Rotary Blade Assembly Removal

[fenneran]

I have an old (I mean OLD) 5' rotary mower someone gave me. The transfer case is loose and I keep breaking shear bolts, so I need to take it off and replace the bolts (and sharpen the blades while I'm at it).

I've got it up in the air and removed the center shaft bolt with an impact wrench.

Now what?

Nothing will move. I've soaked it with WD40 and smacked it incessantly with a sledge hammer, but the assembly (big round plate and blades) will not budge.

Any ideas?:confused2:

 

[CharlieS]

The big round plate you refer to is generally called a stump jumper, as its purpose, besides mounting the blades, is to guide the cutter assembly over obstacles, rather than let the blades hit them full force. More than likely the gear box shaft has rusted to the stump jumper, particularly if the mower sat for a long period of time.
If, and i stress IF, there are a pair of holes in addition to the center hole, you may be able to loosen the plate with a large puller, however don't pull on the outside edges of the plate or you will surely bend it.
Lacking that you can try some heat with an oxy/acetelene torch around the gear box shaft on the stump jumper plate in hopes that will break the rust bond between the plate and shaft. Don't heat the shaft directly though as too much heat would take the temper out of the metal.
Note too, removing the blades before pulling the stump jumper will make the whole operation easier, and they'll need removed anyway for ease of sharpening.
On the subject of breaking shear bolts, its possible too, you are mowing such dense material the mower is overloading thus causing the bolt to shear. While the gearbox mounting bolts do need to be tightened/replaced, this may not end your bolt shearing issues.

 

[fenneran]

Thanks Charlie. I do not see any additional holes besides the middle one, so a puller is out. I may try and get a buddy's torch and try that and see what happens. Taking the blades off may prove tricky as well...everything has been sitting and they are pretty rusted as well.

 

[twoone]

There should be a hole on top exposing the the nut holding the shoulder bolt that the blade spins on. its a bear to brake loose as it take 450lbs of tighting torque when it was put on so you will need a impact gun and probably a cheater bar (a little knocker loose wont hurt either) Paul

 

[fenneran]

The center nut was a 1.5", and the blade nuts are bigger. venture a guess as to what size socket I need to go get?

 

[twoone]

Had the boy go check our bush hog he told me it.s a 1-3/8 nut. hope this helps. Paul

 

[twoone]

We have a 5ft Bush Hog the blade nut size is 1-3/8. I do not know what brand or size your cutter is. Any way I hope this helps. Paul

 

[fenneran]

It has to be bigger than that because the 1 1/2 socket is too small. I found a friend who has a large socket set that we're going to use and hopefully get them loose. Thanks!

 

[twoone]

No problem Frank am sorry I could not be of more help. Have you been able find out what size cutter and make you have? Tid Bit: am from VA originality ment to look up Staunton am from Blackstone Paul

 

[fenneran]

Paul, Its a 5' of unknown brand .
Staunton is at the intersection of I-81 and I-64, West of Charlottesville in the Shenandoah Valley