A pump which exhibits an adjustable delivery volume, the pump comprising: (a) a pump housing (1, 2), comprising: a pump port for connecting the pump to a reservoir of a fluid to be delivered; a delivery chamber which comprises a delivery chamber inlet on a low-pressure side of the pump, and a delivery chamber outlet on a high-pressure side of the pump, for a fluid; and a suction region extending from the pump port up to at least the delivery chamber inlet on the low-pressure side; (b) a delivery member which can be moved within the delivery chamber for delivering the fluid from the low-pressure side to the high-pressure side, preferably a delivery rotor which can be rotated about a rotational axis (R 10) within the delivery chamber; (c) an adjusting device (20, 25, K) for adjusting the delivery volume of the pump; (d) a control valve, arranged outside the suction region, comprising: a pressure port for a setting fluid which is diverted from the fluid of the high-pressure side; a working port for the setting fluid, which is connected to the adjusting device; a relief port for the setting fluid; a valve space, and a control piston which can be moved back and forth within the valve space between a first piston position and a second piston position; and a tensing device for generating a tensing force which acts on the control piston in the direction of one of the piston positions; (e) and an additional control device (36, 37, 40) for generating a control force which acts on the control piston, counter to the tensing force of the tensing device, (f) wherein the control valve connects the working port to the pressure port when the control piston is in the first piston position and separates the working port from the pressure port and connects the working port to the relief port when the control piston is in the second piston position, characterised in that (g) the relief port is connected to the suction region by bypassing the reservoir, and (h) the control valve is not in fluid communication with the reservoir via the relief port, such that no fluid flows from the reservoir into the valve space of the control valve via the relief port, and in particular no fluid flows from the control valve to the reservoir via the relief port. (a) a pump housing (1, 2), comprising: a pump port for connecting the pump to a reservoir of a fluid to be delivered; a delivery chamber which comprises a delivery chamber inlet on a low-pressure side of the pump, and a delivery chamber outlet on a high-pressure side of the pump, for a fluid; and a suction region extending from the pump port up to at least the delivery chamber inlet on the low-pressure side; (b) a delivery member which can be moved within the delivery chamber for delivering the fluid from the low-pressure side to the high-pressure side, preferably a delivery rotor which can be rotated about a rotational axis (R 10) within the delivery chamber; (c) an adjusting device (20, 25, K) for adjusting the delivery volume of the pump; (d) a control valve, arranged outside the suction region, comprising: a pressure port for a setting fluid which is diverted from the fluid of the high-pressure side; a working port for the setting fluid, which is connected to the adjusting device; a relief port for the setting fluid; a valve space, and a control piston which can be moved back and forth within the valve space between a first piston position and a second piston position; and a tensing device for generating a tensing force which acts on the control piston in the direction of one of the piston positions; a pressure port for a setting fluid which is diverted from the fluid of the high-pressure side; a working port for the setting fluid, which is connected to the adjusting device; a relief port for the setting fluid; a valve space, and a control piston which can be moved back and forth within the valve space between a first piston position and a second piston position; and a tensing device for generating a tensing force which acts on the control piston in the direction of one of the piston positions; (e) and an additional control device (36, 37, 40) for generating a control force which acts on the control piston, counter to the tensing force of the tensing device, (f) wherein the control valve connects the working port to the pressure port when the control piston is in the first piston position and separates the working port from the pressure port and connects the working port to the relief port when the control piston is in the second piston position, characterised in that connects the working port to the pressure port when the control piston is in the first piston position and separates the working port from the pressure port and connects the working port to the relief port when the control piston is in the second piston position, (g) the relief port is connected to the suction region by bypassing the reservoir, and (h) the control valve is not in fluid communication with the reservoir via the relief port, such that no fluid flows from the reservoir into the valve space of the control valve via the relief port, and in particular no fluid flows from the control valve to the reservoir via the relief port.