The invention relates to a turn drive for a wind turbine. The turn drive comprises a shaft, a hydraulic motor for driving the shaft, and a drive line for supplying a pressurized hydraulic fluid to the hydraulic motor. According to the invention, the drive line is provided with a settable pressure-limiting valve. The invention additionally relates to an associated method for rotating the rotor shaft of the wind turbine. By means of the method according to the invention and the turn drive, the rotor blades can be mounted individually on the hub of the rotor, without the gearbox of the wind turbine becoming overloaded.