Gears and gear racks use rotation to transmit torque, alter speeds, and change directions. Gears can be found in many different forms. Spur gears are simple, straight-toothed gears that operate parallel to the axis of rotation. Helical gears possess angled teeth that steadily engage matching the teeth for smooth, quiet operation. Bevel and miter gears are conical gears that operate at a right angle and transfer motion between perpendicular shafts. Modify gears maintain a particular input speed and allow 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 various other steering mechanisms.