The customer is provided with a copy of the calculation for future reference.