Closing the gap

When you see drawings or mockups of futuristic trucks, one of the things you'll notice is there's virtually no gap between the tractor and trailer.

That makes for a very cool-looking concept vehicle, but how do you achieve that in the real world while still being able to back the rig around tight corners?

At the ATA's Technology & Maintenance Council meeting earlier this year, I got to see a demonstration of one way it could be done, courtesy of Jost International, which demonstrated its new Smart Gap System.

Gregory Laarman, vice president of engineering, explains that the idea is to close the gap between the tractor and the trailer so the wind continues over the top of the trailer rather than getting caught in the gap, where it creates aerodynamic drag.

The system consists of a fifth wheel slider assembly, with hydraulic cylinders and actuator controlled by sensors and an ECU. A hydraulic pump and accumulator actually move the fifth wheel. The system senses when it is safe and more fuel efficient to close the gap between tractor and trailer at certain speeds and under certain conditions. There are several positions, based on the speed of the vehicle. The closest brings the gap down to 24 inches.

When conditions indicate the need to return to a more conventional position, as in a turn or an emergency maneuver, the system automatically does so, quickly and without driver involvement.

Laarman explains it to me at TMC:



This animation from Jost shows how it works:



And lest you think that anything can be done with animation, here's a video showing it in action on a real rig:



The platform is the Jost Pro Tech integral angle inboard style slider assembly, which offers a 100-pound savings over conventional sliders, Jost says. In addition, the SGS assembly incorporates a cab actuated air release for the kingpin locking mechanism, advanced technology low lube liners on the top plate, and the Jost Lubetronic system to provide small amounts of lubricant automatically to friction points.

Jost officials told me they're in discussions with truck makers about refining and offering the new system.

One question I had later was, what effect would that have on axle weight regulations? Carroll told me, "We are working through the front axle considerations with some partners."