Interpretation ID: aiam4121
Manager Truck Engineering
MMC Services
Inc.
3000 Town Center
Suite 501
Southfield
MI 48075;
Dear Mr. Ogura: This responds to your request for an interpretation concerning th reservoir strength requirements of Federal Motor Vehicle Safety Standard (FMVSS) No. 121, *Air Brake Systems*. You asked how those requirements apply to multi- chamber reservoirs.; By way of background information, the National Highway Traffic Safet Administration does not give approvals of motor vehicles or motor vehicle equipment. Under the National Traffic and Motor Vehicle Safety Act, it is the responsibility of the manufacturer to certify that its vehicles or equipment comply with applicable standards. The following represents our opinion based on the facts provided in your letter.; The issue raised by your letter concerning the application of FMVSS No 121's reservoir strength requirements to multi-chamber reservoirs appears to be the same issue discussed in a letter of interpretation dated May 23, 1978, addressed to the Johnson Manufacturing Company. As discussed in that letter, only the circumference of the outer reservoir shell is measured, and internal baffles are not stressed by separate compartment-by- compartment testing. We are enclosing a copy of that letter and two *Federal Register* notices cited by the letter. (Please note that an interpretation provided in the earlier of the two notices was withdrawn by the later notice.); Sincerely, Erika Z. Jones, Chief Counsel