PURPOSE: To Prevent occurrence of a neck-in phenomenon in a pipe line due to pressure and temperature during conveyance of ready-mixed concrete led from the suction side by a rotor having at its opposite ends rotors which can rotate and press a pump tube within a drum, from the discharge side to a predetermined position.

CONSTITUTION: Recesses are formed at 6, 9 and 12 o'clock positional at which a drum 9 and a pump tubing is pressed by rollers of a rotating roller, on the drum side 9, and a temperature sensor 8 is located in each of the recesses so that a drive machine associated with the temperature sensors 8 is adjusted in order to prevent occurrence of a neck-in phenomenon in a pipe line on the discharge side.