75w-90 oil in a very big gear box.

[oil pan 4]

Where I work we have diesel driven air conditioners.
Normaly they don't give us to many problems, but when you go some where that has 120'F days every day the weak links come out.
They have a "tripple pump drive" coming off the I-4 turbo charged 102hp john deere engine that like it says, drives 3 different things. The engine turns 2200RPMs.
1 drive goes to a clutched A/C compressor, the second goes to a clutched radial fan (like a over sized turbo charger compressor) and the third goes through a ring and pinion gear and drives a 10Kw generator @1800RPM/60Hz.
Now these gear boxes keep going out, I have had 3 go in the last month. Some break internaly others burn up.
Does any one know of any links to PDF files or any thing that talks about gear oil and can prove we should be using something besides 75-90 weight gear oil?
Common sence does not apply here. (common sence like: duha its hot here, lets use thicker oil. cant do that it would be to easy and make to much sence)

 

[benjamming]

Every done any UOAs? Maybe Terry but I don't know.

 

[oil pan 4]

Nope haven't had any UOA's done.

 

[Pablo]

What brand are you currently using?

When you say "big" what volume of fluid? I don't suppose there is any external cooling of said fluid, so volume is important.

Indeed - UOA's would be good. Break internally? Gear teeth? Bearings seize?

 

[bruce381]

how do they "go out"???? bearing or gear falure?? how hot do they run??? what oil is recomended and YES going to a higher vis will help with gear falure a GL-4 oil maybe in the 460 range "like a 140 vis" post the info that will help to recomend a fix.
bruce

 

[1sttruck]

I'd use a temp gage, and if temps are the problem either increase the sump some how, or add cooling, or use a heavier gear oil as a band aid.

 

[oil pan 4]

The oil we use is Mobil 1 synthetic 75-90.
The oil is not filtered of cooled or force fed in any way.
It weighs about 300lb and they run hot with 4 quarts of oil. The gear box is bolted up the engine.
The oil change hour times are change the oil after the first 50 and every 2500 after that.
The inside of the unit here run hot enough so a person wouldn't last to long if for some reason they were in side.
The gear case has a guard over it when running.
The only chance I would have to get a good temp reading is if one came in and I had to repair the clutch and run it with the gard off and I could get the temp gun on it.
One gear case had a bearing burn up the others have had different gears break up in side them.

 

[Pablo]

To be honest 104 hp, (with guessing - torque about the same, maybe a little more), turning 2200 rpm, gear box holding 4 qts.....this just doesn't sound that stressful.

Almost sounds like poorly made, defective boxes. I can almost understand a bearing failing.... but different gears breaking up doesn't exactly sound like a fluid issue. Perhaps you could try a good synthetic 75W-140 as fluid band -aid.

 

[unDummy]

Use the common sense. Switch to a full synthetic 110wt or 140wt gear oil. Make sure oil level is checked regularly and overfilled a little if possible.
UOA would be an eye-opener.
IR or temp sender readings would be interesting.
Film thickness seems to protect splash lubricated gears much better.
2500hr run times seems excessive for a 'hot' situation. Change it out more frequently.
Forget the 75w90's and go straight weight if that is an option.
If available, Delvac 75w90 is a better choice then Mobil1 75w90.

 

[bruce381]

there is a formula to figer how thick a oil should be for gear units you need speed, temp, gear type and perhaps 1 or 2 other data points I forgot most of it but would try a GL-4 industrial gear oil perhaps a 320 or 460. forget the 75/90 to light vis.
maybe a look up try to find Jack Zakarian or Jody cruz at chevron tech line they can recomend right oil which I Know will be much heavier than current use Bye the way WHAT OIL WAS recomended????
bruce

 

[1sttruck]

You noted that very hot days cause problems, and otherwise they work fine. I'd contact the maker first. Are you following maintenance specs ? Exceeding the operating limits ? If you running air conditioning duct some of that cool air to the engine.

 

[Colt45ws]

102HP at 2200RPM would be about 243FT.LBS torque at 2200RPM.

 

[salesrep]

What does the oem visc. call for?
Thicker is not necessarily better.

 

[oil pan 4]

I am following maintenance specs to the letter. (thats the problem)
The oil that is recomended is mil-2105 (basic cheapest gear oil) but some how we have Mobil 1 synthetic gear oil.
Note Mobil 1 is not the most basic cheapest gear oil.
I guess it can be synthetic and be 2105 at the same time.
Going to Mobil 1 form the most basic cheapest 55 gallon drum gear oil was the cheap fix/band aid.
It looks like it isn't working.

 

[salesrep]

What viscosity??????????? is reccomended.

 

[bruce381]

what vis ??????
bruce

 

[Junior]

Quote:

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To be honest 104 hp, (with guessing - torque about the same, maybe a little more), turning 2200 rpm, gear box holding 4 qts.....this just doesn't sound that stressful.

Almost sounds like poorly made, defective boxes. I can almost understand a bearing failing.... but different gears breaking up doesn't exactly sound like a fluid issue. Perhaps you could try a good synthetic 75W-140 as fluid band -aid.

---

I have to agree. Doesn't sound that bad at all. We have a 100Hp 90 degree straight bevel gearbox with a 3 QT capacity. Runs at 200F all day long with syntethic 75w90.

The gear failure sounds like a metalurgical problem or an alignment issue.

You could always drain the gear box, drill and tap a hole, install a thermocouple and monitor the lube temperature.

 

[1sttruck]

http://www.machinerylubrication.com/arti...20Gear%20Drives

If there is no oil cooler on the industrial gear drive, it’s best to determine the maximum expected ambient temperature during operation and:

Increase one ISO Viscosity Grade if the ambient temperature exceeds 95°F (35°C).
Increase two ISO Viscosity Grades if the ambient temperature exceeds 122°F (50°C).

If there is an oil cooler, the maximum ambient temperature is less important because the oil’s temperature can be controlled. Therefore the viscosity should be based on the oil’s temperature.

Increase one ISO Viscosity Grade if the oil temperature exceeds 150°F (65°C).
Increase two ISO Viscosity Grades if the oil temperature exceeds 185°F(85°C).

If the oil temperature exceeds 194°F (90°C), use a cooler such as a fan or a heat exchanger.

The pour point of the industrial gear lubricant should be at least 9°F (5°C) below the minimum expected ambient temperature during start-up. If this cannot be achieved, use an industrial gear lubricant that has a lower pour point, such as one that is formulated with semisynthetic or synthetic base fluids, or use a heater to heat the oil before starting the industrial gear drive.

 

[salesrep]

"The use of too heavy of a viscosity can result in excessive heat generated, excessive power losses, decreased gearbox efficiency and improper oil flow."

 

[Steve S]

Quote:

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"The use of too heavy of a viscosity can result in excessive heat generated, excessive power losses, decreased gearbox efficiency and improper oil flow."

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Better shock protection though.