A variable displacement axial piston pump comprising: a pump housing ; a cylinder block defining a plurality of cylinder bores , the cylinder block defining a central axis (A) about which the plurality of cylinder bores are arranged, wherein the cylinder block is supported for rotation relative to the pump housing about the central axis (A); a plurality of pistons , each of the plurality of pistons being received in a respective one of the plurality of cylinder bores ; a swash plate pivotally supported relative to the cylinder block , the swash plate providing a piston-supporting surface along which the plurality of pistons slide during operation of the pump ; and a port block defining first and second pumping ports arranged in fluid communication with the plurality of cylinder bores such that, during operation of the pump when the swash plate piston-supporting surface defines an angle other than 90 degrees with respect to the central axis (A), one of the first and second pumping ports is configured to supply fluid to the plurality of cylinder bores for pumping by the plurality of pistons as the cylinder block rotates, and the other of the first and second pumping ports is configured to receive fluid pumped from the plurality of cylinder bores by the plurality of pistons as the cylinder block rotates, wherein the swash plate partially defines at least one variable volume control chamber , and wherein the swash plate is operable to tilt with respect to the port block in response to a fluid pressure change in the at least one control chamber , characterized in that the at least one control chamber is at least partially defined by a back surface of the swash plate that is opposite the piston-supporting surface . a pump housing ; a cylinder block defining a plurality of cylinder bores , the cylinder block defining a central axis (A) about which the plurality of cylinder bores are arranged, wherein the cylinder block is supported for rotation relative to the pump housing about the central axis (A); a plurality of pistons , each of the plurality of pistons being received in a respective one of the plurality of cylinder bores ; a swash plate pivotally supported relative to the cylinder block , the swash plate providing a piston-supporting surface along which the plurality of pistons slide during operation of the pump ; and a port block defining first and second pumping ports arranged in fluid communication with the plurality of cylinder bores such that, during operation of the pump when the swash plate piston-supporting surface defines an angle other than 90 degrees with respect to the central axis (A), one of the first and second pumping ports is configured to supply fluid to the plurality of cylinder bores for pumping by the plurality of pistons as the cylinder block rotates, and the other of the first and second pumping ports is configured to receive fluid pumped from the plurality of cylinder bores by the plurality of pistons as the cylinder block rotates, wherein the swash plate partially defines at least one variable volume control chamber , and wherein the swash plate is operable to tilt with respect to the port block in response to a fluid pressure change in the at least one control chamber , characterized in that the at least one control chamber is at least partially defined by a back surface of the swash plate that is opposite the piston-supporting surface . <EOS>