Would love some input about the following situation: Recently scheduled a generator for bearing replacement but had to take the end bells to a motor shop because the bearings wouldn't come out. Motor shop found that loctite had been used to hold the bearings in the housings, (housings were oversized). Motor shop then correctly sleeved the housings to bring them back to tolerance. A different motor company had reconditioned this generator as part of a remodel. When confronted with this information, their response was that it's common practice in the industry to loctite one bracket in a unit (of course, they actually did both, but aren't taking responsibility). Our opinion, confirmed by another generator manufacturer, is that this practice is totally unacceptable under any circumstances. Your opinion?

-- Patty Erickson (internet:erickp@fm.facm.umn.edu), October 10, 1997

Answers

Loctite on bearings

I have been told by more than one motor shop that if the bearing is turning in the housing but there is no "slop" between the bearing and the housing, machine work is not necessary. There is a special Loctite made just for bearings but I don't know what the number is. (Loctite comes in several grades designated by numbers.) If the bearing will not come out, slightly heating the housing will break it loose. I have done this several times without problems. I will try to find the number for the bearing-type Loctite. Note: these motor shops turned away money for machine work when they suggested using loctite. Any time we have any work done to a mg or commutator, we replace the bearings.

-- Roger (rogershumate@msn.com), October 10, 1997.

I responded to the sender then decided I would post my comments for all, so I send this.

Never heard of this practice with bearings. Montgomery has, in the past, recommended that the sheave attach bolts on their gearless machines be installed with locktite. This was after the sheaves began breaking up while in operation. We note the red rouge that develops at the referenced bolts which is the clue that there is movement between the elements. A mechanical engineer developed the force patterns that develop during operation the result of which was very interesting. Not only is the bolt pattern asymmetrical, but the load is cantilevered from the sheave attach spider on the armature shaft. I have never considered gluing a gearless machine together good practice, nor do I consider gluing bearings in place to be good practice. Both may be risky and add to the ever present liability exposure in this business.

-- Vernon P. Keller (vpkeller@earthlink.net), October 11, 1997.

depending on what generator you have ....most bearings are pressed on the shaft and have to be pulled off and a bearing heater used to put them back on ...your generator has been damaged and instead of fixing the problem they glued the bearing in there .....if you have others in the same building and they have been to motor shop in question id be lookin at them too ...remember it didnt come new that way....they are precision balanced machines a lil movement can cause end bell damage over time and youll never know until its too late

-- anonymously answered, October 11, 1997

I HAVE BEEN A REPAIR MECH FOR 14 YEARS IN NEW YORK I HAVE SEEN THAT AND SOME PEOPLE USE A CENTER PUNCH TO MAKE THE END BELL BIGGER

-- m spiteri (spiterim@cs.com), February 14, 2000.