Gear is a wheeled mechanical part that transmits torque by the engagement of the teeth. The gears are driven by other toothed mechanical parts (such as another gear, rack, worm) to change the speed and torque, change the direction of motion and change the form of motion. Due to the advantages of high transmission efficiency, accurate transmission ratio and large power range, the gear mechanism is widely used in industrial products, and its design and manufacturing level directly affects the quality of industrial products. The gear teeth interlocking with each other will drive the other gear to rotate to transmit power. Separate the two gears, and also use the chain, track, and leather belt to drive the gears on both sides to transmit power.
The gears can be classified according to the tooth shape, the gear shape, the shape of the tooth line, the surface on which the teeth are located, and the manufacturing method.
The tooth profile of the gear includes a profile curve, a pressure angle, a tooth height and a displacement. Involute gears are easier to manufacture, so in modern gears, involute gears are the absolute majority, while cycloidal gears and arc gears are less used.
In terms of the pressure angle, the load capacity of the small pressure angle gear is small; while the large pressure angle gear has a higher load carrying capacity, the load of the bearing increases under the same transmission torque, and therefore is used only for special cases. The gear height of the gear has been standardized, and the standard tooth height is generally used. The advantages of the displacement gear are numerous and have been used in various types of machinery and equipment.
In addition, the gear can also be divided into cylindrical gear, bevel gear, non-circular gear, rack, worm gear according to its shape; according to the shape of the tooth line, it is divided into spur gear, helical gear, herringbone gear, curved gear; The surface is divided into an external gear and an internal gear; according to the manufacturing method, it can be divided into a cast gear, a cut gear, a rolling gear, a sintered gear, and the like.