Oil bath for wind turbine transmission

[KBwind]

Greetings
I am building a chain drive transmission for a wind turbine with a vertical axis. Its much similar to the transmission built by Chris Olsen (thanks for the fantastic projects you share) in that it's based on a chain drive with a high speed shaft to drive the alternator and a low speed shaft driven by the turbine. I use a A35 chain with sprockets which weld onto standard W hubs. I used this set up on my last turbine with very promising results but this time I will be enclosing the transmission in a case made from 1/4 inch steel plate.  I would like the chain to run in a oil bath but really not sure how to accomplish this for vertically mounted shafts. The sprockets and chain are Located about 2 inches above the bottom of the case and are mounted above 4 bolt flange bearings. I suppose I could fill half the case with oil but this seems a little overkill and would leave my bottom bearings completely submerged. I also imagine this could add a lot of drag to the assembly since the whole bottom of the chain will be pushing through the fluid.
Any thoughts???
KBwind

[fabricator]

Depending on the type of bearings they may not hold oil, if they are self aligning bearings they will weep, I'd seriously consider just making an access door and shooting it a couple times a year with good chain lube, there are lots of chains on farm equipment and motorcycles that are constantly exposed to the elements.
You could also some how put a slinger on one of the shafts for splash lubrication.

[DanG]

With an oil bath you will need a sump to hold separated water - think sloped bottom to a lowermost extra boxed-in area with its own drain. If you don't get it away from the moving areas fast it will emulsify into salad dressing.

[KBwind]

These are all great things to know thank you. Yes they are self aligning bearings (on a side note any tips on getting these things self align properly?). I have used the exposed chain with routine oiling but that was far from the ocean. This turbine will be mounted literally 5 meters from the higher tides of the year and will actually be offshore one day a year. This makes for great winds at low hub heights but any exposed steel will rust within a matter of hours. I've learned the hard way that rust never sleeps and have accounted for this with galvanized steel for the majority of the turbine. This transmission is one of the last steel prices (except for the mag rotors of course) left and it'll have to stay that way until I find some galvanized steel plate in the Nicaraguan junkyard for fifty cents a pound. I am somewhat stuck with these steel sprokets. Could I treat the chain and sprockets with some sort of rust inhibitor a little more advanced than the ten coats of anticorrosive paint I use for the other steel parts?

[RP]

Have you considered grease instead of oil?  You could pack it up to the level of the chain in something like wheel bearing grease.

[kevbo]

The lower end of your shafts will either need seals or to be covered if nothing connects to them.  You could use a slinger to lift some oil off the bottom of the case.  Imagine a rod or bar attached just inside the teeth of one sprocket.  This extends radially toward the shaft, and also downward at a slight angle.  When it is spinning, some oil will climb this rod due to centrifugal forces.  Now imagine lots of such bars, or even a conical plate.  That will get the chain oiled.  To get the upper bearings will require more effort, and it may be best to rely on grease here.

[ChrisOlson]

I suppose I could fill half the case with oil but this seems a little overkill and would leave my bottom bearings completely submerged

For a vertical shaft turbine chain case I'd design the box different.  On each shaft I'd have the top bearing mounted in the top of the transmission case, have internal intermediate bearing support inside the case for the bottom bearing, and the sprockets and chain go on the bottom in the sump, below both bearings.  I would not use thru-shafts on a vertical design.
--
Chris

[kevbo]

You could avoid the lower case penetrations and still support the shafts on both sides of the sprockets if you had a plate completely inside the case that holds the lower bearings. (rather than using the floor of the case to mount the bearings)  I am picturing the whole gearbox can be assembled to the top cover, then drops into a pan that might not even need to be structural if it is just an oil sump.

This would also allow you to fabricate and line bore both bearing mounting bores as an assembly rather than trying to get the bores to align on two parts after you bolt them together...so maybe you don't need to use self aligning bearings and could gain some rigidity.

[GoVertical]

Hi, do have any pictures of the earlier project. I am trying timing belts on a similar project.

[fabricator]

You can also get a grease that is like pudding, I have some, I think it's Mobillith AWO, it's made for gear cases that aren't sealed for low viscosity oil.

[GoVertical]

You can also get a grease that is like pudding, I have some, I think it's Mobillith AWO, it's made for gear cases that aren't sealed for low viscosity oil.

Hi, I like the grease on chain idea, if the belt idea fails it is another option. thanks.

[KBwind]

I've been off-grid the last week and haven't had Internet access but thanks for all the input. After reading the comments
I have come to realize that the oil bath isn't the best approach for this transmission. Practically the transmission case's purpose in my application is bearing and chain alignment. I have completed the transmission and with a little tuning it spins so easily that it would take a rather precise instrument to measure the difference between static or dynamic resistance versus direct drive. These mechanical nightmares have not been as bad as expected. I will integrate an access door for the case and see how things go with the pudding type grease. I just finished the stator and mag discs for the 4 pole alt that is driven by the transmission. It should be interesting to see how this thing runs and I should have it together Monday. I also was able to test the new turbine in free-wheel and was very pleased with about 145 Rpm at 4.4 m/s at a TSR of 1.4.
Kbwind from Nicaragua poolside with beer in hand.

[GoVertical]

Hi, please provide photo's if possible, I am very interested. Enjoy the pool side.