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Interpretation ID: GF003064

    Mr. Christopher H. Willison
    General Manager
    Americarb
    5151 Wooster Road West
    Norton, OH 44203


    Dear Mr. Willison:

    This responds to your letter of April 1, 2004, and subsequent conversations with George Feygin of my staff. You ask a series of questions regarding DOT regulations related to a pressure vessel used for tire inflation located inside a hollow semi-trailer axle.

    By way of background, the National Highway Traffic Safety Administration (NHTSA) is authorized to issue Federal motor vehicle safety standards (FMVSSs) that set performance requirements for new motor vehicles and items of motor vehicle equipment. NHTSA does not provide approvals of motor vehicles or motor vehicle equipment. Under 49 U.S.C. Chapter 301, manufacturers are required to certify that their vehicles and equipment meet applicable requirements.

    There is no FMVSS regulating pressure vessels located in hollow semi-trailer axles as described in your letter. In fact, the agency does not have any regulations covering tire inflation systems for heavy vehicles. However, if your system is tied into the vehicles air braking system, it may affect compliance with other safety standards.

    Specifically, FMVSS No. 121, Air Brake Systems, may have implications for your product, especially if your device is an integral part of the brake system. We do not have sufficient information about your device to discuss FMVSS No. 121 implications. However, in a previous letter of interpretation (copy attached) we stated that a tire inflation device would not be considered a part of the braking system if it was separated from the vehicles main braking system by a pressure protection valve in such a way that the main braking system would not be affected by a leakage failure in the device.

    Further, the air supply line between the air supply tank described in your letter and the pressure vessel could be considered a brake hose subject to the requirements of FMVSS No. 106, Brake Hoses. In a previous letter of interpretation, we stated that if a failure of a hose or a supply line would result in a loss of pressure in the brake system, that hose or supply line are subject to the requirements of FMVSS No. 106 (copy enclosed).

    For your reference, I am enclosing a fact sheet we prepared entitled Information for New Manufacturers of Motor Vehicles and Motor Vehicle Equipment. I hope this information is helpful. If you need further assistance, please contact George Feygin of my staff at this address or at (202) 366-2992.

    Sincerely,

    Jacqueline Glassman
    Chief Counsel

    Enclosures
    ref:121
    d.6/8/04