2.1 Head and Neck Restraint: An active Head and Neck Restraint System is a
protection ensemble providing an alternative load path which decreases both
neck stress and head excursion during a vehicle impact without reliance on
helmet impact into structures or nets.
2.2 Separate Restraining Devices:
A. Linkages attached to the helmet which transfer restraining loads directly
to the helmet from the main device which is secured to the driver's
shoulders, torso, etc. Methods for attachment of these linkages to the
helmet and main device shall be prescribed by the manufacturer.
B. The main device shall be a mechanism held tightly to the driver's torso by
seat belts or other strap systems such that the reactive load carrying
components move directly with the torso and controls head, neck, and
torso relative positions during forward or off-center impact situations.
2.3 Reaction Linkage: The means by which the head force necessary to limit
displacement of the head with respect to the torso is reacted. Acceptable
reaction linkages could include load paths to the torso or to the restraint
webbing. Direct attachment to react loads to a fixed point or points on a
vehicle structure or restraint webbing will not be acceptable because of the
potential for torso displacements with respect to these points. Imposed
loading by the reaction linkage to other areas of the body should be applied
using approaches demonstrated to be practical without imposing risk of
serious injury.
2.4 The Head and Neck Restraint System must be designed and manufactured
to allow freedom of movement of head, torso, arms, etc., commensurate with
operating a race vehicle under all race and associated conditions.
2.5 Adjustment and release mechanism(s) shall be accessible to both the user
and to external personnel such that no additional motion is required, other
than the release of the seat belts, to disengage the Head and Neck Restraint
System during emergency situations.