A common misconception suggests that a 4x4 and traction go hand in hand… you can’t have one without the other. The truth, however, is that most 4x4 vehicles send power to the wheels with the least amount of traction once difficult terrain is encountered. The problem is simple – when one (or more) of your vehicle’s wheels loses traction, your highway minded factory differential directs all of your vehicle’s power to those spinning wheels. On road, the standard "open" differential allows each of your wheels to turn independently thus eliminating any binding during turns. Off road, this becomes a major burden as engine power will take the path of least resistance, which occurs at the wheels with little or no traction.
Newer vehicles with limited slip differentials (LSDs), positraction etc may offer some improvement over standard differentials, but more often you’ll find the slipping is not "limited" enough to maintain forward progress. Automatic locking differentials also have their disadvantages. Aside from being noisy, automatic locking differentials often upset the on highway and off road driving characteristics of your 4x4. During normal driving conditions, vehicle responsiveness becomes less predictable, and when highway surfaces become wet or icy, the driver must use extreme caution just to keep the truck in control.
ARB has been challenging conventional thinking on off road equipment designs for over 30 years, and the ARB Air Locker has been a success from the very beginning. Created to provide 100% traction on demand, without sacrificing any of your vehicle’s highway driving performance, ARB Air Lockers employ a 12 volt air compressor designed to activate (and deactivate) a solid and durable locking mechanism inside the differential. This gives you the traction you need, when you need it, all at the flick of a switch, all within the safety and comfort of the driver’s seat.
The advantage of the ARB Air Locker lies in the pneumatically operated locking system inside the differential. When activated, the Air Locker prevents the differential gears from rotating and therefore prevents the axle shafts from turning independently of each other. With both wheels tied directly to the rotation of the ring gear the vehicle maintains maximum possible traction at all times. When unlocked, it operates just like conventional "open" differentials.
In addition to providing outright improvements to a 4x4’s off road capabilities, the Air Locker offers significant environmental benefits. When approaching difficult terrain, less reliance is put on momentum. An Air Locker equipped truck can be driven in a slower, safer and more controlled manner as a result of vastly improved traction. This style of driving greatly reduces the likelihood of incurring vehicle damage and lessens the environmental impact as well.
AVAILABILITY & INSTALLATION
Air Lockers are currently available in over 100 configurations to suit a wide range of 4x4 vehicles from around the world. Because the Air Locker is only engaged when needed, it can be installed in BOTH the front and rear axles, with separate switches independently controlling the locker from within the truck.
Installation should be performed by a qualified differential technician, although no special tools or skills are required apart from those necessary for fitting a standard differential. When installed with an ARB air compressor, the locker system is supplied as a complete kit which contains all of the parts necessary for proper installation, including industrial grade control switches, air lines and fittings. ARB offers two compressor models suitable for Air Locker operation. A dedicated air activation system is available which is extremely durable and compact. Alternatively a larger compressor can be specified, which is also perfect for inflating tires, air mattresses and a host of other applications where compressed air is required.
A complete Air Locker kit – replacement differential, activation switch, solenoid valve, air line and bulkhead fittings. Please note - not all units are supplied with replacement carrier bearings.
AIR LOCKER DESIGN AND ENGINEERING
Please note - some technical features may differ between models.
ARB Air Locker’s patented design has proved extremely reliable, even under the most arduous conditions. The Air Locker’s strength comes via structural components manufactured from aerospace grades of high alloy steels. ARB engineers increase the number of differential pinion gears, where possible, to distribute torque loads evenly, thus adding to the overall strength of the differential. Many recent Air Locker designs utilize timed gear sets, which further improve strength. This latest introduction to our design and manufacturing process has led to the acquisition of a second US patent on the product.
The design process of an Air Locker involves countless hours of testing. Computerized Finite Element Analysis (FEA) allows the designer to subject each Air Locker design to 'virtual' off road driving stress simulations much more extreme than those experienced in real life.
Destructive laboratory testing is carried out on prototypes to ensure the strength of the Air Locker exceeds that of the axles or other driveline components. Environmental test cells subject prototype models to high temperature running conditions (120°C), low temperature running conditions (-24°C), and harsh wheelspin engagement, for cycle durations of more than 20,000 actuations. Finally, field-testing is carried out with units being fitted to test 4WDs - from Jeep Wranglers to Toyota LandCruisers - operating in the harshest environments imaginable.
Once this exhaustive design phase is complete, Air Lockers are manufactured in Australia by ARB, and sold throughout the world.
Air Lockers are manufactured in Australia by ARB, and sold throughout more than 80 countries around the world.
1. Differential Case
Fully machined one piece nodular iron diff carrier case offers the rigidity of a one piece factory differential with twice the standard number of pinion gears to cope with the torque.
2. Flange Cap Assembly
Fully machined nodular iron flange cap incorporates the stationary side of ARB’s tough, proven and patented timed locking mechanism.
3. Splined Side Gear
The highest grade of nickel alloy steel, aerospace grade surface treatments, and ARB’s own patented timed locking system make this the most ‘lockable’ gear in the industry
4. Pinion Gear
ARB has re-defined differential gear tooth geometry to yield structural advantages of up to 30% over commercially available high strength gears.
5. Clutch Gear
ARB’s patented locking system actually supports the side gear teeth, giving you more torque handling exactly when you need it.
6. Spider Block
A billet machined alloy steel spider block supports the cross shafts, using the torque applied at each shaft to support the next shaft along.
7. Long Cross Shaft
Alloy steels and performance surface technology make for a high pressure running fit that can handle an enormous amount of punishment.
8. Cross Shaft Retaining Pin
Custom made one piece hardened retaining pins lock into the assembly using a tapered thread junction.
9. Bonded Seal
Steel reinforced, elastomer bonded annular seal has been proven to handle 20,000+ cycles under the most extreme climactic temperatures on earth.
10. Return Springs
Where other locking differentials depend on complex external actuator systems to engage and disengage the lock, ARB Air Lockers use between 4 and 12 return springs to support the entire profile of the locking gear for a fast, positive, and independent disengagement when the air is exhausted
11. Air Supply
At the flick of a dash mounted switch, compressed air is delivered to a seal housing assembly via a nylon air line.
12. Solenoid Valve
Manufactured from a machined and anodized billet, and sealed against moisture and dust to IP54 standards, ARB’s heavy duty solenoid controls the air actuation. A low watt coil ensures extra long life and protection against hot environments.
Please note - some technical features may differ between models.
AIR LOCKERS IN COMPETITION
Of the many ARB products seen in off road competition, it's the one you can't see that makes the difference - ARB Air Locker diff locks continue to dominate the world's toughest off road events.
As Paul Vanderhorst, manager of Australia's world renowned Outback Challenge, states: "Our event attracts some of the world's best off roaders, competing in incredibly well prepared 4WDs. We've seen a plethora of accessories over the years, with participants constantly striving to improve their vehicle's performance. Throughout the event's seven year history though, Air Lockers are by far the preferred traction aid... 57 vehicles competed in the 2005 Challenge for instance, 48 had Air Lockers. The top 10 place getters all had front and rear Air Lockers fitted.
AIR LOCKER WINNER OF
- Malaysian Rainforest Challenge
- Outback Challenge
- USA Extreme Rock Crawling Series
- Tuff Truck Challenge
- Korean Top Crawler Challenge
- Xtreme Winch Challenge
- Xtreme International
- Java Challenge
- New Zealand Warn Challenge
- Ateco Warn Challenge
- RCAA Series
- UROC Series
PERFORMANCE MODEL LINE
ARB Air Lockers are available for the vast majority of 4x4 vehicles from around the world. In addition, a number of high performance models are available for specialist applications such as drag racing, competition rock crawling and heavy tank-track type snow equipment.
Designing locking differentials for applications such as these presented our engineering team with some significant challenges. Not only must the locker be able to withstand more traction torque than a standard differential, but it must also tolerate massive amounts of torque handling facilitated by the substitution of custom made high alloy aftermarket axle shafts, which are cut with larger than standard diameter splines. This is particularly difficult owing to size constraints dictated by the original axle assembly. ARB met this challenge using a combination of aerospace grade materials, and a design guided by the results of high torque testing using computer simulations and destructive testing.
An ARB Air Locker suited to the 35 spline Ford nine inch differential. This is widely used in competition rock crawling and drag racing around the world.
2005 USA 'DirtSport Driver of the Year' Shannon Campbell believes Air Lockers are one of the keys to his success. The 2 time winner of the world's premier rock crawling event, the UROC, states that "anybody not using ARB Air Lockers is just spinning their wheels."
Different rock-face, different continent, different competition, same traction aid... Air Lockers in action at Australia's Outback Challenge.
Air Lockers keep your 4WD moving, even in the knee deep mud of the Malaysian Rainforest Challenge.