37 Building construction in the field of wind power installations; installation services, namely, installation of wind power machines, turbines, parts and fittings for the aforesaid wind power machines, in particular rotor blades, rotor consoles, blade hubs, machine housings, rotation devices, yaw rings, yaw gears, brakes, main drive shafts, universal joints, gears, gear boxes, couplings, motors, mechanical rotor adjusters, electric generators and emergency power units; maintenance and reconditioning of machines that are worn out or partially destroyed, namely, of wind power machines, turbines, parts and fittings for the aforesaid wind power machines, in particular rotor blades, rotor consoles, blade hubs, machine housings, rotation devices, yaw rings, yaw gears, brakes, main drive shafts, universal joints, gears, gear boxes, couplings, motors, mechanical rotor adjusters, electric generators and emergency power units; servicing and repair of wind power installations; rotor blade assembly