Reciprocating piston pump for conveying a medium with at least one pump module and a drive, wherein the at least one pump module comprises a cylinder head, a cylinder and a reciprocating piston, wherein the reciprocating piston has a reciprocating piston head with a reciprocating piston head surface, wherein the cylinder head, the cylinder and the reciprocating piston head form a conveying chamber, wherein the reciprocating piston is designed for converting a drive movement of the drive into a conveying stroke movement and into a suctioning stroke movement of the reciprocating piston in the cylinder along a longitudinal axis, and wherein the cylinder head, the cylinder and the reciprocating piston are designed for converting the conveying stroke movement into a conveying of a medium out of the conveying chamber by making the conveying chamber smaller, wherein the reciprocating piston pump has an auxiliary reciprocating piston, the auxiliary reciprocating piston is arranged between the drive and the reciprocating piston and has an auxiliary reciprocating piston head with an auxiliary reciprocating piston head surface, characterized in that the cylinder, the reciprocating piston and the auxiliary reciprocating piston head form a lubricating chamber for a lubricating medium for lubricating contact surfaces between, on the one hand, the cylinder and, on the other hand, the reciprocating piston and the auxiliary reciprocating piston that the cylinder, the reciprocating piston and the auxiliary reciprocating piston are designed for converting the drive movement into an auxiliary conveying stroke movement and into an auxiliary suctioning stroke movement of the auxiliary reciprocating piston in the cylinder along the longitudinal axis and for converting the auxiliary conveying stroke movement of the auxiliary reciprocating piston into the conveying stroke movement of the reciprocating piston via a lubricating medium in the lubricating chamber, and that the auxiliary reciprocating piston head surface is smaller than the reciprocating piston head surface, so that, during the auxiliary conveying stroke movement, a pressure of a lubricating medium in the lubricating chamber is greater than a pressure of a medium in the conveying chamber. wherein the at least one pump module comprises a cylinder head, a cylinder and a reciprocating piston, wherein the reciprocating piston has a reciprocating piston head with a reciprocating piston head surface, wherein the cylinder head, the cylinder and the reciprocating piston head form a conveying chamber, wherein the reciprocating piston is designed for converting a drive movement of the drive into a conveying stroke movement and into a suctioning stroke movement of the reciprocating piston in the cylinder along a longitudinal axis, and wherein the cylinder head, the cylinder and the reciprocating piston are designed for converting the conveying stroke movement into a conveying of a medium out of the conveying chamber by making the conveying chamber smaller, wherein the reciprocating piston pump has an auxiliary reciprocating piston, the auxiliary reciprocating piston is arranged between the drive and the reciprocating piston and has an auxiliary reciprocating piston head with an auxiliary reciprocating piston head surface, characterized in that the cylinder, the reciprocating piston and the auxiliary reciprocating piston head form a lubricating chamber for a lubricating medium for lubricating contact surfaces between, on the one hand, the cylinder and, on the other hand, the reciprocating piston and the auxiliary reciprocating piston that the cylinder, the reciprocating piston and the auxiliary reciprocating piston are designed for converting the drive movement into an auxiliary conveying stroke movement and into an auxiliary suctioning stroke movement of the auxiliary reciprocating piston in the cylinder along the longitudinal axis and for converting the auxiliary conveying stroke movement of the auxiliary reciprocating piston into the conveying stroke movement of the reciprocating piston via a lubricating medium in the lubricating chamber, and that the auxiliary reciprocating piston head surface is smaller than the reciprocating piston head surface, so that, during the auxiliary conveying stroke movement, a pressure of a lubricating medium in the lubricating chamber is greater than a pressure of a medium in the conveying chamber.