• Guest, Help us understand what we can do better in future. Click Here!

Hydraulic pumps and oils

#1
There seem to be some smart people on here when it comes to oils and hydraulic systems.

A few years ago the place I was working at lost a hydraulic pump on a machine. They replaced the pump, but, didn’t do a good job installing the lines, and it leaked like a sieve.

Fast forward a few days, they dumped the old used hydraulic oil in just to keep working

I cringed watching that happen. A lot

Mentioned this to a friend who’s also pretty smart with this stuff, a couple years later. He said, if it’s properly filtered, oil change intervals met, correct oil used....basically a hydraulic pump has a limitless life span. He said it’s constantly bathed in oil, which should provide lubrication and cooling, so if it’s properly set up for backlash there should be no wear, essentially.

I see a lot of you guys talking about changing the oil and keeping stuff clean, I figured this was a good place to ask
 

CalgaryPT

Super User
Vendor
Premium Member
#2
When I took a couple of hydraulic courses at SAIT I learned one of the main causes of pump failure is fluid contamination. Eventually all fluid goes bad. But it's especially common in agricultural and heavy equipment applications. The main fluid problem is moisture: it makes your fluid a milky white. It often happens if the fluid gets too hot, then cools down in the tank and captures moisture in the air. Undersized tanks, lack of coolers, moist environments, bad breather caps, etc., can all contribute. Contaminated fluid can lead to pump failures, cavitation, etc.

For someone with maybe an enclosed pump indoors and low cycle time, you should get years and years and years of use. If you are buying something used, I always swap out the oil just in case.
 
#3
When I took a couple of hydraulic courses at SAIT I learned one of the main causes of pump failure is fluid contamination. Eventually all fluid goes bad. But it's especially common in agricultural and heavy equipment applications. The main fluid problem is moisture: it makes your fluid a milky white. It often happens if the fluid gets too hot, then cools down in the tank and captures moisture in the air. Undersized tanks, lack of coolers, moist environments, bad breather caps, etc., can all contribute. Contaminated fluid can lead to pump failures, cavitation, etc.

For someone with maybe an enclosed pump indoors and low cycle time, you should get years and years and years of use. If you are buying something used, I always swap out the oil just in case.
Ok, that makes sense.

I own a small loader for around the shop. Payed around $1000 for it 7-8 years ago. It’s built in the 60’s.

Needless to say it doesn’t get much love.

The gearboxes had so much water in them they froze up two winters ago.

I started tackling the milky hydraulic oil last year. It’s been parked inside since almost 2017, I’ve been trying to give it some love. Parking it inside and out of the elements is a big step forward.

I found out you can buy water element filters to help filter the hydraulic oil, which is my next step. I’ve drained and filled it twice with clean oil, I’ll drain and fill it again while trying a new water element filter.
 

Alexander

Super User
Administrator
#4
I just had a CNC machine overflow its hydraulic tank. This was because so much colant had contaminated the oil. In this case the coolant from the cutting tool was able to get in the non pressure side of the hydraulic cylinder used to clamp the hydraulic chuck. It simply drained back into the hydraulic tank and i had almost 20L of water in the system. Everything survived but im still worrying about the pump. Hopefully they bring me a new inline hydraulic filter this week. I didn't want to run the machine with the old filter but that decision was out of ny hands. Here is what the filter looks like. Also attached is a diagram of what happened.
 

Attachments

Tom Kitta

Active Member
#5
Yeah water gets in... I drained oil from my surface grinder - all 5 gal of the stuff and like 10% plus was... water. It was not even mixed with the oil.