Hydraulic lift pressure adjustment

[MarkV]

I find it interesting that the pressure was that far off in the first place. I guess that in any manufacturing setting there is error so you have to wonder if your 3pt or loader is operating 10 or 20% below its rated limits. Might not be a big deal on large machines but on my little tractor a drop in loader capacity could be a real deal breaker on some projects.

Hayden, I understand where you hooked up the pressure gage and the logic of checking all the systems from that point. A couple of questions though. You said you set the loader relief valve to 2200, how does one do that? And, what type of gauge does one look to buy for this type of application.

I sure do like having you smart guys around to guide those like myself through these things.

MarkV

 

[jrlichina]

JBecker.

Item 210 is the shim used to change the relief setting.

 

[Anonymous Poster]

</font><font color="blue" class="small">(

Item 210 is the shim used to change the relief setting. )</font>

Interesting...they are listed as "nuts" in the diagram I was looking at ('missed the attachment in your message) and go on the end of the bolts that hold the hydro delivery tubes in place. Oops! There is more than one part "210"! Now I see them...they are control valve components. (pg 98)

Thanks!

 

[hayden]

I too was surprised to find the pressure off by that much, but I'm glad that I didn't need to set it over pressure (just to the correct pressure) to get my chipper to lift.

The loader relief valve is on the loader valve. If you remove the cover over the control lever, there is a stacked-nut thing (sorry, I don't know how to describe it better) to the left of the actual valve control plungers. The top nut is actually a cover over a screw, and the second nut in the stack is a lock nut for the screw. Remove the cover, losen the lock nut, and you can turn the screw to set the relief pressure.

I'll mention again that you really shouldn't screw (no pun intended) with this unless you know what you are doing. Over running the pressure can be damaging to your tractor and dangerous to you. Hosed and other parts could crack and fly apart, and an over powered loader will do what you want, which is also what you shouldn't do - lift more weight than intended.

OK, now I can continue with a clear conscience.

Regarding the pressure gauge, I bought one from Northerntool, but it's glycerin filled (for damping of movement) but it's not fully filled so there's a big bubble at the top of the display. It's very annoying, but not worth the return shipping the get it fixed, so I'll just stay mad at Northern. I picked the IN line on the loader valve. It brings fluid directly from the pump and there are no relief valves upstream from it. It took a Tee and a collection of other fittings and several trips to the local hydraulic and tractor show to get everything. I took pictures and will post them one of these days, but they are still on the camera and need to be shrunk to a TBN-friendly resolution for posting, and I'm too tired right now.

 

[JerryG]

</font><font color="blue" class="small">( Regarding the pressure gauge, I bought one from Northerntool, but it's glycerin filled (for damping of movement) but it's not fully filled so there's a big bubble at the top of the display. It's very annoying, but not worth the return shipping the get it fixed, so I'll just stay mad at Northern.)</font>

There is nothing wrong with your gauge, the air bubble is for expansion. /forums/images/graemlins/smile.gif

 

[hayden]

Here are some photos of the pressure gauge. The first is the dial gauge, and you can see the big air bubble (are they all that big?). Next two show the adapters on either side.

 

[rbargeron]

Hi Peter - good job getting that 3 pt up to spec !

Btw, filled gages do NOT all have that big an air space. But unless it is on a system with rapidly fluctuating pressure (usually a piston-type pump) the damped movement isn't needed anyway.

Another point I'd offer is that many standard industrial hydraulic systems run at 3000 psi. So it wouldn't be a surprise to find that most of the hoses, fittings, cylinders, seals, etc will handle that ok. You are smart to keep your system in the region of 2000 - the links, arms, etc have more safety margin down there.

A nice characteristic of fluid power is that things don't explode. They usually just develop a serious leak. Like the time I connected a splitter without a relief valve to my International 3414. It extruded the pump's seals right out thru the gap around the shaft. Took my whole checkbook to get them back in. (Cessna pump - very nice, but $$)

Its always nice to see somebody who's thinking beyond the owner's manual. Good going !

 

[jrlichina]

<font color="blue">A nice characteristic of fluid power is that things don't explode. They usually just develop a serious leak. </font>

Don't fool yourself into a false sense of security when working with high pressure hydraulics. Any part in the the stsyem can fail: lines, hoses, and other components DO EXPLODE. Hard lines can split(just search for the guy with the NH loader that blew out) and can cause serious injury. Granted it doesn't happen often but certainly can and does.

 

[JerryG]

That is a pretty large bubble. The ones that I am familiar with don't have quiet as large a bubble as that, but different manufactures may put in different amounts of glycerin.

 

[rbargeron]

I should have explained myself a little better. The term "explode" usually involves rapidly expanding compressible media, or chemically-driven expansion as in combustion. Medium-pressure hydraulics certainly can rupture and cause all kinds of damage, but an explosion is quite something else. With hydraulic failures there is not a sudden release of a large amount of stored energy. Will high-pressure oil drill a hole in you? yes it will. Would it send your tractor in shreds across the yard (as in Medina, OH)? No it won't. That's all I meant to say.