Patent ID: 8022564

Claim:
A yaw drive apparatus of a wind power generation apparatus comprising: a first gear attached to one of a tower and a wind power generation unit supported to an upper end of the tower so as to be capable of yawing, a second gear engaged with inner teeth of the first gear, the second gear enclosed by the tower and wind power generation unit, a drive motor attached to the other of the tower and the wind power generation unit for rotating the second gear when drive energy is supplied thereto, thereby yawing the wind power generation unit, and a reduction means for producing the drive energy, which is supplied to the drive motor for a predetermined time from when the supply of the drive energy to the drive motor begins to start, is smaller than the drive energy supplied to the drive motor in a common yawing, wherein when the drive motor is composed of a fluid motor, a pair of supply/discharge passages which supply and discharge the fluid to and from the fluid motor is connected to each other by a connection passage, and a throttle is interposed in the connection passage, such that the rotational speed of the fluid motor when it performs a pump operation is controlled by the throttle, the pair of supply/discharge passages connect the fluid motor and a switching valve, the supply/discharge passages being switched into a parallel-flow position or a cross-flow position so that one side becomes a high pressure side and the other side becomes a low pressure side, whereby the fluid motor positively rotates or inversely rotates.