Two
motors and Two gear speed gear box?
A heavy human powered vehicle (HPV) that can drive 450lbs total combined weight up the steep hills in Vancouver will need at least two gears to climb the steep hills with a legal wattage. Read more: cycle tractor.
With 7500 rpm output for maximum momentum efficiency using a high voltage motor, you will need a lot more gear reduction (like 13:1 total) to keep it down to about 11-13mph [17-21kmh] on a 9% to 10% grade but even that would be quite a fast gear with Canadian legal power.
So two motors would be needed. Making the vehicle illegal only when you need to turn on the second motor. But it will still not be able to drive faster than the speed limit if the gears are low enough. About 16mph [26kmh] on flat land.
A retro-direct drive is a fast (high gear) in the forward direction and a slow (low gear) in the reverse.
Making a switch to reverse the motor: (see the middle of page 5): Epicyclic retro-direct 2 speed transmission.
There’s
a problem with the design of planetary gears – there is inherent
backlash and play between the gears. There can be problems with
binding or jamming. It would be better if the prototype was made
without planetary gears.
A
hypocycloid gear could be a better way of gearing down but without
tight fitting gears you can have the same problem. A harmonic
drive
would
be much better if you could design one to do this retro-direct
switching.
2 Speed Tranny Idea
Epicyclic retro-direct 2 speed transmission
Miles' Retro-Direct Gearbox
Some
thoughts on two speed transmissions:
2 Speed Tranny Idea
Epicyclic retro-direct 2 speed transmission
Miles' Retro-Direct Gearbox
 |
The
ring gear is attached to the output
shaft and the planet gears are
stationary
on a plate with a one-way bearing in the opposite direction. |
more here
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