Interpretation ID: aiam1539
Bendix Corporation
401 Bendix Drive
South Bend
Indiana 46620;
Dear Mr. Farron:#This responds to your May 28, 1974, question whether short neoprene connector of two steel vacuum brake lines in the Bendix Hydrovac unit is subject to Standard No. 106, *Brake hoses*.#The neoprene connector functions as a brake hose under the definition set out in the standard:#>>>'Brake hose' means a flexible conduit that transmits or contains the fluid pressure or vacuum used to apply force to a vehicles brakes.<<<#The determination of the 'flexibility' of a particular brake line material is a difficult but important decision. Flexibility is required in brake lines for at least two reasons. First and most important is the flexibility required to accommodate large amounts of relative motion in service, in frame-to-axle applications for example. Less obvious but important is the flexibility required in event a brake line is displaced during repair or alteration of the brake system or other nearby vehicle components. A mechanic's decision to bend a brake line during repairs may depend on whether it 'looks' flexible, and therefore appearance becomes an important element of the determination. On this basis the NHTSA has concluded that copper and steel chassis plumbing, for example, do not invite bending during repairs because their appearance makes their relative inflexibility obvious.#In contrast, plastic air brake chassis plumbing and small sections of hose used to connect steel or copper tubing, are examples of 'flexible conduits' that invite bending in order to make repairs. To ensure that these 'flexible conduits' are not damaged when they are displaced, they are considered brake hose subject to the bend and deformation requirements of the standard. In the case of the Hydrovac, the presence of the neoprene connector would appear to permit flexibility to compensate for component misalignment and to permit removal and repair of the steel tubing. It therefore is considered a brake hose under this standard.#Sincerely yours,Robert L. Carter,Associate Administrator,Motor Vehicle Programs;