Page 99 - CITS - WCS - Mechanical

WORKSHOP SCIENCE - CITS

1 Simple gear train.
2 Compound gear train.
3 Reverted gear train.

4 Planetary or epicyclic gear train.
Planetary gear train (PGT) has been widely used in the transmissions of helicopters, automobiles, wind turbine,
aircraft engines, etc. The main advantages of this transmission are its high efficiency, its compactness, its large
transmission ratio and its large power-to-weight ratio, etc.
A gearbox, also known as a gear drive, has three main functions: to increase torque from the driving equipment
(motor) to the driven equipment, to reduce the speed generated by the motor, and/or to change the direction of
the rotating shafts.

Assignment

Examples
A load of 1200 kg is lifted using a simple machine having a velocity ratio of 5 . Find out efficiency of
machine, if effort applied is 300 kg
Solution: MA =LOAD/EFFORT

= 1200/300
=4
Velocity Ratio = 5 (given)
Efficiency if machine =(Mechanical Advantage )/(Velocity Ratio)

= 4/5=0.8=80%
A load of 75 kg is lifted using a simple machine having a velocity ratio of 4 . Find out efficiency of machine,
if effort applied is 25 kg

Solution: MA=LOAD/EFFORT
= 75/25
=3
Velocity Ratio = 4 (given)
Efficiency if machine
=(Mechanical Advantage )/(Velocity Ratio)

= 3/4
= 0.75
= 75%
Examples

1 According to figure the lever has to support a 100 kg load with a 17 kg equivalent force supplied to it.
Find the distance between the load and point of force.
Solution: Load = 100 kg; Effort = 17 kg

Load arm = 50 cm
Let effort arm = x cm
As per principle of levers:

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CITS : WCS - Mechanical - Exercise 8