A cam phaser apparatus comprising a triple member gear system for
transferring a driving torque from a drive member to a driven member and
for selectively adjusting the angular relationship between the drive and
driven members, said triple member gear system comprising a first member
comprising a driving part, a second member comprising a driven part
connectable to a cam sprocket or pulley, and a third member comprising an
adjusting means connectable to a camshaft, said third member being
connected to means for rotating said third member or applying a braking
torque and/or a motoring torque to said third member to vary the angular
relationship between the first and second members, wherein the cam phaser
apparatus further comprises a selectively actuable coupling means for
selectively coupling two of said first, second and third members. In one
embodiment the coupling means comprises a magnetic coupling.