how to get a gearbox apart
I'm sprucing up my big old snowblower. The rear seal on the gearbox was leaking, and the long shaft that goes through the fan is slightly bent. It's a simple gearbox, with a straight-through shaft bevel-geared to a shaft at 90 degrees to run the auger. I removed the seals from both ends of the straight-through shaft, removed the lock rings behind both seals and the shims that set the backlash. I loosened the stake on the interior spanner nut that preloads the bearings and backed it off a ways. I tapped the shaft back and forth a little to start moving the cups and cones out, but now the challenge.
The bevel gear seems to be a press fit on the shaft. I can see the waldruff key that sets it to the shaft, and there are no pins or set screws. I believe the gear is bottomed out on one side against a shoulder on the shaft, but it needs something to keep it from floating too close to the other gear, so I guess the tight fit keeps it from floating. I put the whole thing in a press with a 20 ton jack, tapped the gear to set up a vibration, etc., but the shaft wont budge. I'm afraid to use more pressure because the gear is pushing on the housing, which is cast, and liable to crack. Even though the gearbox sits squarely on the bed of the press, I still don't trust using excessive pressure to push the shaft through.
Anybody pressed one of these things before? Am I in a losing battle with this thing? Should I just put new seals in and forget about straightening the shaft and leave it alone? I mean the blower works and all, but I think my performance would go way up if I could get this big wobble out of my fan. Sure, I could cut it all apart in 5 minutes, but tracking down new parts(the company is long gone)would be tough, not to mention extremely expensive. It's a Hayes-Dana 40 gearbox.
Re: how to get a gearbox apart
I sort of get lost in your description...but I think I'd get some more eyes on that gearcase..and make sure that shaft comes off the way you think it does. After that..if you wish to put it back in the press..and apply some pressure..you can probably heat the gear to a straw color without hurting the hardness of the gear. You have to be carefull...but it can be done. We heat connecting rods with pressed in pins to a straw color to enable us to drop in the wrist pin...so I don't think it will be too much heat.