PURPOSE: To automate the assembling of a fitting member while inserting the key of a pump shaft into the keyway of a coupling by shifting a model shaft and the coupling in the direction of the pump shaft while engaging said shaft with said coupling, and by turning them in a body.

CONSTITUTION: A model shaft 69 is turnd with a low speed by a motor 67. The model shaft 69 is lowered with the rotation by a vertical cylinder 28, and enters into the hole of a coupling 8, allowing the key 73 of the model shaft 69 and the keyway of the coupling 8 to coincide with each other. Keeping this situation, the coupling is held with a aucket 51, and shifted to the position of a pump shaft 5. The model shaft 69 again goes down with the rotation, and the key 7 of the pump shaft 5 turns togehter with the pump shaft 69 while said key enters into the keyway of the coupling 8. When the rotation stops, a forcing tool 55 is lowered by a forcing cylinder 37, and the coupling 8, is pushed down, thus the assembling may be completed.