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
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!
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
My footpedal only has a cable going to the spool valve it works the spool valve up and down
The other two valves next to the foot valve Is for travel for the tracks
This valve I would assume would be for a button on my joystick that moves the boom cylinder right and left
Here are some pictures of the hydraulic system
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
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?
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.
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
Foot pedal spool valve is the one from the left is the one right next to the yellow cap going right
Quick question what does a balance valve do? I notice I have one on my boom offset.
Number seven is the foot pedal spool valve
Here is the description of the main valve body
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.
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.
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
Good morning OK I got a seal kit Took forever to come from Europe I’m going to attempt to try to make this work I’ll take the spool valve off and see what’s going on I will let you Know what happens
Ok so I replaced my boom element because it was hissing when trying to lift the machine off the ground that’s all fixed. So I took the old boom element apart and compared it to my aux foot valve spool it looked different so I said let me see if I can get Bi directional flow out of this auxiliary foot valve since it was the boom spool and it had Bi directional flow, so I swapped everything from boom element to aux foot valve element and I had flow out of both discharges A and B discharges without even touching the foot valve.So I changed everything back but forgot to change the pressure compensator in the middle #39 in Diagram and upon checking I had flow out of both A and B ports again without touching the Aux foot valve. Apparently 31 and 39 are different pressure compensators one has a notch that goes towards the middle of the compensator and different part number.You could see it in the picture if you compare. The one on the left is the boom element spool and the one on the right is the auxiliary foot valves spool. Once I put the the original pressure compensator back in I had no flow out of both A an B discharges. So I am back to square one with both lines off and I move the auxiliary foot valve In both directions and have flow out of both discharges I would assume not Bi directional. I guess I would have to buy an auxiliary foot element that is Bi directional because I guess the ports must be different inside the element.That’s just a guess I really thought it was gonna work. Thanks for everybody’s help I appreciate it. View attachment 238195
Here are some more pictures from the hydraulic element
Try hooking a small cylinder to the ports. You will always get oil out of both ports because one is pump pressure, the other is return which may be 25 psi or more back pressure.
Old element
Interesting didn’t realize that! I do have a cylinder I just have to get two hoses to try that thank you. Now that you mentioned that when I slowly did move the foot valve one way it seems like hydraulic fluid came out of the port A the top first and when I moved it the other way it seemed like it came out of port B first but then both of them interesting... Thank you that is tomorrow’s project I’ll get this one way or another hopefully.
Actually after reading this on my PC rather than my phone, I have a better grasp of what you did there. Why not just swap in the complete boom element? I'm guessing the only issue with the boom element was a weak port relief valve, though I could be wrong.
Good day Hammer Please see attached. Kind regards Uffex
Good morning I don’t think my element has a load sensing valve or is it just a port or channel that goes though the entire main block assembly, when I took it apart there was nothing above pressure compensator and the plug. Interesting I’m learning a lot. I will check this today too get back to you thank you very much. Uffex do you have a diagram of the flow with the spool moving in each direction like the one you sent me that would be interesting to look at thank you again
https://linksharing.samsungcloud.com/mCPNlqoxDUu2
So I had 2 hose made up today and put them on and low and behold the thumb works unbelievable I guess looking at the fluid come out the of the ports without actually checking it with a hose and pressure was my downfall. Also put the pressure relief valve from the old element on the auxiliary foot valve element. I appreciate everybody’s help thank you very much what a relief!
https://linksharing.samsungcloud.com/gAuFtMIuJSj9
Good day I guess it is for you Hammer that is good news, I assume I there is no need for any further information? Kind regards Uffex
Yes it is a good day thank you I guess this all started When I replaced the two auxiliary pipes at the top of my boom that were cut and pinched off after replacing them I operated the auxiliary foot valve and flow came out of both lines. I didn’t realize that you have flow in both lines like lantraxco said “hooking a small cylinder to the ports. You will always get oil out of both ports because one is pump pressure, the other is return which may be 25 psi or more back pressure“. So that was a big lesson learned in my mind on the actual flow of hydraulics.The illustrations of the spool was also Inspiring to me to find how everything worked inside. Thank you to everyone
Glad you got it going, good job!
Soooo, I am in almost the exact same situation, though my machine is set up a little different. I'm trying to clarify what you did here, and see if it will apply to my machine? I have an EC25 and just installed a Manca thumb. The machine has two aux lines on the stick, and I mistakenly did not realize that one was a return as the Aux control pedal moved in two directions (so I ASSumed it was for a dual action cylinder). But, It's just a pressure and return, so I have no way to retract the thumb. Did you change the spool in the valve to make it work in both directions? What else? I imagine I will either need to run a second line to the thumb, or plug the return at the tank and use that line. That's fine as I don't ever see myself using a hammer or tool needing continuous flow. Thanks in advance, I read this a few times but am still a little confused. SD
I should've dug into may machine before posting.. Traced the lines, the aux spool has two lines going out to the boom. One is capped and the other goes out to the stick. I cracked the cap and I get oil when the pedal is rocked back. Looks like I need a hose and I'll be in business. Fingers crossed