Power steering oil

Hi,

I have an ongoing issue with the power steering on my 1993 7745. Every now and again it gets real heavy ........ just will not respond to the steering wheel. I may just have to reverse a meter or so and hey presto it comes back to life. This would never happen at high speed (ie on the road). Its just around the yard or say if I need to come to a stop or almost a stop on the road and I need to turn in either direction as I move on again.

Now I use standard ATF fluid in my system mainly because that is what was in the tractor when I bought it second hand.
However there is a Zetor sticker on the window of the cab lising all the oils and greases recommended by Zetor for the tractor.
For the steering it clearly recommends standard gear oil. It goes on to list various products from the main suppliers Shell, Esso, Elf etc.

Now I am sorely tempted to change over? Dose any of you experts have a strong opinion on the merits or otherwise of doing this.

BTW my problem is not related to low fluid level, or blocked filter or leaks in the system. I take care of those issues.

One other thing is I do not know whether I have hydraulic or so called hydrostatic steering. What is the difference in any case and how would I know which one is actually on the tractor?

Do you have any fysical connection from your steering wheel to the frontwheels, a link stage or something, then you have a servo assisted steering system. If you have a hydraulic cylinder with rubber hoses to an orbitrol under the steering wheel you have a hydrostatic steering. I think the ATF oil are very well for the system. Does it help to run up the engine to more speed or do you always have to reverse?

Regards Tage W.

Hi Tage,

I have a large cylinder running from the steering to the front axel. And I have what appears to be a damper or shock absorber on the other side.
Normally I either stop and reverse a little or maybe a combination of engine revving and turning the steering wheel from side to side prompts the system to come back to life.

Then I think you have a valve at the end of the cylinder and when you are steering the construction affect the valve and give you help with the steering. It could be something with the adjusting of the pin into the valve. You can also have some poorly fitted links wich give too much movements in the link system.
You need to have someone to steer and then you looking what are happening out from the steering gear to the cylinder back end where the valve are located.
I had a 6245 before and I think you have the same system, now I have a 6341 with hydrostatic steering.

Write here if you find anything.

Regards Tage W.

We used 10w/30 for a while, but it was hard on the operator. Then i asked the oil guy, who said mostly ATF 2 would do.. So we changed and theres no problem.

Yes i think the valves touch stem might need adjustment.. also check the vertical front wheel bearings.. that can make it hard to steer too...

I know this is a rather old post... but i have read all 2000 odd posts on this subject in the last 2 days (in the hope of finding out if i can cure my 6745 lazy power steering) and decided to respond to this one (with my industrial chemist's hat on) ...........

on the subject of mixing ATF, UTO, AW22 (or other Hydraulic oil) in principal these are all made from miniral base stock and are therefor basically compattable.
However it is possible for some additive packages to be inconpattable and either cancell each other out or sedement out of solution.

from the reasurch i have done so far it would apear there should be no reaction between ATF and Hydraulic oil.

From another forum:
"Most ATF's are blended from SAE10w base stock. It's the friction modifiers and additives that make their application more specific and cost more than AW hydraulic oils. Specific AW hydraulic oils are available in ISO 10, 22, 32, 46, and 68. General purpose AW oils suitable for hydraulic use are available in ISO 5 through 460. Almost all petroleum based oils are miscible, and will go into solution".

Also check out: http://www.insidersecretstohydraulics.com/hydraulic-oil-inventory.html

If in doubt flush it out
however a simple compatability test can be done:
at ratios of 10/90, 50/50, and 90/10 in a clean glass jar
shake it all up and let it sit for a few days
look for any sedement or gel or seperation.

I would be very interested to hear from somone that has actually (first hand) had a reaction from mixing ATF and Hydraulic oil, and what happened.

Regards
Steve

ISO 22 can also be used, though its viscosity doesnt remain the same at summer/winter, which ATF does. The viscosity has a big effect on the behaviour of this old servo system, it is more sensitive to oil viscosity than a modern orbitrol system.
Next to that ATF is available at every gas station, where ISO 22 is rare. I design construction machinery for a living, we use ISO 46 and dont have any other viscosity in stock....

Therefor the best advice is draining all off, and fill up with ATF 2. Best availability, most stable viscosity.

I havent seen the chemical reaction myself, but i wouldnt take chances by mixing it... a wee drop which is soaked up in the powersteering filter wont hurt, but as a rule of thumb its better to not mix.

Just a side note,
Dextron II ATF for all intents and purposes is now obsolete, (along with Dextron I) in fact in NZ it is almost impossible to find DII ATF, as it has been 100% replaced by Dextron III, which has been formulated to be completely compatible with all DI and DII designed transmissions.
For power steering it does not matter if it is Dextron ATF or non Dextron ATF (ie, GM, type 2, or the new F type (for Fords) and most of the new OEM Jappa stuff (Honda, Toyota, Nissan etc)

Just never never use Dextron type ATF (not even as a top up) in an Automatic Transmission made for non Dextron ATF, as the friction coefficient reducer additive in the Dextron type ATF will cause the clutches to slip and burn out in non Dextron designed trannies.
(NB. if you use 100% GM type ATF in a trannie designed for Dextron ATF you can effectively put 5 times the power through it before the clutches slip, > this is a common quick fix on drag cars and old slipping trannies. but the gear shifts will be very harsh at light throttle!)
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Almost forgot to mention....... Dextron ATF (and most likely all ATF but not certain) also contains "Seal softeners" (to slow down the leaks on those old 1970's and 80's trannies), this is why some of you have noticed a reduction in power steering ram leakage when using ATF

on a ZF wheel loader transmission, we do an AEB test (dont know what it stands for, but it tests clutch pack lash and saves that data to decide how the servo valves will be controlled during a shift) after changeing from ATF to engine oil. (both are approved)
And the axles with limited slip differential, require an LS additive in the gear oil... probably same thing which is used in ATF ??

Anyways, thanks for sharing knowledge from your specific background... i love learning from people with hands-on experience

on a ZF wheel loader transmission, we do an AEB test (dont know what it stands for, but it tests clutch pack lash and saves that data to decide how the servo valves will be controlled during a shift) after changeing from ATF to engine oil. (both are approved)
And the axles with limited slip differential, require an LS additive in the gear oil... probably same thing which is used in ATF ??

Anyways, thanks for sharing knowledge from your specific background... i love learning from people with hands-on experience

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Hi Renze,
Actually i think the LS additive may be the opposite of the additive in Dextron ATF, i believe that standard EP oil is too slippery for LSD applications and the LS additive may in fact be a Friction coefficient increaser.
but i do not have any firm data to this effect.

Anybody else know the answer to this?

Well, i have another question: All ZF axles have a problem of squeeling axles, when steering the wheel loader with the brakes applied, a stick-slip effect occurs that grunts and squeels throughout the whole wheel loader. The LS differential friction disks do the same.
Then when later the diff busts after 4000hrs, the customer says "i told you it had a problem, the axle made that noise since new so its a manufacturing error" Then ZF says no, this noise is the stick-slip effect and is perfectly normal in paper lined friction disks.... Its something you can never get out of, customers dont accept ZF's answer, while ZF doesnt accept the repair bill.. (you just cant sell this theoretical B.S. to a customer with an 8000 euro repair bill)

IS there any oil additive that may reduce this stick-slip effect and therefor this annoying noise that worries customers ?

You could try AS oil as specified for ford wet brake rear ends or else one of the additives so loved across the pond for smoothing out auto transmissions.

or else one of the additives so loved across the pond for smoothing out auto transmissions.

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That doesnt sound like its good for brake safety...

Renze,
I have asked the good folks at BASF (Oil additives div.) what their recomendation is (as i sell some of their additives at work, along with about 1200 other industrial chemicals)
i will report back my findings next week.
Cheers
Steve

Steve, thanks a LOT !!

Sometimes with big firms, they tell you a theoretical explanation "its stick-slip effect, dont worry about it" But machinists dont feel comfortable on a jobsite with grunting axles, their customers talk about it....
Thats the difference between a booksmart engineer that has to explain this only once when he gets in the field, and the machinist who has to tell his customers that say "hey your machine is broken" that same phrase every day.... And when it DOES break down, the aggrevation about the noise comes out, and they dont want to pay the repair because they "allways heard this worrying noise, about which you didnt take me serious" We hear the same from importers of other machines using the same axles...

just a thought from my side, could the LS additive be causing this ? and do paper lined wet disk brakes need LS additive ? IF not, we could change over to the optional 100% hydraulic lockers, and use non-LS oil ???

Anyways, if you could use your entries in BASF to provide a clue, i would be very gratefull