I check the site pretty frequently and didn't see anyone post this yet.
"Ready for a bit of a mental mechanical challenge? Try your hand at understanding how the D-Drive works. Steve Durnin's ingenious new gearbox design is infinitely variable - that is, with your motor running at a constant speed, the D-Drive transmission can smoothly transition from top gear all the way through neutral and into reverse. It doesn't need a clutch, it doesn't use any friction drive components, and the power is always transmitted through strong, reliable gear teeth. In fact, it's a potential revolution in transmission technology - it could be pretty much the holy grail of gearboxes... if only it wasn't so diabolically hard to explain."
http://www.gizmag.com/steve-durnin-d...-geared/15088/