Hitachi's Variable Timing Control Cover Assembly is an aluminum cover that contains the Variable Timing Solenoid valve. This cover mounts to the engine's Timing Chain Case Front Cover, which encapsulates the Variable Timing Gear (Camshaft Phasor). The Variable Timing Conntrol Assembly main function is to control oil pressure to the camshaft phasors (camshaft sprockets), which control the engine's valve timing. The camshaft phasors (Variable Timing Gear) are mounted to the camshaft.