PYO Clutch

[greg_g]

Ok, but I want to make sure we get our terminology straight. When discussing this type clutch, disc refers to a friction disc. A dual stage clutch has two; one for the main drive, one for the PTO. A single stage clutch obviously has one - it's for the main drive only, none for the PTO. Plate on the other hand, refers to a pressure plate; four in a dual stage, one of which is the flywheel. Two in a single stage.

The six fingers you counted indicate that yours is in fact a dual stage. The three fingers closest to the throw out bearing (TOB) are for the main drive, as is the friction disc in the middle of the clutchpack. The other 3 fingers are for the PTO clutch, as is the friction disc against the flywheel.

Check your manual for the exact gaps, I'll just give you ballpark figures. The TOB should be adjusted so that the face is within 2mm of each the 3 main drive fingers. Note that I underlined the word "each". It's imperative that all 3 to contact the TOB at the same time. As such, Foton probably wants them to be within 0.1mm tolerance.

By pushing in the clutch halfway, the TOB has pushed those 3 fingers far enough forward to disengage the transmission (main drive). At this point it should be just touching the 2nd set of 3 fingers. Same thing applies, all three should contact the TOB simultaneously. By the time your clutch pedal hits the stop, the PTO clutch should be disengaged. I'm guessing here, but I'm pretty sure that the PTO fingers should be about 6mm to 8mm behind the main drive fingers.

Adjusting the PTO fingers on the tractor can get a bit complicated, so let's not go there yet. I recommend you start by just adjusting the gap between the main drive fingers and the TOB face to the specs in your Foton book, and by making sure that all 3 fingers are the same distance from the TOB face. That alone might be enough to get the PTO clutch to engage/disengage properly. Not sure about your tractor specifically, but that's ordinarily accomplished by lengthening or shortening the external clutch pull rod. Try that and report back.

//greg//

 

[FotonOwner]

Greg,
Peering into the hole with a torch I estimated the clearances as follows.

Results (mm)
out half in Clutch in
0 1 0
0 7 5
1 0 0
5 4 3
0 0 0
3 2 0


I used a block of wood to hold the clutch in position. Half way was about 10 mm from the stop and full in about 2 mm.
I had some unenthusiastic help at the end and was able to look at the fingers while the clutch was released. The bearing seemed to move back while the clearance remained at zero or close to it.

See the depth of the slot in this view.

 

[greg_g]

I have no idea what you're doing. The gap between/among fingers is done with the clutch fully engaged (pedal up). The only need for a 2nd person might be to help rotate the flywheel. The only gap you're interested in is between the 3 main fingers and the vertical face of the TOB; 2mm. And each of the 3 fingers should be within 0.1mm of each other (relative to the TOB) to ensure simultaneous contact with the bearing face. To achieve that gap, you adjust the length of the external clutch pull rod - which moves the TOB toward or away from the main drive fingers.

Once that's set, you hope that all 3 PTO fingers are set approximately 6mm to 8mm behind the main drive fingers. Again, the 0.1mm tolerance among PTO fingers applies. As the pedal moves the TOB forward, you want those three to contact the bearing face simultaneously as well..

//greg//

 

[FotonOwner]

I have no idea what you're doing. The gap between/among fingers is done with the clutch fully engaged (pedal up). The only need for a 2nd person might be to help rotate the flywheel. The only gap you're interested in is between the 3 main fingers and the vertical face of the TOB; 2mm. And each of the 3 fingers should be within 0.1mm of each other (relative to the TOB) to ensure simultaneous contact with the bearing face. To achieve that gap, you adjust the length of the external clutch pull rod - which moves the TOB toward or away from the main drive fingers.

Once that's set, you hope that all 3 PTO fingers are set approximately 6mm to 8mm behind the main drive fingers. Again, the 0.1mm tolerance among PTO fingers applies. As the pedal moves the TOB forward, you want those three to contact the bearing face simultaneously as well..

//greg//

Okay then we have the first column only

0
0
1
5
0
3

1 3 and 5 would be the main drive and all close to zero.
2, 4 and 6 the PTO fingers appears uneven particularly the number 2 position.
I would probably need to slide a feeler gauge in to get a better reading.

"you adjust the length of the external clutch pull rod"

I guess these are described in the diagram as "Main clutch release rod" and "Auxiliary clutch tie rod"

 

[greg_g]

Well, if the 0 means no gap at all, I hope the TOB isn't already starting to turn blue. You should be able to reach inside there and spin the bearing on its race. If you can't, one or more main drive fingers are too close. 2.5mm (+/- 0.5mm) is the typical spec for the first three. And all three of the PTO fingers are too close. Given that I'd expect them to be 6mm to 8mm behind the main drive fingers, those numbers should be in the neighborhood of 8mm to 10mm. Not 0, 5, and 3.

All I can say is that it sounds like somebody that didn't know what they were doing has been playing with the clutch adjustments. I might be able to tweak it in myself - if I was actually there turning the wrenches. But there's no effective way to talk someone through this sort of thing on an internet forum. I might be able to get the thing working again, but - tinkering with the fingers through the hole - there's no way to tell if I got the stack height correct. The correct way to get the adjustments done precisely, would be to split the tractor and adjust the clutch by the book.

Do you have a heated garage or shed with a hard and level floor - where you might be able to take this thing apart ?

As far as adjusting the TOB position, I'd have to see your manual. Typically it's done at the external pull rod like I said above. But we've already seen there are some things on this Foton that aren't typical. On others, it's the threaded rod that connects the clutch pedal to the arm that sticks out the side of the bell housing. The rod is pinned to the arm through a yoke. The pin is removed, and the yoke is rotated one way or the other to lengthen or shorten the "pull". That in turn moves the TOB carrier toward or away from the clutch fingers.

//greg//

 

[FotonOwner]

Thanks Greg,

I was hoping to avoid pulling the thing apart, so will just have to live with it.
I do have a big shed with a good floor, would have to tow in (not too hard I think) - it's 100 in the shade here so don't need any more heat.

It does have the external threaded rod from the pedal to the arm that I can adjust, but when I measured the free movement and clutch release both were as specified in the book.

What I don't have is a workshop manual, could you suggest a web site that may have one?

 

[gabrielleexpress]

if your clutch is like the one in post 42, the two nuts that are jammed together on the left side are the ones that adjust the fingers for the pto clutch. i think you would be better off to contact AFFORDABLE TRACTORS in texas or the jimma dealer in newport news, va. and ask them to send you the info on adjusting the clutch. it is not that hard but just take your time with the adjustments

 

[greg_g]

Ok, there was zero info in your profile to even hazard a guess as to where you might live.

Adjustments to the free travel - if even necessary - are done after ensuring the gap between TOB and release fingers are within spec. When those finger gaps are inaccurate, your whole clutch release geometry starts off wrong. It simply gets worse with each subsequent out-of-sequence attempt at adjustment.

You've raised so many simultaneous issues here that I've lost track of the big picture. Did your main drive clutch ever work since you bought this? That is, has the tractor actually ever started and moved in both directions through all gears ? If yes, I have an idea of what the PTO problem could be. If no, I'm afraid my recommendation is still to split the tractor and perform a proper stack height alignment.

To the best of our collective knowledge, none of the Chinese tractor manufacturers have translated a shop (repair) manual into English. At least for the North American market. It's one of the big reasons that forums like this exist - to fill in the gaps left by what meager documentation that does come with them.

//greg//

 

[gabrielleexpress]

northern tool has manuels on there tractors, like the 254

 

[FotonOwner]

Greg,

The tractor is basically new and I have never used the PTO clutch before. I use the tractor irregularly, all gears and no dramas.

I have just checked the TOB and you are right it does rotate freely by hand. I also re-measured the clearances using improvised feeler gauges with better results. Easier and less chance of a stuff-up doing them in pairs.
Main
#1. < 1 mm
#3. 1.0 mm and
#5. about 1.5 mm.

Aux
#2. 7 mm
#4. 7 mm and
#6. 6 mm

Thanks for the help