Hydraulic fluid

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Geochurchi
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Hydraulic fluid

Post by Geochurchi »

Hi All, how do I determine how much fluid should be in a system, about 20’ total 3/4” hose, 2 truck motors, there is a tank that is approximately 5 Gal, I can’t believe that needs to be full, probably about 1 1/2 gals in it now.

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Re: Hydraulic fluid

Post by Soot n' Cinders »

It shouldn't be full, maybe only 3/4 full. Need some room for the oil to expand when it gets hot.
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Steggy
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Re: Hydraulic fluid

Post by Steggy »

Geochurchi wrote: Wed Apr 06, 2022 1:23 pmHi All, how do I determine how much fluid should be in a system
Dump four gallons into the tank and run the loco wheels-up in both directions to force out all air from the plumbing. After you've done that, shut ’er down, wait a few minutes and then inspect the tank level. It should be 1-1/2 to 2 inches below the top. If it’s more than 2 inches add some oil. Do not overfill the tank, as it will spew oil when everything gets up to operating temperature.

What kind of oil do you plan to use? Does this system have a return line filter?
Last edited by Steggy on Sun Apr 10, 2022 11:39 am, edited 1 time in total.
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Geochurchi
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Re: Hydraulic fluid

Post by Geochurchi »

NAPA General purpose, it does have a new return filter, Loco will get limited use.
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Re: Hydraulic fluid

Post by Glenn Brooks »

There is probably a flow rate associated with your pump that could tell you what the absolute minimum oil reserve should be. Otherwise the above recommendations would be fine. Never hurts anything to have a larger than necessary tank, if you have the space…
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kcameron
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Re: Hydraulic fluid

Post by kcameron »

The amount of fluid would also help with traction by adding weight. If the rest of the body isn't heavy enough, filling more of the tank would add more pounds. As said, watch the tank when you get up to temp and stay inside the tank as that's your high limit for filling. One other downside of extra fluid, even if needed for weight, would be the size of possible mess if a line or other spill happens.
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Steggy
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Re: Hydraulic fluid

Post by Steggy »

Geochurchi wrote: Fri Apr 08, 2022 12:18 pmNAPA General purpose, it does have a new return filter, Loco will get limited use.

Most pumps and motors are rated for use with motor oil, not hydraulic oil. The difference is a hydrostatic power transmission system depends on continuous parts movement to function, which is the same sort of scenario seen in an automobile engine. Ergo the oil needs strong lubrication properties, as well as good temperature tolerance. Applications involving cylinders and/or rotary actuators see only intermittent flow, which makes the oil’s lubricating properties less critical and has marginal effect on temperature.

You might find that the system will work better if you use motor oil, not hydraulic oil. Since your system has a return-line filter, I’d recommend you use 10W-30 detergent oil, API-SJ being more than adequate. Don't bother with “high mileage” oil, which is just regular motor oil with more additives. Also, I don't recommend use of synthetic oil. My experience with synthetic oils in hydrostatic power transmission is they aren’t chemically stable at the temperatures and pressures typically seen under load.
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Geochurchi
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Re: Hydraulic fluid

Post by Geochurchi »

Hi, newer Loco with Eaton pump and motors MFG. recommends AW 46 hydraulic fluid, other 2 have been running on general purpose hydraulic fluid, with no issues.
If it ain’t broken keep working on it until it is .
Geo 🇺🇸
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