Gearboxes are used to change the ratio of torque to speed, while keeping the power constant. They come in 4 ratios - 2:1, 4:1, 8:1, and 16:1, and will affect the torque and speed accordingly. Reduction gears increase the torque and decrease the speed; acceleration gears do the opposite. Be warned: these need to be lubricated to work at their full potential; most unlubricated gearboxes will gradually wear down, and reduce the transmitted torque accordingly.