Piston pump, in particular axial piston pump or radial piston pump with a high delivery rate at a low rotational speed, comprising: - a frame (2, 2'); - a control element (10, 10') rotatably mounted about a central axis having at least one control surface (12', 12", 12"'), - a plurality of cylinders (13', 13", 13"'), each having pistons (14', 14", 14"') displaceable therein, - a suction connection (21, 21') for an inflow of a fluid into the cylinders (13', 13", 13"') of the piston pump (1, 42), and - a pressure connection (22', 22", 22"') for an outflow of the fluid out of the cylinders (13', 13", 13"') of the piston pump (1, 42), - wherein the cylinders (13', 13", 13"') are connected by lines (18', 18", 18"', 20', 20", 20"') to the suction connection (21, 21') and to the pressure connection (22', 22", 22"'), - wherein the cylinders (13', 13", 13"'), the pistons (14', 14", 14"') and the control element (10, 10') are configured and arranged in such a way that the positions of the pistons (14', 14", 14"') in the cylinders (13', 13", 13"') can be changed by a movement of the control element (10, 10'), - wherein the cylinders (13', 13", 13"') and the pistons (14', 14", 14"') are mounted in such a way that the cylinders (13', 13", 13"') and the pistons (14', 14", 14"') do not rotate completely about the central axis when the control element (10, 10') rotates, and - wherein the cylinders (13', 13", 13"') or the pistons (14', 14", 14"') are connected respectively to a rotatably mounted roller (15', 15", 15"'), characterised in that the contact region between the rollers (15', 15", 15"') and the control surface (12', 12", 12"') of the control element (10, 10') is lubricant-free such that an oil space which is to be sealed is not formed around the contact region. - a frame (2, 2'); - a control element (10, 10') rotatably mounted about a central axis having at least one control surface (12', 12", 12"'), - a plurality of cylinders (13', 13", 13"'), each having pistons (14', 14", 14"') displaceable therein, - a suction connection (21, 21') for an inflow of a fluid into the cylinders (13', 13", 13"') of the piston pump (1, 42), and - a pressure connection (22', 22", 22"') for an outflow of the fluid out of the cylinders (13', 13", 13"') of the piston pump (1, 42), - wherein the cylinders (13', 13", 13"') are connected by lines (18', 18", 18"', 20', 20", 20"') to the suction connection (21, 21') and to the pressure connection (22', 22", 22"'), - wherein the cylinders (13', 13", 13"'), the pistons (14', 14", 14"') and the control element (10, 10') are configured and arranged in such a way that the positions of the pistons (14', 14", 14"') in the cylinders (13', 13", 13"') can be changed by a movement of the control element (10, 10'), - wherein the cylinders (13', 13", 13"') and the pistons (14', 14", 14"') are mounted in such a way that the cylinders (13', 13", 13"') and the pistons (14', 14", 14"') do not rotate completely about the central axis when the control element (10, 10') rotates, and - wherein the cylinders (13', 13", 13"') or the pistons (14', 14", 14"') are connected respectively to a rotatably mounted roller (15', 15", 15"'), characterised in that the contact region between the rollers (15', 15", 15"') and the control surface (12', 12", 12"') of the control element (10, 10') is lubricant-free such that an oil space which is to be sealed is not formed around the contact region.