Ford 1715 PTO Clutch Adjusment -- Help

   / Ford 1715 PTO Clutch Adjusment -- Help #71  
I hoping tht is the problem, that was what was wrong with Kioti,,Im just trying to figure out where this actually located in the in the case, on the Kioti is was all right behind the pto plate on the rear, just looking at NH parts digram it looks like its on the front
 
   / Ford 1715 PTO Clutch Adjusment -- Help #72  
A little late to the thread. I bought a 1715 with 2400 hours this winter, and it has 'the' problem. Of course they didn't tell me... :( Parts are about $600 to 'fix' the problem, if it's the overrunning clutch. I only need the PTO for a tiller, and I can always add an clutch outside if I want to cut weeds. I'm a pretty decent machinist, and IF I can get at everything from the top without splitting the tractor, I'm tempted to either A.) carbide drill through the bearing and press in either a roll or dowel pin in place right thorough the bearing or, B.) if there is room, make a pair of split collars to go around the over running clutch and clamping it out of commission, in both cases making this a solid shaft. Can anyone who has opened up the case tell me if this is outlandish or not?
 
   / Ford 1715 PTO Clutch Adjusment -- Help #73  
I'm updating my own post. I drilled a 1/8" hole through the overrunning clutch assembly with a carbide drill bit. Use solid carbide; anything else will dull quickly. You can get a cheap bit on ebay. You will be using a short bit; it's very close to a clearance limit depending on your drill. Turn slow. I'm a decent machinist, but if you do it, go slow and expect to break a bit or two. Also, keep the drill turning while you back out of the hole; that's the only time I broke a bit. I drilled about 10 mm to break through the outer race, then drilled to about 17 mm to hit the bearing carrier. You will likely hit between two rollers. To go deeper will be very slow because as you drill you are spinning the roller on each side of the drill bit. You can stop there or go deeper; just don't break the drill bit or you get to start over, AND I wouldn't want a piece of carbide falling out in the gearbox. After you stop, drive a spiral type roll pin (these are stronger than a normal roll pin-- I ordered them from Grainger) and drive it in until it stops. Beat on it. Grind off any excess. The 1715 can put out 650 ft-lb of torque at the PTO, at this diameter, that roll pin will see about 1000 lbs of shear. It may never break BUT... If it does, the roll pin will eventually ruin the bearing race and jam the clutch solid, which is what I want anyway. If that fails, I'll drill a 3/16" hole and use a bigger roll pin; I already have a good pilot hole. If I ever need overrunning protection, I'll buy an external overrunning PTO clutch.

Pictures below. It's the least work fix I could think of. I didn't even have to split the tractor.

IMG1261.jpgIMG1262.jpg
 
   / Ford 1715 PTO Clutch Adjusment -- Help #74  
To add my piece to this discussion. My 1715 had/has a similar problem of the sprag clutch releasing randomly. I discovered two things .... when first purchased from the dealer it would only rarely disengage, as the tractor warmed up it would work all day and not disengage. A couple of years ago I changed the fluid and went with TS premium fluid .... the problem got notably worse and required the tractor to be warmed up even more. I use the PTO almost exclusively for a back hoe pump ... so I'd get it engaged and let it sit there and run the pump at idle for five minutes or so and usually fine after that. Strangely enough I found that the PTO engages immediately when the tractor is in reverse and you can usually shift to a forward gear and it stays engaged. In all instances with the tractor warmed up it engages and operates properly.

I've worked with industrial sprag clutches and motorcycles which use often use sprag clutches to engage the starter ... they are very sensitive to oil viscosity. If you are familiar with the way they work, they depend on the rollers making a very small movement to climb a ramp and expand against the outer shell of the clutch. Thick oil will prevent them from climbing the ramp "wedging" against the outer shell, that's why they work so well dry. I suspect that slipperier modern oils, with their better viscosity control are hindering the engagement until they are thinned out by increased temps.

Of course this does not address BROKEN sprag clutches where the outer shell has been damaged or the roller cage damaged due to poor design or excessive forces.

I've totally eliminated the bad behavior by altering how I operate the tractor and getting the gearbox warmed up good before using the PTO ... climbing a hill a couple of times will usually do it. Next fluid change I will try NH spec fluid, which I suspect will be of lower viscosity and I'm betting it will require less warm up.

PS. My unit was a dealership rental unit with about 900 hours when I bought it, so I'm sure it saw it's share of abuse .... I noticed clear evidence of the entire rear end being disassembled prior to my ownership ... I would almost bet that was to replace the problematic original ORC unit. Mine does not disengage under heavy load, it is more likely to disengage when load is disrupted, say pulling on a root and the bucket pops out of the ground ... which causes a momentary over run, the sprags release the outer shell of the OTC and the thick oil prevents them from easily moving back out again. Again, this behavior disappears when the gearbox is fully up to temp.
 
   / Ford 1715 PTO Clutch Adjusment -- Help #75  
Before anyone comments, I know this is an old thread but it's full of a lot of good information so makes good sense to revive it...

My '93 1715 started having the PTO issue last fall. I've had the tractor since 2004 and have put 800+ hours on it bush-hogging and 3pt finish mowing w/o issue.
I got a small 3pt chipper last summer and operated it for maybe 20hrs, then noticed one day that the PTO wouldn't turn. Sometimes it turns fine for a few
seconds then stops, other times it never turns. There's no grinding when operating or rough feeling when I turn it either way by hand. I did change the
fluid and filter using the TSC "FNH-134 equivalent" maybe 6-8 yrs ago, but will try replacing it with fluid and filter from the dealer before tearing anything apart.

My questions is this; is there anything I can add to the fluid and run under minimal load before draining that will help loosen any sludge so
I can start cleaner with the FNH oil? I'm thinking something like Riselone engine flush from many yrs ago.
 
 
Top