Vertical main shaft

The invention provides a vertical main shaft which comprises a pipe joint and a rotor, a first channel is formed in the pipe joint, a second channel is formed in the rotor, the axis of the rotor is arranged in the vertical direction, and the pipe joint is arranged at the upper end of the rotor so that the first channel can be communicated with the second channel. Cooling fluid can be introduced into the second channel of the rotor through the first channel of the pipe joint, and a leakage position is arranged at the joint of the pipe joint and the rotor; the floating cylinder is located below the pipe connector and located on the peripheral side of the rotor, the pipeline disc is located on the peripheral side of the floating cylinder, a liquid passing opening is formed in the floating cylinder, a discharge opening is formed in the pipeline disc, and one end of the liquid passing opening can receive fluid leaked from the leakage position; and the other end can be communicated with the discharge port so as to