Interpretation ID: nht75-2.28

DATE: 07/18/75

FROM: AUTHOR UNAVAILABLE; J. C. Schultz; NHTSA

TO: Volvo of America Corporation

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of June 19, 1975, seeking an interpretation of Standard No. 124, Accelerator Control Systems, with regard to an accelerator control system which contains either elements in parallel or a complete parallel system.

The requirements of S5.2 of Standard No. 124 are met if, after a severance or disconnection of any component of the accelerator control system, the throttle returns to the idle position within the time specified in S5.3, measured from the first removal of the opposing actuating force by the driver, or from the disconnection or severance. You are correct in your interpretation that Standard No. 124 is intended to protect against a single severance, and that there are no requirements in Standard No. 124 concerning the severance or disconnection of the remaining one(s) of two or more parallel elements in an accelerator control system.

SINCERELY,

June 19, 1975

James Schultz, Chief Counsel National Highway Traffic Safety Administration

Re: Request for Interpretation of FMVSS No. 124

Section S5.2 of FMVSS No. 124 - Accelerator Control Systems specifies requirements for return of the throttle to the idle position ". . . whenever any one component of the accelerator control system is disconnected or severed at a single point." The operation of this section of the standard is clear when the accelerator control system consists of a single series of links and/or cables and/or other connecting devices. Severance or disconnection at any one point will result in a loss of control by the operator and the return of the throttle to its idle position.

The situation is not as clear when the accelerator control system contains either elements in parallel or a complete parallel system. In this case if one of two or more parallel links, cables or other connecting devices is severed or disconnected, the operator still maintains control of the accelerator control system. Since the throttle does not return to the idle position at the time of severance or disconnection, the requirements of S5.2 will be met if the system returns to idle within the time limit specified by S5.3, measured from the first removal of the opposing actuating force by the driver.

With regard to the above situation it is our understanding there are no requirements in FMVSS No. 124 concerning the severance or disconnection of the remaining of two or more parallel elements in an accelerator control system since S5.2 refers to the severance or disconnection of only one component.

Thus the requirements of S5.2 would be met if such a system returns to the idle position within the specified time after the removal of the opposing actuating force.

Your verification of our understanding of the standard's applicability to parallel links or systems would be appreciated. Thank you for your prompt consideration of this request.

VOLVO OF AMERICA CORPORATION Product Engineering and Development

Donald J. Gobeille, Jr. Product Safety Engineer

CC: E. SKARIN/AB VOLVO