A planetary gearbox is a specific type of gearbox. They are known for offering high precision and higher torque-to-volume ratio when compared to other types of gearbox. This makes them well suited to applications which involve; increasing torque, reducing speed, precise positioning or controlling reproducible machinery.
Planetary Gear Box Design
Planetary Gearboxes have a unique design and way of working. The input and output gears rotate around the pinion or “sun gear”. The centre of the input gear revolves around the centre of the output gear and the input and output shafts are aligned.
This alignment is often compared to our solar system where the gears move similarly to the planets revolving around the sun, therefore they are named “Planetary Gearboxes”.
At the very centre of the planetary gearbox, there is a central gear. This is often the input gear and transmits torque to planet gears. Rotating around the outside of the central gear there are 2 or more (typically 3) outer gears. Then, surrounding the outer gears there is a ring gear which holds the formation together. The planet gears are connected by a carrier which in turn is connected to the output shaft.
The gears can rotate at different rates. Only 2 of the types of gears can rotate in any formation or all three types can rotate around each other. This is a very distinct way of working which is unique to planetary gearboxes. The number of teeth in each gear must be exact for the planetary gearbox to function correctly.
Choosing a Planetary Gearbox for your Application
Planetary gearboxes are suitable for a wide range of applications where this type of motion is required. When choosing one for your application it is important to know some of the key points to consider;
Specifications required is important specifications of the application must be known, this includes output torque, speed, backlash and ratio of the application must be taken into consideration.
Application environment is the planetary gearbox going to be in an environment where it will be exposed to corrosive material? What is the noise level like? Will the gearbox be exposed to dust, dirt or moisture? All these aspects must be taken into consideration when selecting the correct gearbox for your application. Space is another environment consideration – planetary gearboxes come in various shapes and sizes which make them suitable for different applications.
Lubrication for planetary gearboxes to work effectively they must have the correct amount and type of lubrication; this could be either grease, oil, or sometimes synthetic gel.
Advantages of Using Planetary Gearboxes
Although they tend to have a higher price because of their complex design, planetary gearboxes have the following advantages.
? Repeatability – planetary gearboxes have increased repeatability when compared to other gearboxes.
? High precision – the rotating angular stability improves both accuracy and precision.
? Quiet operation – this is due to the amount of surface contact.
? Increased torque transmission – due to the number of teeth in contact, planetary gearboxes can transmit and withstand a higher level of torque.
? Highly durable
? Highly efficient
Planetary gearboxes are used for various types of applications in different industries. Some of the more common applications which use planetary gearboxes include;
? Medical scanners
? Operating tables
? Wheel drives
? Slew drives
? Track drives
? Cutter heads
? Renewable energy
? Antenna orientation
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