This system is marketed under the name ARB Air Locker and is available for a number of common axles. Reliability is the main drawback to this system. Sticking of the solenoid or leaking of the air tubing are the main causes of failure. These problems are easily repaired in the field. A blow-out in the seal within the compressor or the piston inside of the differential are not so easily repaired, but are much less common.
Some people object to the cycling of the air compressor, both when in use and when in standby.
This is the most expensive type of differential. Currie Enterprises is planning an electrically actuated locker for March 94. It has the advantages of the ARB in that it can be turned on or off, but has no air hoses to break. Lockers are manufactured by two companies. One brand is called the Lock-Rite or L.A. Locker.