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Worm gears find applications in various robotic systems, lifting mechanisms, conveyor systems, and other
applications where high torque, self-locking capability, and holding the load in place are critical requirements.
Planetary Gears
These gears also known as epicyclic gears, are a type of gear system that consists of a central gear (sun gear),
multiple gears surrounding the sun gear (planet gears), and an outer ring gear (ring gear). They are named after
their resemblance to the solar system’s planetary motion. Here are some key details about planetary gears:
Ring Gear
Sun Gear
Planetary Gear Carrier
• Sun Gear: The sun gear is the central gear in a planetary gear system. It is usually fixed or connected to the
input shaft and provides the driving force. The planet gears rotate around the sun gear.
• Planet Gears: Planet gears are gears that surround the sun gear and are mounted on a carrier or arm. The
number of planet gears can vary but is typically two or more. The planet gears mesh with both the sun gear and
the ring gear simultaneously.
• Ring Gear: The ring gear is the outer gear in the planetary gear system. It has teeth on its inner circumference
that mesh with the planet gears. The ring gear is often stationary or serves as the output shaft, depending on
the design.
• Gear Ratios: Planetary gears offer multiple gear ratios within a single system. The gear ratio depends on how
the components are connected. The different arrangements include:
o Speed Reduction: When the sun gear is the input and the ring gear is the output, the gear ratio is higher
than 1, resulting in speed reduction.
o Speed Increase: When the ring gear is the input and the sun gear is the output, the gear ratio is less than
1, leading to speed increase.
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o orque Amplification: By fixing the ring gear and rotating the sun gear, the planet gears rotate around
the sun gear, amplifying the torque output.
o Reversible Output: By fixing any two components and rotating the third, the direction of the output can
be reversed.
• Compact Design: Planetary gears offer a compact and space-efficient design due to the shared load distribution
among multiple planet gears. This allows for high torque transmission with minimal size and weight.
• Advantages: Planetary gears provide several advantages, including high power density, high efficiency, and the
ability to handle large torque loads. They also offer precise motion control, low backlash, and the potential for
coaxial input and output shafts.
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