Abstract: Assembly of components inside a large wind turbine, positioned between the upper section (3) of the tower (1) and under the nacelle. The components, which are transported pre-assembled to the site, are horizontal, circular platforms (6a and 6b), a vertical ladder (5) that goes through both platforms (6a and 6b) and a central structure (7) that joins and integrates the entire unit. The middle connection part (8) fitted onto the nacelle frame (4) allows the aforementioned unit to be coupled to the nacelle. The platforms (6a and 6b) house electrical devices for the drive train and the yaw system, as well as the lubrication and refrigeration system for the drive train. Once all the components have been assembled, they turn together with the nacelle while it rotates to face the wind.