Information and images provided by ARB adapted by SA4x4 magazine
ARB’s three-piece Air Locker design has a great reputation with the off -road fraternity. Trusted since the 80s, it’s become the yardstick, the diff -lock by which all others are judged. So if it ain’t broke, why mess with it? Well, there were a small number of Air Locker models that underperformed compared to the rest of the range.
Enter one Daniel Bongard, now head of ARB’s Air Locker division, who was originally hired to improve these particular lockers. Th is turned out to be a tricky job. Says Bongard: “When we increased the strength in one area of the locker, a diff erent area or component was weakened. Aft er four complete design options had been explored and dismissed, we knew it was time for something radical. So we put aside the existing Air Locker design and started from scratch.”
That kicked off six months of computer-generated concepts revolving around a new two-piece design, new components and a unique ‘timed’ gear set which demonstrated gains in strength, durability and locking speed. One percent better can be classed an improvement, but with the new design Bongard and his team were able to predict an astonishing 40 percent improvement in static torque strength compared to the three-piece design.
Six more months were devoted to proving and refining the design, which included destruction testing in the lab and with prototypes fitted to vehicles driven through obstacle courses and across all types of terrain. Try as they might to break the prototypes, the two-piece Air Locker came out tops. It was so good that ARB immediately started a programme to fi t the new design throughout the Air Locker range.
‘Timed’ Gears A key feature of the new design is the ‘timed’ gears. In the three-piece locker, the gears stop and ‘lock’ in arbitrary positions when the Air Locker is activated; this means the gear teeth aren’t always in the best positions for locking strength. With the two-piece design, Bongard and the team engineered new patented gearing technology which ensures that no matter when the Air Locker is activated, the gear teeth will always ‘lock’ into predetermined positions that offer the greatest surface area between the gear teeth. This ensures that optimal locking strength is attained every time the Air Locker is activated. The only downside with these new ‘timed’ gears was that no machine in the world could manufacture them. So Bongard worked closely with a gear manufacturer to modify existing machinery in order to make the gears a reality.
This machinery remains exclusive to the manufacturing of ARB Air Lockers. New Components Among the many advantages of the new two-piece Air Locker is the elimination of one third of the components used in the three-piece design. This ensures increased precision and compliance among the components, making for a more cohesive finished differential that delivers a much firmer and responsive grip in terrain for the end user. The new two-piece design also features a number of ‘shared’ components which can be used within a diverse range of differentials – the components are so flexible that a Nissan differential can now be fitted to a Toyota vehicle with very little retrofitting required.
This type of design flexibility has proven particularly useful for modified vehicles with specialist applications such as drag racing, competition rock crawling and heavy tank-track type snow equipment. The redesign of existing components has also meant a much more efficient use of space, which has resulted in an increase in load bearing capabilities and a significant reduction in actual locking times. The gears within the two-piece are now less than 0.5 mm from the locking mechanism, whereas the three-piece had to travel at least three mm before locking. While this might not seem like much, the end user will feel a much quicker response when the Air Locker is engaged and disengaged.
Off Road Users activating the two-piece Air Locker for the first time will immediately feel the difference. The level of grip on most terrain is now noticeably tighter. The 40 percent increase in strength translates to even greater control and reliability, allowing vehicles to be driven in a slower and safer manner when climbing difficult terrain. Reliance on momentum is reduced, and the Air Locker also requires less air consumption, meaning there are more actuations before the compressor must start up. This makes it much more efficient and responsive even in the most extreme hill climb competition scenarios. The changeover to the two-piece design has been quietly occurring since 2000, and with 95 percent of all ARB Air Lockers now operating with this design, it has already proven the difference to over 88 000 off-roaders worldwide.
As most people know, ARB has its primary manufacturing plant in Melbourne, Australia. This is the place where products like bull-bars, roofracks, underbody protection and even snatch blocks are manufactured from base materials. It’s also where the majority of Air Locker components are manufactured and assembled. Of the 24 – 26 components required for each Air Locker, every metal-based piece is manufactured in-house except for the gears. These gears, while not made at ARB, arrive at the plant as blanks, so it’s up to the Air Locker production team to complete the finishing processes to customise them to Air Locker applications. It’s this commitment to Australian manufacturing combined with aerospace grade materials and state-of-the-art machinery, production processes and quality control measures, that’s earned Air Locker its reputation for quality and reliability.