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.

 

[herringchoker]

Now I see where the Ford guy is coming from...your tractor pump puts out 26 GPM and your backhoe valve is designed for 14 GPM. I'm no hydraulics expert, but it seems to me that would put quite a restriction in the circuit.

 

[MadReferee]

Well, now it makes a little more sense. It always helps to have the entire set of specs and circumstances.

First of all, I would never plumb the backhoe before the loader valve, even if the loader valve didn't have power beyond. Since you never activate the backhoe valve and loader valve together, the loader not having PB is a non-issue.

With the backhoe having less flow capacity (it will still flow but heat might be an issue) the diverter option or simply breaking the circuit and installing the backhoe only when needed (manual diversion) is starting to sound better.

 

[jgbanshee]

Well about 30 posts before this one the 9-14 GPM spec was listed. That is why I had so many talks with Ford people and post on here and was not completely understanding. So I would have two choices to go with now.

One being, plumb the backhoe and loader in series with a diverter valve that transfers excess flow back to the reservoir.

Two being a selector valve that I would have to throw the valve on to use either the backhoe or loader.

Anyone have any opinions on the first one being a bad option?

 

[MadReferee]

Well about 30 posts before this one the 9-14 GPM spec was listed. That is why I had so many talks with Ford people and post on here and was not completely understanding. So I would have two choices to go with now.

One being, plumb the backhoe and loader in series with a diverter valve that transfers excess flow back to the reservoir.

Two being a selector valve that I would have to throw the valve on to use either the backhoe or loader.

Anyone have any opinions on the first one being a bad option?

Hey, 30 posts ago is a long time.

As for option one, I don't think there is such a thing that "diverts excess flow". All the common diverters I have ever seen diverted all flow to whichever output was selected. You would want something like a splitter or metering valve that will take the full flow and split it between 2 outputs. Keep in mind that this can't be done simply with a valve. Since fluid will take the path of least resistance some type of metering will have to be done inside the splitter. Maybe the valve the dealer suggested does that, but before I spent any money on that suggestion I would want to see the spec sheet on what he is proposing to see what it "really" does.

 

[jgbanshee]

Again I misused the word diverter, I mean divider. Im looking through a Surplus Center catalog and found dividers that have Max Input of 30GPM and divide the flow to two outputs ratios like 2:1. The one I found has a priority "A" that is adjustable from 2-14GPM and the excess will flow out "B." The only thing is that the ports are 3/4" NPT and not 1".

Surplus Center Item Detail

 

[MadReferee]

That will work. You have to plumb so that the loader valve is first, the flow divider is second and the backhoe valve is last. This gives full flow to the loader and whatever you have the divider set for to the backhoe.

Where is the 3pt in all this? It's hard to make out the earlier diagram.

 

[jgbanshee]

Good. The 3pt hitch on this tractor has its own hydraulics system seperate from the front mount engine pump.

If I use the divider valve and direct fluid from outlet "B" on divider valve back to the reservoir can I TEE that into the same return line that will come from the backhoe outlet.

 

[montejw]

Well about 30 posts before this one the 9-14 GPM spec was listed. That is why I had so many talks with Ford people and post on here and was not completely understanding. So I would have two choices to go with now.

One being, plumb the backhoe and loader in series with a diverter valve that transfers excess flow back to the reservoir.

Two being a selector valve that I would have to throw the valve on to use either the backhoe or loader.

Anyone have any opinions on the first one being a bad option?

I'm not trying to dispute what MadReferee has been saying, just adding my 2 cents worth, and maybe just saying the same thing a little differently.

The outlet from the loader valve (open center, no power beyond) is all flow IF nothing is plumbed after the loader valve. If you plumb the backhoe in series after the loader valve in the loader valve outlet line you will be able to operate the backhoe if the loader isn't being used at the same time. However you will be restricting the flow through the loader valve because your backhoe valve is only rated at 14 gpm. That's all the flow you'll get through the loader valve even if the backhoe isn't being used.

If you use a diverter, it's plumbed between the pump and the valves, giving full flow to whichever the diverter is set to select.

If the loader valve has power beyond the backhoe is plumbed to the power beyond line, and the outlet line is still going to the tank.

The 3 pt hitch is the last thing plumbed no matter as it dumps to the tank directly. At least you can't easily get to the outlet in any case. Plumb it to either the outlet of the backhoe or loader, whichever is second. Or plumb it to the power beyond of the last thing if that's what's there.

Monte

 

[MadReferee]

Good. The 3pt hitch on this tractor has its own hydraulics system seperate from the front mount engine pump.

If I use the divider valve and direct fluid from outlet "B" on divider valve back to the reservoir can I TEE that into the same return line that will come from the backhoe outlet.

I don't see why not, unless I am missing something.

 

[MadReferee]

The outlet from the loader valve (open center, no power beyond) is all flow IF nothing is plumbed after the loader valve. If you plumb the backhoe in series after the loader valve in the loader valve outlet line you will be able to operate the backhoe if the loader isn't being used at the same time. However you will be restricting the flow through the loader valve because your backhoe valve is only rated at 14 gpm. That's all the flow you'll get through the loader valve even if the backhoe isn't being used.

Yes, if the flow is restricted by any valve then your flow can only be that value.

If you use a diverter, it's plumbed between the pump and the valves, giving full flow to whichever the diverter is set to select.

Correct.

If the loader valve has power beyond the backhoe is plumbed to the power beyond line, and the outlet line is still going to the tank.

Yes. The loader's PB outlet line goes to the backhoe and the tank outlet line goes to the tank. PB valves have 2 outlets so you must be specific as to which you are talking about.

The 3 pt hitch is the last thing plumbed no matter as it dumps to the tank directly. At least you can't easily get to the outlet in any case. Plumb it to either the outlet of the backhoe or loader, whichever is second. Or plumb it to the power beyond of the last thing if that's what's there.

According to the poster, the 3pt has its own circuit (see above).