question about forklift steering hydraulics

[avz]

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.

 

[Mechanos]

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.

 

[avz]

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.

 

[AKKAMAAN]

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.

read this one to start

 

[kennyd]

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.

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.

 

[avz]

Thank you for your replies and a special one to Akkamaan. I'll try to fix it next week.

 

[J_J]

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.

 

[J_J]

This will give you an idea what a steering valve looks like on the inside.

http://hydraulics.eaton.com/products/pdfs/C-STCU-TS006-E.pdf

 

[Wayne County Hose]

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.

 

[avz]

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.

 

[Wayne County Hose]

It's not that the parts aren't available, they don't want to bother with you. Post a pic of the contactor panel and I can get you the tips. Or, remove the contactor assembly and go to a Raymond forklift dealer. Raymonds used almost identical contactors to the Cats and most Raymond dealers have old timers that know almost everything. They can match up tips.

 

[avz]

WCH
Thanks for the help. I'll take some pics of the cotactor and upload them.
as per you second idea - I dont believe that we have a Reymond dealership here in Israel. I hope that it wont sound too weird but I'm trying to make new contacts from copper (the conductor) and copper brillium (the tips).
btw - you have mentioned that you might have the schematics and/or some other technical stuff. I hope its not too fresh to remind you.

 

[Wayne County Hose]

WCH
Thanks for the help. I'll take some pics of the cotactor and upload them.
as per you second idea - I dont believe that we have a Reymond dealership here in Israel. I hope that it wont sound too weird but I'm trying to make new contacts from copper (the conductor) and copper brillium (the tips).
btw - you have mentioned that you might have the schematics and/or some other technical stuff. I hope its not too fresh to remind you.

Israel!!!! Umm, ok, didn't realize that! I looked around, I don't have much info on that truck. Try this website, FORKLIFTACTION.COM:Used Forklifts, Buy forklifts, Sell forklifts, Business Directory for forklifts manufacturers and dealers,Marketplace, Forklifts News, Forklifts Forum, Forklifts Jobs, Forklifts Resumes. There are probably some guys there that can help. You can take out the tips and file them lightly to get you by for a while. Good luck and be safe!

 

[melizaarora]

Check hydraulic cylinders, valves, hoses, fittings, and other hydraulic components to ensure that leakage has not developed to maintain the forklift operation efficiently.