High pressure gauge for excavator pump

Case450

Member
Is there a specific gauge or range I need to be on the lookout for in a gauge? I'd
like to check the line pressure on my 1986 liebherr 932 Shovel to see if it's where
it should be or even what it is for that matter.

Not too sure the best way to go about this.

Thanks in advance for any suggestions
 
First get a gauge that is OIL FILLED to reduce needle bounce and give a more accurate reading. Find out what the pressure is supposed to be. Most European machines are made to have high PSI, up to 4500 - 5000psi, so make sure that your gauge can handle that pressure. U.S. machines are usually around 2400 - 2800psi and use large cylinders to achieve force vs. European high pressure, small diameter cylinder to achieve force. I always had trouble keeping the high pressure machines from leaking. so I specified the normal U.S> range of hydraulic pressure.

When checking pressure on a machine, I often "teed into a hydraulic line in some place convenient and install a quick coupler to connect the gauge. I often left the T and quick couple on the machine if I had reason to believe that I would be coming back to the machine sometime later.
 
Just about all construction equipment, for at least the last 20 plus years, run upwards of 5000 psi. I routinely check equipment with a 6000 psi gauge without any problems.

That said, what issues are you having that you need to check the pressure? I ask because a machine needs both pressure and flow to operate correctly, and you can have one without the other. Usually on an excavator, you'll notice the reduction in both flow, and pressure both in the track motors. In other words travel will be suffering, while you may notice almost no problem with the digging functions. This because the track motors typically take ALL of the pump flow, ((and pressure depending on ground conditions)), to operate at the correctly, while a cylinder will only use part of the flow ((and the pressure, again dependent on ground conditions)).

The only way to check both flow and pressure, together, is to use a flow meter on the main line coming off the pump. Without a flow meter, the best you can do is to check the pressure. The best way to do this is to tap into a line directly off the pump, or at one of the cylinders on the boom. This will allow you to bottom out the cylinder, thus deadheading the pump against the main relief.

I'm not that familiar with the Liebherr's but the majority of excavators have two individual pumps. When traveling they handle one drive motor each. When digging they will be divided according to which functions the mfg believes will occur at the same time. In other words while pump one is putting flow to the boom lift cylinders, pump two will be providing the flow for the dipper or bucket cylinder. This gives much faster cycle times, and allows each pump to do no more (build no more pressure) than necessary for the work at hand.

In other words, you'll need to check pressures in two places to get even close to an accurate assessment of both pumps.

If you've got any other questions, please feel free to ask. I know I've got a manual for one of the Liebherr excavators, and they usually maintain essentially the same pressures across the machine sizes, and I'll be glad to check and get you at least an idea of what pressure to be looking for.
 
You need a 0 to 600 Bar gauge for most of the Liebherr machines as they work at 420 Bar a good quality oil filled gauge is needed,the Liebherrs that I come across here in the UK mostly have quick break couplings on the pump for pressure testing,you were on about the pump before did you replace it,what's wrong now,without any gauges you can tell when the bucket is put in the ground and you start to dig the engine tone should change,if that's not happening the most likely thing that's wrong is the O'ring on the nose of the main regulator valve is leaking and letting the pressure bypass,there is one O'ring and two backing rings on the nose and couple on the valve body,I would change them first which is common practice before testing the pressures,the valve can be removed without altering the pressure setting by the inner most nut,just relieve the system pressure,is the engine running good and at the right RPM,there are lots of things beside the pressures,engine power,speed,cylinders etc.
AJ
 
I had to keep my gauge wiped clean and wrapped as I carried it in my suitcase as I flew around the country. I wonder what TSA would do if they saw one of those on their screen today?
 
Yeah I posted about it a while back but never touched it. Been parked for the last
couple years and now a buddy of mine wants to buy it as a pit monster. I'd like to
get things working at least fairly proper before the guy takes it. I've been very
upfront with him as to what's good and what's bad on the Shovel. I don't want anyone
saying I ripped them off or lied.

So I'll be into it this weekend I hope.
 
Case 450,I'm in the UK and those machines are common here,they are classed as the upper crust of machines and used a lot in the demmo business and rail work,about working on the hydraulics it is a job for a time served engineer and not a layman regardless of what is said on here,that machine has a lot of electric controls and working modes and tampering with them is not a good idea,a visit from a Liebherr service engineer would be money better spent than on pressure gauges and flow meters needed to troubleshoot any problems it may have,I'm in the repair business for a lifetime and are using test equipment nearly every day fitting rock breakers,munchers etc and unless its know how to use it it's useless.
Good luck
AJ
 
No need to check as I have the gauges that is used by Liebherr,O&K and Poclain all 600 bar,the gauges need to be well over whats needed so they don't peg out and bend the needle,why do you think it matters,better to have them too high than too low.
AJ
 
Thanks for the advice. The liebherr service guy is about a 2 hour drive from me so
it's gonna cost me like 400 just to get him here and another 400 to send him home
plus however long he's here for. I don't really wanna spend 2 thousand dollars for
him to tell me what's wrong with it. I paid 10 grand for the Shovel and i put
maaaaaaaaaybe 200 hundred hours on it all told. I'm finished my project so I want to
get rid of the Shovel now.

I'll keep poking around see how things pan out lol
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top