10' rotary cutter blade problem...

countrybumpkin · Jul 27, 2017

Yes a overlap of about 4" is about right on those style of cutters. Hope it's a easy fix by just being out of time, but there is also the possibility one of the outer gear boxes has been replace with the wrong ratio, do both outer boxes look the same and also look to see if the I.d. Tags are on them, if so see if they are the same ratio, if changing the timing doesn't work.

cutworm · Jul 27, 2017

Ok, I really appreciate the feedback. Last night I raised the bush hog up and spun each stump jumper (they ARE round) and I can spin one and the other one does not spin with it. I can spin the other one and the other one will not spin with it, almost like they are not connected together at the center gearbox even though I can clearly see that they are. Although one side did spin the pto shaft everytime (I had it disconnected from the tractor) while the other side seemed to only spin the pto shaft very intermediately. I'm stumped. I'm leaning towards one gearbox may be stripped or something.

CincyFlyer · Jul 27, 2017

Yep, sounds like a stripped gear-unless there is a shear pin.

LD1 · Jul 27, 2017

There is normally a little play. One stump jumper will move quite a bit before the other one.

IE: if you have a set of blades at 3 and 9 o'clock and one at 12 and 6.....it's not uncommon to be able to go to 11 or 1 o'clock before the other side moves.

If you can spin it round and round and the other side don't move, that's an issue. Normally I'd say a secondary shaft. They are usually coupled to the center gearbox via rubber couplers. Of one of those goes out, you'd only be driving one set of blades.

It since both sets of blades make the center gearbox turn I'm at a loss and fear gearbox damage. But check out those secondary shafts anyway

cutworm · Jul 27, 2017

Thanks, I'm going to give each gearbox an internal look at.

Spanner · Jul 27, 2017

cutworm said:
Ok, I really appreciate the feedback. Last night I raised the bush hog up and spun each stump jumper (they ARE round) and I can spin one and the other one does not spin with it. I can spin the other one and the other one will not spin with it, almost like they are not connected together at the center gearbox even though I can clearly see that they are. Although one side did spin the pto shaft everytime (I had it disconnected from the tractor) while the other side seemed to only spin the pto shaft very intermediately. I'm stumped. I'm leaning towards one gearbox may be stripped or something.

This is the lesser damaged side, still with power transmission from PTO through two gearboxes (Centre & Side) to the blades.

Your problem is in the other side... between Centre gearbox and the blades, somewhere.

Now, just to find the fault.

Are you confident (Mechanically) to continue further disassembly? It seems you may be..

If so - Can you post a picture of the BH for us pls? (Top-side preferably although multiple pics are better. The more the merrier!)

Before opening the gearboxes, look at the drive-shaft 'between' the Centre & Damaged side. Look at the Couplings and possible shear-pins etc.

The shaft should have some sort of cover - Plastic or solid metal?

:wrench:

LD1 · Jul 27, 2017

I might have missed read. I though both sides caused PTO shaft movement. If only one side did, then the other side isn't connected to the center box.

My money is on whatever couples the center gearbox to the outboard on that side. Usually it's a driveshaft with rubber coupler discs. I am betting one of them bit the dust

cutworm · Jul 27, 2017

I would agree except that one side is moving the pto shaft as expected. The other side only moves the pto shaft sporadically, it actually doesn't move it more than it does move it. Is it possible for an internal shear pin to have sheared and when I move the stump jumper that it grabs once in a while to move the pto shaft? That is my thought. I will post pictures tonight after I remove the covers.

Spanner · Jul 27, 2017

It is. That's the fault we are reading it as. But more likely (hopefully) the sheared part (pin or coupling) is external to the gearbox.

So, you check the easy stuff first. Shafts are easier to check than insides of gearboxes.
You work from the outside inwards. Eliminating as you go.

We know that when the PTO shaft turns the centre gearbox turns.
When the centre gearbox turns the one side box turns. And we know that, because the blade disc turns uniformly on that side.
The other side is turning intermittently so something is catching and releasing...
Since both sides are driven by the same gears in the centre box we look outside the centre box to the driveshaft couplings and then the gearbox on the 'bad' side.

Removing the covers will expose the shaft & couplings (I hope) and aid the process of elimination to identify the location of the fault.

You may still end-up looking inside the gearbox. If gears have stripped it will be less expensive to replace the offending gearbox as a whole unit I would think.

Yes pics always help.
:wrench: