Stupid Clutch Question

[GDC]

Any ideas as to why a new clutch might suddenly stop disengaging? I had a new clutch put in my Shenniu 254 last summer and everything was just fine until I was plowing snow the other day when it suddenly stopped disengaging. There was no change in pedal feel or any noises; just all of a sudden, depress the clutch and keep going.

Thanks
Greg

 

[greg_g]

Don't know about the Shennui specifically, but owners of similar Chinese tractors (Jinma 254 for example) have reported broken roll pins in the clutch linkage. There's one pinning the outside clutch release lever to its shaft, and another pinning the clutch fork to it's shaft. It's common practice to double pin the clutch fork (nested roll pins), something your mechanic may not have known. The release lever is outside the tractor, but the clutch fork is inside. Fixing that means splitting the tractor again.

//greg//

 

[RonMar]

The way to check is to pull the side plate and watch the clutch work as the pedal is depressed(engine NOT running). If you have a front end loader, you may have to remove one of the loader support arms to gain access to one of the clutch access ports... Also a good time to make sure teh throwout bearing to clutch finger spacing is correct and that the fingers are engageing equally.

 

[3RRL]

So you step on the clutch to disengage it but it doesn't ... the tractor keeps going.
See if making an adjustment externally helps with disengaging the clutch. But keep in mind even though you can make an external adjustment that will disengage the clutch, there could still be an internal problem to cause that. That's totally different than having to adjust the linkage for a worn (wearing down or slipping) clutch. If the external adjustment does nothing, do what Greg and Ron said. And if it is not a broken roll pin or something like that, it sounds to me that you (could) have a frozen or faulty throw out bearing. Check that and also the 3 fingers that move the clutch(es) apart when the pedal is depressed. They could be either worn down or worn off. It happened to me.
Tell us what you find find first before continuing to sort out the problem. How many hours on the tractor?

 

[SPYDERLK]

~Can the stuck clutch transmit full engine torque and stall the engine? Try rocking the tractor backward while holding the clutch in and with the trans in a forward gear. ...help any? -- It may be that the spline on the clutch plate is sticking on the transmission input shaft. This could give the symptom...BUT I cant imagine it staying engaged so hard as to be able the stall the engine.
larry

 

[Eagleview]

There was no change in pedal feel or any noises; just all of a sudden, depress the clutch and keep going.

If the pedal still feels the same as usual , the cause could be a sticking clutch spline . The clutch plate spline can stick/freeze to the input shaft and stop the plate from moving away from the flywheel , this will cause constant drive even with the pedal depressed .

 

[SPYDERLK]

If the pedal still feels the same as usual , the cause could be a sticking clutch spline . The clutch plate spline can stick/freeze to the input shaft and stop the plate from moving away from the flywheel , this will cause constant drive even with the pedal depressed .

OK... Ill 1st and 3rd the motion.
larry

 

[rdbrumfield]

One question, do you still have the feeling of freeplay? The little bit of just spring tension before the throwout bearing is engaged by the throwout forks. If there is not much distinction, the rolled pin on the finger shaft is sheared.

 

[greg_g]

OK... Ill 1st and 3rd the motion.
larry

Not me. Given the evidence submitted so far, this sounds like something that happened while the tractor was active. A frozen friction disc is almost exclusively the result of an extended period of inactivity in wet conditions. This is especially true of a recently replaced clutch. Even though it may mean dropping a loader bracket to look inside, I'd verify the integrity of the roll pins first. If the external pin is solid through and through, move on to the inside pin(s). If you don't have a 2nd person to work the clutch pedal, disconnect the pull rod and work the outside clutch release lever while watching the throwout bearing. If it doesn't move forcefully into the clutch release fingers, It's the pin(s) holding the clutch fork (behind the throwout bearing)

//greg//

 

[Eagleview]

Not me. Given the evidence submitted so far,
//greg//

Unless the OP has made an error in reporting the facts , "the evidence submitted so far" points away from that being the case . If a roll pin had sheared on the throwout shaft , it would not feel the same as before . Without the resistance from the pressure plate return springs the only back pressure against the clutch pedal would be the little return spring and I'm betting the OP would notice the light pedal .