Interpretation ID: nht67-1.2

DATE: 06/19/67

FROM: WILLIAM HADDON, JR. -- M.D. FOR LOWELL K. BRIDWELL, NHTSA

TO: E. W. Kintner

TITLE: FMVSS INTERPRETATION

TEXT: Re: Your Request for Interpretation -- Initial Federal Motor Vehicle Standard No. 105

This is in response to your letter of May 29 on behalf of Minnesota Automotive, Inc., requesting an interpretation of Initial Federal Motor Vehicle Standard No. 105 such as would allow the installation of a one-way check valve hydraulic parking brake system as a supplement to the friction type system required by that Standard.

Standard No. 105, by its own terms, applies to passenger cars and not to any other category of motor vehicle. As to passenger care either of the statements set forth in your letter in correct and you may so inform your client. This Standard does not proclude or prohibit the installation of one-way check valve hydraulic brake systems on passenger care which, of course, must be also equipped with parking brakes meeting the requirement.[Illegible Word] $ 4.3 of that Standard.

Since this interpretation is fairly obvious it is not suitable for publication in the Federal Register.

Thank you for the support expressed in your letter.

Sincerely,

May 29, 1967

Lowell K. Bridwell Federal Highway Administrator Federal Highway Administration U.S. Department of Transportation

Re: Request for Interpretation -- Initial Federal Motor Vehicle Standard No. 105

Dear Mr. Bridwell:

Minnesota Automotive, Inc., which I serve as counsel, has authorized me to submit a Request for Interpretation of Initial Federal Motor Vehicle Standard No. 105 to your office for clarification of the permissible use of brake lock safety devices as a parking brake system, in addition to the safety equipment required by that standard.

Minnesota Automotive, located in Mankato, Minnesota, manufactures a line of hydraulic brake products, including a one-way check valve hydraulic parking brake which connects into the primary braking system hydraulic unit and shoes. This device, without interfering with normal brake service, will fit any vehicle on the road having a hydraulic braking system, and when actuated will effectively convert the system into a powerful, reliable parking brake lock. Where a dual service brake is employed, two of these devices can be used, one geared to each hydraulic system. These devices serve as important supplements to the standard parking brake system of the vehicle.

The hydraulic brake lock is designed to meet the needs of heavy duty and high frequency parking brake usage. I might mention parenthetically that the brake locking devices manufactured by Minnesota Automotive are no longer under patent; other automotive equipment manufacturers have marketed and are marketing safety brake lock products using the one way check valve principle.

Problems have arisen in the marketing of these safety products, particularly with respect to vehicles currently subject to the jurisdiction of the Interstate Commerce Commission, because of that agency's safety regulation on parking brakes. Specifically, Section 193.41 of the ICC Motor Carrier Safety Regulations provides that the "parking brake or brakes, shall . . . remain in the applied condition . . . despite . . . leakage of any kind. . . ." Since the brake locking device in connected into the service brake hydraulic system and consequently will not function if there is leakage in the latter, many potential users of the device have construed the ICC regulation as prohibiting the use of such a device, even when installed in addition to a parking brake system meeting the requirements of the regulation.

A potential difficulty is again presented by Paragraph S4.3 of Initial Standard No. 105, as well as related standards which may be developed by the Bureau in the future. Standard No. 105 requires a "parking brake system of a friction type with a solely mechanical means . . . "Although we would agree that neither this language nor the above noted standard necessarily implies that safety locks are not permitted, the marketing resistance based on the existing ICC regulation indicates the need for clarification in this area.

In view of this experience, we respectfully request an interpretation as to whether Initial Standard can be construed as follows:

1. Paragraph S1 of Initial Standard No. 105, which sets out the purpose and scope of the standard, is not to be construed as prohibiting the use of hydraulic holding devices, such as one way check valves, in hydraulic brake systems, in addition toparking brakes which meet the requirements of Paragraph S4.3: or alternatively,

2. The requirement of Paragraph S4.3 that a parking system of a friction type with a solely mechanical means be provided does not preclude the installation of hydraulic holding devices, such as one way check valves, in addition to the mechanical parking brakes.

Because of the desirability for all manufacturers producing these safety devices of an official position establishing the propriety of using such one way check valve brake locks, we further request that any interpretation to this effect be published in the Federal Register.

On behalf of Minnesota Automotive, I want to take this opportunity to assure you of our complete support of your efforts in attempting to meet the challenging goal of developing meaningful vehicle safety standards. We congratulate you on the significant progress made thusfar.

Should you require any additional information with respect to our Request for Interpretation, please do not hesitate to contact me.

Sincerely,

Earl W. Kintner -- ARENT, FOX, KINTNER, PLOTKIN & KAHN