Features - Technical
APRIL 4, 2000
Head and Neck Support (HANS)
BY PETER WRIGHT
Daimler-Chrysler carried out a broad based review of systems capable of preventing the driver's head impacting the steering wheel or cockpit rim, while at the same time relieving his neck of the tension and shear forces generated when it attempts to decelerate his head and helmet, weighing together around 15lbs. The two most promising technologies were an airbag that deployed from the rim of the cockpit, and was pulled across the steering wheel prior to being inflated; and the HANS device invented by Dr Robert Hubbard of Michigan State University. Hubbard's Head and Neck Support system (HANS) had been in use by sports car drivers and racing boat pilots for some years and had proven effective, but was not suited to the semi-reclining seat position used in single-seaters.
Daimler-Chrysler carried out 53 Hi Ge sled tests on a Hybrid III dummy fitted into a Formula3000 monocoque. The results of these tests indicated that the airbag system and the HANS produced similar results, in both cases reducing the head and neck injury criteria below critical levels. Without either the airbag or HANS, the head injury criteria were exceeded by 50%, and the neck by 40%, in a simulated 44g frontal impact. The HANS system was selected as it is a totally passive system, and does not require electronics, pyrotechnic devices, nor the extensive development that would be required to prove these systems in a race environment.
The HANS works in a simple and elegant manner. A CFRP yoke is worn by the driver, fitted around his neck and under the shoulder belts. His helmet is loosely connected to this yoke by tethers ensuring free movement of the head. In a frontal impact, the yoke is locked to the torso by the tightening belts, and the helmet is restrained by the tethers. The helmet provides an ideal means of decelerating the head, and the neck is relieved of the injurious tension and shear loads, being restrained relative to the torso.
Currently, HANS is being integrated into cramped single-seater cockpits, and tailored to the individual drivers' physiology. Once integrated, the HANS is likely to become as standard a part of a driver's safety equipment as his helmet and harness.