Convert Linkage Controlled Hyd Thumb to Solenoid?

[Country Angler]

Hello Everyone, long time reader, first time poster here. Great site.

Last fall I bought a Daewoo Solar 035 excavator, somewhere around 2000ish vintage. Like everything I buy, it was neglected and broken, but it's coming together pretty well, fixing leaks, cutting out rust, fabbing new parts, etc.

It has a linkage operated "PTO" valve on the main valve block which operates it's hydraulic thumb, with what looks like an inline pressure relief valve that is tee'd right into the lines that go to the thumb cylinder. Right now, there is a crummy little foot pedal that operates the thumb, and I'd like to change that to a thumb switch style solenoid valve controlled by my joystick buttons.

I found a thread called

"What solenoid directional control valve for thumb."​

Which answers about 95% of all of my questions, looking at uffex's PDFs he posted, etc. But, my machine does not have a pilot pressure controlled valve at the thumb ports like the original poster of that thread. My rig has mechanically actuated valves on travel, dozer, and what they call pto, which is my thumb. The other valves are pilot pressure controlled.

My main question is, how do I do the plumbing from the solenoid valve to the excavator in my case? Maybe I should say where do I get the P line, and where to send the T line? Wiring and plumbing to thumb and joysticks I think I've got figured out.

I'm not a great communicator, hopefully a few of you guys can see what I'm getting at.

Thanks guys,

Jack in Vermont, USA

 

[Shimmy1]

I think you might have a hard time with this venture. Only way I could see is you will have to somehow tee into the pressure side of the system.

IF your system is closed center, might be possible to tie open the spool for the thumb circuit and use that for supply, but that's above my pay grade.

 

[uffex]

Good day
If I interpret your post correctly, you have a mechanical (Rod-Cable) controlled valve segment for an existing thumb, you are looking to control the thumb with pilot pressure. This would involve installing hydraulic spool caps to the thumb segment. From this you could control the spool with solenoid valve by either using a borrowed pilot valve or direct with pulse width modulation (Electric scroll buttons on the levers) this is a more expensive and complex system.
Kind regards
Uffex

 

[materthegreater]

Any pictures of your current valves and joysticks?

 

[Country Angler]

First of all, thank you for your quick responses, what a bunch of helpful people!

If I interpret your post correctly, you have a mechanical (Rod-Cable) controlled valve segment for an existing thumb, you are looking to control the thumb with pilot pressure.

Yes, the valve segment that controls my thumb is mechanical, rod type.

I don't know if it has to be pilot pressure or not? I believe that is how the thread that I was referring to was set up, with pilot pressure to the other guys foot pedal from the facrory. Im just trying to control my thumb with 2 momentary electric switch buttons on my joystick, one for in, and one for out on the cylinder. I don't care if I can adjust the speed of the thumb while actuating, instant full on and off is fine, it's not really that fast at full speed anyway.

My two joysticks however do use pilot pressure to control all of their functions, so the machine is equipped with pilot pressure in general.

I do not know if my system is open or closed center, is there an easy way to check? I do see what shimmy 1 is getting at.

his would involve installing hydraulic spool caps to the thumb segment. From this you could control the spool with solenoid valve by either using a borrowed pilot valve or direct with pulse width modulation (Electric scroll buttons on the levers) this is a more expensive and complex system.

If there was a way to just remove the linkage from the ends of my spool on that segment, and install solenoids powerful enough to pull on the stock spool on either side of the valve, that would be all that I was looking for. But hat seems like an awful lot of electromagnetic force that would be needed to accomplish that? And how would the caps connect to my valve segment?

Mater, I will be over working on the machine later on today, I can post some pictures of my setup if the forum will let me post pictures this soon after joining.

The joystick handles that I just installed are just the cheap $30 Amazon ones you can buy with three momentary buttons on each handle, with 6 wires coming out of them. The wires are really thin, I would need to use them as a trigger wire on a relay setup I would think.

Thanks for all of your ideas so far guys, I really appreciate it.

Jack

 

[uffex]

Good day
Please see attached, I would suggest that you consider using a pilot control borrowed from another circuit (Slew > offset) or another no more expensive and much better control. If you are just using this to grasp logs you may also give some thought to connecting in series to the bucket line.
Kind regards
Uffex

 

[Country Angler]

Thanks uffex, just the direction I was looking for. Didn't know this stuff existed. I'll definitely look at converting that portion to pilot control.

Did some work on the machine yesterday. I reset all of the relief pressures that needed it on the machine according to my pressure gauges, since some of the functions seemed awful weak. For example, with the blade down 180 degrees from the boom, it could barely pick itself up off of the ground, and only when you use the arm and boom together.

I adjusted all of the relief valves to the pressures the service manual pdf said, but I'm a little foggy if I did it 100% right. The manual conflicts itself a bit in what relief valves should be what pressure. I didn't want to go over any specd out pressures for any valve, so I just made sure no function resulted in a higher pressure than was stated. A few were reading quite low, and turning them up mad a bit difference. Maybe I'll start another thread at some point on the order of operations of setting relief valves at some point and see what you guys think. I'm mostly trying to get this thing reassembled and out of my garage.

Also changed out the track tensioner yoke, that was a huge fight. Original one was bent, and the grease tensioner thing was jammed in there bad. I think I lost weight fighting with that for 6 hours. But, after the work I did, I bet you I could change another one in 15 minutes now.

Amazing how much easier maintenance will go if you actually keep up with it instead of just riding her hard, and putting her away wet.

Thanks again,

Jack