Valve Timing Unit

The valve timing unit turns the intake camshaft in relation to the primary chain to advance and retard the timing.
The unit consists of a body and sprocket assembly separated from an inner sleeve by a ring piston and two ring gears; the inner sleeve is bolted to the camshaft.
The ring gears engage in opposing helical splines on both the body and sprocket assembly and the inner sleeve, to transmit drive from the assembly to the inner sleeve.
Engine oil pressure moves the ring gears and piston to turn the inner sleeve in the advanced timing direction and a return spring reverses the direction for retard.
Additional springs absorb rotational and axial backlash to reduce noise and wear.