What a Drag

Everybody remembers their parents telling them to not drag their feet, and as an ex-racer, I’m always looking for ways to reduce parasitic drag. Of course, there are obvious items that are a parasitic drag on your truck and trailer. All the rage today is mainly focused on two areas. The first area is aerodynamics. The air flowing over our trucks is probably one of the easiest to identify parasitic drag on the efficiency of our operation. Over the years, the shape of the truck, and in some cases the trailer, has been changed to reduce the amount of drag that the air poses, as we travel down the highway.  

Lately, all the rage is on engine down speeding. Turning an engine slower reduces the amount of parasitic drag on all the internal components of the engine. Of course, tires have not been overlooked in the quest to reduce parasitic drag through low rolling-resistant tires. The area that does not get as much attention is liftable axles. What I’m referring to in my case is the Hendrickson Liftable Axle 6x2 Configuration that we have used on our 2022 Cascadia. In a 6x2 axle configuration, you eliminate a short drive shaft, an inter-axle differential, and a ring and pinion from the equation. How big a deal is this? Well, when Detroit came out with the active lube management system for their rear axles, the advertised efficiency gain by controlling the amount of lube hitting the ring and pinion, came in at 1.5% increased efficiency. So, imagine... if you completely eliminate the ring and pinion and inter-axle differential, how much of an increase in efficiency this would be.

Now, let's take this a step further by lifting that axle off the ground whenever it’s not needed for its weight-carrying capacity. With the axle lifted, we have completely taken the parasitic drag out of not only the ring and pinion and the inter-axle differential, but the tires and wheel bearings are also no longer causing any kind of a drag. What makes it worse in a tandem axle assembly, is that no road is perfectly straight, and in some places, the roads are even twisty. As we turn to any degree, there is a certain amount of tire scrub, as we are, in reality, dragging the tire a little bit sideways. Obviously, when in town or on twisty roads, this is worse than going across I-10 in Arizona, for example.  

Literally, you can see all the rubber that’s left on the pavement wherever there are a lot of tractor-trailers turning on the roadway.  

To me, the 6x2 Hendrickson Optimaax liftable axle configuration should be the norm, and a 6x4 axle configuration should be reserved for duty cycles that require a high degree of off-highway travel.  

So, much like your parents lectured you about dragging your shoes, you can stop dragging your tires around with the Optimaax suspension system when they aren’t needed.