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#2357402 - 08/25/11 12:51 PM Hydraulic Fluid vs ATF
OnTheWaterfront Offline

Registered: 08/08/11
Posts: 19
Loc: DE
I have a new crane that utilizes outriggers with hydraulic cylinders for stabilization, but the hydraulic cylinders are a little bit spongy, so I complained to the manufacturer who has told me to replace the hydraulic fluid with an ATF fluid. They refuse to disclose the nature of the problem or why the ATF fluid fixes the issue.

Does anybody have any idea what the problem could possibly be?

They viscosity of the ATF (Mobil Esso ATF 200) and the Hydraulic fluid (Q8 Handel 46) are very close, the ATF is slightly thinner. I'm also worried about voiding the warranty on the hydraulic pump (multi-stage piston pump with variable swash plate, very expensive) by running ATF.

Edited by OnTheWaterfront (08/25/11 12:52 PM)

#2357437 - 08/25/11 01:32 PM Re: Hydraulic Fluid vs ATF [Re: OnTheWaterfront]
440Magnum Offline

Registered: 02/01/09
Posts: 6099
Loc: Texas
The only thing I can guess is that ATF has better anti-foaming additives.

As for the warranty on the pump... good question! You say the manufacturer is recommending ATF- I'd at least get that in writing to be sure the pump is still covered.
'66 Dodge Polara & '69 Dodge Coronet R/T both 440/727
'08 Ram 1500 4.7/545RFE
'12 Challenger SRT8 392/6-speed
'99 Cherokee 4.0, '11 Grand Cherokee 3.6

#2357742 - 08/25/11 07:21 PM Re: Hydraulic Fluid vs ATF [Re: OnTheWaterfront]
MolaKule Offline

Registered: 06/05/02
Posts: 14115
Loc: Midwest
Check your breather or reservoir tank and see how much foaming is occurring because spongyness is usually due to air entrainment.

Also have the mechanic check input line or low pressure lines and fittings to see if they are tight and no air is getting sucked in.

Magnum gave some good advice. Get that in writing before changing over.

ATF and I repeat, ATF DOES NOT have the same level of anti-wear additives as do regular hydraulic oils, regardless of closeness in vscosity.

Edited by MolaKule (08/25/11 07:22 PM)
I told a chemistry joke....there was no reaction. smile

#2357818 - 08/25/11 09:08 PM Re: Hydraulic Fluid vs ATF [Re: OnTheWaterfront]
roadrunner1 Offline

Registered: 04/08/09
Posts: 777
Loc: oh
+1 on checking for suction side leaks, instead of ATF, if no leaks are found, try an ISO 32 viscosity.
'07 f350 6.0

#2367301 - 09/04/11 07:55 PM Re: Hydraulic Fluid vs ATF [Re: OnTheWaterfront]
deeter16317 Offline

Registered: 12/07/07
Posts: 1339
Loc: SE, PA
Also check the rating on the hoses (they may be part of the sponginess), I saw this on a drill rig I ran at one point.
2004.5 Dodge 2500 Cummins

#2411053 - 10/20/11 10:22 AM Re: Hydraulic Fluid vs ATF [Re: OnTheWaterfront]
OnTheWaterfront Offline

Registered: 08/08/11
Posts: 19
Loc: DE
The crane manufacturer is going to replace the original hydraulic fluid (Q8 Handel 46) with a different hydraulic fluid (Mobil DTE 10 Excel 46) in an attempt to get rid of the sponginess. I don't see how changing from one ISO 46 fluid to another ISO 46 fluid will make any difference.

#2413691 - 10/23/11 01:49 PM Re: Hydraulic Fluid vs ATF [Re: OnTheWaterfront]
George Bynum Offline

Registered: 12/18/04
Posts: 172
Loc: Greenville SC
Originally Posted By: OnTheWaterfront
I don't see how changing from one ISO 46 fluid to another ISO 46 fluid will make any difference.
Without suggesting that one oil is better than the other, it may be that one has better de-airation properties. Reservoir design (hot oil across almost horizontal surface for thin layer of fluid) is incorporated in many of them. Different oil chemistries do have different bulk modulus values.

#2431960 - 11/11/11 03:01 PM Re: Hydraulic Fluid vs ATF [Re: George Bynum]
FKPhil Offline

Registered: 11/11/11
Posts: 1
Loc: UK
I struggle to see foaming as the issue here.
Air entrainment into the liquid could be the problem, and so good “air release” is desirable but air release property of the oil can be independent of foaming characteristics.
Also air getting into the pressure side of the hydraulic system might be due various mechanical or operational problems (some suggested above); might not be the oil.

If the cylinder is under high load the “sponginess” might not be air, but be due to low viscosity of the oil. Temporary viscosity loss shearing characteristics due to the Viscosity modifiers in these oils mean they can be well below the ISO46 when in high stress operation and this will slow cylinder filling. ISO46 on the can might not be what the equipment experiences. Temporary low viscosity means the pump is inefficent due to internal leakage. If this is the cause then ATF also will be poor; ATF's generally have poor temporary viscosity loss characteristics. However the Mobil DTE 10 Excel 46 is very good in this respect. (and no I don’t work for Mobil).