K&T 205 sa coolant gear pump seal?

Brandenberger said:

Hi,
Servicing the coolant gear pump on a 205sa mill.

The drive gear has a worn rubber seal which I can’t seem to identify a replacement. The parts manual only shows the bronze bushing, no seal, but mine has an all rubber, fairly flexible u-cup type seal.

1.25” OD, .750” ID, about .290” tall.

Pictures of pump housing, drive gear, and seal removed and in place.

View attachment 338750View attachment 338751View attachment 338752

The bushing is bronze or brass, with what seems to be a drain port back to tank. So it seems as if the intent is for some cutting oil lubricant to bypass the seal, lubricate the shaft in the bushing, and then drain back to the coolant tank.

So the u-cup seal should be pretty flexible and low friction it seems, a very restrictive seal might prevent the shaft and bushing to be lubricated.

It seems like most of these pumps only had the bushing, maybe depending on only that and the drainage path to avoid leakage?

I tried one seal from McMaster, the only one they have which is all rubber and 1.25x.75”, it was far too hard (90 durometer) and too tight on the shaft, I was worried it would starve the bushing and shaft of lubricant.

Thanks,
Phil

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dana gear said:

We rebuilt our K&T mill a few years back and I recall the only thing on the drive through the housing was the Iron oilite bearing, if there was a seal ours didn't have it.

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Brandenberger said:

Thanks. I was surprised to find a seal too, even the parts manual for the machine (which came with it in 1965) doesn’t show a seal… just the bushing/bearing.

I found a 70 durometer low friction u-cup seal at grainger which I’ll try.

Phil

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