This is a great example of using your available parts and some creativity to solve a problem, and it also reminds me of modern cars -- even in a modern manual transmission, the car's computer is always "watching" what you do in order to try to optimize fuel usage, minimize emmisions, etc. The manual transmission in the new Nissan 370Z even reacts during a shift to blip the engine RPM to match the new gear. Hmm..., anyone want to try adding that to Sean's idea?
NXT user Sean Corzine emailed me a picture and description of this nice modification to the 3-Speed Transmission with Clutch project on nxtprograms.com. His design adds the ultrasonic sensor to "see" the gearshift lever to determine which position it is in (high, medium, or low), then he added Math blocks to calculate the resulting output shaft speed based on the input RPM and gear ratio, and modified the NXT display to display output RPM instead of engine RPM.