Interpretation ID: nht71-3.37

DATE: 07/16/71

FROM: AUTHOR UNAVAILABLE; L. R. Schneider; NHTSA

TO: Minnesota Automotive, Inc.

TITLE: FMVSS INTERPRETATION

TEXT: This is in reply to your letter of June 29 asking whether the installation of MICO brake locks, as a supplemental parking brake system, is acceptable to the National Highway Traffic Safety Administration.

We understand that the MICO brake lock is used only in hydraulic brake systems of trucks. There is no Federal motor vehicle safety standard currently in effect covering truck hydraulic brake systems, and installation of MICO brake locks by a dealer, prior to first sale of a vehicle, is permissible as long as the lock does not impair conformance of brake hoses and brake hose assemblies with Federal Motor Vehicle Safety Standard No. 106. That the installation might impair conformance is inferred in the Chevrolet Dealer letter, DD-1412, May 19, 1971, which you enclosed.

A proposal has been issued (Docket No. 70-27) that would require trucks equipped with hydraulic brake systems to meet certain performance requirements, effective with trucks manufactured on or after October 1, 1972. If this proposal is adopted as a Federal standard, installation of the MICO supplemental brake system on a truck, by a dealer, prior to first sale of a vehicle would be allowable as long as the installation does not affect conformance of the required mechanical parking brake system with Federal requirements, or with Standard No. 106.