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30th January, 2021

What makes an Air Locker?



The original Air Locker was developed in the 1980s. This design featured a three-piece case with an air actuated cast piston. A true, revolutionary piece of 4WD equipment, the Air Locker made its way to North America. Around 1990, the first ARB Air Locker was installed in the United States by Jim Oostdyk.

Over the years, four-wheeling has changed drastically. Large tires and engines in that era do not compare to what is being used today. In order to get ahead of the curve, ARB’s team of engineers were tasked with designing an Air Locker that would hold up to the future of four wheeling. The research and development consisted of many torque and failure tests on the Air Locker and other lockers. At the beginning of the 21st century, the new and improved Air Locker was released. It featured a two-piece design, less internal parts, forged gears, and a patented timed locking system; all of which make it the world’s strongest locking differential. Today, there are over a thousand different Air Locker applications available across hundreds of vehicle platforms.



The original prototype Air Locker featured a vacuum operated locking system. After countless trial and error, the final Air Locker prototype used compressed air as its official source of engagement. Air allowed for a faster and more secure engagement along with faster disengagement.

From the push of a button, air flows from the compressor to the differential. This compressed air pushes against a seal to drive the internal clutch gear which then locks the internal spider and side gears. This patented locking system only allows the locker to be locked in the strongest position possible, which increases the strength by up to 40%. Once locked, each tire begins to move at the same speed giving the vehicle equal traction when needed.



All castings are manufactured in Australia. Each locker is CNC machined and precisely milled using current generation, cutting edge technology. Once this step is completed, accuracy is ensured using programmable CMM, Coordinate Measurement Machine. Gears are then forged, broached, heat-treated, shot-peened, and coded for traceability. All fasteners are torqued during assembly. Prior to packaging, each locker receives a spline and pneumatic activation test. Once completed, the Air Locker is coated to prevent corrosion when distributed around the world.



Air Lockers and motorsports go hand in hand. Air Lockers continue to evolve due to the support of off-road racing. Air Lockers have been able to survive through some of the toughest off-road races, including the Ultra4 King of the Hammers; one of the most difficult and technical off-road races around. But this accolade was not enough to satisfy our engineers.

ARB redesigned the two most popular race application lockers that suited a Ford 9” housing. The Competition Edition Air Locker was developed: RD99CE (35-spline) and the RD249CE (40-spline). The new features consisted of ring-gear bolt locking tabs and a unique casting that improved the overall case strength by over 290 percent.

“The thing the people don’t realize about ARB, is that they have been developing the parts as our series and sport has grown… they keep evolving as the sport has evolved.”

-Jason Scherer

Air Locker, the official locker of Ultra4 has won 8 King of the Hammers and 6 Every Man Challenge championships. These championships show that ARB’s extensive research, design, quality, and commitment is a true reflection of the Air Lockers success.

“They hold to the abuse that our cars provide… I can still put the hammer down and know that they are going to live at the end of the race.”

-Wayland Campbell


ARB has invested heavily in current-generation manufacturing equipment and experienced personnel. The Australian-made, utmost quality and integrity, two-piece design, patent lock ring, and five-year unlimited mile warranty is what sets the Air Locker apart. Our commitment to the four-wheel-drive community has sold over 500,000 Air Lockers throughout 100 countries.

Shop ARB Air Lockers >>

ARB Air Locker Application Guide >> 



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