Rotary Cutter Just bought a used JD 606 rotary cutter and it sure seems to turn slow....

[stvbird]

Yesterday, I bought a used JD 606 6' rotary cutter from an old man who has just had it sitting for fifteen years. It's mechanically sound, well greased, and everything works smooth. However, it sure as heck seems to turn slow. The clutch is good and with the tractor humming you can watch the blade go around and pretty much count the swings. It's almost like it is geared crazy low, but it has the factory decal on it from JD that says it's for a 540 PTO. I know it's not the tractor, it spins my finish mower just fine.

Any thoughts?

Thanks...

 

[ddd75]

Yesterday, I bought a used JD 606 6' rotary cutter from an old man who has just had it sitting for fifteen years. It's mechanically sound, well greased, and everything works smooth. However, it sure as heck seems to turn slow. The clutch is good and with the tractor humming you can watch the blade go around and pretty much count the swings. It's almost like it is geared crazy low, but it has the factory decal on it from JD that says it's for a 540 PTO. I know it's not the tractor, it spins my finish mower just fine.

Any thoughts?

Thanks...

yea something is jamming it up. does the gear box have oil in it? if it does i'd take it apart and see whats going on in there.

 

[stvbird]

It doesn't seem jammed up as the drive shaft and tractor engine/pto are spinning fast. It's not bogging down from resistance. It's smooth, just not turning the blades fast. I'm gonna go out and look it over more here in a few, but it seems that if it was a jam it would bog the tractor.

 

[PHPaul]

Maybe the hub that connects the blades to the output shaft of the gearbox is slipping?

Or the slip clutch (if equipped) is slipping? Sometimes folks take all the pre-load off the slip clutch when storing to keep it from seizing up.

 

[jenkinsph]

Somewhere in the mix you are slipping. I doubt from your description that the gear box is the issue. I would start by determining if the tractor pto clutch is slipping with this heavier loading. While it may turn the finish mower okay it might be slipping with the heavier 606. You need to determine if the pto shaft is turning fast at rated speed while under load.

Next I would block the blade carrier and try turning the gear box input shaft with a wrench to make sure there isn't slippage. If there is a sheared key or bolts you would be able to turn the input shaft without the blade carrier moving. I am not real familiar with the 606 but would suspect that slippage would point to a sheared key on one of the gears I the gear box or a key on the lower blade carrier. If the input shaft is hard to turn with the blades blocked and is easy to turn with the blade carrier free to turn then check between the pto stub shaft and the drive line for slippage.

I would expect the finish mower to turn several times faster than a brush mower with a 6 ft blade set. That said in operation the 606 should be turning fast enough at idle that you could not count the revolutions. Have you tried it out clipping a pasture yet? Under load it might be easier to determine if there is a problem.

 

[Harry in Ky]

For what it's worth, the parts book for the 606 gearbox shows a 29 tooth gear driving a 21 tooth gear. My 4th grade level math tells me that's about 1.4 to 1 ratio. That means 540 rpm on the input should be about 745 output.

 

[jenkinsph]

For what it's worth, the parts book for the 606 gearbox shows a 29 tooth gear driving a 21 tooth gear. My 4th grade level math tells me that's about 1.4 to 1 ratio. That means 540 rpm on the input should be about 745 output.

That is good information to have:thumbsup:, when I typed my reply above I was wondering what the ratio was. Since the OP has said the pto shaft is turning fast it is looking more like a sheared key in the gear box or blade carrier slipping.

 

[stvbird]

Turns out it was busted clutch discs. Who would have thought shattered discs could run so smooth. Oh well, simple fix.