| 摘要 |
A tidal turbine 1 includes a fail safe mechanism for pitch adjustment of the turbine blades. A pitch change rod 7 is rotated with the turbine shaft 2. A nut 8 threaded on a pitch change rod 7, is rotated by a motor 13 at the same speed as the rotor. By varying the speed of the motor 13, there is relative rotation between the nut 8 and rod 7, causing axial movement of the rod and increasing or decreasing the blade pitch. If rotation of the nut 8 ceases, for example due to failure of a control system, continued relative rotation of the pitch change rod moves the turbine blades to a feathered condition. Nut 8 may be coupled to shaft 2 by a clutch (17, figure 5) so that the motor 13 does not need to be driven continuously.
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