a shift mechanism for a vehicle wheel wherein a pneumatic annular actuator , through air pressurization and depressurization , produces clutch ring movement to engage and disengage the wheel from the vehicle &# 39 ; s drive axle . the components of the wheel end providing an air tight cavity in which the clutch ring is manipulated and which is subjected to air pressure changes . the components include a pneumatic annular actuator , a cv - joint , a rotary seal between the actuator and the cv - joint and a vent passage formed between the air chamber and rotary seal and breaching said air tight cavity . an air line from said passage to non - contaminated ambient air to provide continuous ambient air pressure to said cavity .