Protective helmets are commonly worn by people such as firefighters, construction workers, and athletes to shield their heads from flying or falling objects. The helmet usually includes a rigid protective shell of impact resistant material. For some applications, the helmets may also include visors or face shields to protect the eyes or the entire face of the wearer, and may further include a respirator to protect the wearer's respiratory system.
Various government agencies and industry organizations define certain requirements and standards for protective gear, including helmets and respirators. In the United States, for example, the National Institute of Occupational Safety and Health (NIOSH) certifies certain safety equipment for the workplace and the American National Standards Institute (ANSI) recommends voluntary consensus industry standards. Other agencies and organizations around the world also establish safety standards for helmets and respirators. For protective helmets, some of these standards relate to impact energy attenuation, penetration resistance, force transmission, stiffness, flammability, and head coverage.
To meet these safety requirements and standards, protective helmets usually comprise a rigid outer shell of metal or plastic and a suspension system inside the shell. The suspension system serves many purposes, including providing a proper fit of the helmet to the wearer's head, holding the inner part of the helmet away from the wearer's head, distributing the weight of the helmet over a larger area of the wearer's head, and attenuating the force transferred to the wearer's head upon impact of an object with the outer helmet shell. Suspension systems often comprise a headband attached to a crown support assembly which includes crisscrossing crown straps and a crown pad. In some applications, however, additional protection may be desired. In these situations, a foam liner may be provided between the inner shelf and suspension of the helmet to provide additional impact protection.
The manner of attaching suspension systems to a helmet typically depend on whether or not the helmet has a liner. In many cases, a suspension system in a helmet having a liner incorporates the liner itself into the suspension attachment system. These suspension systems will not typically fit properly into a helmet that does not have a liner. For example, U.S. Pat. No. 5,150,479 (Oleson) describes a helmet having a foam liner and a suspension system, where the suspension system has a plurality of straps attached to anchors which rest in a channel in an outer surface portion of the foam liner. Thus, the manner of attaching the suspension system to this helmet relies specifically on the presence of a liner in the helmet.
Similarly, the manner of attaching a suspension system in a helmet without a liner will not typically provide the necessary space to accommodate the insertion of a liner. To use these systems designed for linerless helmets in a helmet having a liner, a portion of the liner may need to be cut away to allow the suspension to be inserted into the helmet. The removal of liner material may cause an undesirable reduction in the impact resistance of the helmet. To maintain a sufficient amount of liner material in the helmet, helmets having a liner therefore typically require a different suspension system design than that used in helmets without a liner.