allowed enabling earn phasing operation of the camshaft phaser fig2 shows an enlarged front view of camshaft phaser 1 of fig1 with front side cover 11 and assembly bolts 3 removed increased step diameter 32 of base portion 38 of rotor 7 is shown interacting with reduced diameter housing protrusion 33 in housing sprocket 29 increased step diameter 32 provides sufficient material through which locking pin assembly 35 consisting of locking pin 4 locking pin spring 5 and locking pin cartridge 6 may be inserted reduced volume pressure cavity 36 is formed in a volume created by rotor increased step diameter 32 reduced step diameter housing protrusion 33 and vane 19 pressure cavities 34 are formed in a volume created by rotor 7 vanes 19 and housing protrusions 20 oil ports 37 in rotor 7 allow for ingress and egress of engine oil from pressure cavities 36 as is shown pressure cavities 34 may be larger than a similar camshaft phaser in which a diameter of rotor 7 is uniform throughout its circumference this reduction in diameter of rotor 7 in the portions of the circumference other than that of increased step diameter 32 also allows for increased surface area of vanes 19 at those other areas which in turn allows force to be exerted over that increased surface area of vanes 19 by a constant engine oil pressure during operation of camshaft phaser 1 also shown are sealing lips 8 and leaf springs 9 fig3 shows an isometric assembly view of the camshaft phaser 1 of fig1 with front side cover 11 and assembly bolts 3 removed.