two questions ... oil viscosity .... pump brand

[xtal01]

Two more questions ....

Ted (hydtools) has been awesome and helped me design the perfect power unit. Unfortunately, I realize nothing is perfect so I am looking at a back-up power unit. Nothing fancy, just an simple unit that will lift and lower my cylinder if my primary unit fails ( which could happen since the pump/motor and cylinder is out of a 40 year old forklift ). My thinking is to just put a dry break coupler on right off the lift cylinder. If my pump or controls fail ( or even if I just break a hose), I just unplug the main system and plug in the backup unit. This would cover any failure other than the main lift cylinder failing.

So this leads to to two separate but connected problems.

1) The simplest (and I am guessing the most reliable) power unit I am seeing out there the units used for automotive lifts. Small footprint, pump on top of tank standing vertical. 4 gal tanks all putting out 2500 - 2900 psi at about 2 GPM. I have looked at several ( Norther tool (NorTrac), SPX (Stone), Haldex, ebay specials, ....). They are all Chinese built .... all in the $400 to $600 range. Push button (hold on) for up ... no valves, motor runs and cylinder lifts ... some don't even have contactors, just a heavy switch. 220 vac at about 15 amps single phase. Manual valve gravity lower. Not great for a primary unit ( although auto shops use these all day ) but of a backup I think they will be great.

So my first question ... is any brand better than another? They all seem to be about the same. Since they are all Chinese, probably all about the same quality ???????

2) Choosing this pump ( or any similar unit ), leads to an oil compatibility problem.

My forklift has a label saying "Texaco Rando HD-B" ..... can't even find a specification for this on the web. I called Chevron (Texaco), they say the equivalent is Texaco Rando HD 46.

The pumps I am choosing all say ISO 32 or Dextron III ( I checked, Dextron is about ISO 29 ).

So, these two pump require oil one step apart .... 32 vs 46.

The unit is being used inside so I really don't need cold weather capability. The unit will be used only a few times a day for 1 - 2 minutes a day, so I don't need to worry about heating up the oil after hours of use.

Would it be terrible to use either 32 or 46 in both units?

I can use the correct oil in each unit and since each has it's own reservoir and if I switch connections while the cylinder is at the bottom of it's stroke, there would be minimal oil exchanged but it would be nice to use just one type of oil in both power units.

Again I am "guessing" that the oil viscosity is controlled / limited by the pump and not the cylinder ????????????

Thanks again so much !!!!!!!!!!!!

Mike

 

[HPost]

First thing to say is that Haldex is not Chinese, it's Swedish origin and they make the pumps in the US among other places too.

The quality across the range is likely to be the same across most units apart from perhaps the odd one that should be thrown under the crusher. The thing that sets them apart from each other is the material quality and strength, so the better pumps last longer and have a better volumetric efficiency.

Oil viscosity is a function of temperature and so the only part in changing viscosity played by the pump is to put heat energy in to the oil and thus reduce its viscosity.

The difference in viscosity between 32 and 46 in terms of shear is not high and with very low temperatures, both could affect the pump as the pump would struggle to fill. That said, in a small unit like this with pump practically immersed in the oil, the temperature would need to be down at about -50 or lower to get the oil up to about 1500 cSt or past its pour point. In other words, not liquid, more like syrup.

pay no attention to oil called up by supplier, that's just a commercial deal set up between the oil company and the pump/cylinder supplier.

Use what you want...

 

[hydtools]

What Hpost said.

We used a lot of Texaco Rando HD AZ.

Ted

 

[xtal01]

I don't know what I would have done with out this forum ... you guys are great!

Thanks for straightening me out on Haldex pumps. The replacement pump on my truck ( for the snow plow ) is a Haldex and I just assumed it was cheap Chinese like most of the other replacement pumps.

I do realize these pumps I am looking at are would all be very limited in there longevity. As I said, these are just a back-up. With luck they would only be used a couple times a year to test the system ( learned a long time ago to test the back-up system a couple times a year .... you don't want any surprises when you need to use it ).

My main pump is a Cessna. I am assuming that this is decent pump. If for any reason I need to replace the main pump in the future, I would not hesitate to spend a good chunk of money on it since it is the primary unit.

The ambient temperature should be between 65 and 85 degrees ( we don't have an A/C unit here in Vermont for the very short time we get warm days ... only had three days above90 last summer ). So I would think ISO 46 will be fine since it will never see low temperatures.

Even with the back up unit putting out 2 GPM ( the primary puts out 8 GPM ) it will only take 1 minute to raise the lift ( cylinder has a 2 gal volume ). It will only be used a few times a day so I don't think the oil will ever get warm never mind hot. Either 32 or 46 I'm sure will work from what you say.

i am thinking I will go with Texaco Rando HD 46 since this is what is specified for my primary pump / system.

It is funny how I just can't get any straight answers from local vendors ... and sometimes even from companies. I noticed a note in the manual saying to use "ISO 32 or Dextron III". There was a second note saying "so not use synthetic fluid as it may not be compatible with Buna o-ring seals the pump". I was a little confused since Dextron IV ... which should be direct replacement for Dextron III is synthetic. I have now called two supplies and one manufacturer ( Valvoline ) and have still not gotten a straight answer as to whether or not Dextron IV is compatible with Buna rubber.

Thanks again so very much for all the advice!!!!!!!!!!!

Mike

 

[HPost]

Where you say Dextron...do you mean Dexron, which is trade spec for transmission fluids???

 

[xtal01]

Sorry, yes ... Dexron.

It just seems to be an "all purpose" oil.

My snow plow pump uses it. My 4 speed gearbox and transfer case.

Several of the hydraulic power units ( such as the one I am looking at that is meant for a automotive post lift ) specify "ISO 32 hydraulic oil or Dexron III".

I always use the "newest" Dexron and I always try to use synthetic lubricants.

Valvoline "maxlife" ATF meets Dexron II, III and IV ( along with Mercon LV, Allison C-4 and TES 389, Toyota T, T-II, T-IV, WS, .....) and it is synthetic.

I was "thinking" of using it for the fluid in my system ( ISO 29 ) but on second thought I am "guessing" that Texaco Rando HD would be better as it is hydraulic oil not ATF being used as hydraulic oil ??????

Thanks ..... Mike

 

[hydtools]

The downside of ATF is that it can attract water and unlike automatic transmissions your hydraulic will not get hot enough to drive out the water. Texaco Rando HD AZ and other fluids like it are high VI ISO32 fluids. ATF is attractive because it is readily available; some designers default to ATF because it is used in outdoor machinery transmissions and reduces keeping more than one oil on hand. Many common seal material are compatible with ATF. Manufacturers' warning against its use may be honest or a CYA advisory.

Ted

 

[xtal01]

Thanks for explaining the difference! I imagined that a true hydraulic fluid had to be better than an ATF.

I am not hung up on "texaco" oil, it is just what was recommended by the forklift manufacturer and it seems to be a "standard" in the indusrty.

So, I went to the Chevron (Texaco) lubrication page:

http://www.chevronlubricants.com/en...-equipment/hydraulic-fluids.html#.Vq0-fk_RUa4

There is no Texaco HD AZ listed. I do see an HDZ ... is this the same thing?

If this is correct, is HDZ better than HD?

Is there any reason ( again, I just like synthetic oil ... I use it in everything I own ) that I may want to go to something like: Clarity Synthetic Hydraulic Oil AW ???

Is there any other brand (natural or synthetic) you would recommend I look at .... I will need about 10 gallons ( 5 primary, 5 back-up)???

I am guessing like other oils, even though it will not get many ours of use, I should change this oil once a year?

Or maybe using a lift only a few times a day it is just a waist since my duty cycle is so light ????

You don't know how much I appreciate your advice!

Thanks again ..... Mike

 

[hydtools]

Go with the synthetic ISO 32. As long as you have good filtration and keep the fluid clean, you should not have to worry about annual change.

Ted

 

[xtal01]

Fantastic!

Thanks once again for all the help!

Mike

 

[gruntguru]

ATF is often specified because of its high VI (viscosity index). This means its viscosity doesnt change as much as temperature varies. Viscosity of ATF at 40*C will be similar to an ISO 32 oil and at 100*C it will be similar to an ISO 46 making it a bit of an all-rounder.

je suis charlie

 

[hydtools]

I like Rando HDAZ because its VI is 212. ATF's is 174.

For even higher VI look at Exxon Univis fluids.

Ted

 

[IceStationZebra]

You have to remember that many forklifts are operated in freezers, which is why they called out ATF as an option. Like GruntGuru said the high VI offers better cold temperature operation. If you are just running this rig periodically and it will never really get warm I would go with VG32 or maybe even VG22. ISZ