Rotor restraining apparatus and method for wind turbines

A rotor restraining apparatus for a wind turbine, comprising:

• a locking element being rotatable about an axis in cooperation with, and operable to restrain, a rotor of the wind turbine, a rotational axis of said rotor defining an axial direction,
• the locking element comprising a plurality of engagement formations disposed on a periphery of the locking element;
• and
• a restraining member, comprising a plurality of engagement formations,
• wherein the restraining member is movable substantially along said axial direction between:
• (a) a non-restraining position;
• and (b) a restraining position in which the member engagement formations are able to engage the locking element engagement formations,
• wherein the restraining member has a rear edge furthest from the locking element, and a front edge closest to the locking element,
• and wherein the restraining member engagement formations comprise a gradient formed between said rear and front edges, so that the rear edge of the restraining member extends radially further inward than the corresponding front edge of the restraining member.