A thick-matter pump with a hydraulic systems for the drive and actuation of the same having two delivery cylinders (10, 10') which contain in each case one delivery piston (22, 22') and which issue at end-side openings (12, 12') into a material-supply vessel and which, by means of a pipe switch or a slide valve of the thick matter pump, are connected to a delivery line alternately during a pressure stroke of their delivery pistons (22, 22'), having two hydraulic drive cylinders (16, 16') which contain in each case one drive piston (24, 24') and the drive pistons (24, 24') of which are connected to the delivery pistons (22, 22') by means of in each case one common piston rod (26, 26') and can be actuated and controlled by means of drive hydraulics of the hydraulic system that comprise a reversing pump (18, 20), and having a placing boom that can be actuated and controlled by means of boom hydraulics of the hydraulic system, wherein the drive hydraulics and the boom hydraulics form a common primary circuit and further with a tank, which is at atmospheric pressure, for accommodating hydraulic oil, wherein the primary circuit - has at least one motor-driven primary pump (36, 38, 61, 71) that is charged with hydraulic oil via a first suction line, - is connected at the outlet side to at least one first return line, - and has a suction/return filter which communicates at the outlet side with the first suction line and which, at the inlet side, is charged with returned oil from the at least one return line, - wherein at least one of the primary pumps (36, 38) is in the form of a charging and feed pump of the working hydraulics and a further one of the primary pumps is connected to the boom hydraulics, whose return line 74 on the inlet side is connected with the suction/return filter, wherein a branch line is provided which is branched off from the first suction line and which issues into the tank via a preload valve, wherein a secondary circuit is provided, - which secondary circuit has at least one motor-driven secondary pump (60, 62) which is charged with hydraulic oil via a second suction line, - and which secondary circuit is connected at the outlet side to at least one second return line, - wherein the second suction line communicates with the tank directly or via a further suction filter, - wherein the second return line either ends in the tank or is connected to the inlet side in the suction/return filter, - wherein one of the secondary pumps is connected with its pressure side to the inlet of the suction/return filter and/or wherein one of the secondary pumps is connected to a hydraulic stirring mechanism drive, the return line of which is connected to the inlet side of the suction/return filter - wherein the first suction line communicates with the tank via a separate replenishment suction line and a further suction filter, - and wherein a replenishment suction valve is arranged in the replenishment suction line, which is preloaded in the direction of the further suction filter, which is dimensioned such that an oil deficit in the primary circuit may be compensated. - has at least one motor-driven primary pump (36, 38, 61, 71) that is charged with hydraulic oil via a first suction line, - is connected at the outlet side to at least one first return line, - and has a suction/return filter which communicates at the outlet side with the first suction line and which, at the inlet side, is charged with returned oil from the at least one return line, - wherein at least one of the primary pumps (36, 38) is in the form of a charging and feed pump of the working hydraulics and a further one of the primary pumps is connected to the boom hydraulics, whose return line 74 on the inlet side is connected with the suction/return filter, wherein a branch line is provided which is branched off from the first suction line and which issues into the tank via a preload valve, wherein a secondary circuit is provided, - wherein at least one of the primary pumps (36, 38) is in the form of a charging and feed pump of the working hydraulics and a further one of the primary pumps is connected to the boom hydraulics, whose return line 74 on the inlet side is connected with the suction/return filter, - which secondary circuit has at least one motor-driven secondary pump (60, 62) which is charged with hydraulic oil via a second suction line, - and which secondary circuit is connected at the outlet side to at least one second return line, - wherein the second suction line communicates with the tank directly or via a further suction filter, - wherein the second return line either ends in the tank or is connected to the inlet side in the suction/return filter, - wherein one of the secondary pumps is connected with its pressure side to the inlet of the suction/return filter and/or wherein one of the secondary pumps is connected to a hydraulic stirring mechanism drive, the return line of which is connected to the inlet side of the suction/return filter - wherein the first suction line communicates with the tank via a separate replenishment suction line and a further suction filter, - and wherein a replenishment suction valve is arranged in the replenishment suction line, which is preloaded in the direction of the further suction filter, which is dimensioned such that an oil deficit in the primary circuit may be compensated.