Mr. Tom Byrne
Vice President
Goodridge (USA) Inc.
20309 Gramercy
Torrance, CA 90501

Dear Mr. Byrne:

This responds to your request for an interpretation of the whip test requirements in Federal Motor Vehicle Safety Standard No. 106, "Brake Hoses."

You ask about Table II of S6.3.2, which specifies the amount of "slack" that should be introduced when mounting brake hose assemblies on the whip test apparatus. The amount of the hose indicated as slack in Table II is the difference between the projected length of the hose assembly when mounted in the whip test machine, and the free length of the hose while maintained in a straight position. Slack must be present in the hose when mounted on the whip test machine to enable the proper "whipping" movement of a brake hose assembly. Without such slack, some assemblies would be incapable of withstanding any rotation of the moveable header of the whip test apparatus described in Standard No. 106 without rupturing.

Table II specifies the amount of slack for some sizes of assemblies, and not for others. The table specifies the amount of slack for assemblies having "free length between end fittings" of between 8 inches to 24 inches, inclusive. You ask whether brake hoses that are either shorter than 8 inches or longer than 24 inches have to comply with the whip resistance test in section S6.3. The answer is no.

The agency addressed this question in a December 9, 1988 interpretation to Volvo Cars, stating, with regard to assemblies with a hose free length of a size other than 8 to 24 inches:

With regard to the National Highway Traffic Safety Administration's (NHTSA's) Standard No. 106 compliance testing, . . .[d]ue to the absence of the slack specification, NHTSA does not require the testing of such assemblies to the whip resistance requirements of the standard. . . . With regard to your certification that the brake hose assemblies you manufacture comply with all applicable requirements of Standard No. 106, you are correct that hydraulic brake hose assemblies of the size you describe are not subject to the whip resistance requirements. However, the agency urges manufacturers to ensure that these assemblies perform in a safe manner while subject to environmental conditions of vehicle operations which may result in flexing of the brake hose or brake hose assembly.

You believe that safety would be best served if all brake hose assemblies had to comply with the whip resistance requirement. You are particularly concerned with the safety of assemblies that have free lengths in excess of 24 inches, because these longer assemblies "are subject to operating conditions more similar to those represented by the whip test." NHTSA would welcome any test data or information that you can provide showing a need to amend S6.3.2 to specify testing of assemblies in excess of 24 inches. Upon receipt of such additional information, NHTSA will consider initiating a rulemaking to amend Standard No. 106

If you have any further questions, please contact Mr. Marvin Shaw of this office at (202) 366-2992.


Samuel J. Dubbin

Chief Counsel