Hi, I have a 140H VHP which has suddenly lost all drive in forward and reverse through all the gears. have tested filter port pressure and runs low idle 400 psi. then tested solenoid port pressures and found that solenoid 1,2,and 3 pressures will not rise. all other pressures will rise as per the selection pattern required. initiall there were no active codes so i disconnected the 1,2 and 3 solenoid wires at the control valve. all relevant codes then came up so i assume the coils are ok. it feels like the clucth pedal has been applied and therefore there is no commanded drive. any assistance and ideas would be appreciated.
have you looked at your axles. try putting your diff lock in
hi, i had considered a mechanical failure but the fact that it is missing one of three solenoid port pressures for any given gear made me thinks more of an electrohydraulic problem. will definitely check with the diff lock in.
If it lost all gears suddenly then the most obvious thought is something electrical/electronic, although don't rule out completely something like the inching pedal input to the transmission control. If you want an Electrical Schematic for your machine PM me with a Serial Number and your e-mail address (as per instructions from mods DO NOT post them here unless you want to be deluged with spam e-mails) that I can send it to.
hi nige, my instinct tells me it has something to do with the clutch/inching pedal. there are no codes what so ever related to the trans ecm except the ones i instigated by disconnecting solenoids. how do i test the inching pedal and commanded signal to the ecm as i think the solenoids are doing what they are instructed by the controller and the machine thinks that the operator has his foot on the clutch. is there a park brake released signal that need to be delivered before the ecm will engage gears as this may be another cause. i have a basic version of sis and the relevant schematics for wiring.thanks
Does it perchance have a park brake activation/transmission disconnect switch in the operator seat cushion..? The transmission ECM will definitely have an input from the inching pedal sensor (I assume it's a PWM signal position sensor). Your schematic should show it.
i have looked and there are no broken wires from the inching pedal. is there any way to test it ?
You don't say what Serial Number prefix you have. On most machines the inching pedal is connected to the transmission by a cable which operates on the transmission control valve. Mounted on the control valve body is a normally open pressure switch that closes when the inching function is active. That switch signal is an input to the transmission control.
I worked for one outfit that owns 140Hs by the dozen. Rule of thumb was most would need a transmission rebuild around 7500 hours. By the time I arrived on scene, they were not keeping them around that long. They didn't keep me around that long either, but that's another story. Just know that in the end, the joke was on them. You just can't build a highway with lap top computers run by recent college graduates. However, you CAN lose money in the millions by fingering a touchpad. But I digress. Sounds like inching pedal symptoms. The resident expert, Nige, is on it.
Have a 666 Wabco Motor Grader that won't shift out of second gear. Any ideas as to why?
I had the same problem with my 140H a few months back. After the mechanic from Caterpillar came to check the 140H. Turned out it was the transmission solenoid. After switch out the solenoid, it went back to work like a brand new machine.