How Does a Manifold Work?

[Iplayfarmer]

This is related to my "What's this fitting" thread, but it's enough different I'm giving it its own thread...

What are the advantages and disadvantages to hydraulic manifolds? How do they work? What are their limitations?

My particular application is adding a loader to a SCUT. All of the diagrams of the aftermarket loaders for my Massey 1215 start the hydraulics with some kind of a manifold block, but there's no indication how this manifold block gets on the tractor. Some day in the future I'm going to add a Backhoe too.

I've been chasing fittings to do the plumbing in series with hoses, but I'm wondering now if I'd be better off looking at a manifold block under the cowl for the loader and a manifold block at the rear just before the 3pt. for the backhoe.

Part of the fun of this whole project is learning how things ought to be done. I know I can do it with just a bunch of adapters, NPT fittings and hose, but I'd like to at least know the right way.

 

[kennyd]

The "manifold" they are speaking of in the FEL manuals is just a block on the tractor with ports to tap into the hydraulic system. The manifolds are provided by the manufacturer of the tractor, or they come already installed.

The way you are doing it is perfectly acceptable.

 

[Wayne County Hose]

A manifold can have a bunch of functions. It can be a simple junction block, use it instead of Tee fittings, or it can have some type of valve in it. They usually have some kind of component in them, like a relief valve, check valve, or a solenoid valve.

They are usually a block of aluminum with ports drilled through them to send the fluid where it should go. There's nothing magical in them. They really have no limitations I can think of, I see them in 6,000 psi circuits on excavators.

Kenny types way faster than I do. Keep your hand out of the table saw.

 

[Iplayfarmer]

Why do most "factory Installed" hydraulic systems seem to use a manifold? I guess I'm assuming that there's some advantage to it vs. running hoses.

 

[J_J]

As stated above, the manifold is a distribution point. It saves on the number of hoses, and as Wayne stated serves other functions. They are easy to manufacture, and several circuit can use the same manifold. I have at least three manifolds on my Power-Trac. One of those is to collect the case drain fluid from the hydraulic motors, and route it to the cooler radiator. One of the other manifolds has three relief valves installed. The one in the front has six inlet and outlet ports, for hydraulic motors, and PTO circuit, and front hydraulic motor case drain.

This is a simple manifold below

Burden Sales Surplus Center Item Detail

 

[Iplayfarmer]

...I have at least three manifolds on my Power-Trac. One of those is to collect the case drain fluid from the hydraulic motors, and route it to the cooler radiator. One of the other manifolds has three relief valves installed. The one in the front has six inlet and outlet ports, for hydraulic motors, and PTO circuit, and front hydraulic motor case drain.

So is your PT a closed center or open center system?

In an open center system, how would this block you mention with six inlet and outlet ports work? Do you have to have something hooked to all six ports to get the system to work? Even if that something is just a dummy hose to complete the circuit.

Maybe another way to ask this is how do you have multiple hydraulic circuits in an open center system?

 

[kennyd]

Maybe another way to ask this is how do you have multiple hydraulic circuits in an open center system?

You use the PowerBeyond ports on the valves to feed the next valve in series. ALL valves are plumbed in series.

 

[J_J]

So is your PT a closed center or open center system?

In an open center system, how would this block you mention with six inlet and outlet ports work? Do you have to have something hooked to all six ports to get the system to work? Even if that something is just a dummy hose to complete the circuit.

Maybe another way to ask this is how do you have multiple hydraulic circuits in an open center system?

On the Power-Trac, we have both, the drive system is a closed loop, and the other two pumps are gear pumps, pushing fluid through open center valves. On a manifold, you can have both open and closed loop fluid flowing through the manifold. The path can be separate or combined as in the wheel motor case drains. My PTO fluid comes through that same manifold through another channel. A manifold is a simple devise to connect things together. or could be complicated by adding relief valves, or shuttle valves, or a hydraulic accumulator.

Yes, all the lines need to be connected, so the fluid can be routed to a valve, or reservoir or back to pump.

The below picture is a manifold with three electric valves using three different circuits.

 

[J_J]

Here is a pictorial of what the inside of a complicated manifold would look like.

http://www.mandwmfg.com/gallery/2d-3d-final/100566-3D.pdf