As an example, look at a person riding a bicycle, with the individual acting like the electric motor. If see your face tries to trip that bike up a steep hill in a gear that is designed for low rpm, she or he will struggle as
they try to maintain their balance and achieve an rpm which will allow them to climb the hill. However, if indeed they shift the bike’s gears right into a speed that will create a higher rpm, the rider could have
a much easier period of it. A constant force could be applied with smooth rotation being supplied. The 
same logic applies for industrial applications that servo gearbox require lower speeds while maintaining necessary
torque.
• Inertia matching. Today’s servo motors are producing more torque relative to frame size. That’s because of dense copper windings, light-weight materials, and high-energy magnets.
This creates greater inertial mismatches between servo motors and the loads they want to move. Using a gearhead to raised match the inertia of the electric motor to the inertia of the load allows for using a smaller electric motor and outcomes in a far more responsive system that is simpler to tune. Again, this is accomplished through the gearhead’s ratio, where in fact the reflected inertia of the strain to the electric motor is decreased by 1/ratio2.
Recall that inertia may be the way of measuring an object’s level of resistance to change in its motion and its function of the object’s mass and form. The greater an object’s inertia, the more torque is needed to accelerate or decelerate the thing. This implies that when the strain inertia is much bigger than the electric motor inertia, sometimes it can cause excessive overshoot or enhance settling times. Both conditions can decrease production range throughput.
However, when the electric motor inertia is larger than the load inertia, the engine will need more power than is otherwise essential for the particular application. This improves costs since it requires paying more for a engine that’s larger than necessary, and since the increased power intake requires higher working costs. The solution is by using a gearhead to complement the inertia of the engine to the inertia of the load.