If the electric motor has a coupled rotating mass at one point inertia is equal to that of the electric motor, the reversing times and departure and therefore, there are losses when it is compared the electric motor time to empty, tends to be double.

The original thermal equilibrium electric motor may be restored when there is a reduction in the number of reversals by 50%. The relationship between the time of the empty allowed and permitted load with reversal of time reversal usually occurs when it is equal to the relation between the moment of inertia of the electric motor and the moment of total inertia.

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The inertia factor is the ratio between the total moment of inertia which is referred to and further to the electric motor shaft and where there is the inertia of the electric motor.