Description

Gear (or cogwheel) is a mechanical part with teeth on the rim that can continuously mesh to transmit motion and power. The gear transmits torque by the meshing of the teeth. The gear is transmitted with other toothed mechanical parts (such as another gear, rack, worm), and the transmission mode is meshing transmission, which can realize functions such as changing the speed and torque, changing the direction of motion, and changing the form of motion. Due to the advantages of high transmission efficiency, accurate transmission ratio, and large power range, gear mechanisms are widely used in industrial products, and their design and manufacturing standards will directly affect the quality of industrial products.

The teeth of the gear interlocking with each other will drive the other gear to rotate to transmit power. Separate the two gears, and you can also use chains, crawlers, and belts to drive the gears on both sides to transmit power. Gears are generally composed of teeth, tooth grooves, end faces, normal faces, addendum circles, dedendum circles, base circles and index circles.

When the two gears are external gears, the direction of rotation will be opposite, as shown in the right figure. In the case of an internal gear mechanism, the direction of rotation will be the same.

Features

Compared with other transmission devices (eg, friction transmission, etc.), gears with a fixed transmission ratio have a strong advantage in some precision machinery (eg, watches that require extremely precise transmission ratios). When the driving device and the driven device are close to each other, the advantage of gear transmission over other transmission methods is that it increases the number of required parts. The disadvantage is that the processing and manufacturing of gears is more expensive and requires lubrication.

Type

There are many types of gears, which can be divided into three types: parallel shafts, intersecting shafts and staggered shafts according to the relative position of the gear shafts. Parallel axis gears include spur gears, helical gears, internal gears, racks and helical racks, etc. Intersecting axis gears include straight bevel gears, spiral bevel gears, zero-degree bevel gears, etc. Cross-axis gears include cross-axis helical gears, worm gears, hypoid gears, etc. Classified by transmission ratio, there are circular gear mechanisms with fixed transmission ratio (cylindrical, conical) and non-circular gear mechanisms with variable transmission ratio (elliptical gear).