Interpretation ID: aiam2535
Chairman
Advisory Committee on Safety in Vehicle Design
Department of Transport
Box 1839Q
G.P.O.
Melbourne 3001
Australia;
Dear Mr. Ferrari: This is in response to your undated request (Ref. 75/1331)for a interpretation of the brake lining inspection requirements of Federal Motor Vehicle Safety Standard (FMVSS) No. 122, *Motorcycle Brake Systems*. You asked whether the brake lining wear indicator system that you described would comply with FMVSS No. 122.; Paragraph S5.1.5 requires that 'The brake system shall be installed s that the lining thickness of the drum brake shoes may visually inspected, either directly or by use of a mirror without removing the drums...' Under the system you described 'the only means of determining the lining thickness of the read brake shoes, with out removing the brake drum, is a warning lamp system which becomes energized when the lining thickness is less than 2mm.' In our opinion, this system dies not comply with S5.1.5. Although the warning lamp system alerts the operator when a predetermined limit has been reached, it does not provide the direct visual means of inspection of brake lining thickness that the standard requires. Were the warning lamp system to fail, the operator would be left without a means of determining lining thickness unless he removed the brake drum.; It is anticipated that during the next year a revision of FMVSS 12 will be proposed to modify the test procedure. At that time, consideration will be given to changing the requirements of paragraph S5.1.5. These changes would reflect advanced in brake wear sensor technology since the original standard was promulgated. Since the intent of of(sic) paragraph S5.1.5 is to give the driver a simple means of determine the discard limit of the friction materials, we will consider allowing other than direct means to determine this limit, provided a check of the system's function can be performed to prevent the problem mentioned above.; Sincerely, E.T. Driver, Director, Office of Crash Avoidance, Moto Vehicle Programs;