How They Build It: Selectable Lockers

For most four-wheelers, the idea of building a rig to fit our needs is way cool and way fun. Depending on skill level, we'll take on tire and suspension swaps, slip on a new set of headers, a cam, or steering system, or even fabricate our own body armor. Our more technically sophisticated trailmates might even delve into setting up ring-and-pinion gears or installing a locker. Kick that up a notch and call it an ARB Air Locker.

Well, if you are like us, you may have wondered what goes on inside that mystical little box when you push "the button." We recently put this question to several guys on the trail sporting ARB stickers. The response, "It's the button on the dash. I push it, it goes click, locks up, the tires grab traction and away we go. And that's all I know." We decided to super-size the question, and the answer. We recently visited the ARB facility in Melbourne, Australia, to get the scoop on what goes into the "click," the "lockup," and the "away we go."

So what did we discover? One cool thing is that the guys at ARB take pride in Australia. From the foundry to the cardboard box that it is shipped in, ARB Air Lockers are entirely manufactured in Australia. Keeping production close to home allows ARB precise control of quality and engineering specifications, and ensures that every Air Locker fits right and functions properly every time. Another point of discovery was the level of extensive research and testing that goes into every application before it ever sees the trail.

We first checked in with Engineering Supervisor Daniel Bongerd to find out what happens behind the scene. It starts in the conceptual and design stages where the ARB CAD jockeys (Computer Added Drafting engineers) use a program called Solidworks to build models on a digital drafting table.

Once the design stage is complete and exact tolerances are dialed in, this is where the fun begins. In the virtual lab, engineers can push the envelope with regard to design and stress loads much further than those encountered in real-life situations. A computer process called Finite Element Analysis (FEA) is used to force each unit to the point of virtual failure, and renders a color-coded image of stress points and possible failure zones. Surviving the CAD stage, specifications are sent out for prototype units to be built.

Due to the fact that stuff happens in the real world, ARB performs an extensive series of physical tests with components the unit will be installed into. For example: a locker for a Toyota 8-inch axle would be assembled into a Toyota differential and taken to ARB's Destructive Testing Lab. Set into a fix jig, the axle and differential are put under a load until something snaps. And, that something can be anything other than the locker. (Don't try this at home-safety glasses and Kevlar vests are highly recommended.)

If they haven't beat up the prepubescent locker sufficiently, it is then taken to the temperature lab, where it is heated to 248 degrees Fahrenheit and cooled to -11 degrees Fahrenheit. It is then subjected to an acute wheelspin engagement test (see photo) to simulate a full-load wheelhop condition on a 100 percent tractive surface. If the unit survives this gauntlet of abuse, it is then run through a longevity test of 20,000 actuation cycles of the pneumatic mechanisms. By this point, one would think the unit is ready for the consumer, but not just yet. The ARB guys then get a chance to play with it for a while, abusing it on the harshest terrain and fiercest real-world conditions.

We asked Bongerd why ARB performs such extensive testing. The response, "Everybody claims to have the best materials and processes, but if you don't pit them against each other in an objective environment of laboratory-controlled abuse, then you never actually know. Usually these materials and technologies fall more under the banner of aerospace than automotive-this sort of strength is not needed in a regular car." ARB credits the Air Locker's success to simplicity and its commitment to strength and quality. Recent engineering enhancements have revamped the design of most units to implement the use of timed gear technology (see illustration), which has reduced the number of moving parts and increased strength by up to 40 percent.