Pumping unit for a machine to distribute concrete

A pumping unit for a machine to distribute concrete, the pumping unit comprising:

• at least a pair of cylinders (12, 13) provided with a relative pumping piston (22, 23) movable linearly in relative chambers (25) of the cylinders for a determinate travel (S) and able to feed the concrete to a determinate circuit to distribute the concrete,
• a main hydraulic command circuit (11) operatively connected to both the cylinders (12, 13), and able to determine an alternate pumping movement of the relative pumping piston (22, 23),
• at least one sensor member (15) operatively associated with at least one of said cylinders (12, 13) in order to detect, at every instant on the whole travel (S), one or more data relating to the operating condition of said pumping piston (22, 23) during its movement, wherein said data comprise at least one of position, speed, stress and direction of movement of the relative piston (22, 23),
• a connection pipe (18) which connects the relative chambers (25) of the cylinders with respect to each other, and
• a hydraulic block (37) directly hydraulically connected to at least one of said chambers (25) and to said connection pipe (18) connecting the relative chambers (25), thereby defining an auxiliary hydraulic circuit which selectively introduces/discharges hydraulic fluid into/from the chambers (25) of said pumping cylinders (12, 13), in addition to the main hydraulic circuit, based on the signals being detected and transmitted to the hydraulic block (37) by the at least one sensor member (15), wherein the hydraulic block optimizes, in a continuous manner, the volume of hydraulic fluid contained in each of the chambers (25) of the cylinders connected by the connection pipe (18) and the performance of the pumping unit.