One of the really exciting things about the trucking industry is that we never seem to stand still. Even after a product is introduced the industry continues to work on improving and refining it.
Since in 2013 when we published our original Confidence Report on 6x2 axles, we’ve seen the development of second and third generation products. The third generation is 6x2s with liftable pusher axles and automatic load-sensing/load shifting and traction control. This generation of product has turned out to be a good option for fleets expecting to carry less than 60,000 lbs. at least 30% of the time they are on the road.
For fleets with diminishing or variable loads where the full carrying capacity of a tandem axle (up to 34,000 lb.) is not needed at all times, the liftable tandem axle 6x2 configuration may be a more cost-effective solution.
The liftable tandem axle system has the drive axle in the rearward position. While operating in the up position, a liftable system performs like conventional 6x2 systems with one drive (live) axle and one free-rolling (dead) axle resulting in the same fuel economy benefits (2.5%) as the non-liftable tag axle systems.
During the recent Run on Less fuel economy demonstration, Ploger’s Joel Morrow was driving a 2016 Volvo equipped with a 6x2 liftable axle. I talked to Joel recently to get his thoughts on 6x2 liftable axles. He told me that the time the axle was up exceeded his expectations, which resulted in more fuel savings than he thought he would see. He also believes that the spinning inertia of components have a bigger influence on efficiency than most think – think about these liftable wheel ends just hanging there, or smaller parts spinning in lower displacement engines.
Another big savings came in the area of tires. When the axle is lifted, the tires are not on the ground so there’s no tread wear during those times.
Overall Joel is pleased with the performance of the liftable 6x2 and the additional fuel economy it gives him. While I know that liftable 6x2 axles aren’t right for all applications, you might want to take a look at them especially if you operate at less than 60,000 lb. GCWR at least 30% of the time.