Sliding sprocket

Is this a "one-off", or are you looking to build lots to the original design?

If a one-off (e.g. to prove a concept), I'd suggest looking through a scap-yard. Junked morobike gearboxes may be a useful source, but you'd have to do some work getting a standard cycle sprocket fitted.

Just having a play, but could you use a cam style shifter? (Actually after doing the drawing I realised it was a different question!) Never mind, hope you like the drawing anyway!

What about an enclosed gear box that runs a bicycle sprocket for an input.

In automotive racing applications, a hydraulic throw-out bearing is used (I don't recall the manufacture). I'm not talking about the master/slave cylinder setups that push on the throw-out bearing arm. These extend the bearing against the clutch fingers like a toroidal piston. Something like that could locate an attached sprocket horizontally, sliding on a splined axle shaft. Maybe a Sprag clutch bearing on a smooth axle? That would allow free-wheeling. One of the problems I see is a possible lack of chain stiffness. It would have to be securely guided.

You would more then likely need to design your own setup.

The only thing that visually comes to my mind, is a pnuematic driven gear on a shaft. All your veriable sized gears will need to be on the same mesh plane. I would actually suggest an electronically driven transmission, such as one like the Allison 6-speed used on high perfamance automobiles. These new transmissions work with an electric paddle controller located just under your finger tips on the steering colluum.

Or in a normal automatic condition under servo load.

Or, you could go the way of a CVT, constant velocity transmission drive unit, such as similar to the ones being tested by Mitsubishi and Honda auto makers.

Or you could follow the same principle of a CVT and designe your own centrifigal clutching system that engages at different RPM loads.

Good luck, 8>) Maximo

Are you trying to built automatic transmission in bicycle .you can look in junkyard if looking for scrap . look google= cvt= search through consigning sites for same ,you will get it with links .

A bicycle with an automatic derailleur has been developed and was being sold on TV about five years ago. This guys idea is in moving the sprocket set instead of the chain in a confined space if I understood correctly.

Sliding sprockets. The solution exists in Germany. You all know the Torpedo 3 speed compact gearchange on a bicycle. The same exists now with, I think 6 speeds and able to switch under load. In a good bicycle shop you should find it.

Regards,

Theo

I think many posters are getting hung up on the bicycle idea. I believe Energy Hunter is using the derailleur mechanism for a different application. Keep your minds open.

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"Does anyone know of an "off the shelf" sliding sprocket device - preferably of a suitable size for use with a standard cycle chain. "

More input from energy hunter would help!

A chain for use w/a deraileur is made to be twisted [deflection].

A belt & stepped pulleys will give similar results.

I'm not sure what the purpose of your device is or how much power it has to handle but a good method of varying speed under load is a V style belt on one or two adjustable width pulleys (variator). I believe this type of system is much more forgiving than sliding chains on and off of sprockets, especially under a load.

http://www.teamcalamari.com/zuma/variator.html

This site deals mostly with auto adjusting types but a manual adjustment system would not be hard to devise and are also available.

Just a little more information to look at for some ideas.

Good luck with your endeavor.

http://uk.ask.com/web?q=DAF+variomatic+transmission&search=&dm=all&qsrc=0&o=312&l=dir

I would like to thank all the contributors to date.

Perhaps if I explain the problem in more context the possibility of alternative ideas would be seen as inappropriate.

This is on a bicycle and involves the storage of energy (not electrical but mechanical). Two variable gear units are involved.

One relates to the energy stored for use on downhill - the other relates to energy taken out for use on uphill.

If both gear units are set the same, the energy being stored is equal to the energy released, thus no use is made of the storage. By moving the gears in unison (one getting higher as the other gets lower) various steps of energy being stored or released can be used as the terrain differs.

This therefore cannot have gear changes where the energy can escape between changes, as with a clutch on a vehicle gearbox.

The drive must at all times be positive, this rules out the variomatic system as there can be belt slippage. The other point must be the least friction loss.

Initially I tried double derailleurs (spelt right this time) both on incoming energy and on delivery but the problem arose in trying to shift a gear whilst it was under tension on one of the set of sprockets and in a confined space.

The answer appears to be to slide a single sprocket to engage with the next gear. This does not give as great a variation from low to high as was inteneded but could be altered.

I considered the sliding spline type of system used on agricultural implements where the variation in length of the drive shaft is coped with as a hydrauylic lift raises the running implement. As it will be subject to considerable tension I visualised that some sort of ball bearing type system running within the splines would be available to reduce the drag of frequent changes of gear.

Hence my question.

Anyone interested in helping with the project please contact eblucy@btinternet.com

Thanks again to all the contributors to date.

You are correct ball bearings resting in a spline will do it

Take a look @ a constant velocity coupling as used on a front wheel drive car.

How are you storing the energy?

Flywheel?

32 yards of strong rubber - twisted.

Light & effective

Sounds promising