2. Transmission elements

To allow the transmission of the motion as seen in the previous paragraph, special mechanical parts are required. A gear is a mechanism used to transmit a movement and / or a mechanical moment from one object to another. Generally it consists of two or more toothed gears, which can be of the same or of different size. One of the two gears transmits the motion (driving gear) and the other receives it (driven gear). The driven gear rotates in the opposite direction to the driving gear. The smallest gear is commonly called a pinion, while the largest is simply called a gear.

There are different types of toothed gears, the most common are: spur gears, helical gears, bevel gears, rack and pinion and worm gears. Each type of toothed gears allows the transmission of motion between differently positioned axes.