The present invention relates to a piston pump for pumping fluid. The piston pump is at least two cylinders each having a movable inner cylinder along the longitudinal axis of the cylinder (14, 15) by the drive (90) the piston (22, 22 ) (14, 15) I have. Cylinder (14, 15) are mounted on a common pump flange (10), the chamber within each cylinder (14, 15) (23, 23 ) is formed, a piston (22, 22) of the cylinder (14 When moving at 15), the volume of the chamber is changed. The present invention relates to a pump flange (10) extends along the movement direction of the piston (22, 22 ), the pump flange (10) is attached to at least one inlet (12) and one outlet (13) its longitudinal axis extends along the pump flange (10), the center of the valve plate (20) is attached to the side of the cylinder pump facing away from the (14, 15) flanges (10), a valve Plate (20) is in contact with the pump flange (10), during pumping operation of the piston pump, continuously rotating, the rotational axis of the valve plate (20) is elongated in a direction transverse to the pump flange (10), inlet and Each of the channel in the region of the outlet (30, 31), and each of the cylinder openings in the region of the cylinder (14, 15) (32, 33, 34, 35) is introduced into the pump flange, the valve plate ( 20) has at least two cavities (25) on the side of the flange, the first cavity (25) of which, when the valve plate (20) is rotated to a first angular position, the first cylinder of the cylinder (14) opening (32) and the flow path of the outlet (13) coincides with (30), at the same time, the flow passage (31) of the second cavity (24) an inlet at a first angular position (12) and a second cylinder (15 ) consistent with the cylinder opening (34) in, the valve plate (20) is rotated to the second angular position, the first cavity (25), the flow path of the outlet (13) (30) and the second cylinder ( 15) match the cylinder opening (35) in the same time, in the second angular position, the second ca
