PYO Clutch

[SensibleNick]

Well, I'm sorry to say that my Manual doesn't cover your gearbox, and the detent system is a little different, but on the detent there is only one ball per spring, and the ball is at the bottom of the spring.

It does rather seem to me as though Bluechip (hello by the way) has got it covered, and that it's most likely a stuck clutch-plate. With regards to the fingers on the clutch-Fork: On the single stage there would only be one fork, and on the 2-stage (as i have here) there's still only one fork - so broken fingers would mean that you can't disengage drive to the wheels either.

Aside from the stuck clutch plate, it may be that the PTO clutch or "Auxiliary clutch" as the manual calls it, hasn't got it's separator levers correctly adjusted.

I'm guessing a photo of the clutch exploded diagram and parts list would be useful to you at this point... want me to post a picture, or have you ordered manuals?

 

[FotonOwner]

Well, I'm sorry to say that my Manual doesn't cover your gearbox, and the detent system is a little different, but on the detent there is only one ball per spring, and the ball is at the bottom of the spring.

It does rather seem to me as though Bluechip (hello by the way) has got it covered, and that it's most likely a stuck clutch-plate. With regards to the fingers on the clutch-Fork: On the single stage there would only be one fork, and on the 2-stage (as i have here) there's still only one fork - so broken fingers would mean that you can't disengage drive to the wheels either.

Aside from the stuck clutch plate, it may be that the PTO clutch or "Auxiliary clutch" as the manual calls it, hasn't got it's separator levers correctly adjusted.

I'm guessing a photo of the clutch exploded diagram and parts list would be useful to you at this point... want me to post a picture, or have you ordered manuals?

SensibleNick

Thank you for the response,

I realised that the pedal stop was missing, so the pedal could be depressed too far. Is there any chance that could have damaged something?

I have a manual of sorts (one for the engine and one for the tractor) but they are not all that useful. They don't show the clutch in much detail; although, there is a description of clutch adjustment. I can't see how to do that without pulling the tractor to pieces.

My mechanic said you can't do anything with the clutch without pulling the tractor to pieces, and that I may be better off just starting the tractor with the implement engaged. I have done that and it works fine.

I only need to use the slasher, but have a Toro mower so can get by without it.

I have trouble imagining the balls being at the bottom of the spring. Can't see what they would do except to make the spring effectively longer, so why not just make longer spring or a shorter hole? Doesn't make any sense to me. Anyway the spring and pins didn't protrude far enough to engage the cam so if there is a ball in the bottom of the hole it isn't working.

An exploded view of the assembly would be useful if there was some way I could free the clutch without dismantling the tractor otherwise probably not.

Thanks again for the advice.

 

[bluechip]

It is possible that trying to push the clutch too far without the stop may damage the fingers or break a pull rod on the clutch. some cluthes have 6 fingers, 3 for main and 3 for PTO others have 3 and pull rods that are adjusted so that as the main pressure plate retracts, it will go so far then pull the 3 pull rods wich take the PTO pressure plate off teh PTO disk. If one of those pull rods (0r bolts) is broken, the clutch will never disengage. you may be able to look inside through an inspection cover if one is available, sometimes they are covered by loader brackets.

 

[FotonOwner]

2 stage or single, stepping on the clutch shoud stop the pto. sometimes they will keep turning if they don't have any load on them as there is not a brake. conentric shafts, the pto disk slightly touching the flywheel, etc. With an implement attached, the pto should not start turning until you let up on the clutch pedal, and you should not get grinding if you put pto in neutral, start the tractor with foot on the clutch, engage pto, then release clutch. If tractor has set for long time, could be PTO disk is rusted to flywheel. sometimes you can break it with shock of heavy load on PTO starting implement or with tractor off and PTO engaged, clutch depressed, try to turn pto shaft and see if it is disengaging. use the higher pto speed, it will be easier to turn the shaft.
I noticed an empty bolt hole directly in front of the clutch levers travel. most tractors have a stop screw to prevent over depressing the clutch. Is your missing? I am not 100% sure foton 254 has a stop, but the hole looks suspiciously empty. If there is an access point to veiw the clutch and check that all the fingers are intact. a broken finger will stop the clutch from disengaging and the missing stop screw may have caused that... good luck.

Bluechip,
Thanks for the detail.

You are correct again, there was a stop screw missing and I have subsequently put a bolt in the hole that works well. It may be a mm or two too long, but the clutch works to disengage the drive. I will grind a bit off the end and re-fit it.

I had a quick look for the clutch access point but didn't see it, so will need to do a more thorough inspection.

I was thinking along the lines you have outlined (i.e. depressing the clutch pedal, engaging the PTO with the slasher attached then cranking the engine) That should encourage the it to free up.

 

[FotonOwner]

Foton products and Kama/TaiShanproducts are similar, but not identical. The ball-detent concept however, is fairly universal. It's usually detent-->ball-->spring-->pin. That's for sliding rails anyway. Without a parts manual, I can't speak specifically to your device - especially since you're calling them "blind holes".

I strongly suggest you expend all efforts to put together a full set of user manuals (usually 4) for that tractor. Despite numerous complaints about the "Chinglish", I'd consider it money well spent. The exploded diagrams in the parts manuals really help first time owners understand how these things are put together.

I don't understand (1) how a clutch pedal could be installed upside down, or (2) why it had to be cut off with a torch. That could be part of your clutch travel problem right there !!

If you're talking about external filtration, I doubt the hydraulic filter bolt was too long. More likely there was a bad seal. I have a similar issue with my KM454, which requires a very precise alignment before tightening down the cannister bolt. Otherwise - the seal is compromised.

Chip must be out of town, so I'm going to take the liberty of addressing your response to him. Just like a manual tranny in a truck or car, a one stage tractor clutch has no PTO function. Its only job is to engage and disengage the transmission. This type is called a "transmission PTO". On this type, the PTO is basically engaged full time. A two stage clutch does both; transmission and PTO. With this type you can engage/disengage the PTO with the clutch pedal. It's called a "live PTO". There's a 3rd type - the "independent PTO" - but I don't know of any Chinese tractors that employ one. CLICK HERE. But adjusting pedal travel at this point amounts to putting the cart in front of the horse. Before doing that, the throwout bearing must be verified as correctly positioned relative to the clutch release fingers. Since it's typically about 2mm, that could MORE than account for that 15mm you can't account for. Have you even opened up the clutch inspection window to see what's going on inside?

//greg//

Thanks you Greg_g,

You can see in the photo where the pedal was cut off and re-welded. I think it must attach off centre and wont depress it it upside-down as it catches on the chassis.
Regarding the detent, the below photo shows the shaft assembly removed, the shaft has a flat machined into it, the spring and pin drop into the blind hole (with the wire in showing there is no hole in the bottom into the gear box).
The pins protrude about 3 mm above the surface and the springs about 2 mm. The hole in the shaft block is about 3mm deep to the outside of the shaft and about 5 mm to flat side of the shaft. The holes in the block are only wide enough to accommodate the pin, but not the spring.
The spring seems to have a convex appearance at the bottom end, so could sit on a ball or something.
It seems to me that there is no way the pins will engage with the shaft as they are too short. Also the springs don't seem to do anything, as they are compressed by the block on top, and the blind hole at the bottom.
Unless there is something happening at the bottom of the spring holes.

Regarding the manuals do you have any idea where I could get hold of them?

When I got the tractor the hydraulics didn't work. I got a hydraulics expert who found the triangular plate on top of the reservoir, under the seat, was cracked. He found the hollow bolt that attached the filter (in the reservoir) to the scavenge line, was too long to be tightened up without cracking the top plate. He fitted a shorter bolt and managed to weld the cracks in the plate then nearly all was well. I inspected all the parts and have no doubt he was correct.

 

[SensibleNick]

Hi again.

I've now taken photos, and you'll find them here.


Confusion appears to have arisen because what BlueChip was calling "fingers" are called "clutch separate levers" ( in the manual they're parts 17 and 19 on clutch assy 2), and what I was calling "fingers" were the fingers that stick off the "clutch fork". (part 8 in Clutch assy 1)

All I can do that is slightly helpful is post the pictures....

Listen to the other guys... they know what they're talking about.

Manuals... how about here?

Good luck with it!

All the best,

/Nick

 

[SensibleNick]

The pins protrude about 3 mm above the surface and the springs about 2 mm. The hole in the shaft block is about 3mm deep to the outside of the shaft and about 5 mm to flat side of the shaft. The holes in the block are only wide enough to accommodate the pin, but not the spring.
The spring seems to have a convex appearance at the bottom end, so could sit on a ball or something.
It seems to me that there is no way the pins will engage with the shaft as they are too short. Also the springs don't seem to do anything, as they are compressed by the block on top, and the blind hole at the bottom.
Unless there is something happening at the bottom of the spring holes.

Right... I just re-read this, and here's my take on it. ... although I'm technically a tractor newbie, I am a mechanical engineer and machine designer for a big R&D department here in Sweden: I live and breath mechanisms.

While this isn't the root of your problems, I reckon it'd be nice for you to know exactly how and why this assembly works.

So... here's how I see it.
The springs are compressed by the block that sits on top of them. The balls that the spring/rod/cup assembly compresses only try to move upwards when you change a gear or move the gearstick.

Thus while the gearbox is in gear or neutral, no pins will appear to be able to engage the shaft. When the clutch is NOT pressed down, the rod is rotated in such a position that it blocks the upwards path of the pins (you mention a 3mm depth, and 3mm protrusion of the pins - this makes sense). When you press the clutch pedal the rod rotates, allowing the pins a small amount of upward motion (with the depth becoming 5mm, that means you get 2mm of pin movement). This allows the detent balls in the bores below to lift upwards against the compression of the springs, and thus allows you to change gear.

Look at the shaft with the flat on it: it has been impacting the tops of the pins as it's supposed to.

I suggest you prove this to yourself by SLOWLY moving the gearstick. I'd bet a beer or two on some pins moving upwards by 2mm - depending upon which gear you try to get into, different pins will move. Don't go hammering at it: you may launch the pins/springs into oblivion

 

[FotonOwner]

Right... I just re-read this, and here's my take on it. ... although I'm technically a tractor newbie, I am a mechanical engineer and machine designer for a big R&D department here in Sweden: I live and breath mechanisms.

While this isn't the root of your problems, I reckon it'd be nice for you to know exactly how and why this assembly works.

So... here's how I see it.
The springs are compressed by the block that sits on top of them. The balls that the spring/rod/cup assembly compresses only try to move upwards when you change a gear or move the gearstick.

Thus while the gearbox is in gear or neutral, no pins will appear to be able to engage the shaft. When the clutch is NOT pressed down, the rod is rotated in such a position that it blocks the upwards path of the pins (you mention a 3mm depth, and 3mm protrusion of the pins - this makes sense). When you press the clutch pedal the rod rotates, allowing the pins a small amount of upward motion (with the depth becoming 5mm, that means you get 2mm of pin movement). This allows the detent balls in the bores below to lift upwards against the compression of the springs, and thus allows you to change gear.

Look at the shaft with the flat on it: it has been impacting the tops of the pins as it's supposed to.

I suggest you prove this to yourself by SLOWLY moving the gearstick. I'd bet a beer or two on some pins moving upwards by 2mm - depending upon which gear you try to get into, different pins will move. Don't go hammering at it: you may launch the pins/springs into oblivion

SensibleNick,
Yes I agree, some friends and I discussed the arrangement yesterday and came to a similar conclusion. It seems to be a mechanical interlock to stop something, and gear-change seems likely as it is on top of the gearbox. We were puzzled as to why 4 spring/pins, but your suggestion of 4 gears seems possible (what about reverse?). Normally (like in a car) you don't have to protect the gearbox against someone accidentally knocking the gear-stick, but perhaps the agricultural environment is not as friendly as a paved road and that is the reason.

 

[FotonOwner]

It is possible that trying to push the clutch too far without the stop may damage the fingers or break a pull rod on the clutch. some cluthes have 6 fingers, 3 for main and 3 for PTO others have 3 and pull rods that are adjusted so that as the main pressure plate retracts, it will go so far then pull the 3 pull rods wich take the PTO pressure plate off teh PTO disk. If one of those pull rods (0r bolts) is broken, the clutch will never disengage. you may be able to look inside through an inspection cover if one is available, sometimes they are covered by loader brackets.

Loader brackets are fitted so that may be the inspection point, not too easy to take off. Will try starting with PTO engaged first.
Cheers

 

[FotonOwner]

Right... I just re-read this, and here's my take on it. ... although I'm technically a tractor newbie, I am a mechanical engineer and machine designer for a big R&D department here in Sweden: I live and breath mechanisms.

While this isn't the root of your problems, I reckon it'd be nice for you to know exactly how and why this assembly works.

So... here's how I see it.
The springs are compressed by the block that sits on top of them. The balls that the spring/rod/cup assembly compresses only try to move upwards when you change a gear or move the gearstick.

Thus while the gearbox is in gear or neutral, no pins will appear to be able to engage the shaft. When the clutch is NOT pressed down, the rod is rotated in such a position that it blocks the upwards path of the pins (you mention a 3mm depth, and 3mm protrusion of the pins - this makes sense). When you press the clutch pedal the rod rotates, allowing the pins a small amount of upward motion (with the depth becoming 5mm, that means you get 2mm of pin movement). This allows the detent balls in the bores below to lift upwards against the compression of the springs, and thus allows you to change gear.

Look at the shaft with the flat on it: it has been impacting the tops of the pins as it's supposed to.

I suggest you prove this to yourself by SLOWLY moving the gearstick. I'd bet a beer or two on some pins moving upwards by 2mm - depending upon which gear you try to get into, different pins will move. Don't go hammering at it: you may launch the pins/springs into oblivion

Sensible Nick,
Some spare time Christmas Day.

I checked the pins while changing the gears and they appear to pop up while transitioning. I was thinking a safety measure, but perhaps it is more fundamental and holds the gears in.

Anyway I noticed this forum site

Chinese Tractor Owners Association - CTOA Forums - Tractor Operation and Maintenance - Foton TE254 not enough clutch travel

Someone has reported the exact same problem with a Foton TE254. The clutch pedal arrangement looks more like the Jimna than the FT254.

Interestingly he seems to be having difficulty locating an inspection hole even after removing the FEL brackets.
I have looked at the FEL brackets and think it should not be too much problem to support the arms with ropes and remove the brackets. I would guess the arms (rear end) without the brackets should be less than about 50 kg each.
I seem to recall that the inspection cover bracket was removed to allow the FEL to be fitted. I will check my parts locker as the covers may still be there.