Automatic Two-Speed gear-box Animation???

[Hugh-Jassman]

I have been having insomnia trying to visualize how this gear box works.

The large pulley is the low gear and when the shaft spins faster than the drive is pushing the shaft, the large pulley ratchets back words???

But how does the input push the output faster? Through another free wheel? Or does the torque just change from the slow to the fast gear without a second free wheel???

There must be hundreds of other people trying to visualize this also so they can build one. It would be fantastic if Chalo or someone would make an animation showing how it works.

 

[spinningmagnets]

The transmission on the bottom is one of Thuds. It uses a dog clutch, which is the part in between the two sprockets on the lower shaft. The clutch is keyed to the shaft, and it can slide left or right. The two lower sprockets float on the lower shaft, and can only connect to the shaft through the clutch.

The two upper sprockets are permanently attached to the upper shaft. And both chains constantly run. It must be shifted manually.

 

[macribs]

There is a thread here for the dogbox from thud, https://endless-sphere.com/forums/viewtopic.php?f=28&t=14818&p=221255&hilit=two+speed+transmision+gear+box#p221255

 

[Hillhater]

I have been having insomnia trying to visualize how this gear box works.

The large pulley is the low gear and when the shaft spins faster than the drive is pushing the shaft, the large pulley ratchets back words???

But how does the input push the out put faster? Through another free wheel? Or does the torque just change from the slow to the fast gear with out a second free wheel???

There must be hundreds of other people trying to visualize this also so they can build one. ]

Can't build the animation, but I'm pretty sure the secret is the centrifugal clutch which engages a second gear train when the rpm is high enough.
These are common on the old gas RC cars.

 

[Hugh-Jassman]

so there is a hollow shaft connected to the high gear and actuated with the centrifugal clutch?

Can't build the animation, but I'm pretty sure the secret is the centrifugal clutch which engages a second gear train when the rpm is high enough.
These are common on the old gas RC cars.

How about this Evo gear box? it looks like it has to have a loose belt that is held down by a plastic devise......that should be a roller.
http://scooter.wikia.com/wiki/Evo_two_speed_transmission

http://scooter.wikia.com/wiki/1-Touch_Tension_System

 

[Hugh-Jassman]

I can see that this using the same input shaft will never let the high speed catch up with the low speed unless they are so close that running the shaft faster will push in some slack in the low gear chain. then as it wears there would be more slack.

And that the second gear freewheel will always be moving slower than the input shaft. so it would catch up and engage teh free wheel all teh time. boy that is a mind twister if there ever was one.

 

[Hugh-Jassman]

ok now if I could figure out how to post Youtube videos

this loogs very good, but maybe too heavy for a eBike????

https://www.youtube.com/watch?v=OtcFXSR33kM

I have got to get a set of Legos!! Do they have them with belts and free wheels??

 

[Hugh-Jassman]

OK so there is not way no make one of these work???


https://endless-sphere.com/forums/viewtopic.php?f=7&t=17794

 

[spinningmagnets]

Any one of the ideas posted here will work, all it takes is money.

 

[macribs]

I would think that the least amount of money would be to get one of the scooter racing CVT's. Those are smaller and lighter then stock and you can play with both the weights in primary and the spring to find your sweet spot for take off RPM. Secondary clutch you can change springs to match. Should work well with light weight high RPM RC motors, or small powerful inrunners like Astro's. You should be able to cruise around in walking speed in traffic jams, ease into tight places downtown and never have trouble with take off due to the CVT letting the motor(s) spin up before clutch engages so even in steep hills with a heavy trailer behind you there should be no need to peddle the bike from zero mph. Just crack the throttle and let it rip. Should give you ability to climb anything as long as you got traction, and will also cater for maximum top speed. Good thing will be that there are no custom made parts, you can get spare parts if needed. Of course if you played with them weights and filed/removed material you will need to do that next time as well. But those CVT are as close to maintenance free you can get. They last you forever.

It will take a little of the efficiency and it will "eat" some power - but heck just keep adding more motors until you find the power you need 8)

 

[Hugh-Jassman]

Any one of the ideas posted here will work, all it takes is money.

It takes a little more than money, my friend....I need instructions. That last photo looks the easiest, but does it not take some kind of freewheel? or does it just move the torque to low gear automatically? Looks like it will need to be manually shifted some how.

 

[spinningmagnets]

Are you a machinist who can make your own custom parts, or are you contemplating having custom parts made by someone else?

Thuds dog-clutch 2-speed is the easiest to make from scratch. Do you want to actually make an automatically-shifting 2-speed, or do you just want to understand how they work?

 

[Thud]

Are you looking to build a two speed vehicle?
Here is the repository with current drawings.
https://endless-sphere.com/forums/viewtopic.php?f=28&t=7832&start=25#p309846