PURPOSE: To make it possible to measure the axial thrust of a high-torque rotary machine highly accurately, by attaching a high-torque transmitting mechanism to a coupling on the side of a driving shaft, and attaching an axial-thrust transmitting mechanism comprising a hollow shaft to a coupling on the side of a driven shaft.

CONSTITUTION: A coupling 3 is fixed to a driving shaft 1, which is linked to a driving source, through a lock nut 5. A coupling 4 is fixed to a driven shaft 2, which is linked to a vertical shaft pump or a vertical shaft water turbine through a lock nut 6. A high-torque transmitting mechanism A and an axial- thrust transmitting mechanism B are coupled with the couplings 3 and 4 so as to form unitary bodies, respectively. Shaft couplings are formed by both trasmitting mechanisms A and B. The axial-thrust transmitting mechanism B has a hollow shaft 12. At this time, the hollow shaft 12 transmits the axial thrust but does not transmit the torque. Therefore, the axial thrust of the high-torque rotary machine can be measured highly accurately.