Planetary gears: helical, worm and bevel

Planetary gears are used in a very wide range of construction machinery. In principle, all machines moving on caterpillars are driven by a hydromotor transmitting power to the planetary gear. In our opinion, these types of gearboxes are the best way to change the drive speed of tracked machines. Above all, their great advantage is that they are virtually indestructible.

The classification of planetary gears is quite wide. We can divide them according to the number of degrees, the position of the teeth and the mutual location of the axis of rotation. In this article, we’ll focus on gears categorized by the last criterion.

Helical gears

Planetary helical gears are the most commonly used toothed gears. They usually have straight or oblique teeth, less often ridged or arched. The gears can be meshed externally or internally. As in any gear transmission, the use of oblique teeth increases the transmission strength and ensures its quiet operation. The efficiency of cylindrical gears exceeds 99%. They are used, among others in the gearboxes of motor vehicles, aircraft and ships, all types of gearboxes (usually in reducers, located between the engine and the driven device, e.g. winch, mining elevator, etc.), as well as in the turntables of cranes or excavators.

Bevel gears

There are two wheels in this gear, the contours of the heads of the teeth forming the surface of the rolling cones. There are many different designs of bevel gears in which the teeth can be tapered or of a fixed height. Depending on the shape of the tooth line, bevel, straight, helical and arched gears are distinguished. Tapered gearboxes are used where a non-parallel change in the direction of the power transmission is necessary.

Worm gears

In the worm gear, the power is transferred with a large friction share. The great advantage of a worm gear is the ability to obtain very high gear ratios with relatively small dimensions of the gear consisting of a worm (drive wheel) and worm (driven wheel). The worm gear has low efficiency – it ranges from 50% to 90%. For this reason, the worm gear is not suitable for transmitting high power.

Advantages

Certainly, planetary gears are very popular because they allow you to freely chenge speed and rotation force. They are used especially in those machines that operate at high turns and are small overall dimensions. Their adventage is the mulitpoint drive transport. Thanks to this individual teeth in the toothed wheels are exposed to lower load. This affects the life of the planetary gear. Therefor, for years the use of planetary gearbox is the best method of drive transfer in tracked machines.