Discussion:
clark forklift hydraulic motor problem

The hydraulic motor sticks on sometimes and wont shut off. I, along with my two co-workers have been through numerous times to no avail. Any diagnostic suggestions would be appreciated. the model # is TW30B and the serial # is TW235-211-3755. we have also replaced the control valve switches and all contacts.
  • Posted 16 Sep 2007 15:42
  • Modified 18 Sep 2007 17:00 by poster
  • Discussion started by nick_t
  • Washington, United States
Showing items 1 - 8 of 8 results.
It stops only when you turn the key off, then it unsticks, but the moment you turn the key back on it continues to run.
  • Posted 25 Sep 2007 12:48
  • Reply by nick_t
  • Washington, United States
I agree that it appears to be a contactor assembly issue.
1. What was the condition of the tips before you replaced them ? Pitted?
2. What is the conditon of the battery - quite often if the battery is not up to full voltage this can cause excessive amp draw thru the contactor and tips resulting in sticking tips due to excessive arcing.
  • Posted 20 Sep 2007 22:29
  • Reply by johnr_j
  • Georgia, United States
i think that your problem is in the contactor tips sticking together i have had this before on a different type of truck if you have changed the tips it could be worth changing the whole contactor assy for a slightly larger unit as the initial current draw on a hydraulic motor is high so if the contactor is on its limit the tips can stick intermitantly good luck
  • Posted 20 Sep 2007 04:29
  • Reply by gary_d
  • scotland, United Kingdom
Sorry, I did not fully read your initial thread. If you've replaced the switches and contact tips, It has to be a problem with either a contactor or switch sticking- Or- either a control wire for the switches or cable to the motor is shorting out. Is it possible that the motor is loose and when it is turned on it moves a causes a short?
  • Posted 19 Sep 2007 22:03
  • Reply by duodeluxe
  • United States
duodeluxe
we have also replaced the control valve switches and all contacts.
  • Posted 18 Sep 2007 15:43
  • Reply by nick_t
  • Washington, United States
model #tw30b
serial #tw235-211-3755
  • Posted 18 Sep 2007 13:20
  • Reply by nick_t
  • Washington, United States
If it is a model that uses contactors, it is most likely a sticking control valve switch. Once you actuate the lever that is making the pump motor stay on you will see that the lever is attached to the control valve. There is a switch either near the top or the bottom of the control valve plunger. The switch is either out of adjustment or needs replacing.
The pump contacts could also be sticking. That would be caused by burned tips or by running the truck on a dead battery.
  • Posted 18 Sep 2007 05:58
  • Reply by duodeluxe
  • United States
duodeluxe
What Model# and Serial# is the Clark?
  • Posted 17 Sep 2007 05:01
  • Reply by Truck_Tech
  • United States

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