Experimental device may keep trucks from jack-knifing
By Ben Coxworth
August 29, 2012
If there’s one thing that truck drivers don’t want their articulated tractor/trailer rigs to do, it’s jack-knifing. This typically occurs when the tractor skids on the road, and the momentum of the trailer causes it to swing out from behind, ultimately resulting in the tractor and trailer being folded up against one another – not unlike a jack knife’s body and blade. The folded rig usually ends up blocking the road, and the tractor can’t undo the situation under its own power. Fortunately, Greek researchers have recently created a system that they claim could greatly reduce jack-knifing.
First of all, there are already some technologies that help reduce the risk of a jack-knife occurring. These include anti-lock brakes in the tractor, electromagnetic brakes in the trailer, and devices that limit the angle between tractor and trailer at higher speeds. According to University of Patras engineers Nick Koussoulas and Stamatis Manesis, however, nothing tried so far has been sufficiently reliable.
What they have devised is a new type of kingpin. The kingpin is the junction where the tractor and trailer are joined, and it is normally situated in one static location on the rear of the tractor. The new kingpin, however, slides linearly, parallel to the tractor’s rear axle. In this way, sudden movements of the trailer result in the kingpin temporarily sliding over a bit, instead of having the trailer swinging out across the road.
Of course, a sliding kingpin could make regular driving of the rig rather challenging. That’s why the servo-driven sliding function would only activate in emergency situations, such as during hard braking – otherwise, the kingpin would remain fixed in one spot on the tractor.
So far, models of the system have reportedly indicated that it should “constrain jack-knifing to very low limits for a wide range of vehicle loading and road conditions.” The researchers are currently in the process of patenting the technology.
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