Abstract: A hydraulic rotating axial piston engine having a housing enclosing a rotatable cylinder barrel. The engine has a number of axial cylinders with a number of reciprocating pistons. The pistons reciprocate between two defined end positions, and cooperate with a plate angled relative to a rotational axis of the barrel in order to obtain the reciprocating movement. The cylinders have ports alternatively acting as inlet and outlet ports. The housing has an inlet and an outlet channel, each having a kidney shaped port, facing towards the ports of the cylinders and communicating with a number of the cylinder ports. The housing has two parts, one of the housing parts defines the turning positions of the barrel in the end positions of the pistons. A second housing part defines the turning positions of the kidney shaped ports, relative to the end positions. The first and second parts of the housing are alternatively positionable in two different turning positions in the rotational direction of the cylinder barrel.