got a champion grader 720A in for transmission repairs. it just doesnt move in any gear! forward gears 1 through 8 and reverse 1 through 4. the controller seems fine not showing any errors and i checked all solenoids and wiring couldnt find any issues there. checked pump inline pressure, it was showing 50 psi at idle. anyone had such an issue? something wrong in the transmission?
If it's a Gearco 8400 transmission, you should get 215-235 PSI main pressure and 5-25 PSI lube pressure.
Main clutch slipping? Not applicable to torque converter machines
I have a shop manual for the 8400 transmission if it would help. If you want it email me and II will email you back a copy. [email protected]
i doubted main clutch as well but there is not even the slightest movement when i engage any gear! or possible something broken in the main clutch? its a gearco serial 29953 model 705. great thanks laycobeau emailing you now
Quick question for you since you have the manual, or perhaps you or someone else knows without looking it up: My 720 Series V does not indicate the gear that I am using most of the time. There is a round display on the operators pedestal that is supposed to show what gear you are in, but mine is blank most of the time. How to troubleshoot this? My apologies to the OP for getting the thread off track with this side note pertaining to the 8400.
The display connector's supposed to have 4 wires, pin A (red/white) is power and pin D (black) is ground. If you get voltage between these 2 wires then you need another display. 9 times out of 10 the display is bad. We had them changed at least once in all our 750's and 780's. Hope this help
yes max is right.!your display is done! ive never had issues with mine. im thinking of getting the transmission out and have a look inside, any advice?
Did you recheck the main oïl pressure as I stated previously? Because if you only get 50 PSI of main pressure (measured at the transmission pressure check plug) it's quite to low. The only ''inside'' failure that prevent the grader from moving in any gear is an input or output shaft failure, which is unlikely.
That cover on the front can cause you to lose everything when it gets worn. Is it called a "collector block"? Sorry, it's been 20 years since we had the issue, but we lost every gear when it happened. Only other times that happened, it was pump and accessory drive failures. The oldest machine I ran was a series 3, so by that time transmission pumps were all driven off the bell housing, but I thought the older ones had the transmission charged by a double sided pump under the rad. Any mixing of oils?
yes i rechecked the pressure, it stays at 50 psi on idle and goes up to 210 psi on high rpm. whats the normal pressure? at idle and high rpm? drained the oil and havent found any contamination, metal particles or seal pieces! yes this pump runs under the radiator via a prop shaft from the crank pulley.