Pressure testing difficulties

[bumperm]

Okay, "gage vs. gauge" notwithstanding, there's clearly some confusion going on here . . . I only have a few active brain cells left, so don't want them all in a tither over this :c).

On my B3350 and BH77 hoe: with the hoe off, there's a "power beyond" hose to plug into a fitting on the tractor, this is part of a series loop, dumping the hydraulic fluid back into the reservoir (if I understand this correctly). Routing this hose through the backhoe doesn't change a thing, as long as no valves are moved on the hoe . . . the fluid simply routes through the hoe and back to the tractor's reservoir, right? When one moves a lever on the hoe, then the fluid gets pressurized as it's diverted into a cylinder to do work. Any relief valve on the hoe itself, will only bypass back into the original hose going to the tractor's reservoir - - it would thus have no bearing on any work (pressure build up) being done by any other hydraulic cylinder on the tractor. A relief valve on the hoe, if set lower than the main relief valve on the tractor, would not bypass before the tractor mounted relief if the hoe was not in operation (i.e. the hoe itself, when not being used, is bypassing all the fluid back to the tractor and thus experiencing no pressure build up to speak of).

If this ain't the case, I'm lost!

bumper

 

[J_J]

I am not sure of your question, but here goes.

If the BH is connected, the pump flow is directed through all valves in the series path.

Pump ,hyd blk, BH, 3pt, tank.

When any valve is operated, the cyl attached to that circuit is activated, and the cyl expended fluid is sent to tank except is some situations.

If you should only use half lever, some fluid goes to cyl and some fluid goes to the 3pt and then to tank.

All relief flow goes to tank.

If a downstream valve is activated, it will cause back pressure to upstream valves.

If a valve upstream, is activated, most valves downstream will have no flow through the PB port until that valve operation is complete. Again, half lever will allow some fluid to flow.

Looking at your BH, I don't see a valve relief, but I do see 6 work port relief, which dump to tank if cyl pressure is exceeded.

One of the questions earlier was, will the FEL relief operate if using the 3pt, and it can if set lower that the 3pt setting. If both relief are set the same, then either one will operate.

Forget the master relief, the relief valve upstream after the pump is usually in control.

You could set each relief to a different valve to protect that circuit, but if there is a relief upstream set lower, then that relief will activate.

You all have to agree that the lowest relief valve setting in the series flow path is going to operate at the set pressure

For instance, if you had some 2500 psi cyl on an attachment and using the remote valve set at 2450 psi,, and your FEL valve was set at 2950 psi.

The remote valve would operate and protect the cyl when the attachment cyl developed the 2450 psi.

 

[skyhook]

I am not sure of your question, but here goes.

In other words, if my backhoe's relief is set "lower" than the hydraulic block's, it could very well be the reason
my loader is going into relief before it should while the hoe is attached..

Whats your theory on this, JJ.

 

[J_J]

If your BH seems weaker, then it is because it is due to the relief set point or the valve is leaking.

If your loader valve is set to say 2500 psi, and that is the only relief before the 3pt, then the loader valve relief will dictate the relief pressure.

If your BH has a valve relief set higher that the loader, the loader will still dictate the relief pressure.

If your BH has a valve relief and is set lower that the loader relief, then the BH relief will dictate the relief pressure.

The relief valve with the weakest setting upstream will activate first.

As you use valves further downstream, the valve with the weakest relief valve will activate.

 

[J_J]

J_J
OK on my '11 Kubota M7040 with a Kubota LA1353S FEL the feedback rod was set incorrectly so as when the 3 pt was fully raised the 3 pt continued trying to raise. The relieve valve that opened was the 3 pt relief valve not the factory FEL relief valve. No I did not install a "gauge" but used a laser thermometer to determine the heat differentiation plus the sound of the by-passing valve. I wouldn't alter my tractor's factory set relief valves while tractor is in warranty anyway. After adjusting feedback rod noise and heat at rear of tractor disappeared.. Are you trying to state that on a Kubota tractor that FEL relief valve should come from factory set at a lower setting than 3 pt relief valve.?????????????? If the books don't mention MASTER RELIEF then this wild idea must be YOUR THEORY !!!!!!!!!! Did you ever research the differences in CC & CCLS hyd's?
Jim

If your 3pt valve is set lower than the loader relief valve, then the 3pt will definitely relieve.

When you see tractor specs for the tractor with out attachments, usually the only relief is the 3pt.

How the loader valve is set is debatable.

They probably set what ever the attachment manual calls for. If it should be lower than the 3pt relief, then the loader relief will dictate the max pressure, and not the 3pt.

So if you want max pressure out of the hyd system, set them the same.

So when checking pressure, you have to know what you are doing and how things work.

If you are smart, you would set the loader relief to tractor specs and then go down the flow path setting all relief valve the same, including the BH if it has a relief.

Only then will you be getting max pressure out of all valves.

Work port relief are different.

 

[bumperm]

J.J.

Just to be clear, the work port relief/s on my BH77 don't provide relief function for anything other than the backhoe function/s (valves) that have them. When they go into relief, they start bypassing the BH cylinder/s doing work and send the bypassed fluid to the tractor reservoir. The BH work port relief/s do not affect other tractor functions such as the FEL or 3-point. However, a tractor relief port would affect the BH *if* it is set at a lower pressure than the BH work relief ports - in which case the BH work port relief port would never bypass as the tractor's relief port would bypass first, thus limiting the power available at the hoe.

Right?

bumper

 

[skyhook]

I think I'm starting to understand how this work's now,,
whats the difference between "relief ports" and "Work port relief's".

 

[Tx Jim]

If your 3pt valve is set lower than the loader relief valve, then the 3pt will definitely relieve.

When you see tractor specs for the tractor with out attachments, usually the only relief is the 3pt.

How the loader valve is set is debatable.

They probably set what ever the attachment manual calls for. If it should be lower than the 3pt relief, then the loader relief will dictate the max pressure, and not the 3pt.

So if you want max pressure out of the hyd system, set them the same.

So when checking pressure, you have to know what you are doing and how things work.

If you are smart, you would set the loader relief to tractor specs and then go down the flow path setting all relief valve the same, including the BH if it has a relief.

Only then will you be getting max pressure out of all valves.

Work port relief are different.

J_J
My M7040 has performed any hyd task I've asked it to do therefore I will be SMART and leave all relief valves set exactly the way they came from the factory.

Again I'll ask if the tech manuals don't mention "master relief valve" then why do you call FEL a master relief valve when in fact you admitted that the valve set for lower psi will pop off 1st which anyone who understands hyd's know this is a fact. ??????

PS: Skyhook has a good question whats the difference between "relief ports" and "Work port relief's"
I hope you have a good day,Jim










'

 

[J_J]

My day is going good. I love this stuff

With valve lever in neutral, work port relief protect against cyl over pressure.

While cyl's are being pressurized, the valve relief protect the circuit and pmp, whether that valves relief or a relief valve upstream set lower.

A relief port/aux port is the port where a relief valve would fit.

A work port relief will usually work when mechanical work forces a cyl to exceed the set pressure.

An example would be when you slide a load off a trailer, and place the lever in neutral and the load exceeds the cyl potential. The work port relief will release the pressure to tank dropping the load to the ground. The main relief is not in use with valve in neutral.



The term Master relief can be associated with the relief valve that is doing the most work.

If you want to use master relief, then do so to indicate that relief valve in charge.

I really don't care if your/all manuals says master relief, but if there is another valve relief doing all the work, why call the other relief valve the master relief.

The valve relief doing most all the work is also called the Main relief, and that will change if you want it to which valve relief is set lower..

Some of you are grasping at inference.

Inference: Deriving Conclusions from Indications

 

[Tx Jim]

With valve lever in neutral, work port relief protect against cyl over pressure.

While cyl's are being pressurized, the valve relief protect the circuit, whether that valves relief or a relief valve upstream set lower.

A relief port/aux port is the port where a relief valve would fit.

A work port relief will usually work when mechanical work forces a cyl to exceed the set pressure.

An example would be when you slide a load off a trailer, and place the lever in neutral and the load exceeds the cyl potential. The work port relief will release the pressure to tank dropping the load to the ground. The main relief is not in use with valve in neutral.

What's a main relief? Is that a different terminology for master relief?