Hydraulic pressure gauge

[Everhard]

I'm thinking about adding a pressure gauge to my hydraulic system, mostly to make sure it's running at or near the right system pressure for my tractor. I figure if I'm going to test the system I might as well just make the gauge be permanent. So does it matter where the gauge is?
I'd like to put it in line between the loader valve and the custom 3 port valve. (that I added previously which is between the loader valve and the rear hydraulics - rear remote & 3pth.)
Am i right in thinking that will work and the I'll see the system pressure if I T a pressure gauge in on the high pressure line going to the 3 port valve?

Thanks,
E.

 

[rScotty]

It's a good and simple project. Use hydraulic fittings and a 5000 psi gauge. Many are glycerine damped, but pure glyceriin freezes in the winter. You can dilute it. No reason you cannot use quick connects to move the gauge around - except that gauges and fixed Tees are sometimes less expensive than good QCs.

In an open center system, the system pressure is nearly zero at the "in" connection to any control valve stack in the IN/PB/IN series chain until you move a control valve. That is because until you call for fluid to a cylinder, the fluid is just circulating back to the sump through the returns. You may see a tiny bit of constant pressure due to the resistance of the system to flow. This constant resistance pressure should be too small to see on a 5000 psi gauge.

When you actuate a control valve to move a cylinder or two, you will see how much pressure is required to move that cylinder set and any load - like lifting a or tilting a bucket. You won't see how much more is available. The pressure that is used depends on the load and geometery minus any regeneration. Regeneration can be tricky if your system has it.

The way to see system max pressure is to try to "move the unmoveable" until the relief valve cuts in. Relief valves are easy to adjust - but generally do not exceed 2750 psi. for safety on parts.

good luck,
rScotty

 

[Everhard]

Thanks rScotty! That all makes sense. I can very briefly deadhead one of the valves in that block which will then show the flow in the gauge. Good call on the quick connect option, certainly more money but won't break the bank and then I don't have to worry about the gauge getting broken.
I'll confirm what the system pressure should be before I adjust the report valve if it's low.

E.

 

[rScotty]

You can hold it long enough to get a good reading. Needn't be too quick. Some manuals recommend holding the system in relief on cold days to heat the hydraulic oil.

Glycerin can be tweaked. You can do it with a 12cc syringe, screwdriver & distilled water. Put the pressure relief bubble at the top.

 

[WranglerX]

Don't really need full time monitoring unless you suspect problem in system.... If pressure relief is set properly the gauge is just a added place for damage or failure ...
A gauge on hose with QC and a moment of deadheading the hydraulic line should be quite enough to tell if system is up to correct pressure....

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Bolt-On Hooks and Hydraulic Tools for compact tractors.

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[oldnslo]

If you install the gauge down stream from loader valve you will not be able to verify loads on the loader. I just installed a test port on my loader valve so can quickly install a gauge, verify pressure is correct and then remove the gauge so doesn’t get broken.

 

[Smokeydog]

I keep a gauge on mine. Used to not only measure relief pressure but also monitor KSR, Kubota Soft Ride feature. Being an eccentric engineer like seeing real time measurements. The electronic gauge has features like different scales, max pressure, tare, back lighting, etc. Down side is battery life in cold weather. Turning off in cold weather conserves battery.

Be aware hydraulic components down stream from control valve are effective by load and are not relief valve protected on most tractors. Some bigger, expense, more powerful construction equipment do have crossover relief valves. My gauge is on the loader lift circuit. If I lift to relief pressure ~2700psi, close the loader lift valve and then try to curl and or push with the transmission against the load, I can see lift circuit pressure almost double. Dynamic load pressure on top of relief pressure.

Pulling back with grapple tines spikes the dynamic load pressure on 3rd function circuit.

Similar spikes carrying a loads over rough terrain. KSR really dampens those spikes and can feel the difference.

Hydraulic circuits to grader blade angle and top link cylinders can see considerable pressure spikes do to the lever arm force against the closed cylinder circuit.

My relief valve pressure for the loader is a little low. Older tractor 1500 hours. Still scary strong. See people shim theirs to max or higher. Just keep in mine it’s the dynamic loading that they don’t see or monitor after the relief pressure that can cause component damage.