The document describes the D-drive, an infinitely variable transmission invented by Steve Durnin. It uses variable speed planetary gears instead of clutches to provide continuous variability between forward and reverse without torque limitations. It works by comparing the speeds of two spinning shafts - when they spin at the same speed the output is neutral, and varying their relative speeds provides different gear ratios from max forward to max reverse. Its potential applications include variable speed spindles for CNC machines and transmissions for vehicles. However, it requires a second motor to control the speed of one shaft, and if either motor fails the transmission is stuck in one ratio.