Abstract: A yaw brake for a wind turbine includes a brake housing disposed on one or both sides of a brake surface disposed about a yaw axis. The housing defines a bore and a piston is disposed within the bore. The piston is configured for movement within the bore along an axis between first and second positions in which the piston applies different braking forces to the brake surface. At least one portion of the piston and at least one portion of the bore of the brake housing have complementary non-circular shapes. The at least one portion of the piston is configured to be positioned within and least one portion of the bore when the piston is in the first and second positions. A bushing is disposed radially between the at least one portion of the piston and the at least one portion of the bore of the brake housing.

Abstract: A servicing system (30 or 300) for servicing a brake device (24) of a brake system comprising the brake device (24) and a brake disc (22) is described. The servicing system (30 or 300) includes a frame (32 or 302), and the servicing system (30 or 300) further comprises: mounting means (34 or 318) for mounting the frame (32 or 302) in a fixed position relative to the brake disc (22), supporting means (48 or 338) which are adapted to allow the brake device (24) to be moved on the frame (32 or 302) relative to the brake disc (22) and lifting means (46 or 304, 306) which are adapted to allow the brake device (24) to be raised or lowered relative to the brake disc (22).

Abstract: A wind turbine comprises wind turbine blades extending substantially radially from a hub on a main shaft having a substantially horizontal axis. The blades together with the hub form a rotor, which can be put into rotation by wind. The main shaft is rotatable mounted in a nacelle on top of a tower, and the nacelle may be rotated around a vertical axis in relation to the tower to adjust the rotor in relation to a prevailing wind direction. The wind turbine further comprises a yaw brake comprising a brake calliper and a brake disc or ring having a first side with a first surface and second side with a second surface, the yaw brake, when activated, acting as a rotation restriction of the nacelle in relation to the tower. The brake disc or ring is provided with one or more grooves formed in the first and/or second surfaces.