A hydraulic axial piston pump comprising a cylinder block closed at sides by a head and by a containment casing for piston actuating a plate, an electric motor coupled to the plate, reversible locking means for a bypass valve inserted in a seat of the body and kinematically connected to a microswitch connected to the electric motor, the reversible locking means comprising a retention element insertable transversely to the seat in a receptacle formed in the body without structure discontinuity, the bypass valve head being integrated in a shell external to the body and enclosing the microswitch and the kinematic system.