As an example, look at a person riding a bicycle, with the person acting like the engine. If that person tries to trip that bike up a steep hill in a gear that is made for low rpm, he or she will struggle as
they attempt to maintain their balance and achieve an rpm that may allow them to climb the hill. However, if they change the bike’s gears into a rate that will produce a higher rpm, the rider could have
a much easier period of it. A constant force can be applied with even rotation being provided. The same logic applies for commercial applications that require lower speeds while maintaining necessary
torque.
• Inertia complementing. 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 are trying to move. Using a gearhead to raised match the inertia of the engine to the inertia of the load allows for using a servo gearbox smaller electric motor and outcomes in a more responsive system that’s simpler to tune. Again, this is attained through the gearhead’s ratio, where the reflected inertia of the strain to the motor is decreased by 1/ratio2.
Recall that inertia may be the measure of an object’s resistance to change in its 
movement and its function of the object’s mass and shape. The greater an object’s inertia, the more torque is required to accelerate or decelerate the thing. This means that when the strain inertia is much larger than the motor inertia, sometimes it could cause extreme overshoot or boost settling times. Both circumstances can decrease production range throughput.
On the other hand, when the motor inertia is bigger than the strain inertia, the motor will need more power than is otherwise essential for the particular application. This raises costs since it requires spending more for a electric motor that’s larger than necessary, and because the increased power consumption requires higher operating costs. The solution is by using a gearhead to complement the inertia of the electric motor to the inertia of the load.