connector b is connected to the axial pressure connector p the hydraulic medium under pressure flows via radial openings 65 out of the hollow piston 41 into the working connector b from here the hydraulic medium flows into axially extending bores 66 arranged within the valve housing 27 and configured as blind bores closed at their end facing the camshaft 2 by a closure part 67 bores 68 open into the bores 66 that are provided at the bottom of an annular groove 69 in the outer peripheral surface 70 of the valve housing 27 the bores 63 open into the annular groove 69 provided within the base member 8 of the rotor in the peripheral surface 70 of the valve housing 27 an additional annular groove 71 is provided and bores 72 open into the bottom of this groove and are distributed circumferentially they connect the annular groove 71 with axial bores 73 in the valve housing 27 as illustrated in fig5 the bores 73 are shorter than the bores 66 the bores 73 open into the end face of the valve housing 27 facing the camshaft 2 and are closed by a closure part 74 radial bores 64 in the base member 8 of the rotor open into the annular groove 71 positioned at an axial spacing from the annular groove 69 radial bores 75 that are distributed about the circumference open into.