can I use hydraulic fluid (ISO32) instead of ATF on Bennett trim tabs?

[vas]

all in the title basically.

since I have the hydraulic fluid used in the stabilisers, I'm slowly turning everything to that fluid.
Last year I changed the passerelle from ATF to ISO32 hydraulic.
Now I've replaced the old tabs with the ones that have the measuring coil in them so that I can get indication of their position on my N2K instruments.
So, it's the right time to change fluid there as well.
Next plan is to swap it in the hydraulic steering a/p combo!

what do you think?

cheers

V.

 

[Montemar]

The manual for my 1991 Bennet tabs says ATF. The only other system I have is Hynautic steering which uses Hynautic fluid.
Basically it depends whether or not the seals can will accept it.
Personally I would stick to the manufacturers spec.

 

[superheat6k]

Look Vas they are a plastic cylinder and piston with an O ring seal on the piston. I reckon chip oil would work. Don't fuss IMHO.

 

[Rocksteadee]

Look Vas they are a plastic cylinder and piston with an O ring seal on the piston. I reckon chip oil would work. Don't fuss IMHO.

Bit of salt and vinegar, smell nice too

 

[DrSpock]

Two different oils for different purposes. Stick with ATF.

 

[vas]

thanks for the comments and conflicting suggestions

Trev, I know what the actual ram is made off, for safety I replaced the twin o-rings on them. So I'm pretty sure that the ram will be OK. Was mostly concerned about the actual pump bit which I've not taken apart so not sure how it's setup and what materials it's made off although I guess it's also plastic with a metal or plastic plunger with o-rings.

DrSpock, would really like to believe that but not sure ATF has any magic properties or even is better hydraulically than hydraulic oil used in construction machinery and whatnot (AFAIK that's what ISO32 is). Any pointers welcomed.

boat is getting back in the water tomorrow, keen to fit the rams today, but not that bothered about filling and running the system as yet. Only going to move 1km to port...

cheers

V.

 

[DrSpock]

ATF has different friction, viscosity and thermal properties to hydraulic oil. If Bennett wanted hydraulic oil in their trim tabs they would specify it. What exactly do you think you'll gain over using ATF?

 

[BruceK]

Personally I'm surprised they spec ATF for it. I'd have thought hydraulic oil more appropriate.

 

[vas]

DrSpock, I'll gain NOT having to carry bottles of ATF onboard I know it's not something great, but it seems to me that using ATF for anything else than automatic transmissions is kinda wrong.
In this app, what you do is press some oil from the controller to push a plastic piston down. Big deal, piston/o-rings/pump is basically what hydraulics are made for...
changed passerele from ATF to ISO32, still works, hasn't exploded (yet!)

V.

 

[scottie]

I would not make any recommendations on which oil to use but it is possible that ATF was specified as it is a easily sourced item ??

 

[vas]

possibly, iirc it's also suggested to use ATF in hydraulic gboxes, whereas you can/should use normal hydraulic oil...

 

[DrSpock]

Personally I'm surprised they spec ATF for it. I'd have thought hydraulic oil more appropriate.

Why? It's not a high-pressure hydraulic system?

Maybe contact Bennett and tell them you know more about their systems than they do

 

[DrSpock]

DrSpock, I'll gain NOT having to carry bottles of ATF onboard I know it's not something great, but it seems to me that using ATF for anything else than automatic transmissions is kinda wrong.

A bit of a lame reason.

ATF is also widely used is steering systems - I suppose they're wrong too? Try swapping that out with hydraulic oil and see how well your steering works

 

[BruceK]

Why? It's not a high-pressure hydraulic system?

Maybe contact Bennett and tell them you know more about their systems than they do

While you are on your high horse would you care to tell me where I said that? I just expressed an opinion that being a ram operated device I'd expect to have seen hydraulic oil. Not a statement of fact! Nor for that matter can I see the need for the added detergents etc, the rams are not going to be operating in an environment to making oil sludge. ATF has specific friction properties to operate clutch while still lubricating moving parts. The RAMs nor pump has need of these. It has low viscosity and operates at lower temps and pressures to hydraulic oil which is purer, has no additives and operates at higher temps and pressures. That and that alone was the rationale behind my presumption. Go wave your flag somewhere else, or at least bring some useful comment to the discussion

 

[DrSpock]

Your presumption is wrong - that's the trouble with opinions when they're not based on fact.

The HCU in a Bennett system uses two solenoid valves to control the flow and self-bleeding of the ATF. Try fitting new empty rams and cycle the HCU on hydraulic oil and let me know how it goes..

 

[BruceK]

errmm. Do you know how it works? The hydraulic power unit has a reversable electric motor and one solenoid per actuator /ram. That motor and solenoid either pumps fluid in or sucks it out. Bleeding is an absolute non issue. Pump out all fluid, the rams retract full up. Fill and go.

 

[Assassin]

Bruce, just for information only.

Manufacturers of compact hydraulics are turning to ATF as it is mass produced in huge quantities and cheaper (more profit).
Compact hydraulics produce more heat for the same pressure generation and ATF is much more tolerant of this heat while under pressure whereas many pure hydraulic oils are marginal at elevated temperatures.

 

[Rocksteadee]

Could also be that ATF is a water based hydraulic liquid whereas standard hydraulic oil is oil based. The plastic used could be oil hygroscopic

 

[vas]

regretted asking this Q tbh...
thank god I didn't ask a similar one when I chopped some Vosper MiniFins that were originally on a 16m displacement mobo to fit them on my 13m planning one...
Let it rest please, I'll fill it with hydraulic oil and see what happens, maybe the boat sinks, who knows.

 

[penberth3]

regretted asking this Q tbh...
thank god I didn't ask a similar one when I chopped some Vosper MiniFins that were originally on a 16m displacement mobo to fit them on my 13m planning one...
Let it rest please, I'll fill it with hydraulic oil and see what happens, maybe the boat sinks, who knows.

OK, ignore the manufacturer's spec if you want. Waiting for your next thread - "where can I get new seals for....."