Open question regarding gear sets

[Potlatch]

I have a question regarding the identification and practical application of a specific gear set type. First let me say I am not an engineer nor do I have an engineering background, but I do have extensive construction industry experience so specifications in relation to blueprints and sections come fairly easy to me.
My proposed gear set consists of two parts, first an outer gear I could only describe as a internal ring gear, I think the terminology for this gear is also “helical” because the gears need to be slightly skewed or slanted. Picture (Ring gear attached)
The second gear would be a geared shaft that fits inside the ring gear. The shaft for my application needs to be considerable in length, at least 20’ with an approximate diameter of 2”.
My particular application would require the ring gear when fit over the geared shaft, would rotate as it descended from top to bottom (and vis versa) of the stationary shaft, more importantly though is the reverse of this same process, if the ring gear were not allowed to rotate, but the ring gear is moved vertically over the geared shaft, can it turn the geared shaft? Are there specific ratio’s involved is creating such gears and how would I begin to understand the process enough to intelligently research such a design?
Any help or input to my question would be greatly appreciated.

 

[ornerynorsk]

By any chance are you describing a helical spline rather than a gear? Sounds like you're describing a very long-pitch leadscrew.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[Potlatch]

Thank you so much for your response.

A helical spline sounds like a logical description, I have searched and searched the internet, but cant seem to find a picture of my proposed application. If ring gears are matched with splines then yes.

The only picture I can find that displays my description in attached. But I cannot find any gears of substantial length, say up to 20', is is possible to manufacture such a design?

 

[ornerynorsk]

This is a little out my expertise, but I know it is possible to internally helically broach a ring "gear" (spline). I do not think 20 feet would be impossible, and that with the proper equipment, a male spline could be generated in similar fashion.

If you are in the US, a thorough search of ThomasNet would turn up some possible vendors.

Good luck with your project.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[DubMac]

Go look at Lufkin gear, Fairfield Industries, Philly gear, etc. for the large manufacturers which may have info on their websites. If you want to talk to a smaller shop that can cut custom gears for you, talk to Collin at C-B Gear in Houston.

Not many gear cutting machines left in the U.S., hurry and call before they relocate to China.

 

[MintJulep]

I think maybe you are looking for a lead screw or ball screw.

Since you are not an engineer you should try describing what you need to accomplish, not how you think it should be accomplished.

 

[IceStationZebra]

The big question here is what kind of pitch do you need? Or to put it in simple terms how many times does either shaft need per foot of travel?

One problem you may have to deal with is the deflection you would see on a 20ft splined helical shaft. If the design is anything but a 1:1 ratio (like a lead screw) it would either cause an undesirable gear mesh or even skip.

Another problem will be dealing with frictional losses and leverage, but we need more information to determine the scope of the issue.

A third problem may be dirt and lubrication.

ISZ