The Designer is confronted with the problem of transferring power from one shaft to another while maintaining a define ratio between te velocities of rotation of the shafts. Various types of gearing have been developed for this purpose which will operate quietly and with very low friction losses.

Helical gears are ideally suited for very high speed and take up appreciable load, though their efficiency is lesser than that of spur mesh. Helical gears primarily connect to parallel shafts, with their teeth lying along helices.

A Bevel Gearbox has an advantage over the Worm Gear because its efficiency is much higher. Yet another advantage being bevel gears is that bevel gears gives you the flexibility of right angle solution at a lower ratio.

Chain drives are used where positive action is required. The velocity is constant to some extent. Power is transmitted, in this case over a shorter distance than in the case of belt or rope drives. Chains are made up of rigid links and of various types.

The specialty of a Worm Gear and Worm Wheel is that they provide a large speed ratio but with significant sliding. Another feature being of the worm gear is that most of the designs are non reversible .