Challenger MT865C transmission shift problem - The Combine Forum

 
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post #1 of 5 (permalink) Old 10-19-2016, 11:22 AM Thread Starter
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Challenger MT865C transmission shift problem

We have a Challenger MT865C that we are having some shift problems with.
This is what symptoms we observe while using on a grain buggy.


1. Inching pedal will not work and will not go through calibration process properly even after many repeated attempts. Have to use the shift lever only to start and stop tractor.
2. Driving tractor along and transmission will shift to neutral with no warning.
3. If tractor goes to neutral have to stop, shift to park, then put back in gear and it will go. (not a real good feature while unloading on the go into the grain buggy)
4. When up shifting or down shifting at times the shift will be delayed.


The problem does not appear to be in the transmission itself as there is no slippage or any irregularities. When the transmission is working everything shifts and works properly. It is just at times it does this acting up. Tractor is in the 3000 hour range and no previous transmission problems.


One thing we have just remembered that we have not checked out yet is that we had a MT755 transmission that got to acting funny and the resolution to that problem was that the shifting handle had to be replaced. In other words the shifting buttons got to where they were not working properly. We have not checked to see if that is the problem yet on this tractor but will.
If anyone has had any similar experiences or any suggestions to solutions I would appreciate it.


Thanks


John Burns

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post #2 of 5 (permalink) Old 10-19-2016, 06:31 PM Thread Starter
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We think we found the problem

We think it is operator error or more specific lack of operator training on how exactly the inching pedal works and when it is appropriate to use it.


Darrin took the tractor out by itself today so he could play with it and see if he could recreate the problems. As long as he operated the tractor properly he could not make it do what a couple different operators were having trouble with.


But then by doing some things specifically he should not do he was able to recreate the problems the operators complained of.


Specifically, in one instance one operator was having trouble when dumping grain into the truck from the grain buggy. He would hold the inching pedal down till needing to move forward. If the pedal is let come up just slightly, the switch clicks on telling the tractor it is in inching mode. Then as the operator continued to sit there waiting for the grain to pile up the tractor senses it is not moving when it should be and kicks itself in neutral. Just about the time the operator needed to move up so the truck runs over. Solution: operator needs to be in firs or second and use the gearshift to move forward and not hold the inching pedal down forever. Or if the inching pedal is held down, hold it all the way down so switch does not start engaging the transmission.


The other situation where the tractor was jumping to neutral while going through the field we believe the operator approaching the combine at high speed while downshifting would accidentally or intentionally touch the inching pedal. Darrin was able to get the tractor to kick itself in neutral by doing this. Solution: Operator keep away from inching pedal while operating the tractor - this is a powershift and not a manual clutch tractor. Inching pedal is for inching, not clutching.


We are not 100% sure yet, but pretty sure it was just the tractor protecting itself against operator error.


Always check the simple stuff first.


Oh, and the inching pedal calibration problem was simply that this tractor needed the pedal held down longer in the sequence of calibration than what the 765's need so once the timing of the sequence was correct it all worked.


John

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post #3 of 5 (permalink) Old 10-19-2016, 10:05 PM
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Quote:
Originally Posted by jburns View Post
We think it is operator error or more specific lack of operator training on how exactly the inching pedal works and when it is appropriate to use it.


Darrin took the tractor out by itself today so he could play with it and see if he could recreate the problems. As long as he operated the tractor properly he could not make it do what a couple different operators were having trouble with.


But then by doing some things specifically he should not do he was able to recreate the problems the operators complained of.


Specifically, in one instance one operator was having trouble when dumping grain into the truck from the grain buggy. He would hold the inching pedal down till needing to move forward. If the pedal is let come up just slightly, the switch clicks on telling the tractor it is in inching mode. Then as the operator continued to sit there waiting for the grain to pile up the tractor senses it is not moving when it should be and kicks itself in neutral. Just about the time the operator needed to move up so the truck runs over. Solution: operator needs to be in firs or second and use the gearshift to move forward and not hold the inching pedal down forever. Or if the inching pedal is held down, hold it all the way down so switch does not start engaging the transmission.


The other situation where the tractor was jumping to neutral while going through the field we believe the operator approaching the combine at high speed while downshifting would accidentally or intentionally touch the inching pedal. Darrin was able to get the tractor to kick itself in neutral by doing this. Solution: Operator keep away from inching pedal while operating the tractor - this is a powershift and not a manual clutch tractor. Inching pedal is for inching, not clutching.


We are not 100% sure yet, but pretty sure it was just the tractor protecting itself against operator error.


Always check the simple stuff first.


Oh, and the inching pedal calibration problem was simply that this tractor needed the pedal held down longer in the sequence of calibration than what the 765's need so once the timing of the sequence was correct it all worked.


John


Yes. All correct except there's no reason why you can't use the clutch to inch at the cart. I usually use 6th gear as it engages way smoother and its easier to slip the clutch for smooth motion.

Hold the clutch right down, or if you back it off to the point the switch opens but don't move push the clutch back down to re-set the switch and it will engage again.
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post #4 of 5 (permalink) Old 10-20-2016, 09:54 PM Thread Starter
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Ok, thanks for the reply.

Had some other replies over on Machinery Talk that I will link here just in case someone else runs into similar problems.

Viewing a thread - Challenger MT865C transmission shift problem

John
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post #5 of 5 (permalink) Old 02-15-2017, 03:42 PM
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Did you get this problem figured out?

Under the arm rest there is a main harness, we have had problems in the past with pins or wires being pulled as the operator swivels the seat. If something is rubbing there your armrest module will do all sorts of funky stuff.. Pull the harness and have a look... Also check cab grounds.

If the inching pedal isn't working you may have a bad position switch any other codes on the tractor?

Last edited by service101; 02-15-2017 at 03:49 PM.
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