Increased grease life in gearboxes

[mustangs]

Is there any type of grease product that can be put into a enclosed gearbox, (not sealed, just protection from the elements) so that once the unit is put together I wouldn't have to add more grease for the life of the box.

I'm trying to avoid using semifluids mainly because I don't want to have to seal the box.

There a couple of problems though. First, the gears are running at about 3-4000 rpm and the system will have to be able to run for 3-4 hrs. per day for about a 5 years. Also, I'm guessing that the temperature with the type of stuff I'm looking for won't really matter but, the operating range is beween -20C and 60C.

Most of the tacky greases I found on the internet would fly off of the gears at the speeds I'm running at. I talked to a local manufacturer and he didn't really know of anything that would help.


Another engineer that I was talking to said something about a baked grease or grease that can be baked on to gears. He said that he thought it could do the trick but didn't know what type of grease it was or if it even really existed.


Any suggestions would help at this point.

Thanks

Mustangs

 

[evelrod]

I KNOW this is NOT the answer you are looking for, Mustang. I just could not resist---In the early 80's I bought a famous brand Italian car. When it came time to service the gearbox we found that the 'drain boss' had not been drill/tapped/pluged as you would expect---long story short---still had the same fluid in it at over 100,000 miles and five years later when it was sold.
As Joe Friday said, "Just the facts, mam !"

Rod

 

[76GMC1500]

We use some really, really tacky stuff for the reduction gear on our ship. It's fun to put it behind door handles. It takes a while to get off of your hands due to the tacky factor. Anyways, I don't know what it's called, so I don't why I even made this post. I guess it lets you know, something does exist that might work in your application.

 

[sreid]

I think that you are not going to find the solution you seek. Oil on gear teeth not only provides a hydrodynamic surface so that the gear teeth do not actually touch, replacement of the oil (via, say, an oil bath) also removes the heat created in the oil at the teeth interface as the teeth slide during engagement/disengagement.

Grease is oil in suspension which slowly releases oil onto the gear teeth as it slumps onto the teeth.

 

[mustangs]

I tried a very tacky grease that I got from a local supplier but, the stuff flew off after a short testing period. The gears are helical so everything was nice and queit but the heat readings shot up after a couple hours and I had to stop. Opened up the casing and found steaming, fairly dry gears with fair amount of blue grease on the outer wall. It is a pain to get that stuff off your hands.

I figured if there was anything out there that would do the job, someone here would know about it. I guess I get to go and make some mods to the casing.

I also tried having extra grease in the casing but that didn't really help at all.

So I guess the search continues for my fictitious, million dollar grease that you never have to reapply.

 

[Tmoose]

If anybody can do Kluber can.
4000 rpm may be the killer.

 

[boo1]

I have seen sales lit. on Boron additives to lube oils ans greases. The boron becomes molecularly attached to the surfaced. .....

 

[rmw]

Grease has to be there to lubricate. Tacky greases tend to get pushed aside, or out from between the gear teeth, and their tackiness keeps them there (away from the gear teeth). In ball and roller bearings, for example, Lithium #2 is usually specified, because the lithium soap that carries the lubricant allows the grease to "flow" into, and out of the bearing as it changes temperature due to the amount of work that the bearing is seeing.

That is why gear boxes are normally lubed with liquids, because the gears act as pumps, and continually carry lubricant to the gear train.

If you do in fact, use a grease, instead of a liquid lube, then you should consider a grease that can "go with the flow".

Sreid makes some good points above about the other duties of the lubricant. They carry the wear particles to the sump, as well, where they can settle out, or be found by the magnet in the plug.

The statements I am making are to discuss grease lubrication vs semifluid lubrication, and are not to be construed as an approval of your using grease lubrication in a 4000 rpm gear box.

rmw

 

[unclesyd]

Check these people out. This is the oil and grease we used in troublesome spots. Their oil will track the gears. It will also tell if the seals are bad as it will come out the uppermost seal just as easily as it comes out of the loer ones.

We have this oil running in some overhead gear box (German made) with 1 input and 3 outlet gears running slightly different speeds up to 2400 RPM. These boxes (8) have run 24/7/365 for 15 years and the oil has been changed in only one box. Oil has been added to 3 boxes due to small seal leaks. The last time (5 years ago)I looked at the gears there is absolutely no sign of wear, with only one or two gears showing a little polishing. There has been only 4 bearing failures on the boxes. 2 were very close to start up the others had other problems.
Monday I will get the specific type/weight oil used in boxes.

http://www.le-inc.com/products/Go/GO_Industrial.html

 

[rmw]

Unclesyd,

I have an association with a manufacturer of a planetary hub axle, european style.

With generic gear oils, 90w, or 85-140, when the vehicle comes in off the road, one cannot put his hand on the planetary hub, or if he does, it does not stay there long.

Upon changing to LE, (this has been some time ago, are they the red one, or the green one?) it was observed that in identical service, the same hub on the same vehicle was barely warm to the touch.

Quite a testimonial to the LE products, which I do not sell, but I do use in a motorcoach that I take care of for the church.

Good recommendation, whether mustangs uses grease, or oil.

rmw

 

[unclesyd]

It's the red one that nobody likes due to it getting all over the machinery if the seals are bad. As you state the cooler running saves the seals. If for some reason it starts to deteriorate it turns brown but still has the benefit of a solid film lubricant.
We have changed this oil on the fly in high temperature recirculating fans.

Every time we had bearing or gear failure the first thing was to rework the assembly and install an LE product. The repeat failures were less than 5%.

Like I said we have had great success with the LE products and even more so due to lack of lubrication technician on site anymore due to budget concerns.