A hydraulic pump including a containment body (2) having inside a cylindrical cavity (3) provided with a conduit (4) communicating with a hydraulic actuator and capable of holding a fluid. A piston (5) is movable in the cylindrical cavity (3) and a reservoir (12) of the fluid is in fluid communication with the cylindrical cavity (3). An actuation device (6) connected to the piston (5) move the piston (5) within the cylindrical cavity (3) to operate the hydraulic actuator. The pump also comprises structure (13) for closing or opening the connection between the reservoir (12) and the cylindrical cavity (3). The reservoir (12) is substantially lined up with the cylindrical cavity (3) along an axis of longitudinal development (X) of same cylindrical cavity (3), so as to reduce the overall dimensions and the weight of the pump.