A hydraulic device in an internal combustion engine for adjusting a rotation angle of a camshaft in relation to a crankshaft includes a tubular stator and a rotor connected in fixed rotative engagement with the camshaft and having plural vanes in spaced apart relationship to define pressure chambers on both sides of the vanes. The stator is connected in fixed rotative engagement with a crankshaft-drive timing pulley and constructed to define with the rotor vanes the pressure chambers. The stator is made by a shaping process without material to effect a mass reduction. Pressure medium is supplied to or purged from the pressure chambers to selectively adjust the position of the rotor in relation to the stator and thereby the position of the camshaft in relation to the crankshaft.