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Home Engineering Mechanics Kinematics of Machine To study various types of gear trains - simple, compound, reverted, epicyclic and differential
Kinematics of Machine Lab Experiments

To study various types of gear trains - simple, compound, reverted, epicyclic and differential



Aim

To study various types of gear trains - simple, compound, reverted, epicyclic and differential.

Apparatus used

Arrangement of Gear train system

Theory

Definition of Gear train, Classification of Gear train, Diagrams of different types of Gear train, Working & Construction of different types of Gear train.

Gear train:A gear train is a combination of gears used to transmit motion from one shaft to another. It becomes necessary when it is required to obtain large speed reduction within a small space. The following are the main types of gear trains:

  • Simple gear train
  • Compound gear train
  • Reverted gear train
  • Planetary gear train
  • Differential gear train

Simple gear train:A series of gears, capable of receiving and transmitting motion from one gear to another is called a simple gear train. In it, all the gear axes remain fixed relative to the frame and each gear is on a separate shaft.

simple-geer-train

Train Value = (Number of teeth on driving gear) /( Number of teeth on driven gear )

Compound gear train:When a series of gears are connected in such a way that two or more gears rotate about an axis with the same angular velocity, it is known as compound gear train.

compound-geer-train

Train Value = (Product of Number of teeth on driving gear /Product of Number of teeth on driven gear)

Reverted Gear Train:If the axes of the first and last wheels of a compound gear coincide; it is called a reverted gear train. Such an arrangement is used in clocks and in simple lathes where ‘back gear’ is used to give a slow speed to the chuck.

revert-geer-train

Train Value = (Product of Number of teeth on driving gear/Product of Number of teeth on driven gear)

Planetary or Epicyclic Gear Train :When there exist a relative motion of axis in gear train, it is called a planetary or an epicyclic gear train (or simply epicyclic gear or train). Thus in an epicyclic train, the axis of at least one of the gears also moves relative to the frame. Consider two gear wheels, the axis of which are connected by an arm . if the arm is fixed, the wheels constitute a simple train. However, if the wheel s is fixed so that the arm can rotate about the axis of S, the wheel P would also move around S. therefore, it is an epicyclic train.

planetary-geer-train

Train Value = (Product of Number of teeth on driving gear/Product of Number of teeth on driven gear)

Differential Gear:When a vehicle takes a turn, the outer wheels must travel farther than the inner wheels. In automobiles, the front wheels can rotate freely on their axis and thus can adapt themselves to the conditions. Both rear wheels are driven by the engine through gearing. Therefore, some sort of automatic device is necessary so that the two rear wheels are driven at slightly different speeds. This is accomplished by fitting a differential gear on the rear axle.

differential-geer

Applications

  • Gear trains are used in automobiles.
  • Reverted gear train are used in clock and simple lathe.
  • Epicyclic gear are used in transmission, computing devices.
  • Gears are used in different machinery.

Conclusion

Simple, compound reverted, epicyclic and differential gears were studied









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