Gears used for connecting intersecting shafts?

Explanation:

Bevel Gear: 

• Bevel gears are used to transmit motion between shafts at various angles to each other.
• The teeth profile may be straight or spiral.

Additional Information

Spur Gear: 

• The teeth are cut parallel to the axis of rotation. 
• The spur gears are used to transmit power between two parallel shafts.

Helical Gear: 

• In a helical gear, the teeth are cut at an angle to the axis of rotation.
• It is used to transmit power between two parallel shafts.
• The end thrust is exerted by the driving and driven gears in the case of helical gears and the thrust may be eliminated by using double helical gears. These gears are called herring-bone gears.