Summit Monoblock Directional Control Valve

[RickB]

The tank port on this valve is rated for 725 psi. Your tractor goes to about 2500. If you plumb the tank port into the 3pt (which is what you'd do if you put it in the BH loop) you'll damage the valve the first time you pick up something heavy on the 3pt.

You need to get it with a PB port and run that to the 3pt and tee the tank into the tank line from the loader. I'll second @ptsg's suggestion to get a valve with a detent on one spool to run the BH off of. Then you can get rid of the BH loop sticking out the back. I'll also suggest that you get a valve with a spool that goes into float. It can be useful for some implements.

I have two factory valves and a dealer installed 3rd valve on the fender. I moved the lever to point forwards instead of up and it's very easy to use that way. This valve would let you do the same.

Post #7 clearly shows the tank port of the newly added valve going directly to tank.

 

[mechtheist]

My plan is to hook the BH lines to the new valve, not bother with PB, if I need the BH, just switch the lines. I'm not sure I understand how the loader gets involved. Does the hydraulic fluid to the BH come off the loader?

 

[RickB]

My plan is to hook the BH lines to the new valve, not bother with PB, if I need the BH, just switch the lines. I'm not sure I understand how the loader gets involved. Does the hydraulic fluid to the BH come off the loader?

Typically pump flow goes to the loader valve first then on to remotes, pb for a backhoe (if so equipped) and finally to the 3 pt hitch valve.

 

[K5lwq]

My plan is to hook the BH lines to the new valve, not bother with PB, if I need the BH, just switch the lines. I'm not sure I understand how the loader gets involved. Does the hydraulic fluid to the BH come off the loader?

Yes the backhoe most likely gets its fluid from the loader valve through the power beyond port.

If you look at the diagram you posted in post 7 you can see how the flow works. If you ignore the new valve in the diagram and just draw a line from the loader valve PB to the Power in for the backhoe that is how it works.

Your Three point hitch valve gets its power through loader valve as well.

 

[mechtheist]

That's a Summit example but it looks like it is also how the 3520 is connected. Below is from the 3520 Service Manual. The red labels are added. Since I don't have rear remotes, that must be standard on the cabin model, I'm assuming the backhoe setup just uses the same lines and the way it looks on the tractor kinda resembles the schematic drawing '7'. If that's true, then it's pump to front valve to backhoe to rear-3pt.

I'm a lot more familiar with electric systems but I know they are highly analogous. To me, the lines that flow from the pump through the various valve inputs to their powerbeyonds is like the voltage rail for a power supply, they're 'shorts', so if you removed a valve and replaced it with a pipe or hose from inlet to powerbeyond outlet, nothing would change downstream [assuming no inputs to whatever the valve was controlling to muck up the analogy].

If that's the case, then when the backhoe is attached, the 3pt. hydraulics are getting 'used' hydraulic flow but that's fine since the 3pt bits are all disassembled when the backhoe is there so you won't be using the lift arms. [But then, how does that flow get to the tank? See below]

So that brings me back to the question of what is the issue with the loader valve wrt the backhoe hydraulic lines and the tank port ratings etc? The tank port only gets flow from the fluid used on the front loader and it's really really unlikely they'd ever both be getting used at the same time. It seems like installing this valve controller would essentially be adding the rear remotes that come with the cabin model.

The electrical analogy only goes so far, power supplies don't mind at all if they're facing an open circuit but hydraulic pumps have to flow if I understand it correctly else they'll burn out. So if you only go to one valve, if it's not in use, the high pressure flow has to go somewhere and I assume from prior posts above it can't just be shunted directly to the tank so how is that handled? Also, why can't you just 't' off for any valves needed like you could in an electrical circuit and do away with powerbeyond? I appreciate the patience shown here, I'm trying to get a handle on these things and it takes a while to sink in my ignorant decrepit head.

 

[K5lwq]

Okay, forget about electric systems or hydraulic systems for a moment.

Lets say you have one outside water faucet with a splitter. Then you have two garden hose hooked to that splitter. At the end of each hose is a sprinkler. When you open the valve both sprinklers will work.

Now turn off the water and remove one sprinkler and leave that hose open. What happens to the other sprinkler when you turn the water back on? It will not work because all your water is taking the path of least resistance out the hose that is open.

Same thing with splitting a supply line on a open center hydraulic system. You will not be opening both control valves at the same time so the fluid will take the path of least resistance which is thru the valve not used and back to tank. You will not have any power to move a cylinder.

Now think of that water hose again. If you have only one hose and crimp off the flow, what happens to the pressure? It climbs till it reaches equal pressure that is in your water system.

When you use the tank port of a hydraulic valve to feed another valve and you use the new valve the line pressure builds to equal pressure of the system. This back pressure on the tank port will fracture the valve because it is designed to be open with only flow pressure. When you use the power beyond sleeve that port now can handle the system pressure.

Does that make sense now?

 

[JM7500]

I have a backhoe for my 4820R. With the backhoe package, additional hydraulic lines are added, larger than the rear remotes which I have. When the backhoe is off the tractor, the backhoe hydraulic lines are connected together and fluid flows through unless hydraulic fluid is used somewhere upstream. The factory rear remotes on my tractor are 1 spring and 1 detent. I plan to get a hydraulic top link soon. In the future, I want to add a hydraulic thumb on the backhoe connected to the detent rear valve. I'll add another valve by the backhoe controls to operate the thumb.

 

[ericm979]

The flow goes through all the valves in series. Pump -> loader -> 3pt. On each valve the flow goes out the tank port or PB port if the valve has PB, and on to the next valve. Unless the valve is actuated, then flow goes out the work ports. When you operate the 3pt, the pressure to run that comes from the pump, through the loader valve.

Now add an additional valve: Pump -> loader -> new valve -> 3pt. The pressure to lift the 3pt goes through the new valve. If you plumb it without using PB the tank port will see that pressure, which maxes out at about 2500 psi.

There are valves with tank ports that can handle full pressure. The dealer installed additional remote on my 3725 is one. But they are not that common.

BTW the last time I heard the factory remote kit was a lot less than other manufacturer's remote kits. With all the stuff you'll need to buy to DIY, easily another $150, plus fabbing brackets, it might make sense to price the factory kit. It does integrate nicely in the cabin.

 

[mechtheist]

Okay, forget about electric systems or hydraulic systems for a moment.

Lets say you have one outside water faucet with a splitter. Then you have two garden hose hooked to that splitter. At the end of each hose is a sprinkler. When you open the valve both sprinklers will work.

Now turn off the water and remove one sprinkler and leave that hose open. What happens to the other sprinkler when you turn the water back on? It will not work because all your water is taking the path of least resistance out the hose that is open.

Same thing with splitting a supply line on a open center hydraulic system. You will not be opening both control valves at the same time so the fluid will take the path of least resistance which is thru the valve not used and back to tank. You will not have any power to move a cylinder.

Now think of that water hose again. If you have only one hose and crimp off the flow, what happens to the pressure? It climbs till it reaches equal pressure that is in your water system.

When you use the tank port of a hydraulic valve to feed another valve and you use the new valve the line pressure builds to equal pressure of the system. This back pressure on the tank port will fracture the valve because it is designed to be open with only flow pressure. When you use the power beyond sleeve that port now can handle the system pressure.

Does that make sense now?

It makes sense but it doesn't answer the main thing I don't understand. [Plus, if I forget about hydraulic systems, how am I then to think about water in a hose?] From what you're saying, it must be the case that the hydraulic system can have the fluid flow blocked most of the time, it's the only way for pressure to build up, so my stated assumption was completely wrong. If using the powerbeyond in a valve, then the downstream valve would have to NOT use its PB or, basically, the last valve would have to NOT have its PB connected to anything [which is kinda true by definition].

I haven't suggested using the tank outlet anywhere or if I did, it wasn't intentional.

In my 3520, what I guess is going on is the backhoe hoses are downstream of the PB on the loader valve which then goes to the 3pt lift valve which is where the end of the line is that allows the pressure to build. I hope I have got it right now?

 

[K5lwq]

Fluid flow is not blocked most of the time. It is redirected to perform some type of work. This is why they call the valve a directional control valve. Fluid is always flowing somewhere as long as the pump is pumping.

I guess I do not understand what your main thing you don't understand is.