sudden and violent PTO engagement with new Kubota MX5800

[bigdeano]

To me it just sounds like bad engineering, it's just slamming into engagement. If there's an orifice that can be changed to soften the engagement I'd install one small enough to work correctly, even if I had to make it myself.

 

[DieselBound]

I don't know, I'm having a hard time believing that Kubota would put something out like this (unless a defect). Kubota is really good with hydraulics.

 

[DieselBound]

What sort of remotes do you have on this?

 

[rbtjr]

I second the idea of starting the pto with the cutter on the ground. Not in tall grass, but on a nice flat surface. The wheels being anchored to the ground by the cutter's weight will absorb a lot of the jolt you are feeling.

Good thought. I will try it. It makes sense that it would help to dampen the shaking of the mower itself.

 

[rbtjr]

What sort of remotes do you have on this?

Three sets but none are in use yet.

 

[rbtjr]

Probably not the problem here, but......
Can the two pieces of the PTO shaft be put together wrong? That is, are the two universals 90 degrees out of phase with each other?
Seeing how the vibration stops once up to speed, and most pto shafts can't put together incorrectly, this is probably not the problem, but something to keep in mind on PTO vibration problems.

No, the PTO shaft was okay except that the original shaft was too short, not proper overlap. New one will be in action this weekend.

 

[rbtjr]

The shape of the pto shaf.....triangle.....lemon.....or square ? Square can give you problems !

triangle

 

[DieselBound]

Three sets but none are in use yet.

That you KNOW of. The reason I'm asking is because if you've got a full detent valve and it's engaged your hydraulics will be quite messed up. I bumped mine the other day and was trying to figure out why my tractor was really struggling. The positioning of the lever isn't real clear-cut. I doubt that this is your issue, but I thought it wouldn't hurt (sometimes the easiest explanations get overlooked).

On the suggestion of having your cutter on the ground... I'd never thought to start one up OFF the ground. Yeah, that tail will waggle and jump like crazy. But, there's still this issue of why you get such a nasty engagement sound and why, if the cutter is off the ground that the engine stalls (I am not sure if I would even want to try do duplicate this on either of my tractors).

 

[rbtjr]

Interesting thought about the remotes--that I KNOW of. I'll try to eliminate that variable. I have a pressure gauge I can use to check to see if there is any pressure on any of the remote outlets. As to starting the mower, I don't start rotary mowers with the tail wheel off the ground. I usually start them with the front of the mower raised enough that the mower and PTO shaft are close to being level with the ground but with the tail wheel on the ground.

 

[countrybumpkin]

I've seen some shake pretty violent when the pto is engaged that had the electric engagement, but never seen or had one stall. I'd be having the dealer Checking it out, they can test the hydraulic pressures on the pto clutch to make sure they are in spec along with finding out why it is stalling, I'm thinking a saftey switch is at fault for that if all else checks out. I too would be interested in seeing a video of yours to see just how it's starting up.