Tool assembly and method for lifting wind turbine parts

1. An assembly for lifting a wind turbine nacelle or hub, wherein the wind turbine nacelle or hub includes an external outer wall and an external inner wall, the external inner wall facing an internal cavity area within the wind turbine nacelle or hub, the assembly comprising:

a tool having a stem, a first end and a second end, wherein the tool has a length so as to extend through the external outer and inner walls of the nacelle or hub into the interior cavity area of the nacelle or hub so that the first end is accessible to a person within the interior cavity region;

the assembly further comprising a stem receiving portion configured with the external outer and inner walls of the nacelle or hub and having an opening therethrough into the interior cavity area of the nacelle or hub;

a releasable lock configured around the first end of the stem within the interior cavity area of the nacelle or hub; and

wherein the stem of the tool is adapted to freely pass through the opening in the stem receiving portion until the first end of the stem passes through the stem receiving portion into the interior cavity area and is locked against a bottom portion of the stem receiving portion by the releasable lock applied around the first end of the stem by the person in the interior cavity area, thereby preventing the stem from separating from the stem receiving portion when the nacelle or hub is lifted by the tool,

wherein the releasable lock comprises a stem projecting portion releasably attached to the first end of the stem so as to surround and project radially from the stem such that the stem cannot be passed through the stem receiving portion when the wind turbine art is lifted by the tool, and

wherein the stem projecting portion comprises a ring, the ring comprising two pieces selectively coupled in an assembled condition to surround and project radially from the first end of the stem.

2. The assembly of claim 1 , wherein the second end of the stem is adapted to be engaged by a lifting equipment.

3. The assembly of claim 1 , wherein the opening in the stem receiving portion is defined by substantially vertical walls so that the stem of the tool is vertical when passed through the stem receiving portion.

4. The assembly of claim 1 , wherein the stem projecting portion is adapted to be at least partially fitted into an enlarged portion formed in the stem receiving portion when the wind turbine part is lifted by the tool.

5. The assembly of claim 1 , wherein the releasable lock further comprises at least one wedge part disposed such that the relative displacement of the wedge part and the stem of the tool causes the wedge part to engage the stem receiving portion to prevent the stem from being passed through the stem receiving portion when the stem of the tool is pulled out for lifting the nacelle or hub.

6. The assembly of claim 1 , wherein the assembly further comprises a holding means to temporary hold the stem to the stem receiving portion until the stem is engaged by the lifting equipment.

7. The assembly of claim 6 , wherein the holding means comprises a protrusion projecting from the stem such that the stem is arranged at a predetermined relative position with respect to the stem receiving portion.

8. The assembly of claim 1 , wherein the assembly further comprises a stop plate provided at the first end of the stem, between the stem projecting portion and the nacelle or hub.

9. The assembly of claim 2 , wherein the second end of the stem includes a through bore adapted to be engaged by the lifting equipment.

10. The assembly of claim 6 , wherein the holding means is positioned closer to the external outer wall than engagement means of the second end of the stem configured to be engaged by the lifting equipment.