Helical external gears are generally used when both high speeds and high horsepowers are involved. External helical gears have been built to carry as much as 45,000 kW of power on a single pinion and gear. External gears are the most common and consists of a wheel with exterior teeth. Helical gears are cylindrical in shape. However, the teeth on helical gears are set at an angle relative to the axis of rotation. It is widely used in automotive applications. It can be used in parallel in, like spur gears, or at right angles.