Flail Mower Caroni TM1900 - PTO Shaft Is too Long - How Do I Measure The Correct Length?

[dutch1821]

We have a John Deere 4400 Tractor with a Caroni TM1900 Flail. It appears that the PTO shaft is too long. What is the correct procedure on how to measure the correct length before we cut the shaft (eg where exactly to measure from/to). Is this something that can be accomplished by an amateur or does it need to be brought to a driveshaft shop? Thank you in advance for any help you can offer.

 

[GManBart]

First off, welcome to TBN!

I'm sure there are multiple ways people go about this, but what I've done is to separate the PTO shaft halves, then connect the implement to the tractor. Then you can connect the free half of the shaft to the PTO on the tractor and hold the two halves next to one another, so you can see how much overlap you have. The general rule of thumb is that you want approximately 50% overlap...that gives them room to expand/contract as the mower moves up and down, and ensures enough contact to handle the torque. Measure how much you need to remove, then cut half of that off each tube with a hacksaw (or metal cutting bandsaw if you're lucky), and use a file to remove any burrs left from cutting.

A good tutorial:
http://www.farmimplements.com.au/manuals/PTO Shaft Information Sheet.pdf

 

[leonz]

Hello Dutch1821,

I want to welcome you as the newest member of the Flail Mower Nation.

T shirts and Coffee mugs will be available at a later date-Just Kidding, no dues no BS just lots of help with flailmowers.



There are a small herd of informative videos about the
proper measuring and cutting a PTO shaft that is too long

You can find the links here on the forum here and more
than a handfull of topics will come up.

You will also find it on you tube in several videos.

Measure twice, cut once, and always, always, always, remember that when the mower is raised to
its full height will be where the compressed PTO shaft will be at its shortest length!!

 

[nybirdman]

Good thing you know enough to check;lots of made expensive mistakes!

 

[bigtiller]

Hello Dutch1821,

I want to welcome you as the newest member of the Flail Mower Nation.

T shirts and Coffee mugs will be available at a later date-Just Kidding, no dues no BS just lots of help with flailmowers.



There are a small herd of informative videos about the
proper measuring and cutting a PTO shaft that is too long

You can find the links here on the forum here and more
than a handfull of topics will come up.

You will also find it on you tube in several videos.

Measure twice, cut once, and always, always, always, remember that when the mower is raised to
its full height will be where the compressed PTO shaft will be at its shortest length!!

That's not always, always, always true.

My jd 2720 is longest when the tiller is fully raised.

 

[kco]

Everything attachments has a good video for shortening the shaft on YouTube:

https://www.youtube.com/watch?v=0vBFJcvs5SE

 

[Halftrack]

My thinking was that the pto shaft was the shortest when the gearbox shaft is level with the tractor pto shaft. But then you throw in the lift arms curved path, the fact that their pivot point is below the pto shaft, whether the gearbox is above or below the lift arm pins pivot point, then factor in whether the top link raises the rear of the flail as it lifts or lowers it and now I'm thoroughly confused. So I have opened a can of worms for the smarter members of the forum to discuss and settle. Or measure the distance from the end of one shaft to the other in both positions and go from there. Oh well, as said before, measure twice and cut once.

 

[Dave M7040]

Remember that the universal joints on either end of the shaft need to be indexed together otherwise you will have severe vibration. Some older shafts had a ball bearing pressed into the side of the shaft which would only side into the outer half when the ball was lined up with a groove. Cutting the shaft often eliminated the ball bearing and the two halves of the shaft would go together in any position. This could result in severe vibration. Newer shafts are odd shapes which will only go together the correct way. When you cut the shaft you will also have to cut the shield.
It is a job that just requires care not great skill.
Dave M7040