§FMCSR.com
Historical textIn force on Sept. 30, 2010Source: annual CFR editions 2007–2012

§ 393.49 Control valves for brakes.

Wording in the annual edition revised as of Oct. 1, 2007, superseded by the 2013 annual edition.

govinfo, 2009 edition ↗
Before Jan. 1, 2017 the record is one snapshot per annual CFR edition, revised as of October 1. This is the 2009 edition's wording. An amendment that took effect between Oct. 1, 2009 and Sept. 30, 2010 would not appear until the next edition, so check the citations below and the Federal Register for exact effective dates.
49 CFR § 393.49 — Control valves for brakes.. Text in force on September 30, 2010. This wording effective October 1, 2007 to October 1, 2013. Source: govinfo, 2009 edition, https://www.govinfo.gov/app/details/CFR-2009-title49-vol5/CFR-2009-title49-vol5-sec393-49. Retrieved from FMCSR.com, https://fmcsr.com/reg/393.49?asof=2010-09-30, on October 26, 2026. Unofficial compilation; verify against the official source.

(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 busses 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]

Amendment history

3 distinct wordings on file since Oct. 1, 1996
  1. Oct. 1, 2013 → presentannual editions 2013–2016diff vs. previous
    [72 FR 9871, Mar. 6, 2007, as amended at 78 FR 58484, Sept. 24, 2013]
  2. Oct. 1, 2007 → Oct. 1, 2013annual editions 2007–2012diff vs. previousviewing
    [72 FR 9871, Mar. 6, 2007]
  3. Oct. 1, 1996 → Oct. 1, 2007annual editions 1996–2006

A new entry appears whenever the regulatory words change between government snapshots. Day-precise from the eCFR (2017 onward); before that, one snapshot per annual CFR edition (revised as of October 1). Bracketed citations are the Federal Register history printed with the section.