Hyd oil

[TJ Smith]

What does everybody use for hyd oil in their  press?

Thanks TJ

[macbruce]

That, it a very narrow brush to paint a broad question  :)  You can use something as common as ATF or power steering fluid with good results but the variety and choices are huge.......Generally if you go to the farm store or auto parts place anything labeled ''hydraulic oil'' will get the job done......

[ptree]

Hydraulic oil can be water if the equipment is chosen correctly. That said lets look at some of the needs of modern hydraulic systems

1. Lubricity. Many parts like rod bearings and pump bearings need lubricity.

2. Viscosity. Viscosity needs to at least come close to the viscosity to maintain hydrodynamic lubrication that is a fluid film in simple bearing surfaces.

3. Extreme pressure additive. An additive for very highly loaded simple bearing surfaces

4. Anti-wear additive. Self explanatory

5. corrosion inhibitors. Most of these work by either nuetralizing acid, or preventing acid formation by encapsalating water.

6. Anti-foam additive. Foam compresses and cause caviation in the pump. Caviation kills pumps quick.

7.Vapor pressure point. A fluid with the wrong vapor pressure caviatates at the pump inlet, see above.

8. pour point. The lowest temp the oil is fully fluid.

 

With all that said, In almost any modern system ATF meets or closely meets all the above requirements.Has one of the lowest pour points an great extreme pressure additive package, great anti-wear and corrosion inhibitor package, the right viscosity for almost every single component I have seen.

It is cheap, available and if one remembers that many of our shops are cold in the winter that low pour point and great corrosion inhibitor package is just as important as it is in an unheated car.

So you ask how does water get into my indoor system? Think about a hydraulic cylinder. Usually has a rod on one end only. So as you extend the cylinder, more oil goes into the cylinder than comes out of the rod side. So oil goes from the tank into the cylinder. That volume is made up with cold, usually moist air. Cold meets warm and bingo condensation. so every stroke of the press makes the tank breathe. Every temp change makes the tank air volume want to condense out water.

[jeremy k]

That is very interesting - Thank You Ptree.

[ptree]

Jeremy K. When I started my first real job after the ARMY and college, it was in a R&D Lab for a premier maker of hydraulic and pnuematic cylinders and valves. One of my first tasks there was starting up a high water content hydraulic fluid test bench and then testing cylinders. That fluid was 95% water, 5% oil concentrate. ATE cylinder seals:)

At my next employ we had a 1100 ton 4 post press made in 1913 that used straight water for fluid. The cylinders were rope packed and leaked like a summer downpour. Good thing we used water as we were pressing boiler drum end caps from up to 4" thick steel at forging temp!

Later as I was given more responsibility for stuff I was sent to a hydraulic fluids and filtration class and that was a great week of learning. Then I became the filtration expert for the entire 40 acres of shops and about 750 machine tools. I also got to specify and buy the oil.

Once they sold my division I still was responsible for 450 machine tools and gained 2 central coolant systems for coolant that each held 27,000 gallons one water based the other straight oil.

Later at the upseter forge shop I was buying the oils there and we used 1300 gallons a week or so of EP-460 gear oil in those monsters. They were total loss so the oil went into the bearings and then out the ends and weeped down the frame. Then dripped into the water filled pit to be skimmed off, collected and sent to be recycled and returned to us. I got to set that all up. (Afetr the "New" oil vender cheated on the oil quality and we broke the crank on a 9" upsetter twice. The guy who had the responsibility for oils had tested the oil for quality after the first break by asking the vender to test! Of course it was fine. The second broken crank was after I had been there a few months nd I was asked to test nd I sent it to a real lab. Each broken crank was about $100,000 to fix and 8 to 10 weeks downtown.

Just a bit of background on how I come to my choices:)

[jeremy k]

Jeff - So should I drain the hydraulic fluid and replace with ATF due to partially heated shop in the winter? Can ATF be mixed with existing hydraulic fluid and still be ok?

[ptree]

ATF is fine to mix with regular petroleum oils if the called out viscosity is similar.How much oil are you talking and how old is the existing fill. If you are partially heated, I would probably leave he oil in the machine if fresh. If you see cold weather issues like sluggish then change. For a home shop checking condition of hydraulic oil is harder than in industry. I can send off samples and get full results.

when to change hydraulic oil

1. if it smells burnt.

2. if the oil becomes cremey whithish. (Water in oil)

3. If the hydraulic oil has darkened.

[ptree]

By the way, ATF IS hydraulic fluid, just a very high grade and usually died red.

[jeremy k]

This hydraulic fluid is new ( I'll bet less than 20 hours running on the press), but I know the tank is just over half full and have always been going to top it off - you know how things go - kinda the I'll get a round to it deal. This press is never used for long periods of time so I know it's fine with the amount in it but I will top it off.

Again, Thank you for the information Jeff.

[swedefiddle]

Some of the Excavators and logging equipment are using vegetable oil as the hydraulic oil. The reason is, if there is a spill or a hose bursts, you don't have to contact the "HazMat Team".

A new application for "French Fry Oil". Logging Trucks with the smell of French Fries!!! (just kidding). :) :)

[ptree]

Jeremy K you are most welcome.