Brush Hog PTO engagement shaking B2601

[Mossy dell]

I used to pride myself on easing into a 540 rpm rear pto engagement. Can't seem to do it smoothly on my B2601. If I engage the pto clutch at idle, 1,000 rpm, the tractor stalls out. At just above that and higher, it shakes the bejezus out of me and the machine before smoothing out and letting me increase the rpms to operating range, 2,800 rpms.

Do I just have to accept this? Is there a better way? I wonder if it is related to the pto being rigidly fixed, no spin, until it's engaged? I had heard the pto would spin, helping drive shaft hookup, if rear pto is selected but clutch off of course, but mine doesn't.

My last tractor, a JD970, a little bigger at 33 hp, would start the bush hog drive shaft very smoothly. I'd engage it at low idle without shaking and then steadily accelerate without problem.

 

[kubotafreak]

The hydraulic actuated pto clutches are less controllable than the older style cable units. As far as it free spinning it may need to be off of the rear selection, like on mid instead. There is a pto brake that keeps it from free spinning from windage in the transmission. Mine never free spun full 360. They have some resistance but should rotate about 180deg, so you might try rotating the other direction. So if your hooking to rear pto put the selector off rear.

If your using a brush cutter, I would question if the implements blades rotate smoothly on the carrier. They tend to get stemmed junk in them that makes them fixed in an unbalanced position until higher rpm.

 

[jimh406]

Maybe the clutch is out of adjustment.

 

[GeoHorn]

Look under the deck of your hog... one of the blades may be rotated inside the other upon its’ pin/bolt and need to be “extended”... (I believe this may be what kubotafreak mentioned).

 

[Mossy dell]

The hydraulic actuated pto clutches are less controllable than the older style cable units. As far as it free spinning it may need to be off of the rear selection, like on mid instead. There is a pto brake that keeps it from free spinning from windage in the transmission. Mine never free spun full 360. They have some resistance but should rotate about 180deg, so you might try rotating the other direction. So if your hooking to rear pto put the selector off rear.

If your using a brush cutter, I would question if the implements blades rotate smoothly on the carrier. They tend to get stemmed junk in them that makes them fixed in an unbalanced position until higher rpm.

I think you may be onto something with the uneven resting blades. I used to get mine going on pretty level ground. One thing that has made hookup hard is at least one blade folds up against the carrier, the stump jumper, related to even the slightest slope. Not much I can do except try starting it in my one-car garage! And I won't do that.

Hookup has been a lot easier since I rigged a bungee to hold the driveline and remembered that the release pin does not need to be pushed in to release the stop(s) until the driveline u joint is halfway on the pto. I was trying to push in that pin against and wicked tight spring before I needed to.

 

[Henro]

I used to pride myself on easing into a 540 rpm rear pto engagement. Can't seem to do it smoothly on my B2601. If I engage the pto clutch at idle, 1,000 rpm, the tractor stalls out. At just above that and higher, it shakes the bejezus out of me and the machine before smoothing out and letting me increase the rpms to operating range, 2,800 rpms.

Do I just have to accept this? Is there a better way? I wonder if it is related to the pto being rigidly fixed, no spin, until it's engaged? I had heard the pto would spin, helping drive shaft hookup, if rear pto is selected but clutch off of course, but mine doesn't.

My last tractor, a JD970, a little bigger at 33 hp, would start the bush hog drive shaft very smoothly. I'd engage it at low idle without shaking and then steadily accelerate without problem.

For over 16 years I had a similar thing go on when I activated a hydraulic clutch on my BX 2200 to engage the MMM.

I only learned recently that the engagement is much smoother if you increase your engine RPMs. It didn’t make sense to me and seemed counterintuitive, but I tried it anyway and found that about 1/3 throttle, the engagement is much, much smoother than when I engage at idle, even when attempting to feather engagement at idle, by moving the lever slowly.

Perhaps you will see the same thing with your tractor. I suggest you try increasing your engine RPMs a bit before you engage the PTO and see if there’s a difference. I became a believer when I tried it! MUCH smoother engagement.

I realize a brush hog has a lot more inertia than a MMM, so take this idea with a grain of salt!

 

[Tire Biter]

I get the same thing. It’s cuz of the folded blades. Make sure your blades can pivot freely so they can straighten quickly. I engage my PTO at around 1500. You can ease it on a certain amount, but not like a standard two stage clutch in a gear tractor. I have just quickly engaged it and then quickly disengaged it and let the blades straighten as it spins down, then engage it again and wont vibrate so much.

 

[JerryMT]

I used to pride myself on easing into a 540 rpm rear pto engagement. Can't seem to do it smoothly on my B2601. If I engage the pto clutch at idle, 1,000 rpm, the tractor stalls out. At just above that and higher, it shakes the bejezus out of me and the machine before smoothing out and letting me increase the rpms to operating range, 2,800 rpms.

Do I just have to accept this? Is there a better way? I wonder if it is related to the pto being rigidly fixed, no spin, until it's engaged? I had heard the pto would spin, helping drive shaft hookup, if rear pto is selected but clutch off of course, but mine doesn't.

My last tractor, a JD970, a little bigger at 33 hp, would start the bush hog drive shaft very smoothly. I'd engage it at low idle without shaking and then steadily accelerate without problem.

My cutter does the same thing, independent of what tractor I've installed it on. I looked under the cutter and found that both blades were "folded back" when the rotor stopped turning. When the pto was turned on the disk started and the blades are thrown into the cutting position via centrifugal force. The temporary imbalance caused by this process is what most likely is what causes what you are experiencing.
If vibration continues after the rotor has reached steady operating speed then either the blades are not of equal weight or the disk is damaged, shaft bent, etc.