Interpretation ID: 8599
1841 Shady Brook Drive
Thousand Oaks, CA 91362
Dear Mr. Millar:
This responds to your letter concerning Federal Motor Vehicle Safety Standard No. 105, Hydraulic Brake Systems, and Society of Automotive Engineers (SAE) Recommended Practice J201. I apologize for the delay in our response. You asked about the significance of the two documents for manufacturers and consumers. You also asked whether you are correct in interpreting section S5.2.1 of Standard No. 105 as requiring the parking brake of a Toyota Camry with a standard (stick shift) transmission to hold the car stationary on a hill with a 30 percent grade in both forward and reverse directions for five minutes. Your questions are addressed below.
By way of background, the National Traffic and Motor Vehicle Safety Act authorizes the National Highway Traffic Safety Administration (NHTSA) to issue safety standards for new motor vehicles and items of motor vehicle equipment. All motor vehicles and items of motor vehicle equipment manufactured or imported for sale in the United States must comply with all applicable safety standards.
Standard No. 105 is one of the safety standards issued by NHTSA. The standard specifies requirements for hydraulic service brake systems and associated parking brake systems, for the purpose of ensuring safe braking performance under both normal and emergency situations. The standard applies to passenger cars, multipurpose passenger vehicles, trucks, and buses with hydraulic service brake systems. Manufacturers must ensure that each new vehicle complies with each applicable requirement of the standard. The standard specifies the specific test conditions under which each performance requirement must be met.
You asked the agency to confirm your understanding that section S5.2.1 of Standard No. 105 requires the parking brake of a Toyota Camry with a standard transmission to hold the car stationary on a 30 percent grade for five minutes in both forward and reverse directions. Section S5.2.1 reads as follows:
Except as provided in S5.2.2, the parking brake system on a passenger car . . . shall be capable of holding the vehicle stationary (to the limit of traction on the braked wheels) for 5 minutes in both a forward and reverse direction on a 30 percent grade.
Section S5.2.1 thus applies to all passenger cars, except as provided in S5.2.2. The alternative requirement set forth in S5.2.2 is only available for certain vehicles with a transmission or transmission control which incorporates a parking mechanism. Vehicles with standard transmissions do not typically have such a parking mechanism. Assuming that a Toyota Camry does not have a parking mechanism, it would be required to meet the requirements of S5.2.1.
I note that, even assuming that a vehicle meets the requirements of S5.2.1, it would not follow that the parking brake system would hold the vehicle stationary on a 30 percent grade under all real world driving conditions. As indicated above, Standard No. 105 specifies specific test conditions under which its performance requirements must be met. In the case of the standard's parking brake requirements, the specified test conditions include such things as control force and test surface. Also, the requirement only applies to the limit of traction on the braked wheels. Thus, if a 30 percent grade has a slippery surface, the vehicle might slide down the grade even though its parking brake system held the wheels locked. Finally, the requirement applies only to new vehicles and not used ones.
You also asked the significance of SAE J201 to manufacturers and consumers. The Society of Automotive Engineers is an independent, non-governmental group. In some cases, NHTSA has incorporated portions of that organization's recommended practices into its safety standards. Since the agency has not done so with SAE J201, that recommended practice does not have any significance to the Federal motor vehicle safety standards. NHTSA can only comment on the significance of its own standards and regulations and not on ones issued by other organizations or agencies. Therefore, we suggest that you contact SAE concerning the significance of SAE J201.
I hope this information is helpful. If you have any further questions about NHTSA's safety standards, please feel free to contact David Elias of my staff at this address or by telephone at (202) 366-2992.
Sincerely,
John Womack Acting Chief Counsel
ref:105 d:9/l/93