In a camshaft adjustment control device for an internal combustion engine arranged
in the drive train for a camshaft, with an inner body connected to the camshaft
and an outer body rotatable relative to the inner body, and a control space between
the inner and the outer bodies to which hydraulic fluid can be supplied for adjusting
the relative angular positions of the inner body connected to the camshaft and
the outer body driven by the crankshaft, the inner body is mounted to the camshaft
by a bolt having a central bore in which a control spool valve is disposed controlling
the flow of fluid to and from the control space and a check valve is arranged in
the supply lines of the hydraulic fluid to the control spool valve which check
valve opens when a certain pressure is applied thereto.