Interpretation ID: nht88-1.75

TYPE: INTERPRETATION-NHTSA

DATE: 03/17/88

FROM: ERIKA Z. JONES -- CHIEF COUNSEL NHTSA

TO: LEON STEENBOCK -- ADMINISTRATIVE MANAGER, ENGINEERING FWD CORPORATION

TITLE: NONE

ATTACHMT: ATTACHED TO LETTER DATED 02/10/89 FROM ERIKA Z. JONES -- NHTSA TO J. W. LAWRENCE, REDBOOK A33, STANDARD 124; LETTER DATED 10/05/88 FROM J. W. LAWRENCE TO ERIKA Z. JONES -- NHTSA, REQUEST FOR INTERPRETATION FMVSS 124 ACCELERATOR CONTROL SYSTEMS; OCC 2650

TEXT: Dear Mr. Steenbock,

This letter responds to your letter of last year asking whether it is permissible under Federal motor vehicle safety standard 124, Accelerator Control Systems (Standard 124), to install a locking hand throttle control in a new motor vehicle. I apologize for the delay in this response. The answer to your question is no.

While you do not describe what you mean by a "locking hand-throttle control" in your letter, I understood you to mean the following. Some vehicle design configurations have a hand-operated device on the steering column that connects to the throttle leve l. In most design configurations, a driver may operate this device either by a turning or push-pull action. This device is commonly referred to as a "hand-throttle control."

These hand-throttle controls have two common applications. First, vehicles designed to be operated by physically disabled persons sometimes use a hand-throttle, rather than a foot-pedal, as the means for applying the actuating force that regulates the t hrottle valves and vehicle acceleration. Second, on some commercial vehicles, a hand-throttle control can be part of a system that allows a driver to use a hand control to regulate the engine fuel supply, and so to operate a power-driven accessory such as a generator while the vehicle is stationary with the transmission out of "drive." While the intended use of a hand-throttle control in a commercial vehicle may be only to power such an accessory, a driver still could use the throttle to control vehicl e acceleration. Nothing in Standard 124 prohibits a manufacturer from installing a hand-throttle control in its vehicles.

Some hand-throttle controls have a mechanism that permits the driver to lock the throttle valves open in a position other than idle even after the driver removes the actuating force. When you asked about "locking hand-throttle controls," I understood yo u to be referring to this type of design.

2

These "locking hand throttle controls" are expressly prohibited by Standard 124. Paragraph S5.1 of that Standard requires that the throttle valves must be capable of returning to the idle position whenever the driver removes the actuating force. The pur pose of Standard 124 is to minimize the risk of accident due to ongoing runaway. (37 FR 7097, April 8, 1972.) Consequently, a locking hand-throttle control would increase the risk of the very harm Standard 124 was adopted to address.

I hope you find this information helpful. If you have further questions, please feel free to contact Joan Tilghman of my staff at (202) 366-2992.

Sincerely,

(EXCERPT FROM PRODUCT SAFETY AND LIABILITY REPORT DATED 04/02/88)

Leon Steenbock, administrative manager, FWD Corp., Clintonville, Wis., in a March 17 opinion, that it is not permissible under Standard No. 124 -- Accelerator Control Systems (Reference File, 901:0889) to install a locking hand throttle control in a n ew motor vehicle. These devices are expressly prohibited by the standard, Paragraph S5.1 of that standard requires that the throttle valves must be capable of returning to the idle position whenever the driver removes the actuating force. The purpose o f the standard is to minimize the risk of accident due to engine runaway. Consequently, a locking hand-throttle control would increase the risk of the very harm the standard was designed to reduce, Jones said.

7/1/87

Subject: FMVSS 124 Accelerator Control Systems

Attn: Erika Z. Jones:

having discussed this standard requirements with your office in the past, as they pertain to locking hand throttles controls, I was left with the interpretation that a vehicle with a locking hand throttle would not meet the requirements of this standard.

As I have never received a written opinion regarding lacking hand throttle controls would your office consider giving me a written opinion of this standard requirement in regards to the use of locking hand throttle controls.

Your earliest consideration would be appreciated.

Sincerely,

Leon Steenbock Administrative Manager, Engineering FWD Corporation