Interpretation ID: nht91-5.46

DATE: September 12, 1991

FROM: Paul Jackson Rice -- Chief Counsel, NHTSA

TO: Y. Endo -- Meiji Rubber & Chemical Co., Ltd.

TITLE: None

ATTACHMT: Attached to letter dated 6-26-91 from Y. Endo to Office of Chief Counsel, NHTSA (OCC 6187)

TEXT:

This responds to your June 26, 1991 letter (your reference ME-0172) asking about S5.3.4 (tensile strength requirement) of Standard 106, Brake Hoses. I am pleased to be of assistance.

Before answering your specific question, I would like to provide some background on our agency. The National Highway Traffic Safety Administration (NHTSA) administers Federal regulations for the manufacture and sale of new motor vehicles and certain new items of motor vehicle equipment (including brake hoses) sold in or imported into this country. The National Traffic and Motor Vehicle Safety Act establishes a "self-certification" process under which each manufacturer is responsible for certifying that its products meet all applicable Federal motor vehicle safety standards (FMVSS's). This process requires each manufacturer to determine in the exercise of due care that its products meet all applicable requirements. NHTSA tests vehicles and equipment sold to consumers for compliance with the FMVSS's and investigates defects relating to motor vehicle safety. If a manufacturer or NHTSA determines that a noncompliance or safety-related defect exists, the manufacturer must notify purchasers of its product and remedy the problem free of charge. (Note that this responsibility is borne by the vehicle manufacturer in cases in which your hoses are installed on a new vehicle.) Any manufacturer which fails to provide notification of or remedy for a noncompliance or defect may be subject to a civil penalty of up to $1,000 per violation.

You ask about S5.3.4 as applied to certain multi-section hydraulic hose assemblies. Each of these multi-section assemblies includes either two or three sections of hose, which are connected end-to-end. The sections of hose are connected to each other by an intermediate metal fitting. It is not clear from your letter whether the intermediate metal fitting is a single fitting or two fittings which are joined together. As discussed below, however, this would not affect the answer to your question with regard to tensile testing.

S5.3.4 states: "A hydraulic brake hose assembly shall withstand a pull of 325 pounds without separation of the hose from its end fittings." You state in your letter that there is a difference of opinion in your company as to this requirement. You believe that the requirement applies separately to each part of the multi-section assembly. Stated differently, you believe that the tensile test should be conducted for each section of hose with fittings at the ends. In contrast, others are of the opinion that the tensile test is conducted on the complete

combination assembly. Those persons believe that only the ends of the complete multi-section assembly, and not those of individual parts, need be fixed to the tensile test machine.

We agree with your view that each of the fitting-to-hose connections should meet the tensile strength requirement. The purpose of the tensile strength requirement is to ensure that a brake hose does not separate from its end fittings while in service. Under S5.3.4, all hydraulic brake hose assemblies must meet the tensile requirement. S4 of the standard defines "brake hose assembly" as: "a brake hose, with or without armor, equipped with end fittings for use in a brake system...." Each portion of the multi-section assembly which consists of a section of hose with fittings is considered a separate brake hose assembly under that definition. This is true regardless of whether the intermediate fitting is a single fitting or two fittings joined together. (In the former case, the single fitting would be considered an end fitting for each of two sections.) Thus, each such portion of the multi-section assembly must meet the tensile strength requirements. Requiring each individual portion to meet the requirements guards against assembly failures due to the separation of the hose from any of the fittings.

However, technically speaking, the test may be conducted by applying the load to either the complete assembly or to each of the intermediate hose and fitting assemblies. Both of the test methods would provide equivalent results. Under either test, the requisite tensile load would be applied to each of the fitting-to-hose junctures.