Gearbox Design

From Wind wiki

Gearbox is used to convert low-speed rotation from the input shaft of the rotor to high-speed rotation, which drives the high-speed shaft of the generator assembly. This wind turbine component is not an intrinsic part of the whole wind power technology. It is only utilized to increase the speed of the slow running main shaft to the speed required by mass-produced induction generators.

Turbine designers use either parallel shafts or planetary gear system. Parallel shaft gearboxes are the most conventional choice for most wind turbine operators. They eat up more space and weigh more than the other kind of gearbox but they are quiet when they operate. The planetary stage, in contrast, is used in low-speed shaft from the rotor where there is less noise.