top roller seals

[peter de vries]

I am re-building the top rollers on my DD cletrac, but am somewhat perplexed on the sizes of the oil seals required. the outside diameter of the housing is approximately 60.2mm or 2 3/8" but the shaft is 37.85mm which is significantly below 1 1/2" which is 38.1mm. now I can use a 38 by 60 oil seal which will still press into the housing ( they are made significantly oversize) and it is close enough to the shaft size to work ok too. The shaft was measured in the centre part that presses into the support housing so I was not measuring a worn part. so... imperial or metric?? it is interesting to see that the gearbox bearings are all metric in size and the origional NEW DEPARTURE bearing numbers translate directly to current metric bearings, so was wondering if the top rollers follow suit and may be metric instead of imperial.  any ideas??   regards pete.

[peter de vries]

Well I bought imperial seals, as they fit the housings a little tighter, but one mod i have to do is to fit a snap ring outside the seal to prevent it from being blown out of the roller when pumping oil into the assembly. I learnt this when re-building a set of return rollers from a friends AD cletrac. the problem is that the origional seals allowed the oil to be forced out under pressure, yet let no dirt or water back in, wheras the new seals are a double lip seal that wont let anything go in either direction, which is kind of good except for when you want to pump more oil into the assembly. I may also fit a bleeder screw onto the outer top roller oil cover, which i can loosen when pumping oil in to prevent pressure build-up. I am currently turning up new shafts out of 4140 hi tensile steel, and will have the outside hardchrome plated for wear resistance. I do this in preferance to hardening to save the probs of distortion, and for the limited use i have for my old machines this should be fine. I also use a product called oilon for the plain bearings as it is significantly cheaper than phosphor bronze and wears the shaft much slower when things do go wrong!!. In dry situations it is claimed to outlive bronze by 25 times the life, and is basically an oil filled nylon .