sudden and violent PTO engagement with new Kubota MX5800

[s219]

Same applies to disengaging an implement...idle down for 5-10 seconds before disengaging the PTO. Makes for a much smoother transition and, undoubtedly, will extend the life of the implement and tractor.

I think it depends on the type of PTO (live, etc), type of clutches (main, overrun, etc) -- if the implement has a heavy flywheel or flywheel action, that easily can overdrive the PTO and transmission/engine after you throttle down. For example, on my wood chipper, it's far better to disengage the tractor's clutch, then throttle down, then wait for the chipper to stop spinning the PTO and transmission before finally disengaging the PTO. If you just throttle back, the chipper's flywheel inertia could over-run the engine and transmission if there wasn't some sort of over-run slip clutch.

On really old tractors, you could disengage the clutch to take load off the engine but of course the PTO and transmission would still be coupled. It was possible for the PTO implement to then keep driving the tractor forward if it was in gear!! I am sure that caused some pucker moments.

 

[RoyJackson]

On really old tractors, you could disengage the clutch to take load off the engine but of course the PTO and transmission would still be coupled. It was possible for the PTO implement to then keep driving the tractor forward if it was in gear!! I am sure that caused some pucker moments.

Yep...and there are still a number of old Fords (8N's, 9N's etc.) still in service. With these older machines, if you didn't have an overrunning clutch, you could be in trouble when disengaging the PTO.

 

[kebo]

Here's a suggestion the OP can try. (I am sure the safety police here will jump all over it though). The whole problem is that you are up against Newton's 1st law, which is an object at rest tends to remain at rest. There is about 150lbs of mass that is sitting perfectly still, and all of a sudden you are trying to make it turn at 540 rpm's! Hence, it is creating a big shock to the driveline when the PTO is engaged.

So... next time, before you engage the PTO, raise the bush hog about 3ft off the ground. Set the park brake and get out of the cab. Then with your hand, grab one of the blades and see if you can start spinning the blades in their normal direction of rotation. Once it is moving a little bit, jump back up in the cab and adjust the deck height to where the PTO shaft is straightened out as much as it can be and engage the PTO. If you can get the entire drive line spinning, even if it's only turning 5 rpm's, I suspect that *would* reduce the shock a good bit when the PTO engages.

If you try that, let us know how it works. I don't see a problem doing it that way, as long as NO ONE ELSE IS IN THE CAB, when he's trying to spin the blades by hand.

 

[kebo]

Sorry, double post.

 

[TerryR]

I think it depends on the type of PTO (live, etc), type of clutches (main, overrun, etc) -- if the implement has a heavy flywheel or flywheel action, that easily can overdrive the PTO and transmission/engine after you throttle down. For example, on my wood chipper, it's far better to disengage the tractor's clutch, then throttle down, then wait for the chipper to stop spinning the PTO and transmission before finally disengaging the PTO. If you just throttle back, the chipper's flywheel inertia could over-run the engine and transmission if there wasn't some sort of over-run slip clutch.

I don't understand. How could it "over-run" the engine? The engine is already turning at full PTO speed -- the flywheel of the chipper can't make it speed up. It always seems to me to let the engine come down to idle speed so you slow down the flywheel quicker, then disengage and let the equipment come to a stop from there. (This of course if you don't have the old setup where the PTO can drive the transmission.)

 

[Oldoak]

It can't. Lots of confusions around this. There is a big difference between a tractor PTO clutch, a PTO drive shaft slip clutch, and an overrunning clutch. Each have unique features and are independent from one another. Overrunning clutches, if used, are on the equipment itself, most often implements with a flywheel.

 

[arizona98tj]

Here's a suggestion the OP can try. (I am sure the safety police here will jump all over it though). The whole problem is that you are up against Newton's 1st law, which is an object at rest tends to remain at rest. There is about 150lbs of mass that is sitting perfectly still, and all of a sudden you are trying to make it turn at 540 rpm's! Hence, it is creating a big shock to the driveline when the PTO is engaged.

Anyone that engages a PTO driven implement at full PTO RPM probably needs to review the owner's manual a few more times.

 

[rbtjr]

I'm not going to get near the underside of the mower while the tractor is running. I'm going to a/ check with the dealer, b/ follow up on the suggestion about a mechanical/hydraulic way to dampen the PTO engagement a little, and c/ see what experience Travis and others at EA have and what suggestions they have. I will report back one way or the other. Thanks again for the feedback.

 

[buickanddeere]

Won't bother it a bit.

 

[DLTTrekkers]

Lub your PTO shaft ...the inner on the outside....and the outen on the inside...to get a good slide for when shaft is not straight ,