I’m working on a cat 24m and have an issue of no acceleration at stall. Transmission solenoids read 90% on ET I have compared to another 24M which allows you to idle up the engine at stall and all transmission solenoids read 100% It drives ok as long as you start in 1st gear and will easily grade in 2nd / 3rd gear
OK, need more information. Machine Serial Number for a start. That transmission S/N plate in your photo is not OEM. Did this problem start after a transmission exchange or repair.? What RPM do both the problem machine and the "good" one reach at stall.? You have ET, please download a Product Status Report for this machine and the other one that you used to compare it. If you don't fancy uploading them here then you're free to send them to me on a private message.
I've slept on it and the answer is easy. The information that I requested above is not required. The clues are all there in the parts of the text of your OP that I quoted above. Solution is simple - replace the torque converter. The stator sprag clutch is failing.
Ok The problem 24M serial # is B9K00331 I havnt got a great deal of history on tranny hrs however I don’t believe it has been changed or major repair recently The good grader allows 1800rpm stall in 1st gear Didn’t take note of of stall rpm in other gears but it still revs at stall in all gears The one we are having trouble with does not allow acceleration when in gear and foot on brake so we are unable to achieve any stall specs. In neutral it achieves high idle 1800 odd rpm. When the brake is applied
Yep that’s pretty well where we are at. It was a bit deceiving at the start with no engine acceleration but when we engage 1st gear engine load goes straight to 80% so points to the converter
Let me explain in a bit more detail my cryptic post above. The 24 is the only model of Cat grader equipped with a torque converter. Additionally the converter is of the lockup variety so once the machine gets moving past a certain ground speed in 1st gear the lockup clutch engages and you have direct drive, a bit like a haul truck. To prevent heating of the converter when the lockup clutch is engaged the stator is fitted with a one-way sprag clutch, a bit like a ratchet. Only when in converter drive is that ratchet required to hold the stator in a fixed position and transmit the torque from the impeller to the turbine. If it fails you get the symptoms you describe - can't get stall RPM with the machine stopped but once you get it moving and the lockup clutch engages everything is peachy. Attached the SysOp for the torque converter with the relevant parts highlighted.
I would say you’re on the right track. That sprag clutch is the Achilles heel of lockup converters. In fact give yourself a gold star for not suspecting low engine power, that’s normally the first call with those symptoms.