# Gravely 18-H (Ariens GT18) Intermittent PTO



## eyebrowski (Apr 20, 2015)

I have an Gravely 18-H (hydrostatic) that when it is hot the center PTO (don't know about front and rear) will not re-engage after I turn the mower off. If I leave the tractor for a while and come back later (~1 hour) it will fire right up.

When I try to engage the PTO when it is hot I see a small dip in voltage on the gauge.

Any ideas?


----------



## fatjay (Dec 6, 2013)

That PTO should have an electric clutch to engage, my guess is that it's overheated after the work, and when it's cooled down it works again. I have 2 new holland's and an ariens, you may try replacing hte cluch. They're about $150-200 on ebay.

You can check it easily. Your mid PTO is also your front PTO. It should be a shaft out the fornt of the engine, double pulley double belt down to a shaft that goes forward for front PTO and back for mid PTO. You can try energizing the clutch manually, when it's warm to see what happens.


----------



## eyebrowski (Apr 20, 2015)

fatjay said:


> That PTO should have an electric clutch to engage, my guess is that it's overheated after the work, and when it's cooled down it works again. I have 2 new holland's and an ariens, you may try replacing hte cluch. They're about $150-200 on ebay.
> 
> You can check it easily. Your mid PTO is also your front PTO. It should be a shaft out the fornt of the engine, double pulley double belt down to a shaft that goes forward for front PTO and back for mid PTO. You can try energizing the clutch manually, when it's warm to see what happens.


Thanks for the advice, I'll test it out.

Do you know specifically which clutch I need?


----------



## fatjay (Dec 6, 2013)

Go here:
http://partsradar.arinet.com/script...F=Empartweb&loginID=ariensc&loginpwd=consumer

Click on model at the top, then contains. Scroll down until you see 931006 for GT, 16hp Kohler, Hydro. The right side of the window should populate. There you can see Illistrated parts lists, and in there is Front PTO and Electrical Clutch. That will give you an exploded diagram. #28 is the clutch assembly, you should be able to contact an ariens dealer with that part number to obtain a replacement if yours is in fact bad. The part number is 53102300. As far as I know, the same clutch is used for the new holland S-14, Ariens S14/GT14/16/17/18 and Gravely 18h tractors.

Manually engaging the clutch is not to difficult, it should be a single blue wire, on the left side of the engine as you're sitting on the tractor, under the carburator, leading to the PTO clutch. There should actually be a connector right at about that point. If you open the hood, there may be a heat shild on top covering it from view. Two flat head screws that screw into bolts welded to the shield can be undone, to pivot the shield back to expose the PTO shaft to view. If you charge that with 12 volts, it should click and engage the front PTO. If you charge it with the engine off and don't hear a click, you can reach down and spin the pto shaft. If it spins freely, it didn't engage. If not, it's engaged to the engine and you'd be turning the engine over by turning the PTO shaft. If memory serves, the PTO shaft will spin counter-clockwise when facing the front of the engine.

Hope this helps.


----------



## eyebrowski (Apr 20, 2015)

Great info, thanks. 



fatjay said:


> Go here:
> http://partsradar.arinet.com/script...F=Empartweb&loginID=ariensc&loginpwd=consumer
> 
> Click on model at the top, then contains. Scroll down until you see 931006 for GT, 16hp Kohler, Hydro. The right side of the window should populate. There you can see Illistrated parts lists, and in there is Front PTO and Electrical Clutch. That will give you an exploded diagram. #28 is the clutch assembly, you should be able to contact an ariens dealer with that part number to obtain a replacement if yours is in fact bad. The part number is 53102300. As far as I know, the same clutch is used for the new holland S-14, Ariens S14/GT14/16/17/18 and Gravely 18h tractors.
> ...


----------



## eyebrowski (Apr 20, 2015)

What's the clutch air gap supposed to be on these?


----------



## TominDallas (Aug 4, 2015)

My guess is that it could be worn and out of adjustment. Look to see if it's got three nuts on a bracket behind the pulley. If it does, it's adjustable. Use Bing and do a search for "Electric PTO adjustment". You should find detailed instruction and a youtube video.


----------



## film495 (Nov 1, 2013)

umm... not to be a wiseguy, but are you trying to start the machine with the PTO engaged? if so, it likely has a safety that will not allow you to do this.


----------



## eyebrowski (Apr 20, 2015)

film495 said:


> umm... not to be a wiseguy, but are you trying to start the machine with the PTO engaged? if so, it likely has a safety that will not allow you to do this.



No, this is a hot running condition.


----------



## film495 (Nov 1, 2013)

what is the voltage when you see the drop? could be the clutch is about done, could be not enough power to get it to engage, could be air gap. so, just to think through a little, the magnet on the clutch continues to work when hot if you're mowing, but if you turn it off, there isn't enough power to the magnet or it is not strong enough to engage the PTO again. if it is the same clutch as my Ariens I think the gap is .08 or something like that. I'm not sure but basically small enough so there is not contact when disengaged, but as close as possible so it can make a good strong connection when engaged.


----------



## eyebrowski (Apr 20, 2015)

For the archive...

I tightened up the 3 bolts on the face of the PTO and this solved the engagement issue when it was hot. I didn't have a set of feeler gauges to measure the gap so my process wasn't very scientific but I got good results.


----------

