Expectations Matter

Fuel economy benfits of 6x2 axles outweigh disadvantages

It’s always interesting to get together with other like-minded folks to hear about their real-world experience with some of the fuel economy technologies we have studied in our Confidence Reports.

At our recent workshop at ARC Indy in Indianapolis one series of roundtable discussions was devoted to 6x2 axles. The main takeaway from the conversations at that table was that none of the downsides of adoption of 6x2 axles are unmanageable. Not only that but they are not greater than the benefits and savings fleets gets from switching to them. The key is to have realistic expectations and then be prepared to manage the negatives that come with this technology.

For sure 6x2s cause faster wear on drive tires. But since the rear, or tag axle is not powered, you can use trailer tires there. That means your overall tire costs will not go up that much. If you use your own trailers, stick with low rolling resistance tires. The drive tires will wear three time faster but you will have plenty of spots to rotate them back to. If you don’t mate your trucks with your own trailers, use more durable tires on the drive axle even though you will sacrifice a small amount of fuel. They will only wear out twice as fast and you have one spot to rotate them to when they are too worn for the drive axle.

We also heard that some fleets are seeing improved tire wear with 6x2s when they limit torque especially at launch. This was shared with attendees of the Fall TMC conference, where I joined some fleets who are diligently working to improve the tire wear of 6x2 axle configurations. Something to think about.

Even with automatic load shifting, traction suffers when 6x2 axles are installed, but generally not enough to affect a fleet’s operation. Drivers may complain but you can manage driver expectations by training them on the use of 6x2s and by assuring them that you are willing to accept they might have to be towed one icy day a year. But this beats sacrificing the fuel savings 6x2s give you all year long.

Resale value is still lower on trucks equipped with 6x2 axles but this could be an issue of dealers not being educated on how to sell 6x2s. It may also be a problem for you if you plan to sell your trucks into the Mexican market because traction is more of an issue there.

The biggest barrier to 6x2s is still driver complaints. The best defense against that is training and education.

The 6x2 argument may be changing soon as well. The people attending our workshop were interested in talking about liftable axles. They save on tolls, reduce traction issues and have a negligible weight increase. In fact, Dana recently announced its Dual Range Disconnect drive axle system that it says gives users the fuel savings benefit of a downsped 6x2 drivetrain as well as the traction and performance benefits of conventional 6x4 setup with a mid-range axle ratio.  Looks like we will be updating our Confidence Report on this topic soon.  Stay tuned…

We’ll continue to keep you posted on developments with liftable axles. In the meantime switch to 6x2 axles and you are likely to see the 2.5% fuel reduction that is typical of what fleets we spoke with for our Confidence Report say they get. Just remember to manage expectations — yours and your drivers.

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