Valve screwing with my head

[muddstopper]

I have a parker v70, model v70-248-G, air shift and lever shift control valve. I got the valve out of a scrap bin but it is a new valve never been mounted on anything. Supposely the valve is open center, but i have been also told it is a closed center. Both fellows telling me this should know, but neither is really sure. The red cap on top of the valve is In, the blue cap is out, the ports with fittings are A and B. There is also another port on the side of valve, with another red cap that is not marked. There are reliefs for IN port as well as both a/b ports . I can blow air in the IN port, but air doesnot come out the Out port. Ok looks like closed center, but instead of air coming out the OUT port, it comes out the port with red cap on side of valve and below OUT port. there is a plug between the out port and side port that can be removed. Power beyond plug????. If I hand shift valve, air seems to come out the a/b ports, but the in port is so lagre, I cant really tell if anything is coming out of the A/B ports, but I can hear the air change directions inside the valve and only reasonable suggestions is that the air is passing thru the A/B ports. Air is not coming out the side port or the out port when valve is shifted. I dont know what to make of this valve, I am thinking it is indeed a open center valve and the plug between the out port and the side port is for possible power beyond. On the other hand, the relief on the in port could be for pressure sensing and might be set for 650psi for use as a closed center valve. Need a little help with this one. I thought about just finding some fitting and hooking a water hose to the IN port, with such large ports, it hard to get enough air flow thru the valve to really tell whats going on.

 

[muddstopper]

I am wanting to use this valve on my firewood processor that I am building. I intend to use the air shift with a foot pedal to operate the twin cylinders of the splitter. Oil from valve will return to tank with no power beyond being needed. If the plug between the out port and the other port is for power beyond, and I am not sure that is its purpose, but if it is, will I be able to just remove the plug, cap the extra port and just plumb the out port to tank? The plug between the out port and the extra side port can be seen by looking into either port. Also, need some clarity as to why there are what looks like adjustable reliefs on the IN port, as well as the a/b ports.

A little history as to what this valve was originally used for. This valve is used to operate a pair of hydraulic motors in a travel circuit. There are two valves in this circuit, second valve is a selnoid valve that can be switched on to make the equipment 4 wheel drive or off for 2wheel drive. There is some sort of dump valve in the circuit that works as a clutch so the machine can coast when motors are not engaged, or come to a positive stop when you let off the foot pedal. Clutch is actuated by manual lever and cable connection. Hydraulic fluid flows from pumps to a large selnoid valve bank with manifolds, then to valve in pictures before going to selnoid valve for 4wd motor and then to tank. The equipment has several pumps and circuits tied together to make P1-P5 circuits. Some of the pumps are victor vane type pumps, which I assume are charge pumps to the larger variable displacement pumps. Travel circuit is two speed, operating off one pump for low speed and two pumps for high speed. Now there are several selnoid valve banks on this machine to operate a bunch of different operations. If variable pumps where connected directly to this valve, I would think closed center, but since the pumps run thru several valve banks before getting to this large control valve, well, I just aint sure what this valve is

 

[muddstopper]

154 views and nobody has an opinion?

 

[stan33]

Reckon you need to find out from Parker what the exact model configuration was when ordered. You might be able to work it out from these pdf's if you have all the numbers/codes ...takes while to load:
http://www.parker.com/literature/Hy...c bulletins]/Bul HY14-2712-B1 V70 V90 DCV.pdf
Housing number should narrow it down:
http://www.parker.com/literature/Hy...rvice Literature/Bul HY14-2712-M1 V70 DCV.pdf

 

[muddstopper]

Thank You Stan!!, I have searched the Parker sight until my eyes blurred and never found those two pdf files. Which I just promptly downloaded and saved.

From what I can tell, the valve is easily converted from closed center to open center by simply using the conversion plug that is installed between the out port and the extra side port. For normal open center, you just remove the plug, cap the extra port and plumb the out port to tank. For power beyond, you leave the plug in place and plumb extra port for power beyond and the out port of excess flow to tank. And for closed center, you leave the plug in place and cap the extra port, with out port being used to return to tank. For my use, it looks like I just remove the power beyond plug, cap the extra port and use the out port as return.

I guess that sort of explains why my two knowledgeable folks, that have been telling me the valve is open center and closed center, where both correct, it just depended on how the valve was plumbed and what the application called for.

 

[stan33]

The options for plumbing were for when the valve was ordered from Parker. The way you have it now (unless it was changed later) would have been the options/configuration chosen when it was ordered. I don't think they were intended as DIY options....there may be more to it than you describe. I would check with Parker to make sure any changes you want to make, will work.
Each option has a code letter or number. If you can find them stamped on the valve, then Parker should be able to tell you exactly how it configured.

 

[oldnslo]

If this was sued to select two or 4 wheel drive it may have an odd spool configuration also. It may have both work ports common in one position and isolated in the other.

Good luck

 

[muddstopper]

I wont be able to look at the schematics for 3 or 4 more weeks when I get back to work. I am pretty sure this valve is the first valve in the travel circuit and that the oil flows from this valve to the other travel motor thru a selnoid valve and back to tank. I suspect the reason the valve has the power beyond plug. Of course I aint 100% sure. I do know that the steel wheels on the machine will spin at different speeds when in 4wd, which I attribute to differences in the amount of power needed to make the wheels spin. I guess its not really 4wd in the same aspects as one would think a 4x4 truck since the axles are driven independently by seperate, but identical, hydraulic motors. I also know that you can turn off the air shift to this valve and just run off the front axle. Its kind of weird if your not familar with this type of equipment. It actually has two 4 speed transmissions. The rear transmission has a high and low range and the front axle only works in low range. The machine works in 4wd using both travel motors, but travels in 2 wd using just one travel motor. The machine uses all kinds of proportioning valves, flow control valves, pressure switches, electronic CANs, and looking at the plumbing it looks like a bowl of spagetti with all the electric switches, and solenoid valve banks. Just trying to trace hoses sometimes will drive you nuts and all those control cables for the computer system, you just hope the tags arent missing and the schematics are correct and something hasnt been added that isnt original OEM. Most of this equipment is 20-30 years old and has been rebuilt a few times over the years.

 

[stan33]

Other option could be to take it into a Parker dealer to get them to look at it/test it out and let you know how it is set up.
They could also advise on if it can be changed to the way you want.
Failing that you could try a hydraulics shop who has a test bench.

 

[muddstopper]

I had thought about taking to a parker dealer, but the closest one to me that I know of that has a test bench would be about 240miles away. I am sure there are probably a couple closer, but It would still be a hundred miles or more. If I have to, I will just take it apart and see whats in it. I just hate taking apart a new valve.