Discussion:
AC Hydraulic problems

Ser #15645, AC truck
Hydraulic/Power steer motor operates very slowly RPM ( barely enough to operate steering properly and not quick enough for the hydraulics to operate)
Motor is a AC 25 volt three phase ( I think it is variable voltage / variable speed )and gets very hot with-in one to two minutes. Motor was tested and is OK. Voltage at the three motor terminals are 7.5 volts on each this explains the rpm issue but should increase with the hyd functions ??, Could it be a bad inverter ? Battery voltage OK and the indicators on both AC super drive motor controllers do not show any faults.
The dash disply is not visable for codes.

Help would be greatly appreciated
  • Posted 2 Oct 2012 12:15
  • By BrewCrew
  • joined 18 Nov'08 - 108 messages
  • Ontario, Canada
We`re here for a good time
Showing items 1 - 4 of 4 results.
you can see the rpm of the motor from the dash display and the controller signal to see if they match then you know its the bearing. We have a field kit for the drive motor sensor bearing replacement.
  • Posted 6 Jun 2013 16:49
  • By russell_l
  • joined 7 Sep'09 - 32 messages
  • Queensland, Australia
rusty
I already had the motor on the bench, bearings seen better days and long over due so I swapped them out and found a bad wire in the harness ( from sensor ). She`s good to go now.
Thanks for the info Rick and Roger
  • Posted 7 Oct 2012 22:53
  • By BrewCrew
  • joined 18 Nov'08 - 108 messages
  • Ontario, Canada
We`re here for a good time
yeah what roger said. change the speed sensor. it's not difficult.. we've had MANY failures of that sensor. 2 in the shop right now
  • Posted 5 Oct 2012 13:34
  • By rick_c
  • joined 30 Jul'09 - 204 messages
  • Texas, United States
technology: (no user serviceable parts inside)
One of the bearings in the motor has an encoder and they have been known to mess up and send false info to the controller and over heat the motor. I have had it happen to me on a truck. That is where I would start.
  • Posted 5 Oct 2012 06:38
  • By rogeriwt
  • joined 10 Apr'07 - 323 messages
  • Massachusetts, United States

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