JD 790 PTO Adjustment

[svohio]

Hi everyone!

This is my first time posting here. And as the title says I own it, JD 790 Which I recently inherited.

Problem: PTO engages without an implement, but grinds and does not with an implement. In fact, i'm having the same exact issue as this post below.

problems with pto my jd 790, 5' rotary cutter mower

when I connect the rotary cutter mower the pto not engage. It makes noise.when I disconnect works great thanks:thumbdown:

www.tractorbynet.com

What I tried: I've used the manual and made the suggested "free to the top" clutch adjustment, Which I assume means the amount of play in the clutch before resistance. But that didn't seem to help. As for the post up above, I reached out to @Robfnk about how he did the PTO adjustment. He gave me some pointers but suggested contacting someone as to the steps how, because there may be a better way to rotate and identify the bolts needing adjusted. The pictures attached I believe are where adjustments need to be made, And the bolt(s) gap .06.

Thanks!

 

[Roadworthy]

I don't know your steps for engaging the PTO. I leave my tractor at idle and depress the clutch. I then engage the PTO. I let off the clutch and bring the engine up to PTO speed. If you're already doing that and clutch adjustment doesn't help a clutch replacement may be in your future.

 

[beenthere]

Is yours a dual clutch ?

 

[svohio]

It is a dual clutch and I engage it as Roadworthy described.

 

[greenie]

My 790 has not allowed a grind-free pto engagement for years. Attachments with low rotational mass engage easier (fertilizer spreader & winch) but the mower really grinds. Adjusting the clutch throws the transmission out of whack; it's already at the top 1/2" of clutch pedal travel. I get around the mower grinding by engaging the PTO a split second after I start the engine - that way it doesn't grind much at all.

 

[hodge]

Being a 2 stage clutch, are you pushing the pedal all the way down before engaging the PTO? The PTO clutch is all the way down; the transmission engagement is about halfway. You can shift the transmission without breaking power to the implement by depressing the clutch half way.
Only the 2WD's got a single stage clutch- 4WD models have the 2 stage. Are you using adjustment instructions for a single or two stage?

 

[J&K]

Mine takes a minute to stop the transmission before I can engage without grinding. Make sure you push clutch all the way down and wait. Been that was since new. Also echo what @hodge says.

 

[svohio]

Thanks for the replies everyone! Sorry I haven't gotten back immediately. I do push the clutch all the way down and it is a four-wheel drive tractor. I made the adjustments based on the manual that came with it so I'm assuming I'm adjusting for the four-wheel drive. If I start the tractor then the PTO is already spinning. Besides the finish mower, as a test I tried to hook up the bush hog which rotates very easily when engaged and I was having the same issue.

 

[beenthere]

If I start the tractor then the PTO is already spinning.

Spinning under power? i.e. If the mower (or other PTO attachment) is already connected, will the PTO stop spinning if the clutch is fully depressed ?

If just free spinning (no PTO attachment), then maybe needs more clearance adjustment on the PTO clutch or there may be clutch disk fragments catching enough to cause free spinning of the PTO.

Hope to figure out what is happening here so you can find a solution.

Can you post a copy of the page(s) in the manual that address the clutch adjustment ? Is it possible it is not for the two-stage clutch as they are more tricky than the single, if I recall correctly.

Some pics in this link that may help see what adjustments need to be made for both clutches.

https://www.greentractortalk.com/threads/how-to-adjust-the-pto-clutch-on-a-jd-970.225264/

 

[svohio]

@beenthere Thanks for the video I did watch that video but I felt that it contradicted the manual and literally says quite the opposite. So I did attach a pic of the manual as you requested. I should say the manual gives specifications on both the two and four-wheel drive tractor. This is the only section I know of that addresses the clutch adjustment.

I really don't feel that the clutch is bad. There just has not been a gradual indication of wear, engagement trouble, or any type of issue. The tractor has had regular professional maintenance yearly since it was purchased, except last year when I inherited it because it just hadn't been used just a few hours since the last maintenance. Everything about driving the tractor engages and runs smoothly. However this the first time I tried engaging the PTO.

Appreciate your help and insights as well as anyone else's!