a pumping unit for a machine to distribute concrete includes a pair of cylinders provided with a relative pumping piston movable linearly for a determinate travel to feed the concrete to a determinate circuit to distribute the concrete ; and a hydraulic command circuit operatively connected to both the cylinders , to determine an alternate pumping movement of the relative pumping pistons . the pumping unit includes at least a sensor member operatively associated to at least one of the cylinders in order to detect point - by - point one or more data relating to the operating condition of the pumping piston during its movement for the whole travel . the data includes at least one of position , speed , stress and direction of movement of the relative piston .