Problem with Rototiller PTO Shaft

[swede4198]

I just bought a used Yanmar 48" tiller to use behind my Kubota BX23 and I am having problems. I am trying to till in a bed to use as a garden next year and I have broken two PTO shafts. The welds broke on the shaft at the U-joint by the PTO. The last break took out an ear on the joke plus the weld joint. I have never used a 3 pt tiller before but this is getting to be expensive if it keeps up! The tiller was used on a small deere to till two acres and the owner said he had the shaft rebuilt before he sold it to me.

My speed was very slow, max RPM to the PTO, and the tiller was all the way down to the ground. The ground was a garden that we put put several inches of mulch on and left fallow this year. No stones, no sand, just had not been tilled for two month. I did have some vibration but I don't know if that is normal.

Any suggestions will be appreciated.

[638]

Did the shafts break while in the ground tilling or out of the ground at the end of the pass? If I raise my tiller much higher than necessary to clear the sod, the ujoints bind up and make a real racket.

[swede4198]

It broke in the ground. I always take the power off then lift the tiller. I always lowered the tiller then engaged the PTO.

[Wedgie]

Swede-

If I am understanding correctly, you are lowering the tiller down to the ground and then engaging the PTO. While you don't want to raise the tiller too high when making your turns in order to prevent binding on the PTO U-joints, you don't have to disengage the power to the tiller. Anyway, the tiller tines should be turning as you lower it into the ground. That way you won't put sudden force on the PTO shaft when it engages the ground.

George

[Egon]

What is the angle of the PTO when in the ground?

Slip clutch or shear pin?

[dmay]

It broke in the ground. I always take the power off then lift the tiller. I always lowered the tiller then engaged the PTO.

There is no need to do this. If your pto shaft is sized correctly you can run when fully raised. Also your pto should be engaged as you lower into the ground. Pto shafts should not break. They are protected by either a slip clutch or shear bolt. Which do you have?

[284 International]

He may not have either a slip clutch or a shear bolt on this tiller. I don't know of any Yanmar imported tiller that has one. I wonder if it has been converted from a 2 point tiller to 3 point use, and is breaking the drive shafts where they were fabricated. Maybe U-joints are misaligned, or the shaft is just a little bit too long when fully down, and is overloading the yoke. It sounds like it's the same U-joint area causing the problem repeatedly.

What model tiller is it? Some of the 3 point configurations of these tillers came with a 2-piece top link, with the articulating portion much shorter than normal in a conventional Ferguson system.

I'm suspicious that it's a driveline issue, misaligned somehow.

Here is a picture of the top link apparatus, robbed from former member Careyo63:

(The original thread for this photograph is here.)

[DaveOmak]

Where using attachments that use a PTO shaft, It is important to keep "each end" of the PTO shaft parallel to each other. This keeps the universal joints "in sync", or what ever you call it....Adjusting the top link as close to this condition as possible is a really good idea.
Like others have said, "keep the tiller turning when raising and lowering into and out of the ground".
Grease the u-joints and grease points on the tiller. Grease the PTO shaft "slip area".
If the previous owner had all those problems and he/she taught you how to operate the tiller, you might find a manual online and read how to operate it correctly and safely.

[Villengineer]

I have a Yanmar tiller and there are some hitch design issues that need to be accounted for as mentioned previously. They can operated with a std top link, but it usually needs to be very short. On an unmodified tiller a "standard" length top link will put the pto shaft in a terrible angle on most tractors. I used to use a top link I cut down, I've since altered my tiller's hitch and use a hydraulic top link. I still have to be mindful of it and adjust the toplink frequently. Also, the PTO shaft maybe too long for your tractor and it may be binding causing it to fail. Some pics of your set-up would help. Also, I suggest that you travel on down the front page to the Yanmar specific forum. search tiller and start reading. lots of good info.

[swede4198]

The tiller does have a slip clutch. I have not tried to adjust the clutch.

I'll take some pictures this weekend so you can see the setup.

I am using a standard Kubota top link shortened up almost all the way.

I measured the shaft in the down position and had about two inches of travel left but I will measure it in the up position.