Abstract: An air-driven hydraulic pump, comprising an air motor, and an oil pump, which is operatively connected with the air motor, wherein the air motor includes a cylinder element in which an air piston is arranged movable in a reciprocating manner along a centre axis. The air piston is connected with an oil piston of the oil pump for transmitting the reciprocating movement of the air piston to the oil piston. The air piston separates a first cylinder chamber from a second cylinder chamber within the cylinder element. A control valve element is arranged to control the application of pressurized air from a source of pressurized air to the cylinder element. At least one pressure control valve is arranged in the air motor, allowing an air flow from one of the cylinder chambers to the other cylinder chamber when the pressure difference between the two cylinder chambers exceeds a predetermined value.