A piston hydraulic device comprises a cylinder block having a plurality of cylinder assemblies and is rotatable about a first rotation axis. Each cylinder assembly comprises a cylinder and a piston. A port plate has a first port and a second port that are angularly spaced relative to the first rotation axis. A plurality of first conduits connect respective cylinders alternately to the first port or the second port. At least one second conduit is connected to a fluid reservoir. At least one directional control valve is positioned in the first conduit and fluidly connects to the second conduit. The at least one directional control valve connects the cylinder to the port plate in a first position and to the fluid reservoir in a second position. A controller is operatively associated with the directional control valve for switching between the first and the second positions.