How Does a Planetary Gearbox Work?
The planetary system has 3 main components: a central sun gear, a planet carrier (carrying one or more planet gears),and an annulus (an outer ring). The central sun gear is orbited by planet gears (of the same size) that are mounted to the planet carrier. The planet gears are meshed with the sun gear. An outer ring (the annulus) has teeth facing inward that also mesh with the planet gears.
There are several configurations for planetary systems. Typical configurations require that out of the 3 components: one is the input, one is the output, and one is stationary.
For example, one configuration is where the sun gear is the input , the annulus is the output, and the planet carrier is stationary. In this configuration, the input shaft rotates the sun gear. The planet gears rotate on their own axes, simultaneously applying a torque to the rotating planet carrier, that in turn applies torque to the output shaft (which in this case is the annulus).
The rate at which the gears rotate (gear ratio) is determined by the number of teeth in each gear. The torque (power output) is determined by both the number of teeth and by which component in the planetary system is stationary.
Planetary Gearbox Advantages
The planetary gearbox arrangement is an ingenious engineering design that offers many advantages over traditional gearbox arrangements. One advantage is its unique combination of both compactness and outstanding power transmission efficiencies. Typical efficiency losses in a planetary gearbox arrangement is only 3% per stage. This type of efficiency ensures that a high proportion of the energy being input into the gearbox is multiplied and transmitted into torque, rather than being wasted on mechanical losses inside the gearbox.
Another advantage of the planetary gearbox arrangement is load distribution. Because the load being transmitted is shared between multiple planets, torque capability is greatly increased. The more planets in the system, the greater load ability and the higher the torque density.
The planetary gearbox arrangement also creates greater stability (it’s a balanced system) and increased rotational stiffness. Disadvantages to the planetary arrangement include design complexity and accessibility issues. This is one reason automatic transmissions are so time consuming ans difficult to rebuild. The transmission has to be removed and disassembled in order to access them. Make sure the replacement transmission you buy has a quality set of planetary gears in it. Information brought to you by GotTransmissons.com @ 866-320-1182.
