Interpretation ID: 77-4.19
TYPE: INTERPRETATION-NHTSA
DATE: 10/17/77
FROM: AUTHOR UNAVAILABLE; J. J. Levin, Jr.; NHTSA
TO: AM General Corporation
TITLE: FMVSS INTERPRETATION
TEXT: This responds to AM General Corporation's July 18, 1977, request for confirmation that certain aspects of the M.A.N. articulated transit bus conform to the requirements of Standard No. 121, Air Brake Systems, and Standard No. 124, Accelerator Control Systems. In an October 3, 1977, telephone call with Mr. Herlihy of this office, it was determined that the request for interpretation is now limited to confirmation that the four-way pressure protection valve described in M.A.N.'s June 22, 1977, letter would meet the location and functional requirements of S5.1.2.3 of Standard No. 121. Section S5.1.2.3 specifies --
S5.1.2.3 Each service reservoir shall be protected against loss of air pressure due to failure or leakage in the system between the service reservoir and its source of air pressure by check valves or equivalent devices.
I am enclosing prior interpretations of the location requirement of S5.1.2.3. While the agency cannot "approve" systems based on schematic drawings, it appears that the location of the four-way protection valve in the M.A.N. drawings does not violate the provisions contained in S5.1.2.3.
As we understand the description and capabilities of the four-way valve, it appears to be a pressure protection device that is "equivalent" to the check valve otherwise required by S5.1.2.3.
SINCERELY,
AM General Corporation
July 18, 1977
Duane E. Perrin NHTSA Handling & Stability Division
As you may be aware, AM General has entered into a Cooperation Agreement with Maschinenfabrik Augsburg-Nuernberg (M.A.N.) of West Germany for the purpose of importing roughly 400 articulated buses into the United States which, after completion in our Marshall, Texas facility, will be delivered to eleven domestic transit properties. Contractually, the responsibility for compliance to Federal Motor Vehicle Safety Standards is divided between AM General and M.A.N. relative to areas of design and manufacturing responsibility. As M.A.N. is primarily responsible for the major mechanical components, such as the engine, transmission, suspension, braking systems, etc., compliance with Federal and State Safety Standards in these specific areas rests with them.
During design of the braking system, it has been determined that clarification relative to Paragraph S5.1.2.3 of FMVSS 121 is required. More specifically, approval is requested for utilization of a 4-way air pressure protection valve in lieu of the simple service reservoir check valves described in the standard.
The functioning configuration of this 4-way protection valve is completely outlined in the attached material from M.A.N.
Additionally, consideration and approval is requested relative to the outlined testing procedure which will be utilized to demonstrate proof of compliance to FMVSS 124.
I believe the attached material is fairly self-explanatory; however, should you have any questions or require additional information, do not hesitate to call me at area code (313) 722-4900.
Your prompt consideration and approval will be greatly appreciated.
M. J. Shillinger Project Engineer
ATTACH.
To the Department of Transportation
June 22, 1977
Re: Clarification for compliance with FMVSS 121 and 124:
Dear Sirs:
M.A.N. is supplier of articulated buses to AM General, Wayne, Mich., importing these vehicles for the first time to the US, and therefore is confronted to proof compliance with all FMVSS standards applicable.
Due to the fact, that this is the first time we have some specific problems with the interpretation of certain paragraphs, which could not even be clarified absolutely by the friendly assistance of our partner AMG, we are relaying our requests now to you.
Enclosed please find two write-ups of our interpretation of certain details of FMVSS 124 and 121.
The problem area regarding FMVSS 124 concerns the test conditions where we would like to ask you either to approve our interpretation or to inform us of an acceptable solution.
Regarding FMVSS 121 we are quite aware of the tests we have to perform to verify compliance, but we would like you to check the basic schematics of our brake system. Please give special attention to the fact, that this schematic does not allow the incorporation of additional check valves on the inlets of the individual air tanks as air flow in both directions occurs. We assume, however, that these tanks are to be regarded as one system and are sufficiently protected by the four circuit protection valve.
To our knowledge the system as described incorporates safety features superior to the systems presently operating in the US. We would like to thank you for your efforts and to point out the urgency the matter has for us.
MASCHINENFABRIK AUGSBURG-NURNBERG Aktiengesellschaft Werk Munchen
ppa.
(Dr. Hagen)
(i.A.)
(Dr. Domandl)
[ENCLOSURES OMITTED.]