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

 

[FotonOwner]

northern tool has manuels on there tractors, like the 254

Thanks,
I'll see if I can find them.

 

[greg_g]

Ok. Then this is one of those tractors that was sold without a proper clutch adjustment. Experienced dealers have already discovered the hard way that it's wrong to assume these tractors come from the factory properly adjusted. The honest ones take care of that as part of the dealer-prep process.

Remember those numbers I gave you are only representative, they're the ones I use when adjusting the 6-finger clutch on my TS354C. But there's more than one type of Chinese 6 finger clutchpack floating around out there, so it's important to use the right spec. Scour your Foton manual to make sure. I've uploaded a diagram of my 6-finger clutchpack so that you can get the 2.5mm and 8.5mm gaps in visual perspective.

If I were there to help you with this without knowing the actual Foton specs, here's how I'd go about it.
a. Use the clutch pull adjustment to move the TOB carrier rearward until #3 is 2.5mm (or whatever your Foton spec is)
b. loosen the jam nut and open the gap with #1 to match #3 (+/- 0.1mm
c. close the gap with #5 to match #3
Note: don't just go around once and think you're done with the main drive fingers. Because this design uses Belleville springs, any adjustment to one finger can affect the other two. You may have to go around several times to tweak them into the 2.5mm (+/- 0.1mm) spec.
d. if step (a) above was done accurately, PTO fingers #2 and #4 should already be at the requisite 8.5mm from the TOB face. If not, adjust fingers (not bearing) as required
e. open the gap with #6 to match #2 and #4
f. verify that 2, 4, and 6 are now all 8.5mm (+/- 0.1mm), tweak as required
g. tighten down all jam nuts

Unfortunately this is a stop-gap procedure. There's absolutely no way to confirm if these adjustments achieved the stack height spec (which should also be in your manual). It's a frustrating and time consuming procedure when attempted through the inspection window. I'm sure that - long before you're done - you'll come to realize why this procedure is best done with the tractor split.

And please understand - that I'm doing this completely by remote control. Given the potential differences between your 6 finger clutch and mine, there'll be no guarantees.

//greg//

 

[FotonOwner]

Thanks Greg,

Sounds right, it probably didn't go through a dealer.

One more question, if I may, when I push the clutch down to the stop, shouldn't the aux fingers make contact? - because they don't.

 

[greg_g]

Well, disregard everything I said about adjusting those fingers. And it would have been real nice to know that up front, cuz it's sounding more and more like someone who didn't know what they were doing was in there with a wrench. If the PTO release fingers don't move, the PTO clutch never even gets disengaged. Ever. The only work around - and it doesn't always work - is to engage/disengage the PTO manually when the engine is not running. I don't actually know where that lever is on the Foton, I'm guessing maybe down behind your right heel.

Your clutchpack is more screwed up than I thought. to the point that I wonder how the tractor even moves at all. I don't see much alternative now to splitting the tractor and doing a full clutchpack alignment, starting with stack height. Note the 101.5mm figure in my clutch pack diagram, that's the stack height for mine. You've got to start all over with the correct stack height. If it's not correct from the git-go, no amount wrenching through the window is going to accurately recreate it.

//greg//

 

[FotonOwner]

Thanks Greg,

Yes the PTO disengage lever is on the right side behind the gearbox and disengages by pulling up.

The forward movement of the TOB and it appears much less than one would expect, only a few mm.

Checking the external arm to shaft interface shows slippage which may be the reason for the problem.

 

[greg_g]

I don't see appreciable slippage in the photos, but perhaps I'm once again not interpreting your terminology correctly.What it sounds like to me is that your somebody fooled with the various adjustments so much, that there's no longer any tolerance between the PTO friction disc and the flywheel face.

When those PTO fingers are cranked down too much, they put too much pressure on the Belleville spring - which in turn "sandwiches" the friction disc with too great a force to be overcome by the pedal. Then the mistake was compounded by cranking the main drive fingers closer to the PTO fingers, and topped off by moving the bearing carrier as well. The whole thing sounds like a BLT that's been stepped on by a big boot.

It goes to stack height. I once again refer you to the diagram of my six finger clutch. To achieve that 101.5mm stack height, you adjust all six fingers in sequence to get there. But if it's screwed up to the point where the stack height is too tall, one or both of the clutches can't engage. There's not enough tension on the Bellevilles. If the stack height is too short, there's too much tension, the clutches won't release. But given the fact that stack height is measured between the main drive finger tips and the pressure plate, you can see why this is an adjustment that can't be accurately performed through the inspection window.

//greg//

 

[FotonOwner]

Thanks Greg,

If the problem is internal then I will just live with it.

I had a look at the crank to see if I could pull the pin out and found it was broken to pieces, allowing the slippage I noticed.

When I think about it,

the broken shaft pin,
the missing split pin from the pedal end,
the missing stop screw, and
the pedal welded on the wrong way,

then it seems obvious that someone was messing with this, and perhaps welded the pedal the wrong way as a warning not to use it until it is repaired.

Anyway it can't hurt to get a new spring pin to lock the ext lever back in place.

 

[greg_g]

Anyway it can't hurt to get a new spring pin to lock the ext lever back in place.

Yup. and you may as well double-pin the thing while you're at it. If you're not familiar with that, buy two spring pins; #1 with the correct OD for the hole, #2 with the correct OD to install inside #1. Drive the first pin into the hole, drive the second pin through the first pin.

FYI, the clutch fork is likely pinned like that too. Quite a few Jinma 200 series owners suffer breakage of that pin too. Since your main clutch is stated to move the tractor through the gears ok, that suggests yours is still intact. But if/when you split to the tractor to get your PTO clutch working, it would a good idea to put fresh pin(s) in there too (along with new throwout and pilot bearings).

//greg//

 

[FotonOwner]

The clutch she is fixed

 

[Rich Waugh]

Amazing, isn't it, how a fraction of a millimeter of movement at the pivot point of an arm can have so much effect at the other end? Your photo of the arm looked like there was maybe a degree or two of movement on the shaft but that translates to a lot at the end of the arm.

Glad you got it fixed! DId that fix both the main clutch and the PTO clutch?

Rich