Kevin M. Wolford, Executive Director
Automotive Manufacturers Equipment
Compliance Agency, Inc.
1101 Fifteenth Street, NW
Washington, DC 20005-5020
Dear Mr. Wolford:
This responds to your request for an interpretation of Federal Motor Vehicle Safety Standard (FMVSS) No. 106, Brake Hoses (49 CFR 571.106). You asked several specific questions about vacuum tubing connectors which are answered below.
Background of FMVSS No. 106 and Vacuum Tubing Connectors
FMVSS No. 106 specifies labeling and performance requirements for motor vehicle brake hose, brake assemblies, and brake hose end fittings. The standard defines the term brake hose as a flexible conduit, other than a vacuum tubing connector, manufactured for use in a brake system to transmit or contain the fluid pressure or vacuum used to apply force to a vehicles brakes . . . . (Emphasis added) Thus vacuum tubing connectors are not considered brake hoses for purposes of the standard.
Some background information about the rulemaking history of vacuum tubing connectors and FMVSS No. 106 may be helpful. Vacuum tubing connectors were not initially excluded from the definition of brake hose. In a notice of proposed rulemaking published on November 28, 1975 (40 FR 55365), we responded as follows to a petition to exclude from FMVSS No. 106 certain short neoprene connectors used in brake booster systems:
These connectors, although not traditionally thought of as brake hoses, are included in the present definition. However, they have special performance requirements that differ considerably from those of brake hoses, making it inappropriate to apply the standard to them. (See 40 FR at 55366.)
In the final rule published on July 12, 1976 (41 FR 28505), we noted that a commenter had suggested that the exclusion of tubing connectors be limited to those used in vacuum systems. We agreed with this comment, stating that this approach provides the requested
accommodation of an existing practice that has proved acceptable without encouraging the improper design of short air and hydraulic brake hoses. Thus, vacuum tubing connectors were excluded from the definition of brake hose. The final rule added the following definition of vacuum tubing connector:
a flexible conduit of vacuum that (i) connects metal tubing to metal tubing in a brake system, (ii) is attached without end fittings, and (iii) when installed, has an unsupported length less than the total length of those portions that cover the metal tubing.
This definition of vacuum tubing connector has not been changed since the final rule was published in 1976.
With this background, I will now address your questions.
Question One: Your first question is whether vacuum tubing connector means the vacuum supply line between a vehicles intake manifold and its power brake booster. For purposes of answering this question, I will assume that by vacuum supply line, you mean the vacuum supply hose.
The issue of whether a particular item is considered a vacuum tubing connector for purposes of FMVSS No. 106 depends on whether it meets the definition included in the standard. A vacuum tubing connector is a short length of hose used to connect two metal tubes that are in close proximity to each other to allow for limited motion due to vibration and thermal expansion. As earlier stated, section (iii) of the definition specifies a vacuum tubing connector when installed, to have an unsupported length less than the total length of those portions that cover the metal tubing.
In contrast, a vacuum supply hose (also known as the brake booster hose) typically has a free length that is much longer than the portion of the hose that is supported by the end connections. It would thus not meet section (iii) of the vacuum tubing connector definition. If the vacuum supply hose does not meet section (iii), it would not be considered a vacuum tubing connector. In such a case, the vacuum supply hose is a brake hose.
Question Two: Your second question is whether a vacuum tubing connector must meet any testing standard and if so, what standards would apply?
A vacuum tubing connector does not need to meet the test requirements of FMVSS No. 106, because as previously explained, it is excluded from the definition of brake hose. Moreover, we do not have any other standards that specify test requirements for vacuum tubing connectors.
Question Three: Your third question is whether vacuum tubing connectors must be marked, and if so, how must the connectors be marked?
Neither FMVSS No. 106 nor any of our other standards specifies marking requirements for vacuum tubing connectors.
Question Four: We understand your fourth question to ask whether an item which otherwise would be considered a vacuum brake hose is installed on a vehicle in a manner so that it fully meets the definition of vacuum tubing connector (including subparagraphs (i), (ii) and (iii)), would then be considered a vacuum tubing connector and excluded from the requirements of FMVSS No. 106.
The answer is yes.
Question Five: Your fifth question asks why the vacuum tubing connector definition specifies a metal tubing to metal tubing connection. You stated that plastic and composite fittings are now used for connections at the brake booster and intake manifold.
As indicated earlier, the definition of vacuum tubing connector was added to FMVSS No. 106 in 1976. We believe that, at that time, only metal connections were used and plastic or composite connections either did not exist or were not widely used at that time.
Question Six: Your sixth question is whether the requirements in S9 are only for rubber hoses or whether any hose made from any substance, such as a plastic, is required to meet these specifications.
S9 specifies requirements for vacuum brake hose, brake hose assemblies, and brake hose end fittings. The requirements apply to all such devices, regardless of material, unless the standard includes a specific limitation.
I hope this information is helpful. If you have any questions, please contact Ms. Dorothy Nakama of my staff at (202) 366-2992.
Additionally, please note that our address has changed. Our new address is: Office of the Chief Counsel, National Highway Traffic Safety Administration, 1200 New Jersey Avenue, SE, Mail Code: W41-227, Washington, DC 20590.
Anthony M. Cooke
cc: NCC-112 Subj/chron, DN, NVS-200, NVS-100
Interps: Std. No. 106, Redbook (2)