EPICYCLIC GEAR TRAIN

Presented by-RAGHAV MAHESHWARI

Roll no.-124086

GEAR TRAINSA gear train is two or more gear

working together by meshing their teeth and turning each other in a system to generate power and speed.

It reduces speed and increases torque. To create large gear ratio, gears are

connected together to form gear trains.

CLASSIFICATION OF GEAR TRAINSSIMPLE GEAR TRAIN.COMPOUND GEAR

TRAIN.REVERTED GEAR

TRAIN.EPICYCLIC GEAR

TRAIN.

EPICYCLIC GEAR TRAINEpicyclic 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

A small gear at the center whose axis is fixed is called the sun.

Medium sized gears whose axis is permitted to move in an arc of a circle are called the planets.

Planet wheel is carried by Carrier arm which is free to revolve about fixed axis.

A large external gear is called the ring gear or Annulus.

VELOCITY RATIO FOR EPICYCLIC TRAINVelocity ratio of epicyclic gear train is the

ratio of the speed of the driver to the speed of the driven or follower.

The following two methods may be used for finding out velocity ratio of an epicyclic gear train.

1. Tabular method2. Algebraic method

TABULAR METHODTA= Number of teeth on gear A TB= Number of teeth on gear B.Suppose that the arm is fixed. Therefore, the axes of both the gears

are also fixed relative to each other. When the gear A makes one revolution anticlockwise, the gear B will make TA/ TB

NB / NA = TA / TB Since NA = 1 revolution, therefore NB = TA / TB

ALGEBRAIC METHODIn this method, the motion of each element of the epicyclic train relative to the arm is set down in the form of equations.Let the arm C be fixed. Therefore, Speed of the gear A relative to

the arm C= N(A)-N(C) Speed of the gear B relative to

the arm C= N(B) –N(C)

COMPOUND EPICYCLIC GEAR TRAIN

SOLUTION BY TABULAR METHOD

TYPES OF SIMPLE EPICYCLIC GEAR TRAINS

APPLICATIONSThe epicyclic gear trains are useful for

transmitting high velocity ratios with gears of moderate size in a comparatively lesser space.

The epicyclic gear trains are used in the back gear of lathe, differential gears of the automobiles, hoists, pulley blocks, wrist watches etc.

ADVANTAGES-Have higher gear ratios. Epicyclic trains take up less space and have a

lighter weight.Reduced noise and vibration.Input and output shafts of epicyclic trains are

concentric so driver and driven equipment can be mounted in line, providing additional space savings.

LIMITATIONS-Complexity.All the gears must have same module.Efficiency calculations are difficult. Driver and driven equipment must be in line to

avoid additional gearing.

MECHANISM