You are using an unsupported browser. This web site is designed for the current versions of Microsoft Edge, Google Chrome, Mozilla Firefox, or Safari.
The Office of the Federal Register publishes documents on behalf of Federal agencies but does not have any authority over their programs. We recommend you directly contact the agency associated with the content in question.
If you have comments or suggestions on how to improve the www.ecfr.gov website or have questions about using www.ecfr.gov, please choose the 'Website Feedback' button below.
If you would like to comment on the current content, please use the 'Content Feedback' button below for instructions on contacting the issuing agency
Enhanced content is provided to the user to provide additional context.
This content is from the eCFR and is authoritative but unofficial.
Navigate by entering citations or phrases (eg: 1 CFR 1.1 49 CFR 172.101 Organization and Purpose 1/1.1 Regulation Y FAR).
Choosing an item from citations and headings will bring you directly to the content. Choosing an item from full text search results will bring you to those results. Pressing enter in the search box will also bring you to search results.
Background and more details are available in the Search & Navigation guide.
The in-page Table of Contents is available only when multiple sections are being viewed.
Use the navigation links in the gray bar above to view the table of contents that this content belongs to.
49 U.S.C. 31136, 31151, 31502; sec. 1041(b), Pub. L. 102-240, 105 Stat. 1914, 1993; secs. 5301 and 5524, Pub. L. 114-94, 129 Stat. 1312, 1543, 1560; and 49 CFR 1.87.
33 FR 19735, Dec. 25, 1968, unless otherwise noted.
This content is from the eCFR and may include recent changes applied to the CFR. The official, published CFR, is updated annually and available below under "Published Edition". You can learn more about the process here.
Subscribe to: 49 CFR 393.49
No changes found for this content after 1/03/2017.
View the most recent official publication:
These links go to the official, published CFR, which is updated annually. As a result, it may not include the most recent changes applied to the CFR. Learn more.
Information and documentation can be found in our developer resources.
The Code of Federal Regulations (CFR) is the official legal print publication containing the codification of the general and permanent rules published in the Federal Register by the departments and agencies of the Federal Government. The Electronic Code of Federal Regulations (eCFR) is a continuously updated online version of the CFR. It is not an official legal edition of the CFR.
Learn more about the eCFR, its status, and the editorial process.
Nomenclature changes to part 393 appear at 66 FR 49874, Oct. 1, 2001.
(a) General rule. Except as provided in paragraphs (b) and (c) of this section, every motor vehicle manufactured after June 30, 1953, which is equipped with power brakes, must have the braking system so arranged that one application valve must when activated cause all of the service brakes on the motor vehicle or combination motor vehicle to operate. This requirement must not be construed to prohibit motor vehicles from being equipped with an additional valve to be used to operate the brakes on a trailer or trailers or as required for buses in § 393.44.
(b) Driveaway-Towaway Exception. This section is not applicable to driveaway-towaway operations unless the brakes on such operations are designed to be operated by a single valve.
(c) Surge brake exception. This requirement is not applicable to trailers equipped with surge brakes that satisfy the conditions specified in § 393.48(d).
[72 FR 9871, Mar. 6, 2007, as amended at 78 FR 58484, Sept. 24, 2013]