|jonathan heppel||19/02/2014 11:57:47|
|99 forum posts|
Does anyone have any experience with polymer bearings such as DU or DX from GGB (Glacier) or the more modern composites from Igus? I come across them frequently at work and they are for many purposes greatly superior to white metal (Babbitt) and bronze. They excel with soft shafts, low surface speeds, high loads and marginal or no lubrication.
I expect some scoffers, but the fact is there's been a huge amount of research into plain bearings since Isaac Babbitt. They are not just cheaper, they are usually better by a margin. They aren't split which is a limitation in some cases but I believe are well worth looking at for eg axle boxes, links and one piece mains.
There is the related topic of polymer seals, which can make the oil-free steam cylinder a real possibility (even superheated) as in the Spilling engine and in industrial oil-less piston compressors.
Edited By jonathan heppel on 19/02/2014 12:23:25
|John McNamara||19/02/2014 12:17:56|
1311 forum posts
Or Make your own?
I posted this at the CNCZ
Not for high speed a hundred or so rpm max but you get a perfect fit. The epoxy used was 24hr Araldite but most epoxy resins will work.
For other ideas Google Moglice
Edited By John McNamara on 19/02/2014 12:18:41
|colin hawes||19/02/2014 13:12:08|
|509 forum posts|
I believe that if it is necessary to use a plastic bearing on a shaft without lubrication or lubricated by water it is very advisable to use stainless steel for that shaft. A rusting shaft is like a file. Colin
|86 forum posts|
Yes Jonathan, I've had 12mm Glacier DU bearings in the axleboxes of a 5" gauge 0-6-0 diesel outline loco for, I think, 4 years now, and have in the last few months had to take a wheel off an axle, so I had the opportunity to inspect two of the bearings.
Perfect condition, no detectable wear on the axles, other than the chemically blackened finish of the axle being worn off in the bearing area. The DU was nicely run in, exactly as expected from the DU literature.
The other two axles were removed, but not dismantled. The axleboxes felt in good condition.
All axleboxes and DU bearings were re-installed to the loco, so we'll see how they go from now on!
Also some experience of the Igus bearings, in one of Dave Noble's wagon kits, carrying a load of 28kg. Been running for one season now, and again recently inspected. They look good so far!
Oh, and I know of a chap who fitted very small DUs in the Walscheart valve gear of a 5" gauge Black 5, which has been running for some years. Not seen him for quite a while though, so I can't say how well they've performed since the last time we met up.
|1742 forum posts|
Derek Beck had quite a lot to say about these bearings in his ME series "First Affaire with a Lathe".
|jonathan heppel||19/02/2014 17:57:53|
|99 forum posts|
Thanks for the replies. Casting your own is a good solution for specials and threads but less so if it can be done with standard components and more demanding situations.
Cabeng, I'm very pleased to see your post. It has puzzled me for ages that even new designs specify eg bronze for jobs that are not really suited to it even disregarding the cost. I was beginning to think that there must be a technical reason not to use them. If bronze is necessary for aesthetic reasons, then it would even make sense to line it with a polymer shell, so in the unlikely event of wearing it out, it could be easily replaced on a still unworn shaft.
|julian atkins||19/02/2014 23:38:57|
1235 forum posts
have a look at the website for GWR 5542 1st July 2013
|jonathan heppel||21/02/2014 00:14:33|
|99 forum posts|
That's interesting, Julian. I've never heard of vesconite but it's obviously well established. Disappointing that they are so secretive about it, particularly after 50 or so years. It seems their main market is comparatively big stuff machined from stock rather than finished inserts. I'm gratified to see it on a loco though- good example of appropriate technology.
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