EPICYCLIC GEAR TRAIN

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BY:

KAMAL SIHAG

EPICYCLIC OR PLANETARY GEAR

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Epicyclic gearing or planetary gearing is a gear system consisting of one or more outer gears, or planet gears, revolving about a central, or sun gear. Typically, the planet gears are mounted on a movable arm or carrier which itself may rotate relative to the sun gear. Epicyclic gearing systems also incorporate the use of an outer ring gear or annulus, which meshes with the planet gears.

Epicyclic

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Epicyclic Gear train

Epicyclic means one gear revolving upon and around another. The design involves planet and sun gears as one orbits the other like a planet around the sun. Here is a picture of a typical gear box.

This design can produce large gear ratios in a small space and are used on a wide range of applications from marine gearboxes to electric screw drivers.

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Epicyclic Gear train

It is the system of epicyclic gears in which at least one wheel axis itself revolves around another fixed axis.

Epicyclic Gearset

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An epicyclic gear set has some gear or gears whose center revolves about some point.

Here is a gearset with a stationary ring gear and three planet gears on a rotating carrier.

The input is at the Sun, and the output is at the planet carrier.

The action is epicyclic, because the centers of the planet gears revolve about the sun gear while the planet gears turn.

Finding the gear ratio is somewhat complicated because the planet gears revolve while they rotate.

INPUT

CARRIER

Ring

PlanetSun

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Planetary Gear Train (Epicyclic Gear Train)

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Planetary Gear Train…

In this train, the blue gear has six times the diameter of the yellow gear

The size of the red gear is not important because it is just there to reverse the direction of rotation

In this gear system, the yellow gear (the sun) engages all three red gears (the planets) simultaneously

All three are attached to a plate (the planet carrier), and they engage the inside of the blue gear (the ring) instead of the outside.

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Planetary Gear Train…

Because there are three red gears instead of one, this gear train is extremely rugged.

planetary gear sets is that they can produce different gear ratios depending on which gear you use as the input, which gear you use as the output, and which one you hold still.

DRAWING OF PLANETARY GEAR

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ADVANTAGES

Compared to conventional gearboxes has smaller dimensions

Easier to sort through the constant rounds of shot

Greater durability than conventional bikes in gear

Easy to achieve high transmission ratio due to the size

They have higher gear ratios.

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DISADVANTAGESMore expensive than conventional production of

gearboxes

More complex than conventional transmission

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APPLICATIONSThese are used in back gear of lathe, hoists, pulley

blocks, wrist watches etc… They are popular for automatic transmissions in

automobiles.

They are also used in bicycles for controlling power of pedaling automatically or manually

. They are also used for power train between internal

combustion engine and an electric motor

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