Gears and gear racks use rotation to transmit torque, alter speeds, and change directions. Gears come in many different forms. Spur gears are basic, straight-toothed gears that run parallel to the axis of rotation. Helical gears have angled teeth that gradually engage matching teeth for smooth, quiet operation. Bevel and miter gears are conical gears that operate at a right angle and transfer motion between perpendicular shafts. Change gears maintain a specific input speed and enable different output speeds. Gears are often paired with gear racks, which are linear, toothed bars used in rack and pinion systems. The gear rotates to drive the rack’s linear motion. Gear racks provide more feedback than other steering mechanisms.