Sam Francis Fitness

Archive for October, 2009

What’s needed is a full-locking differential, known in some circles as a “locking axle.” (Technically it’s not, but the result is the same.) Once used only by the hardcore offroad fraternity, the device is beginning to find a new home among more general offroad enthusiasts. One such product is an Australian import—ARB Air Locker. The beauty of this system is that it uses compressed air to lock and unlock the dif ferential. You don’t even have to leave the comfort of the cab to engage the mechanism.
According to Jim Jackson, president of ARB USA, “The ARB Air Locker splits the power equally left and right. Now, if a wheel starts to spin, the wheel with traction still gets enough power to keep the vehicle moving.”
Jackson says that most outdoorsmen need only to opt for a rear locking axle. “Most people will find that if they just add a locking dif ferential to the rear, they’ll be able to deal with 95 percent of all offroad obstacles.” But if you routinely hunt and fish in country that lies in that last 5 percent, you should consider front and rear lockers. In this case, all four wheels wifi turn, even if three of them are off the ground. (The fact that the 4×4 is difficult to steer—and well nigh impossible to turn—when both axles are locked is offset by its incredible traction. Once the hard part is out of the way, you can disengage the front or both differentials as needed.)
Another undeniable benefit of a locking differential is that it allows the vehicle to go slower on the trail. “When the wheels are locked, you have a lot more control.” Jackson says. “You’re not worried about tires spinning. The natural reaction if one wheel starts to spin is to say, ‘I’m going to get stuck! I better give it some gas, and get out of here!’ But speeding up creates another set of problems. With the Air Locker, you can lock up the axle when you see trouble up ahead and go through that spot slower, with a lot more control and less risk of damage to the vehicle.”
Although the installation of a replacement locking differential is not a do-it-yourself job, any good gear or rear-end shop should be able to do it. The job involves taking out the old differential, putting the ring gear from the old differential onto ARB’s carrier differential, and re-installing it. There’s no serious modification to the vehicle—only the addition of an onboard 12-volt air compressor and air line, which can also be used to inflate tires, mattresses, or float tubes.
“When you activate the system from the controls in the cab.” .Iackson says, “compressed air goes into the differential and hits a pisI n attached to a locking gear. That locks one of the side gears inside I he case, which locks the two axles together so both turn equally.”
You don’t have to own a four-wheel-drive truck to take advantage ol an Air Locker. In a two-wheel-drive vehicle, if you can fully lock the rear, you will be able to go 95 percent of the places that a standard four-wheel-drive will go.