I have a Sheldon WM56P 13x36 Variable Speed Lathe. I noticed when I was cutting some extremely tough cast iron in back gear at 240rpm that after about 10 minutes the sheave where the dual belts connect to the spindle got extremely hot, to hot touch touch and leave your hand on it. The belts were not slipping, so this is not the culprit.
The dual pulley sheave is one piece and has 2 steel cored V-Belts that run in it. It is not keyed to the spindle and I can hold the sheave and rotate the spindle by hand with no problems so I do not think it is galled. The sheave has an oil hole and it was properly lubricated. I then cleaned out the oil galleys for the tapered roller bearings and cleaned the cups well and flushed out all of the old oil. I then refilled the galleys and oil cups with Velocite 10 which is what the manual calls for.
I then ran the lathe in direct drive which is accomplished by pinning the pulley sheave and the bull gear together via a pin and ran it for
20 minutes at about 1250rpm with no load and no chuck. Again the pulley sheave was the hottest part of the spindle although the bull gear was warm as was the headstock. I measured the temp of the sheave and it was 120 degrees. The bull gear was 100 degrees. The sheave again was too hot to put my hand on.The bearings are adjusted correctly and I even slacked them off a little before running it for 20 minutes just to see if it would help. I checked all of the other clearances and everything is OK. I contacted a gentleman that worked for Sheldon and he is at a loss. I too am at a loss and cannot figure out what is causing this heat problem. If it were the bearings it would be from the outside in and not the inside out that I am experiencing. The spindle nose was a little warm and if it were the bearings I would expect it to be extremely hot as this is one of the thinnest parts of the spindle. Is it possible for a steel cored V-Belt to transfer this kind of heat say possibly from the jackshaft??? I have not checked the heat in the cabinet yet but I just didn't think that would transfer that kind of heat.
Any suggestions will be greatly appreciated. Thanks, Steve