Proportional hydraulic control valves: Proper group?

If this is not the proper group, where should I post such a topic?
I have a smail tractor mounted hydraulic crane where the control valve
assembly is a bit worn. Instead of just spending a lot of money in
getting a suitable 'manual' control valve assy I consider checking a
bit around to see if I can find a surplus electric proportional
hydraulic control valve assy for at least 4 double-acting cylinders
and replace my old control valves with this electric version. (I don't
want wireless remote control, only wire)...
Are there different types of electric proportional valves for doible-
acting cylinders or would almost any model do? (Given that flow and
pressure are supported).
However despite that I work a lot with electronics I don't know how
the solenoids normally are interfaced with the control pots. Do they
use an electronic module between the joysticks and the solenoids which
varies the current between the solenoids according to the position of
the joystick, or is this circuitry normally included in the joystick
assy? Thanks for some comments on this.
Does anyone here have suggestions on where to obtain such surplus
Other relevant comments and suggestions are highly appreciated :-)
regards Tor
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Dear bushtor:
This is as good as any. We have not had many on-topic posts (which yours is) here in a while, so there is no telling how many responders will get back to you or when.
Electronic valves are even more sensitive to wear, so you'll need to upgrade your filtration and perhaps cooling systems too. Many mobile hydraulic systems run at essentially zero pressure until a control valve is moved "off center", so you may have to implement a circuit that will allow free flow back to the tank until you are needing pressure.
Some of the more expensive farm implements might use these. You might see what has "crashed and burned" out in the boonies, for best pricing.
There will be major differences. Starting with maximum flow rates, and ending with whether or not the "pulse density modulation" (or whatever has changed in 25 years) electronics is built into a valve that'll get in excess of 200 =B0F or not. I'm guessing not, but technoligy always changes.
Not sure what that means...
Not between the solenoids, no. Most commonly, the spools the solenoids drive are spring centered, or spring offset. Power is only sent to (usually) 1 solenoid. It is commonly a pulsed DC, possibly AC signal, and not "current control" per se.
My experience has been there is joystick -> harness -> power electronics -> harness -> solenoid(s). I floated 8000# tanks filled with liquid, balancing them between two cylinders... but this was wall- AC powered.
Farm implements would be your most likely source for "free". Some dozers use laser guidance to keep their grading on the level, so they might be another source.
What kind of robotic desctruction are you planning?
David A. Smith
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