How to rebuild a Bush Hog Rotary Cutter gearbox.

[beemerphile]

I broke a shaft on my Bush Hog 286 and have a new shaft coming. I have tried the dealer, Bush Hog, and Comer (the gearbox manufacturer) trying to get repair instructions with no luck. Does anyone know how to get the shafts out of this thing? I can provide some internal pictures if helpful.

The gearbox is a part number 70991 mfg. by Comer.

Lee

 

[Agvg]

Pics would be nice

 

[Agvg]

http://www.bushhog.com/uploads/documents/BHRotaryCutter280seriesPM-11.pdf

What have you tryed to do?

 

[Agvg]

Suppose its hard to loosen nut on outgoing shaft, you may pull out the cover 22 on the draving, remove circlips and force out the PTo shaft out together with the front bearing

 

[beemerphile]

http://www.bushhog.com/uploads/documents/BHRotaryCutter280seriesPM-11.pdf

What have you tryed to do?

Nothing yet. I wanted to know which way to push on the shafts. I have a 40 ton press with a 36 inch throat, torches, heat guns, an oven, measuring tools. All I need is an order of operations and the set-up specs. The parts supplier told me that the output shaft should be shimmed to obtain .005 to .015" lash between the gears and that the nut should be snug with no end-play. It is pretty clear that I can press the output shaft out from the inside once the nut is removed. However, removing the nut will require removing the input shaft and that is my current mystery. I guess that cover #22 will be ruined in removal. I still don't know (after removing the snap ring) which direction the input shaft is removed from.

I am out of town with an ailing mother until Wednesday, so I can't provide pictures until then. Thx all for the input so far.

Lee

 

[leonz]

Hello Lee,


When gearboxes are rebuilt all the bearings, seals, seal retainers and stub shafts and the snap rings must be replaced you cannot just replace the broken shaft.
The other thing is finding out from comer if the shaft bearings are a shrink fit and also if both seals come with a rebuild kit.
I am sure that this is not what you wanted to hear but the over the shoulder method to reach the scrap bin will save you a second gearbox failure.
I would simply return the shaft for a refund and apply the cost of the shaft towards a new gearbox or shop for a new comer gearbox from the many suppliers that sell them.

 

[Agvg]

Like a very easy job, if bearings are ok then it's the seals and other throw away parts that is necessary. I guess it's quite loose fit so it should come a part quite easily.

 

[beemerphile]

The cost of the gearbox is over $1,700. Since I also need the stump jumper and new blades, blade bolts, etc., I would have $2,300 in the repair. At that cost, I would simply replace it. I have bought the shaft and new bearings and seals for the output end. I did not buy bearings and seals for the input side, but that and the #22 cover may be needed as well. I continue to be grateful for the responses.

Right now, I am pressing on with the repair.

 

[HCJtractor]

I’m not familiar with that model, but I just replaced the entire gearbox on my 100 hp rated Woods for a third of that price. It was easy. Are you sure of that cost?

 

[HCJtractor]

Ouch. Just looked that up. That’s crazy expensive. I’ll bet you can find a good generic gearbox that will bolt up for way less. There are online sources that can match them up. A gear box is fairly universal, if you match the shaft sizes, bolt pattern and horsepower rating. My Woods model 720X is pretty stout, and I think I paid around $500 for the entire box. And my stump jumper was bent, but I straightened it and repaired it, saving some $. Same with old bolts. And blades are pretty cheap.