Any tips/tricks for aligning a press-fit gear?

yankeerider · Sep 7, 2012

In the next day or seven, I need to reassemble the Peerless gearbox on my Deere 60 inch finish mower. I am replacing the output shaft due to wear on the exposed end which will not provide sufficent support for the drive pulley. Assembling the nw output shaft requires that I press the driven bevel gear onto the shaft about 2 inches. After the first inch, the keyway in the bore of the gear must align with the key. Does anyone have any tips to help me align and drive the gear right on my first try? The only thing I can think of is to use a small straightedge when I start the gear onto the shaft.

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tommu56 · Sep 7, 2012

Put the shaft in the freezer a good hour or 2 heat the gear in the oven at about 250-300 degrees for about 1/2 hour

pull them out fast (with necessary PPE and help) and they should fall together shaft shrunk gear expanded.

Dry ice on the shaft is even better (colder) but that is harder to come buy.

tom

tom

Don87 · Sep 7, 2012

tommu56 said:
Put the shaft in the freezer a good hour or 2 heat the gear in the oven at about 250-300 degrees for about 1/2 hour

pull them out fast (with necessary PPE and help) and they should fall together shaft shrunk gear expanded.

Dry ice on the shaft is even better (colder) but that is harder to come buy.

tom

tom

24 hours is even better.

The idea is that, the freezing shrinks metal, and the heating expands it.

EDIT: It's been years since I've done what you are attempting, but what I did was slide the keyway down farther than what it was suppused to be..........while putting the gear on at the same time...........if that makes sense.

crazyal · Sep 7, 2012

Have you taken it apart yet? The last one I did had a roll pin through the gear as well as a keyway and just fit snugly on the shaft. Without the roll pin in you could turn the gear to get the key into the slot pretty easily.

George G · Sep 7, 2012

The way we do toggle links on an injection molding machine is, we put the links in a oven at around 250 F over night. Put the bushings in dry ice over night. Next day, put on a heavy pair of leather gloves, real fast like, pull bushing out of dry ice and slip it into the link. You have to be fast, cause in about a second or two they are going to be stuck. So! If they are not right the first try, you have to press out (destroy) the bushing and start over. Thats yust my guess. Thats the way we say" just" around here, OK,OooK.

yankeerider · Sep 8, 2012

Thanks, everyone! Sounds like a plan.

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yankeerider · Sep 8, 2012

Just an update for those who helped and anyone who comes across this thread in the future.

It turns out that the gear was a slip fit on the shaft, retained only by the interference fit of the upper bearing.

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