Gear transmission is a mechanical transmission that utilizes the teeth of the two gears to mesh with each other to transmit power and motion. According to the relative position of the gear axis, it is divided into parallel shaft spur gear transmission, intersecting shaft bevel gear transmission and staggered shaft helical gear transmission. It has the characteristics of compact structure, high efficiency and long life.
Gear transmission refers to the device that directly transmits the motion and power with the main and driven wheel teeth. Among all mechanical transmissions, gear transmissions are the most widely used to transmit motion and power between any two axes. The gear transmission features stable gear
transmission, accurate transmission ratio, reliable operation, high efficiency, long service life, and large range of power, speed and size. For example, the transmission power can be as small as several hundred thousand kilowatts, the speed can be up to 300m/s, and the gear diameter can be from several millimeters to more than twenty meters. However, special equipment is required to manufacture the gears, and the meshing drive produces noise.
There are three types of gear transmissions, namely open, semi-open and closed. The gears used in automobiles, machine tools, aero engines, etc. are housed in precisely machined and tightly closed cabinets. This is called closed gear transmission (gearbox). Compared with open or semi-open type, it has the best conditions of lubrication and protection, and is used in important occasions. In agricultural machinery, construction machinery and simple mechanical equipment, some gear drives do not have a dust cover or casing, and the gears are completely exposed to the outside. This is called open gear transmission. This kind of transmission is not only easy to invade the foreign objects, but also poorly lubricated, so the working conditions are not good, the gears are easy to wear, so it is only suitable for low-speed transmission. When the gear transmission is equipped with a simple protective cover, and sometimes the large gear portion is immersed in the oil pool, it is called a semi-open gear transmission. Although its working conditions have improved, it still cannot prevent the intrusion of foreign objects, and the lubrication conditions are not the best.