question about forklift steering hydraulics

   / question about forklift steering hydraulics #1  
A

avz

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Apr 24, 2009
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Hi
at my workplace we have a Caterpillar F30 (about 20 years old) electric forklift. it stood without use for more then a year and I would like to reuse it. I've found that it has a problem. it's steering has a seperate hydraulic system and the pumpmotor operates constantly. as far as I know, it should work only when the steering is turned. the steering wheel is connected to a round cylindrical thing and to the side of it 4 pressure hoses are connected. I've seen no sign of any elctrical wires conncted to it, so, how does the pump motor "knows" when it sould start operating?
Thanx for your help.
 
   / question about forklift steering hydraulics #2  
It's called and orbital valve. There are load reactive and non-load reactive orbital valves. The pump should run all the time. Try searching for info on orbital valves.
 
   / question about forklift steering hydraulics
  • Thread Starter
#3  
Thanx for the swift reply. wuold you know where I can find the circuit diagram of the foklift? I've sent a mail to Caterpillar, but they didn't even bother to answer.
 
   / question about forklift steering hydraulics #5  
Mechanos said:
It's called and orbital valve. There are load reactive and non-load reactive orbital valves. The pump should run all the time. Try searching for info on orbital valves.
Click to expand...

I agree, the pump needs to run all the time. If it didn't then there would be a delay in steering responce while the pump starts and the flow get's going.
 
   / question about forklift steering hydraulics
  • Thread Starter
#6  
Thank you for your replies and a special one to Akkamaan. I'll try to fix it next week.
 
   / question about forklift steering hydraulics #7  
Steering Valve

https://www.surpluscenter.com/item.asp?item=9-7099&catname=hydraulic

We have similar steering unit on our PT's. This steering unit uses the fluid to push or pull a set of hyd cylinders to steer the unit. A small hyd gear pump feeds the steering unit, and when not steering, the fluid just passes through, and back to tank. It runs constantly. Our steering unit also has a priority valve in it to take all the fluid if needed. The FEL on out PT's use the pass through fluid to operate the FEL.

none load reactive means that the cyl stay where you left them.
Load reactive, means that the steering wheel returns to center.

Check the pressure at the pump, while trying to steer.
 
   / question about forklift steering hydraulics #9  
Your Cat forklift is not made by Caterpillar. It is made by MCFA, Mitsubishi-Caterpillar Forklift Assoc. It's a Mitsu with Cat badges. Cat won't/can't give you any info.
What exactly is the problem? Contact a Cat forklift dealer for info on your truck. Have the model and serial # handy. I may have a book for it, I'll have to look.
 
   / question about forklift steering hydraulics
  • Thread Starter
#10  
Thanx again people. you are very helpful. Wayne, as I wrote, I've sent a mail to Cat after I've tried with the local Cat agent, who told me that they dont have any technical stuff for such an old forklift. one of the problems is that the main pump motor contactor's point are burnet out and I would like to have the technical litrature that might help to take care of it generally.
JJ - your answer helped me a lot to begin to understand how it works. my knowledge in hydraulics is quite basic so far, mainly cylinders.
 
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