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Onan 7.5 JB armature removal question


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  #1  
Old 12-16-2011, 05:36 PM
Don Smith
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Default Onan 7.5 JB armature removal question

I am in the process of tearing down my Onan 7.5 JB with the bad block. About to remove the armature from the crankshaft. Does the JB series have the same crankshaft taper that is used on most RV type Onan generators? What is the best way to break the armature free from the crankshaft. It is a Magnaciter type generator head. Thanks in advance and Merry Christmas to all. Don
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Old 12-16-2011, 06:42 PM
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Billy J Shafer Billy J Shafer is online now
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Default Re: Onan 7.5 JB armature removal question

Remove the center bolt. Then lay something under the rotor to catch it. So that you don't damage the windings. Then you can use a board on the shaft of the rotor. Hit it with a hammer,then rotate it and hit it again. It should drop off. Just make sure the board is not on the bearing or the windings. Also avoid hitting the slip rings.
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Old 12-16-2011, 07:31 PM
Max Thompson Max Thompson is offline
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Default Re: Onan 7.5 JB armature removal question

Billy makes it sound so easy, of course he has done it many times. I found I needed to repeat those steps several times & used a board & a BFH to smack the side of the rotor many times. As Billy said, be sure you support the rotor with blocks or a sling, because when it does come off, it may be all at once.
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Old 12-16-2011, 07:36 PM
Don Smith
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Default Re: Onan 7.5 JB armature removal question

Hi Billy Thanks for the email. I have the center bolt still in place but without the nut. That should keep it from slipping off completely. If my memory serves me correctly I should hit it around the main body of the armature. At a right angle to the shaft. Is this correct? Did not want to damage the shaft or slip rings. Thanks Don
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Old 12-16-2011, 07:44 PM
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Default Re: Onan 7.5 JB armature removal question

Remove the stud from the center. I have seen them break from the weight of the stator. Hit the shaft you will not hurt it.
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Old 12-17-2011, 03:45 PM
Don Smith
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Default Re: Onan 7.5 JB armature removal question

The armature popped off like a dream. Found that one must use a larger hammer to transfer enough energy to pop it loose. Flywheel removal next on the list. Thanks Billy and Max. Merry Christmas
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Old 12-17-2011, 03:57 PM
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Default Re: Onan 7.5 JB armature removal question

Forgot to tell you. As our stackers from the UK say. You need a big Fooken Hammer.
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