Home Brew Pressure gauge setup

[joea]

Got a B21. Seems to be a "screw and jam nut" adjustment for hydraulic pressure.

I was going to cobble up a pressure test rig that I would plug into the backhoe supply, "in series", so the BH could still operate, if I chose to do so.

The test rig would be a simple "T fitting", a 3000 psi gauge, a male and female quick coupler on each end.

Seems this would be the least "dangerous" and most likely to give an accurate reading.

Thoughts?

 

[jaxs]

I think it's an excellent idea and refreshing to hear.

 

[lugbolt]

problem with doing that is that if there is any hydraulic pressure leakage downstream, your gauge will not read relief pressure. Being an open center system, it won't have any pressure to speak of until you actuate one of the valves and even then it won't go in to relief until you bottom out the cylinder. Thus, using a gauge full time is, really, kind of pointless. IT's a tool to check relief pressure, which is only to be done for testing purposes, IMO.

I do not like using a gauge at all, I've seen them blow sky high and make a mess. I only use them when needed, and NEVER when not needed. Watched a tech at training explode a flow meter at 5000 psi and pieces of that sucker ended up on the opposite side of the big warehouse. Had anyone been in the path, probably would have been impaled.

 

[joea]

I get it, I think. It would be just for setting the relief, regardless of what I implied. Just wanting to make sure the pressure is correct as I've read a lot of reports Kubota tends to be set low from the Dealer or Factory.

The TSM calls for a specific adapter, but no longer available. Appears to be just an adapter to connect pressure gauge to test port and allow adjustment.

07916-52391 superseded by 77700-T0077. Just knowing the threads for the case side should be enough.

 

[Matt Ellerbee]

Hydraulic Tools - BoltOnHooks LLC

Bolt-On Hooks and Hydraulic Tools for compact tractors.

www.boltonhooks.com

Buy this. When shopping for a gauge to check my pressure, I couldn’t build this for what it cost from Ken. Even without the hose I was still over.
Plug into a loader QC and test away.

 

[The Evil Twin]

You'll probably want a 4000- 5000 psi gauge. Typically the accepted accuracy is in the 50- 70% range of the measuring instrument.
That aside, it should be plumbed in parallel (not series).

 

[TheOldHokie]

You'll probably want a 4000- 5000 psi gauge. Typically the accepted accuracy is in the 50- 70% range of the measuring instrument.
That aside, it should be plumbed in parallel (not series).

For setting relief pressure it should be a simple deadend.

Dan

 

[joea]

You'll probably want a 4000- 5000 psi gauge. Typically the accepted accuracy is in the 50- 70% range of the measuring instrument.
That aside, it should be plumbed in parallel (not series).

Good idea on the gauge.

Clear me up here. Maybe my terms were wrong. If I have the gauge on a Tee and a fitting on each end, the setup will be "in series", and the gauge in "parallel" ?

I did get up late this morning.

 

[joea]

For setting relief pressure it should be a simple deadend.

Dan

Still foggy this morning.

That's the only pressure adjustment I am aware of. I'm thinking setting the relief is essentially setting the "working pressure", correct?

How long is that "safe" for? Since there would be no "return to tank" in that line, the relief would be lifting almost immediately

 

[TheOldHokie]

Still foggy this morning.

That's the only pressure adjustment I am aware of. I'm thinking setting the relief is essentially setting the "working pressure", correct?

How long is that "safe" for? Since there would be no "return to tank" in that line, the relief would be lifting almost immediately

You don vwant to be in prallel because then you do not know what you are measuring. You want the gauge installed in the outlet line of the relief with no other loads on the line. Then you know exactly what you are measuring - the relief valve cracking pressure.

Below is a drawing of the hookup. You can run like that for way longer than it takes to adjusrt the pressure setting.

Dan

 

[The Evil Twin]

Good idea on the gauge.

Clear me up here. Maybe my terms were wrong. If I have the gauge on a Tee and a fitting on each end, the setup will be "in series", and the gauge in "parallel" ?

I did get up late this morning.

Sorry, that's my mistake. I wasn't understanding what you wrote in the first post.
You can do it like the Hokie drew out. Or, I would think, just have a simple coupler with a gauge on it. In series, you won't hit max pressure until the hoe maxes out. If space is tight then add a little pigtail hose.

Hydraulic Pressure Test Gauge - BoltOnHooks LLC

Hydraulic pressure gauge. Relief valve.

www.boltonhooks.com

 

[TheOldHokie]

Sorry, that's my mistake. I wasn't understanding what you wrote in the first post.
You can do it like the Hokie drew out. Or, I would think, just have a simple coupler with a gauge on it. In series, you won't hit max pressure until the hoe maxes out. If space is tight then add a little pigtail hose.

Hydraulic Pressure Test Gauge - BoltOnHooks LLC

Hydraulic pressure gauge. Relief valve.

www.boltonhooks.com

What relief vslve are we adjusting? Main system relief or inlet relief on hoe and/or loader. Backhoe is last in line and cant raise pressure any higher that the lowest of the two upstream reliefs.

If you plug that gauge into the backhoe outlet you will deadhead the entire circuit from pump to backhoe outlet and pressure will max out the instant you start the engine and stay there until you shut it off.

Dan

 

[Lil Foot]

This is what I use, bought it from Surplus Center, although it seems it is no longer available:

 

[TheOldHokie]

Still foggy this morning.

That's the only pressure adjustment I am aware of. I'm thinking setting the relief is essentially setting the "working pressure", correct?

How long is that "safe" for? Since there would be no "return to tank" in that line, the relief would be lifting almost immediately

Unfortunately I could not locate any manuals for the B21 but I did have a look at the parts drawings. The bits and pieces are hard to fit together but it looks like there is a rear hydraulic outlet block with selector valve for the backhoe. That block contains a relief valve which limits max pressire from tractor to backhoe inlet. I did not look but I assume there is another inlet relief in the baclhoe control valve.

Assuming thats correct first thing you need to know is tractor side pressure. To get that connect your gauge to the backhoe supply quick couler as I showed in the drawing, start engine, move selector valve/lever to backhoe connected position and read pressure. That is the pressure relief settimg on the tractor side and it would be adjusted at the relief valve built into the outlet block.

After checking and adjusting yractor outlet pressure as needed you can adjust the inlet relief on the backhoe valve using your gsuge and tee setup

Dan