ASK ARB – When to
use Air Lockers

Hi ARB,

My recent decision to fit front and rear ARB Air Lockers into our KJ Jeep Cherokee has brought with it much excitement and anticipation of the increased capability of the vehicle.
Being my first experience with lockers, I was wondering if you could give me and others that may be considering Air Lockers a rundown of when and how they are best used. Examples of when one should engage rear only, front and rear together, or even when not to use them at all would be fantastic. Other supposedly simple insights like how quickly they take to engage and disengage would also be appreciated.

Thanks ARB for keeping me and my vehicle off road for longer!
Carl Malouf

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Hi Carl,
Well done on your decision to fit Air Lockers. We are always happy to hear about people wanting to take their vehicles further off road. You’ve made a good choice with the Air Locker as it’s the strongest locking differential on the market, and is also the fastest to engage and disengage, taking approximately 1/10th of a second to lock.

Your question isn’t as straightforward to answer as it seems. Every driver will engage their Air Lockers at different times, depending on vehicle, tyres, driver skill, approach angle, etc. What works for me may not work for you. But I can give you a few general rules that you can adapt to your own situations.
You have probably already noticed that your Air Lockers have been wired so that you must turn the rear on before you can turn the front on. This is a safety precaution which has been done so that people don’t accidentally switch their front locker on when it’s not required. A locked front diff will change the way a vehicle steers compared to having it unlocked, which would be quite a shock if you didn’t expect it.

People often think that an Air Locker is only for 4WDing, but they can be handy when on the bitumen too. The most common use I have found is when driving an empty ute on wet bitumen. There is nothing worse than trying to gently drive away from traffic lights up a hill, and finding that one wheel spins. This can be quickly remedied by the flick of an Air Locker switch.

Once you head off the bitumen and start having some fun, Air Lockers really do come into their own. You’ll find that for dirt road driving and easy 4WD tracks the lockers aren’t required. Cruise along in high or low range 4WD and you’ll be fine.

When you’re on harder tracks, try to read the terrain before you drive it. If you’re unsure whether you’ll get up a hill or through a bog hole then engage the rear diff lock first. It’s a nice security blanket to have. If you are still struggling, back your foot off the accelerator for a second and engage the front Air Locker as well. Do not engage either Air Locker when you are hard on the accelerator and with wheels spinning. This is what we term as ‘crash locking’ and will ultimately cause damage to the Air Locker or other parts of your drivetrain. It’s the equivalent of trying to change gears without the clutch.

Another often forgotten situation for use of a rear Air Locker is going downhill. Steep, rocky, slippery, rutted downhills can be horrible things. The vehicle often has a mind of its own as individual wheels lose grip. Lock the rear Air Locker in at the top of the hill and you’ll be amazed at how well the car descends. When the two back wheels are forced to rotate at the same speed, the vehicle will be held much straighter.

These are just a few examples of when and how to use Air Lockers. The best thing you can do, though, is head bush and learn for yourself. Discover some new areas of the country and teach yourself some new techniques. That’s really the best advice I can give you – go bush and have fun!

Cheers,
Stuart Schoof
(Air Locker Design Engineer)