Posted July 14, 20159 yr 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, 20159 yr by Blakbird : Replaced oversize images with links.
July 14, 20159 yr 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....
July 14, 20159 yr Author 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, 20159 yr by darkboy101089
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