Improved 3 speed automatic gearbox

[darkboy101089]

This is a remote controlled car that I am working on. This is the demo of the 3 speed automatic gearbox that I tried to improve for this project.

It uses a differential gear to transfer the overload torque to select lower gear.

http://www.brickshelf.com/gallery/darkboy101089/Gearbox/imag0245.jpg

http://www.brickshelf.com/gallery/darkboy101089/Gearbox/imag0246.jpg

http://www.brickshelf.com/gallery/darkboy101089/Gearbox/imag0247.jpg

http://www.brickshelf.com/gallery/darkboy101089/Gearbox/imag0248.jpg

http://www.brickshelf.com/gallery/darkboy101089/Gearbox/imag0249.jpg

Current WIP

http://www.brickshelf.com/gallery/darkboy101089/Gearbox/imag0251.jpg

Edited July 14, 2015 by Blakbird
: Replaced oversize images with links.

[darkboy101089]

This is a video demo of how the gearbox functions.

[Alasdair Ryan]

I recommend that you should be testing any gearbox that will be propelling a car along should be tested on the ground,and not static like in the video.

There are two ways I have often thought about building the most efficient auto-gearbox:

Design A The Centre shaft is the one that changes gears,the top is a static axle from the motor and finally the lower axle is where the different output speeds are placed.

Design B A orbital gearbox where the driven axle goes through gearing on a rotational axis which meshes to a static output shaft.

I have tried your idea too but have found that there is not enough force to change gears,design A does work well but it is limited as a lot of gearing will make gear backlash.

Keep it simple....

[darkboy101089]

I know orbital gear are more efficient and works better, but I like the sound of it clicking to new gear

I did test it on the floor and found out that lowest gear does not get selected often, but when I initially throttle the car, it selects the middle gear and goes back to fastest gear after one second. The only time I see lowest gear selected is either going over a bump or putting lots of load on the car.

The spring on the rubber band to change gear must be precisely place to achieve the results that I got. Slightly too hard on the force of rubber band can cause the gear to not be able to select lowest gear. Also the gear selection trigger is reinforced from what I initially started to achieve this. I am still working on improving it with minor changes at a time.

Edited July 14, 2015 by darkboy101089