Spiral Bevel Gear

A spiral bevel gear is one which has helical teeth. Like the helical gear, using a spiral bevel gear brings the benefit of less vibration and noise. Spiral bevel gears are used often in vehicle transmissions as drive from the driveshaft must be turned 90 degrees to drive the wheels.

The biggest benefit to using bevel gears is their mechanical advantage; you can increase or decrease the tooth ratio between the drive and any accompanying wheels to correspondingly increase or decrease the force.