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
  • By nick_t
  • joined 16 Sep'07 - 4 messages
  • 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
  • By nick_t
  • joined 16 Sep'07 - 4 messages
  • 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
  • By johnr_j
  • joined 3 Jun'06 - 1,446 messages
  • 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
  • By gary_d
  • joined 20 Sep'07 - 10 messages
  • 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
  • By duodeluxe
  • joined 11 Feb'05 - 923 messages
  • United States
duodeluxe
we have also replaced the control valve switches and all contacts.
  • Posted 18 Sep 2007 15:43
  • By nick_t
  • joined 16 Sep'07 - 4 messages
  • Washington, United States
model #tw30b
serial #tw235-211-3755
  • Posted 18 Sep 2007 13:20
  • By nick_t
  • joined 16 Sep'07 - 4 messages
  • 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
  • By duodeluxe
  • joined 11 Feb'05 - 923 messages
  • United States
duodeluxe
What Model# and Serial# is the Clark?
  • Posted 17 Sep 2007 05:01
  • By Truck_Tech
  • joined 30 Mar'07 - 152 messages
  • United States

Post your Reply

Forkliftaction accepts no responsibility for forum content and requires forum participants to adhere to our rules of conduct. Click here for more information.

If you are having trouble using the Discussion Forums, please contact us for help.

Global Industry News
edition #1260 - 11 December 2025
In this week’s Forkliftaction News we report on DHL Supply Chain signing a deal to deploy autonomous mobile robots (AMRs) at its Mexican retail operations and look at Guidance Automation’s successful trial of an AMR with a hydrogen fuel cell... Continue reading
Fact of the week
Foundling hatches are safe, anonymous drop-off points for unwanted infants, allowing parents in crisis a way to surrender a baby safely without fear of punishment, ensuring the child is rescued and cared for. The concept started in the 12th century, was abandoned in the late 19th century, then reintroduced in 1952. It has since been adopted in many countries.
Latest job alerts …
Dayton, OH, United States
Erie, PA, United States
Big Joe PDR30-154
Coraopolis, Pennsylvania, United States
Used - Sale
USD7,500
Mitsubishi FGE35AT
Yokohama, Japan
Used - Sale
Upcoming industry events …
January 28-30, 2026 - Bangkok, Thailand
March 4-5, 2026 - Detroit, Michigan, United States
March 24-26, 2026 - Stuttgart, Germany
Editorial calendar - planned features
CONSTRUCTION FORKLIFTS
HANDLING GOODS IN THE COLD
LOADING/UNLOADING FREIGHT
BROWNFIELD AUTOMATION
FORKLIFT ATTACHMENTS
BATTERY AFFORDABILITY AND LIFETIME
FORKLIFT SAFETY
Big Joe PDR30-154
Coraopolis, Pennsylvania, United States
Used - Sale
USD7,500
Mitsubishi FGE35AT
Yokohama, Japan
Used - Sale
Latest job alerts …
Dayton, OH, United States
Erie, PA, United States