Spur gears have teeth parallel to the axis of rotation and are used to transmit motion from one shaft to another, parallel, shaft. Notice that this is a planetary gear train. Vikash Bharti. As the speed of the shaft increases, the torque transmitted reases A rack and pinion is a pair of gears that convert rotational motion into linear motion and vice versa. Assume that the engine is being driven at rpm, the transmission is in 4th gear (direct drive, ratio) to the driveshaft. In this course A, I'