PURPOSE: To eliminate the necessity of taking out a rotary shaft by hanging by a method wherein a plurality of piano wires are hung down into a space at the upper part and the periphery of the rotary shaft to effect the centering of fixed parts by utilizing the plural piano wires as the reference of the centering.

CONSTITUTION: The shaft 10 is supported on a suction conduit 11, a piano wire 2 is hung down from a piano wire support 1 to the upper surface of the shaft 10 and the centerings of a thrust bearing support 3 and the upper cover 4 of the water wheel are effected so that the center distance between the lower cover 5 of the water wheel and the piano wire 2 becomes A. The four pieces of piano wires 9-1W9-4 are hung down from the upper cover 4 of the water wheel with spaces of 90° with respect to the piano wire 2. Distances between the piano wires 9-1W9-4 and the object of centering are measured and the centering is effected so as to obtain the equal values in opposing distances.