In The Shop: The Great Bearing Removal Debate

October 22, 2016 02:32 AM

There is a debate in our shop about bearing removal. A couple other technicians and I are stubbornly old-school. We use an acetylene torch to melt away a bearing’s seal, then heat a couple of the bearing’s balls to a glowing yellow color. 

A quick blast of pressurized oxygen reduces those balls to sparks and melted metal. Two careful cuts of the outer bearing race, 180° apart, allow removal of the halves of that race. 

That leaves the inner race. With practice, it’s possible to surgically slice away that inner race without leaving a mark on the shaft. We figure it takes 10 minutes to burn off a bearing, from striking a flame on the torch to closing the valves on the tanks.

Admittedly, there are downsides to our smoke-and-flames approach to bearing removal. Bearings are greasy, so there can be impressive flames when cutting bearings with a torch. That’s why we dampen the area around the bearing, and always have a garden hose or some sort of fire-dousing equipment within reach.

Burning bearings also leaves the shaft hot enough to liquify the grease in a new bearing if it’s immediately installed. In some cases, it’s hot enough the liquefied grease runs out of the bearing, leaving it under-lubricated.

Those downsides are cited by other techs as reasons to use a cleaner, more “sophisticated” approach to bearing removal. 

These techs use an air hammer with a variety of tips to disassemble a bearing. They use a pointed tip to blast into and flip off the seal, then use a chisel or pointed tip in their air hammer to pry, knock or blast several or all of the bearing’s balls from between the races. 

With the balls removed, they use a chisel or cutting bit in their air hammer to break or mangle the outer race and remove it. Depending on the circumstances, they then use their air hammer to drive the inner 
race off the shaft or a die grinder with a cut-off wheel to cut the inner race for removal.

Their more elegant method is much less of a fire hazard and leaves the shaft relatively cool, ready for immediate installation of a new bearing. 

But, they reluctantly admit, their hammer-and-bash approach can draw blood. There have been emergency room trips after hardened bearing races explosively shattered when attacked with an air hammer. But they contend those minor risks greatly offset the smoke, flame, sparks and general uproar associated with torching off a bearing.

Both factions agree there are other options to remove bearings, depending on the location and accessibility of the target.

Using a gear puller is an option if the bearing is near the end of a shaft and there’s room to get the puller’s jaws behind the bearing.

Another option that’s magically quick is to press a pointed air hammer tip into the end of the shaft, in-line with the shaft, while prying steadily outward on the back of the bearing with a big screwdriver or pry bar. 

If you can manage it, “rattling” the shaft with the air hammer while prying on the bearing often slides old bearings off shafts faster than any other removal technique.

Unique circumstances on different equipment can require special tools to remove bearings. Bearings enclosed in gearcase housings obviously can’t risk the sparks and debris of torching. Special gear/race pullers that use a slide hammer to remove bearings can be effective in those situations.

I’m constantly searching for better, quicker ways to do my job. I’m not adverse to using more sophisticated bearing removal techniques. But then, “sophisticated” and my name are rarely used in the same sentence. 

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Spell Check

Abilene, KS
1/17/2017 06:50 PM

  An Air Chisel is my first choice most of the time if I can get to the backside of the bearing much cleaner not heat involved just make sure you have good eye protection on


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