Interpretation ID: nht74-2.24

DATE: 07/03/74

FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA

TO: White Motor Corporation

TITLE: FMVSS INTERPRETATION

TEXT: This responds to your recent request for an interpretation of S5.3.1.2 of Standard No. 121, Air brake systems. That section permits certain vehicles to avoid the stopping distance requirement if their brakes conform to a retardation formula and values found in another section of the standard (S5.4.1).

The language of S5.3.1.2 makes clear that any truck in the described category need not meet the stopping distance requirements if its brakes satisfy the retardation formula and values of S5.4.1, and therefore none of the exceptions found in S5.4.1 apply to vehicles subject to the requirements of S5.3.1.2.

This interpretation also appears in the preamble to Notice 2 of Docket No. 73-10, and is enclosed for your information.

Yours truly,

ATTACH.

James B. Gregory, Administrator -- National Highway Traffic Safety Administration

Subject: Request for Interpretation of Standard 121, Docket 74-10; Notice 2, Section 5.3.1.2

Dear Dr. Gregory:

The amended standard, Section @ 5.3.1.2 states that a vehicle manufactured before September 1, 1975, that has a front steerable axle with a GAWR of 16,000 pounds or more, or a front steerable drive axle, need not meet the stopping distance requirement if its brakes conform to the retardation formula and values of @ 5.4.1 applied to the vehicle as a whole and to the front axle system separately.

However, Section @ 5.4.1 as now amended, applies only to "each vehicle designed to be towed by another vehicle equipped with air brakes" and, therefore, there are no retardation requirements applicable to either a towing vehicle or to a vehicle which is used by itself. Under the circumstances, it would appear that such vehicles would not be required to meet any specific retardation requirements.

We request an interpretation of the applicability of @ 5.4.1 to these special classes of vehicles for the interim period where no stopping distance requirements are in effect.

Sincerely, WHITE MOTOR CORPORATION; J. W. Lawrence -- Manager Safety and Environmental Engineering