Volvo EC25 looking for aux foot valve bi directional plumbing for a thumb

[Hammer49]

So I have a foot pedal that works a hyd element (spool valve) and has 2 small lines going to the end of the boom. I also have a larger pipe on the side of the boom going down that returned to the tank so thats three lines on the boom.When I work The foot valve in hyd fluid comes out of one the small line at the end of the boom. When I work the foot valve the other way hydraulic fluid just drips out no pressure. On the auxiliary spool valve there’s no pressure compensator on the spool valve I have to order them but I need to know what else to order because it doesn’t work and think I’m missing something may be a T in the line or something. From the right going left it’s the fifth hyd line that’s the spool valve that works the Aux foot Pedal.
I followed the lines from the valve and they go straight to the boom. I haven’t hooked Lines to the hydraulic cylinder for the Thumb but I would assume when I work the foot pedal in either direction fluid will flow out of one line and then out the other line.I get pressure only out of one now. Does anyone know what parts I need to make this a Bi Directional valves and a diagram. My serial # 28121609

Thanks

 

[lantraxco]

Guessing that the larger third line is a low backpressure return line for a hammer. Somewhere there is a lever, valve, screen setting that switches between bidirectional attachment and hammer, but I am not familiar with the Volvos The next poster will no doubt know more!

 

[uffex]

Good day Hammer
Im not so sure what you have as a foot pedal if you could give a shot it would help as I am short of those illustrations, I attach some information which may be helpful.
Keep smiling
Uffex

 

[Hammer49]

My footpedal only has a cable going to the spool valve it works the spool valve up and down

 

[Hammer49]

The other two valves next to the foot valve Is for travel for the tracks

 

[Hammer49]

This valve I would assume would be for a button on my joystick that moves the boom cylinder right and left

 

[Hammer49]

Here are some pictures of the hydraulic system

 

[uffex]

Good day Hammer
I guess I get the picture you have a cable controlled option spool and what you are looking for is two directional control of that spool. With the cable that is going to be messy. What you can do is convert the spool to two directional control by hydraulics, one guy on forum has made that work exactly for thumb (Multi Wilson).
Attached is the document that may help you and have a conversation with the Mutti fellow I am sure he will give you some tips. Any questions please come back.
Kind regards
Uffex

 

[lantraxco]

Double check the steel lines, there may be a ball valve somewhere that dumps the one line off to tank when you have the hammer mounted. I've never seen a setup where they went to the trouble of installing the spool and two way control pedal, and the lines, but made sure it wouldn't work? Makes no sense. Actually look at the end of the boom where the lines mount, do they pass through a steel block? Sometimes the valve is there. Picture maybe?

 

[Hammer49]

Ok thanks to both of you for your help. There is no valves or block from the two lines on the top of the boom going back to the main valve body for the foot pedal spool valve. There is a third line that is slightly bigger on the side of the boom that goes back to the filter ,cooler and tank. That Return line is not connected to the spool valve or the two lines in anyway. Volvo told me it was set up with a breaker kit. So I’m thinking the foot pedal may be blocked off on one line (even though foot pedal valve operates both ways ) because that line needs to be plumbed properly to come back to the spool valve or Pressure compensator valve or to the tank or filter but there is no kit for this machine it was optional when built.

 

[Hammer49]

So uffex The foot pedal spool valve is bi directional right now.Because the foot pedal operates the spool In both directions the problem is fluid only comes out the left line at the top of boom and when I operate it the other way it trickles out of the right line at the top of boom while still sending fluid out the left line I’m thinking the foot spool valve was blocked off I have to take the lines off at this spool valve and check that. And so if it was blocked off and I fixed this situation and I did have fluid going to both sides of the top of the boom with each pedal direction. How would you plumb this hydraulically because just a two way valve to a piston with no relief or safeties can bend pistons and destroy main hydraulic valve body.
Your thoughts would be appreciated thank you

 

[Hammer49]

Foot pedal spool valve is the one from the left is the one right next to the yellow cap going right

 

[Hammer49]

Quick question what does a balance valve do? I notice I have one on my boom offset.

 

[Hammer49]

 

[Hammer49]

 

[Hammer49]

Number seven is the foot pedal spool valve

 

[Hammer49]

Here is the description of the main valve body

 

[lantraxco]

Quick question whatView attachment 236501 does a balance valve do? I notice I have one on my boom offset.View attachment 236501View attachment 236501

Balance, or counterbalance valve acts as both a braking valve and also a lock and relief valve when the control valve is in neutral. The balance valve only allows movement as fast as the oil flows, so if say you were on a side slope the bucket wouldn't swing wildly downhill when you started to move the control valve. The relief function allows movement if an external force creates an over pressure situation, oil flows cross port, or to tank, and the boom or machine will swing until the pressure falls off.

 

[lantraxco]

So uffex The foot pedal spool valve is bi directional right now.Because the foot pedal operates the spool In both directions the problem is fluid only comes out the left line at the top of boom and when I operate it the other way it trickles out of the right line at the top of boom while still sending fluid out the left line I’m thinking the foot spool valve was blocked off I have to take the lines off at this spool valve and check that. And so if it was blocked off and I fixed this situation and I did have fluid going to both sides of the top of the boom with each pedal direction. How would you plumb this hydraulically because just a two way valve to a piston with no relief or safeties can bend pistons and destroy main hydraulic valve body.
Your thoughts would be appreciated thank you

You may have the wrong spool in the valve section, or possibly you just need to adjust the cable so you get full spool stroke in both directions. If you see the cartridge valves with the yellow caps in some other sections, I believe you just need to order two of those and install them in this valve section, you can see the port plugs with the internal hex that can be removed and the port reliefs installed.

 

[uffex]

Good day
Information has come to hand that explains the cable connecting the spool to the pedal is more than Bowden being able to operate in compression and tension, I wrongfully misled Hammer regarding this point. From what I am able to establish the LS signal is only working in one direction however the LS valve is interchangeable with the crawler segments.
Kind regards
Uffex