A reciprocating rotating engine having a combustion chamber and a pumping chamber is provided with two sets of free pistons and pumps vanes each set having two pistons and two pump vanes. The two sets of pistons and pump vanes define four separate combustion chamber portions and pumping chamber portions and reciprocally rotate in concentric circular paths under the force of compression ignited internal combustion forces, pumping and pressurizing hydraulic fluid contained within the pumping chamber.