In its very purest form, a 6×2 axle configuration is merely a three-axle set up with power being distributed to just one of the tandem rear axles. Simply, only two of the six wheel positions are actually powered.
Earlier 6×2 configurations were composed primarily of a drive axle and a dead axle, with most dead axles being liftable. Some were even fitted ahead of the drive axle. In these configurations they were called push axles. Installed behind the driving axle and they were called tug axles.
The Future Is Now
Today, 6×2 axle configurations differ greatly from their predecessors. The new generation of 6×2 setups differentiate themselves through the use of traction control features, automatic load transfers mechanisms and liftable non-driving axles.
As with any new technology introduction, fleets are somewhat wary of these new configurations. Despite the promise of lower vehicle weight thanks to the elimination of a hefty drive axle and reduced mechanical drag on the driveline.
Look at the statistics, however, and you’d think 6×2 drive axles – with their yield of benefits – would be on a larger number our nation’s trucks. In fact, 6x2s represent only 4% of the highway axles on the road right now. The slower growth is likely the result of lower fuel prices.
6×2 With Automatic Traction Control
Are you wondering if a 6×2 configuration might be right for your fleet’s applications? Let’s cover the basics. First up are 6×2 drive axle configurations with automatic traction control.
Some advanced systems incorporate electronics control to facilitate a load transfer to the driving axle in the event of wheel slippage. In these setups, if wheel speed sensors detect a variation in traction between the axles, air is exhausted from the suspension lifting the non-driving axle. This increases the load – and therefore the traction – on the driving axle.
These advanced systems are automatic, and activate anytime there is a wheel-slip event. The main advantage is that the truck driver doesn’t have to flip a switch to activate the mechanism. Although manual controls can be integrated, machines can make the decision a lot faster.
Tag Axle 6×2 Configurations
Tag axle systems are ones where the rear axle in the tandem group is primarily the non-driving axle. This configuration lowers the weight of a comparable tandem drive axle by almost 400 pounds. In some cases, these axle configurations can ring in an axle ratio as low as 2.53:1.
Tag axle configurations can also support dual or wide-based and drum or disc brakes. They are a versatile solution for those requiring varied applications.
Tag axles are also more durable than regular configurations. Due to the thicker wall housings and larger ring gear, its square-tube integrated suspension brackets make for far easier installation.
The only drawback lies in vehicle stability concerns, mainly due to the fact that the fifth wheel is located behind the drive axle.
6×2 With a Liftable Forward
Don’t think you can’t have a 6×2 configuration without a liftable forward axle. Both Mack and Volvo offer 6×2 systems with a rear-positioned drive axle and a liftable non-driving axle in the forward position.
These configurations allow the liftable axle to be kept off the road while the vehicle is empty or only lightly loaded. These novel applications allow for the suspension to be integrated into the vehicle in such a way that it’s a vital component engineered directly into the system.
Many see liftable forward axle technology as becoming the 6×2 choice of the future. A forward lfitable axle can be left up far longer than their rear counterparts. Fuel savings, brake care and less tire wear make liftable forward configurations the 6×2 option of choice for frugal fleets.
In the end, it’s important to consider your fleet’s specific needs when evaluating a 6×2 axle combination. We suspect, however, that these configurations will quickly become the standard as we move into the future.