Gear transmission is a mechanical transmission in which the teeth of two gears engage with each other to transfer power and motion. In all mechanical drives, gear drives are widely used to transmit motion and power between two axes not far from each other.

The characteristics of gear transmission: high efficiency. In common mechanical transmission, the efficiency of gear transmission is high, while the efficiency of closed transmission is 96%~99%, which is of great economic significance to high-power transmission. Compact structure, smaller space size than belt and chain drive; Transmission ratio stability is often the basic requirement for transmission performance. Gear transmission is widely used because of its characteristics; Long working hours, design and manufacture of correct and reasonable, use and maintenance of good gear transmission, reliable work, life can be as long as 20 years, which is other mechanical transmission can not be compared. This is important for vehicles and machines working in mines; But the manufacturing and installation precision of gear transmission is high, the price is expensive, and it is not suitable for the occasions with large transmission distance.

The classification of gear transmission: according to the shape of the gear transmission can be divided into cylindrical gear transmission, bevel gear transmission, non-circular gear transmission, rack transmission and worm transmission.

A gear drive used to transfer power and motion between parallel shafts. According to the relative relation between gear tooth and gear axis, cylindrical gear drive can be divided into three kinds: spur gear drive, helical gear drive and herringbone gear drive.

Bevel gear transmission bevel gear transmission consists of a pair of bevel gears intersecting shafts gear transmission, also known as bevel gear transmission. Bevel gear transmission can be divided into straight bevel gear transmission, helical bevel gear transmission and curved bevel gear transmission, among which straight bevel gear and curved gear are widely used.

Non-circular gear transmission means that the pitch surface of at least one gear in the transmission is not the rotation surface of the gear transmission.

Rack driving gear and rack driving structure, rack divided straight gear rack and helical gear rack, respectively with straight tooth cylindrical gear and helical gear pair use; The tooth profile of rack is straight line instead of involute (plane for tooth surface), which is equivalent to the large cylindrical gear with the radius of dividing circle.