Hello, Working on a CAT 730 Haul Truck serial number B1M02113, Truck will not shift out of first other then some times it will and when it douse it shifts up through the gears better when going down hill but will also on flat ground once in a while. Things i have checked dump body float, speed sensors all seem to be working, Trans gear lock, No active codes. I have ET so i also put machine through a calibration and passes with no issues. One thing i have noticed on ET while operating machine is next to the gear it in it shows a L at higher RPMS when it wont shift and when it douse shift the L is not present. Kinda stumped on where to go to next and any further assistance would be great. Thanks
Based on those symptoms I would bet money that the freewheel stator clutch inside the torque converter is on the point of failing, or has failed. "L" means that the torque converter is in lockup mode (the lockup clutch is engaed so the transmission will upshift) and the absence of the "L" means that it is in torque converter drive, when it wont. See this thread. I think it has everything that you need to know in it without the need to re-invent the wheel here......... All the details regarding your B1M machine versus a B1N in the linked thread are the same. HeavyEquipmentForums h
Great info, I also put a gauge on the LUC valve and getting nothing driving around as well as on ET it said its currant to the LUC solenoid is 89%, Shouldn't i be getting pressure at valve?
You will only get LUC pressure provided certain conditions are met, two of which are the transmission input and output speeds. If they do not correlate correctly there will be no signal from the powertrain ECM and therefore no LUC pressure. If you drive around downhill and successfully get the tranny to upshift above 1st speed then after every shift is completed IMO you should see LUC pressure because under those conditions the clutch should be engaged.
I can some times get it to shift through to higher gears and i still not seeing pressure on gauge.
I would bet that the conditions for LUC engagement are not being met, even if it is upshifting. TBH your symptoms are classic for the stator clutch having given up the ghost. How many total hours on the machine.? Has the converter/transmission assembly ever been out before.?
Almost 20000 hrs, To my knowledge it has not, Any way of inspecting it without pulling all apart? We have change the oil and filter saw very little on magnet oil was a little dark but nothing crazy.
Way (like 5000 hours) overdue for a transmision/converter overhaul in that case. In my experience anything that gets past 15k is living on borrowed time. Unfortunately no, but the total hours on the machine tell the story. You won't see any debris from the stator clutch on a mag plug, Physically there isn't enough of it. Time to get the tools out and get wrenching.........
As a last throw of the dice, here are some tests.....
Thank you, We will pull and do an inspection
Last suggestion before you pull the tranny & converter. Do all the tests in those docs above related to the LUC modulating valve just in case the spool is hanging up and causing the clutch not to engage.
Thanks for all the info, I ended up checking the LUC valve and pulling it off and apart and found it was stuck, I replaced the valve and it ended up fixing the issue. Thanks again.
Glad you got it sorted without the need for removing the tranny. However with the hours on the machine that transmission is going to be coming out for overhaul some time fairly soon anyway.
Come to find out it had a bearing reseal 6000 Hrs ago, I checked with local CAT dealer. Hope for some more time as i think its going for a certified rebuild soon!
Amazing how you find info that you never knew about before when you’re digging into something like this……
Back at it again, This time with completely different symptoms, Machine now shifts fine until it down shifts to 1st gear, While it gos into first from down shifting it will act like machine is in neutral for a few seconds and then slams into first then gos up the gears no problems. Im starting to think this transmission is failing.
Take a look at the LUC valve again.? If the LUC is not releasing fully or quickly enough it might do some weird stuff.
looked back into that valve everything there is good, Now when doing a calibration it fails due to clutch pack 5 at a limit and when checking pressure at pressure port for 5th pack i get 0 pressure until it finally shifts then its quick back to 0
I think the transmission is coming out..........
You may want to try swapping modulation valve with one from anther clutch pack that works. They are the same idea as the lockup clutch valve. May be sticking.
I’d just pull the tranny and torque out of it anyway. Cab comes off easy enough and it does come out reasonably ok.
I genuinely can’t remember what the problem with that was,but there was a level of fun trying to recalibrate it due to the software possibly not cooresponding to the exact tranny that was in it. Nige was extremely and infact,pivotal in getting the thing running again.