1 articles A place where I worked in the 70's had quite a lot of sets of radio gear that used a quite nice fan with a machined alloy case and blades to suck the hot air out. The trouble was that they chopped out the bearings quite frequently. One of the bosses had a son who was into speed skating at the national level. Whenever we found a fan that had gone noisy, we would change out both the bearings and put in new ones. The old ones had to go to the boss guy so that he could put the OK ones into the skates, since they were the exact same size. Usually only one bearings had actually failed, you could feel the grittiness where they had gone through the hardening. I suggested that perhaps if the bearing at one end of the fan had gone, the other might not be far behind and that it might not be a fun experience to have a bearing decide to seize up when skating as fast as possible, but it seemed they were OK with that risk.