I was recently called to look at a small belt driven fan that supplies cooling air to our D.C. motor on our pulp machine. I diagnosed as having bad bearings and belt issues( over tensioned. I was later informed that both bearings were fixed as was so with the new installation. The fan spped is about 2300 rpm and the bearings were small pillow blocks for a 1 3/16" shaft secured with a set screw. The question was asked "How do yo allow for a floating bearing with this type pillow block unit?" I have come across this in the past. Should the set screws be left out of the fan end bearing? If so, what keeps the bearing from spinning on the shaft. Any insight ya'll can supply would be greatly apreiciated.

I don't know about your particular brand of pillow block bearings, but some brands have a pin under the grease fitting that needs to be removed to allow it to float.

After you called the bearings "bad" were they replaced? If so, are you getting the same signal with the new ones?

Haven't collected anymore data yet. Bearings were bad. one had spall on outer race with 2 more developing, had rub marks from cage half way around outer race. The other had rub marks from cage all the way around the outer race and evidence of a thrust load as the balls were not running in the center of the race. There were also other issues that were corrected.