PURPOSE: To prevent generation of pulsation as well as vibration by a method wherein a pair of driving cylinders are provided with operation detectors to begin the advancing motion and pressurize the fluidic body in one pump cylinder when the delivery motion of the other cylinder is almost finished while the continuous delivery of the fluidic body is effected in accordance with the switching motion of delivery ports.

CONSTITUTION: When first driving piston 8a is converted from the retreating motion into the advancing motion thereof and the conversion is detected by a conversion detector 48a, the detecting signal is inputted into a control circuit 51, the solenoid 44a of a solenoid switching valve 42a for first delivery valve is excited to open the first delivery valve 31a and the flow body, such as concrete for example, in the first pump cylinder 2a is discharged through a delivery pipe 30. In this case, the advancing motion detector 47b of the second driving hydraulic cylinder 3b detects the advancing motion of the second driving piston 8b, second servomotor 50b is driven, operating oil is supplied to the fore chamber 6b of the second driving cylinder 3b, second piston rod 5b is retreated and the concrete is induced into the second pump cylinder 2b. According to this method, generations of pulsation, vibration and noise may be prevented.