Backhoe Hydraulics for Backhoe

[jgbanshee]

If I have the loader valve in the series first and the backhoe second, will I need a relief valve after the loader before the backhoe valve? Or will the loader releif take care of that? I am really not sure how when the relief works. I thought once the valves build up pressure the relief kicks in and routes the fluid to the reservoir. Then I would need on after the loader valve.

The relief would be used if I did not connect a loop when I remove the backhoe from the series. Then the relief would dump the fluid back into the "TO TANK" line. Right?

 

[jgbanshee]

Just talked with a Ford/NH service guy and he told me some things.

1. Best way - use a selector valve inline before the the INLET on loader valve. Run back to the tractor quick connects with 3/4" hose and then through the backhoe and to the return with 3/4" hose. Then when I take the backhoe off, use a loop at the tractor quick connects incase someone throws the selector valve not knowing any better. He said this is the way the Ford 4500 tractors were plumbed for their backhoes.

2. Put a Power Beyond plug in the backhoe. Run pressure to the backhoe, through backhoe and then to the loader. I will lose pressure to the loader because the backhoe valves will reduce the pressure.

3. Plumbing loader and backhoe valves in series. He says that this will reduce the flow back to the reservoir like putting a restrictor valve inline. He claims this is no good. I asked if I could put a diveter valve right before the backhoe so the backhoe can use what it needs and the rest will flow to the reservoir. He said that the outlet side of the loader valve does not have pressure.

I would like to run the backhoe in series like you're telling me to because then I can eliminate the step of throwing the selector valve all the time. So, is there pressure on the outlet side of the loader valve?

 

[herringchoker]

Attached is a rather poor copy from the service manual for the backhoe that was factory installed on my old Ford 4500. There is no selector valve and the oil flow is from the pump to the backhoe valve to the loader valve, with the backhoe valve (being first in the series) having the power beyond function. The loader subframe plus the surge reservoir in the tractor nose were the "tank". I don't mean to confuse the issue, but that's how it was set up.

 

[MadReferee]

Just talked with a Ford/NH service guy and he told me some things.

1. Best way - use a selector valve inline before the the INLET on loader valve. Run back to the tractor quick connects with 3/4" hose and then through the backhoe and to the return with 3/4" hose. Then when I take the backhoe off, use a loop at the tractor quick connects incase someone throws the selector valve not knowing any better. He said this is the way the Ford 4500 tractors were plumbed for their backhoes.

2. Put a Power Beyond plug in the backhoe. Run pressure to the backhoe, through backhoe and then to the loader. I will lose pressure to the loader because the backhoe valves will reduce the pressure.

3. Plumbing loader and backhoe valves in series. He says that this will reduce the flow back to the reservoir like putting a restrictor valve inline. He claims this is no good. I asked if I could put a diveter valve right before the backhoe so the backhoe can use what it needs and the rest will flow to the reservoir. He said that the outlet side of the loader valve does not have pressure.

I would like to run the backhoe in series like you're telling me to because then I can eliminate the step of throwing the selector valve all the time. So, is there pressure on the outlet side of the loader valve?

1. that will work.

2. The backhoe valves don't loose pressure. You have no pressure until you activate a spool. You do always have flow and the valve itself may reduce the flow slightly but no more that any other valve would.

3. Total BS. This guy does not know what he is talking about.

Remember you have little or no pressure until something (a spool) is activated that the fluid can work against. Also you have to have flow exiting the valve when all spools are in neutral otherwise you pump will deadhead. I would simply ignore that guy.

 

[jgbanshee]

herringchoker, Thanks I kind of figured that based on what everyone on here told me. The issue with mine is that the Bradco valves will restrict the flow unlike the valves on the Ford backhoes.

 

[MadReferee]

As best as I can see from herringchoker's diagram, the backhoe valve is first in line and is configured for power beyond. The loader valve is last in that circuit and does not have power beyond, which is ok since it's last in the circuit.

 

[jgbanshee]

Madreferee,

1. OK

2. I messed up and said pressure. I meant flow.

3. Is the outlet from the loader valve pressure?

 

[MadReferee]

You always have flow in an open center system. Fluid enters the valve and exits the valve and finally finds its way back to the tank, otherwise you would deadhead the pump. There is no fluid loss in the system.

You only have pressure when the fluid has something to push against, like a cylinder, and you only have that when a spool is activated. You will have some inherent pressure due resistance caused by line size and fitting bends, etc. but it is noise level as far as this discussion is concerned.

There is no pressure on the outlet side of the loader or any other valve. All you have is flow.

 

[JerryG]

3. Total BS. This guy does not know what he is talking about.

I didn't notice the size of valve on the backhoe. Was it stated somewhere?

 

[jgbanshee]

The backhoe requires 9 to 14 GPM.