Summit Monoblock Directional Control Valve

[npalen]

Here is the kit for that valve:

https://summit-hydraulics.com/product/detents-for-p40-p80-monoblock-hydraulic-control-valves/

Thanks! I could not find it but was guessing you could and did.

 

[ptsg]

Thanks! I could not find it but was guessing you could and did.

No worries. It was under accessories for P40/P80 valves or something like that.

 

[LouNY]

Lets see if I can help or hinder questions on hydraulic systems.

The Branson tractors and most small tractors of today have what is called an open center hydraulic system.
What this means is that there is always flow through the system at very minimal pressure.
To confuse people even more some tractors including Branson use two separate hydraulic pumps,
both of these are open center systems.

These systems can have several components and valves inline.

The "pump" which is sucking oil from the "tank" through the "filter" then a "loader valve" then possibly
a second set of "valves" for a rear remote then to the "3 point controls"

The pump is pulling fluid from the reservoir or tank and pushing it to and through the first valve in the pressure port and
out the power beyond port, from the power beyond port it is feeding another control valve in the pressure port of that valve and out the power beyond port to the next valve the 3 point pressure in and then out to the tank.
This flow path is an OPEN flow path from the tank through the pump through the valves (doesn't matter how many) out the power beyond until the last valve which because it does not feed any more valves does not need a power beyond just an unrestricted return to tank.
This system can be operated at full tractor rpm and be producing the maximum design flow rate at almost zero pressure, this is the normal state of the hydraulic system.
Now each control valve also has work ports and a return to tank, the work ports are were we can see pressure being developed.
When a valve handle is operated it is diverting fluid flow from the main loop into a work port it is doing this by pinching off the main flow path and opening a flow path to a work port. (most of our control valves will have an A and B work port) The fluid flow through the work port may be going to a cylinder and trying to extend that cylinder the resistance to that cylinders extension is what is creating pressure in the system. If we extend that cylinder to it's limits and it can not travel any more we will see our maximum system pressure. The system pressure will increase from almost nothing to the system maximum when the load is restricting the fluid travel.
The reason for the A and B ports is that when we operate the valve to divert fluid flow to work port A as we open port A to the fluid flowing through the system we are also open port B to the return line of the valve this allows the fluid on the other side of the cylinders piston to travel from the cylinder through the valve to the return line and back to the tank.
When we bring the valve back to the center position the fluid in the tractors system is no longer pressurized and is just traveling in the open loop.
The fluid trapped from our valve to and from the cylinder will have pressure on one side and minimal on the other. The trapped pressure is what is applied to the lines and work ports from the loads applied to the cylinder.( your loaded holding up a bucket of dirt, if it took 1500 pounds of pressure in your system to raise that to that position it is also how much static pressure you will have in that side of the cylinder the hose and to the work port of the valve.)
All of our control valves will require a return to tank line to direct the fluid that was used for work back to the tank when not needed

To make it a bit more confusing some tractors Branson included actually use two pumps, one is the main system pump the other is the steering and auxiliary pump these pumps can share a common suction and return to tank but do not need to. Often the steering pump will provide the power steering for the tractor as well as the smaller auxiliary circuits such as the pto clutch pack, the hydraulic cooler loop and many times some transmission lubrication points.
The main system pump is for our loaders and remote valves a backhoe or other attachments.

 

[JM7500]

k5lwq, you explained it much better than me.

 

[K5lwq]

k5lwq, you explained it much better than me.

Lol I doubt that. Lou explained it perfectly. Hopefully that clears up the confusion.

 

[mechtheist]

Thanks all, y'all have helped me a lot. I understand now about the problem with using the valve in question and how the BH gets away with just the two lines. One of the main points of confusion I finally disappeared with LouNY's post, if interested see next post. I really appreciate your efforts and patience, have a good one.

 

[mechtheist]

Lets see if I can help or hinder questions on hydraulic systems.

The Branson tractors and most small tractors of today have what is called an open center hydraulic system.
What this means is that there is always flow through the system at very minimal pressure.
To confuse people even more some tractors including Branson use two separate hydraulic pumps,
both of these are open center systems.

These systems can have several components and valves inline.

The "pump" which is sucking oil from the "tank" through the "filter" then a "loader valve" then possibly
a second set of "valves" for a rear remote then to the "3 point controls"

The pump is pulling fluid from the reservoir or tank and pushing it to and through the first valve in the pressure port and
out the power beyond port, from the power beyond port it is feeding another control valve in the pressure port of that valve and out the power beyond port to the next valve the 3 point pressure in and then out to the tank.
This flow path is an OPEN flow path from the tank through the pump through the valves (doesn't matter how many) out the power beyond until the last valve which because it does not feed any more valves does not need a power beyond just an unrestricted return to tank.
This system can be operated at full tractor rpm and be producing the maximum design flow rate at almost zero pressure, this is the normal state of the hydraulic system.
Now each control valve also has work ports and a return to tank, the work ports are were we can see pressure being developed.
When a valve handle is operated it is diverting fluid flow from the main loop into a work port it is doing this by pinching off the main flow path and opening a flow path to a work port. (most of our control valves will have an A and B work port) The fluid flow through the work port may be going to a cylinder and trying to extend that cylinder the resistance to that cylinders extension is what is creating pressure in the system. If we extend that cylinder to it's limits and it can not travel any more we will see our maximum system pressure. The system pressure will increase from almost nothing to the system maximum when the load is restricting the fluid travel.
The reason for the A and B ports is that when we operate the valve to divert fluid flow to work port A as we open port A to the fluid flowing through the system we are also open port B to the return line of the valve this allows the fluid on the other side of the cylinders piston to travel from the cylinder through the valve to the return line and back to the tank.
When we bring the valve back to the center position the fluid in the tractors system is no longer pressurized and is just traveling in the open loop.
The fluid trapped from our valve to and from the cylinder will have pressure on one side and minimal on the other. The trapped pressure is what is applied to the lines and work ports from the loads applied to the cylinder.( your loaded holding up a bucket of dirt, if it took 1500 pounds of pressure in your system to raise that to that position it is also how much static pressure you will have in that side of the cylinder the hose and to the work port of the valve.)
All of our control valves will require a return to tank line to direct the fluid that was used for work back to the tank when not needed

To make it a bit more confusing some tractors Branson included actually use two pumps, one is the main system pump the other is the steering and auxiliary pump these pumps can share a common suction and return to tank but do not need to. Often the steering pump will provide the power steering for the tractor as well as the smaller auxiliary circuits such as the pto clutch pack, the hydraulic cooler loop and many times some transmission lubrication points.
The main system pump is for our loaders and remote valves a backhoe or other attachments.

Thank you for this, [see the red type ^^] I was under a misconception you managed to clear up--I kept thinking the circulating fluid was at high pressure, so I could not understand how, with nothing getting used and that flow getting dumped to the tank, that that wouldn't drop the pressure making the whole thing unworkable. I see now that as soon as a valve diverts that fluid to move a cylinder, that's when the pressure develops. It's all much clearer and I feel a lot less like an idiot. I've been watching a bunch of videos on various hydraulic issue, including trying to understand the schematics, they're more difficult to deal with than electronics schematics. Thanks again sensai!

 

[mechtheist]

OK, one last question. I didn't want to mar my posts expressing my appreciation with another question. The valve under consideration seems to be laid out in a nearly universal pattern, there are tons of these things that are all almost identical. The front valve on the 3520 and probably most others has this layout. The issue with doing what I proposed is due to having to connect the tank output of the valve to the BH line that then goes to the 3pt arms and the back-pressure that could develop when using the 3pt lift which could damage the valve. So I need to connect the powerbeyond on the valve to the 3pt hitch, which requires a way to connect the tank-out to the tank. Since the front valve is laid out like the standard pattern, then it has two tank ports which are essentially two holes to the same space, I assume for flexibility in hose positioning, see red arrow in the photo. This would basically t into the tank line from the front valve. I think this should work but I've proven that doesn't mean much!

I've been trying to pick up some knowledge of hydraulic schematics, below is from the service manual. The system is an open system, all the videos I've seem show an open system as an 'H' when the control is centered, all lines connected, and a closed system has the 4 inputs deadended to a 'T', which is what the diagram shows. I'm still working on figuring out what's going on with that but it may have something to do with the little circle that seems to tie the P input to the T output. There is also a check valve which you could call a backflow preventer here. I'm thinking that should work, but I've proven that doesn't mean much! Since the flow to the spools is blocked and with the check valve, that sure seems like doing this won't muck up anything.

Is this doable? Is there another path to the tank I could use? I'm waiting on a price on the factory rear remotes but I have a feeling it's going to be a few hundred dollars more so I'd rather go cheap as long as it will work.

 

[K5lwq]

I would use a hydraulic T the tank hose off of the loader valve. I circled where I would put it on your picture.

 

[LouNY]

Just be aware that you will need a Power Beyond plug in the valve that you are using to send the fluid to the P port of the next valve.
Many times the power beyond plug will go in the straight thru port that may be marked as a T port until a power beyond plug is installed.
Attached is a link to a Prince mono block valve installation sheet it shows that the power beyond can be installed in a couple of different
locations and that an internal plug has to be installed in some setups.
https://www.surpluscenter.com/_MoreSpecs/iPrinceMBValves.pdf