A valve timing control apparatus is adapted to an exhaust valve side of an
internal combustion engine. A vane member is arranged to rotate with a
camshaft relative to a timing sprocket member. The vane member is rotated
at low speed engine operation dominantly by a camshaft-torque actuation
mechanism and at high speed engine operation dominantly by a hydraulic
actuation mechanism. The camshaft-torque actuation mechanism is actuated
by an alternating torque of the camshaft, whereas the hydraulic actuation
mechanism is actuated by a fluid pump. The camshaft-torque actuation
mechanism and hydraulic actuation mechanism are controlled independently
of each other.