sentences:  To make up for a direct drive generator's slower spinning rate, the diameter of the generator's rotor is increased so that it can contain more magnets to create the required frequency and power.Gearless wind turbines are often heavier than gear-based wind turbines.A study by the EU called "Reliawind" based on the largest sample size of turbines has shown that the reliability of gearboxes is not the main problem in wind turbines.