Automatic Transmission Model

Have you ever wondered how an automatic transmission works? I did, so I looked it up and then designed this desktop model. It has six forward speeds and one reverse. Real automatic transmissions have a hydraulic or electrical system that engages different clutches and brakes to shift gears depending on the driving situation. With this model you control those simplified brakes and clutches yourself. The clutch is actuated by sliding the drive shaft through to different positions (which each have two gear markings), while three separate brakes each also have two gear markings. You select a gear by engaging the brake and clutch position associated with your desired gear. See demonstration video: http://www.youtube.com/watch?v=-FyC3dn3HJY I tried to design the gear ratios to be fairly close to what some real cars use, and this is the result, where the input is the crank and the output is the annulus: 1st gear: 1 : 4.29 2nd gear: 1 : 2.5, 71% increase 3rd gear: 1 : 1.67, 50% increase 4th gear: 1 : 1.3, 28% increase 5th gear: 1 : 1, 30% increase 6th gear: 1 : 0.8, 25% increase Reverse: 1 : -3.93 The OpenSCAD file is included and is highly parametric in case you'd like to play with differ