Auxiliary tool

An annular mounting groove is formed between the side wall face of a positioning column and the inner wall face of a positioning hole, the width of the annular mounting groove is gradually increased in the direction from the groove bottom to the groove opening, the auxiliary tool comprises an auxiliary ring arranged on a crankshaft in a sleeving mode, and a supporting table is arranged on the auxiliary ring in the circumferential direction in an extending mode; the supporting table is clamped in the annular mounting groove, and the side wall surface of the supporting table abuts against the side wall surface of the positioning column, so that the positioning column abuts against the inner wall surface of the positioning hole and the side wall surface of the supporting table, the mounting matching length of the positioning column is increased, when the positioning column is inserted into the positioning hole, mounting is stable, coaxial precision is guaranteed, and the effect is good. By means of auxiliary ins