2 speed tranny

[gwhy!]

I have been thinking about this for a little while and wonder if anyone has any input:

forum member Miles posted a link/picture ( wish I can find it again,,, miles? ) a while back of a very simple 2 speed system on a bike that when peddling normally will give you one gear and if you peddled backwards it will give you another, I have been playing with one of my outrunners and it is very easy to reverse the motor using a the speed controller that I have so could this work but using spur gears and one way bearings ? in a small compact package I guess what Im really asking is would one way bearings and spur gears be up to the task. I know Thud has made a 2 speed tranny but don't really offer a big reduction ( Im not knocking it Thud please dont take that the wrong way ) and also uses some major machine work, using spur gears would give a much higher reduction and would also be much easier/cheaper to make would it not ?.

 

[Miles]

gwhy,

Do a forum search for retro direct. I've been working quite intensively on designs in this area. My proof-of-concept model works perfectly

How quick do you think the reversal could be?

 

[gwhy!]

gwhy,

Do a forum search for retro direct. I've been working quite intensively on designs for this. My proof of concept model works perfectly

How quick do you think the reversal could be?

Thanks Miles,
I have a quick search and there is loads of stuff I will have to read up on whats been going on with it. Motor reversal is very quick and I think I would be quick enough with the speed controllers basic configuration ( with just a switch wired into the controller to reverse the motor ) the motor do need to come to a complete stop before it will run in reverse but this happens in less than a second ( will be even quicker in the e-brake is enabled when shifting ).

 

[Miles]

The boat controllers have reverse but it's far from instant...

 

[gwhy!]

The boat controllers have reverse but it's far from instant...

Im not using a rc controller I have been playing around with the 6fet Infineon.

 

[Miles]

Yes, I've noticed

The boat controllers handle the switch-over but there's a programmed pause.

It would be ideal if the whole changeover (loaded to loaded) took less than half a second...

 

[Hillhater]

a very simple 2 speed system on a bike that when peddling normally will give you one gear and if you peddled backwards it will give you another, .

Just curious as to what benefit you are looking for over a internally geared rear hub ?

 

[gwhy!]

Yes, I've noticed

The boat controllers handle the switch-over but there's a programmed pause.

It would be ideal if the whole changeover (loaded to loaded) took less than half a second...

So you did notice that I am using a baby 6fet :lol:

I think the switch over can be done at these sort of speeds if incorporating the e-brake on the sensored controllers when reversing, I can see why there would be a bigger delay with a sensorless controller. Ok I will have more of a play and try to get some real times . If you think it would be helpful .

 

[gwhy!]

a very simple 2 speed system on a bike that when peddling normally will give you one gear and if you peddled backwards it will give you another, .

Just curious as to what benefit you are looking for over a internally geared rear hub ?

Geared hubs ( as far as I know ) do not give you the benefit of on the fly to gear down for climbing hills or gear up for max speed.

 

[Miles]

Ok I will have more of a play and try to get some real times . If you think it would be helpful .

Thanks

It depends on rotor/drive inertia, of course, but my Astro 3210 stops pretty quickly with braking....

 

[Hillhater]

Geared hubs ( as far as I know ) do not give you the benefit of on the fly to gear down for climbing hills or gear up for max speed.

I am sure some of them are capable of that, but "full load " shifting is never really sensible in any situation ( even F1 cars cut the power momentarily during shifts), and i dont see how a reversing motor system can really be considered "on the fly" ...certainly it wont be shifting under power !
Really its only a matter of how quick a system can shift gear ?

 

[Miles]

Maybe there is a confusion between hub gears and geared hub motors?

Anyway, I'm interested in the ease of automation...

SRAM are developing a 2 speed hub motor using this principle.

 

[John in CR]

...My proof-of-concept model works perfectly ...

Can we see it? Please.
Which version did you go with, the one with the spur gears?
Why automatic instead of manual shifting?
John

 

[Miles]

Not at the moment, I'm afraid.

Automatic makes sense if the gearing is only for the motor. Of course, you can have manual override.