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  • § 393.11
    Lamps and reflective devices.
  • § 393.17
    Lamps and reflectors—combinations in driveaway-towaway operation.
  • § 393.24
    Requirements for head lamps, auxiliary driving lamps and front fog lamps.
  • § 393.25
    Requirements for lamps other than head lamps.
  • § 393.28
    Wiring systems.
  • § 393.40
    Required brake systems.
  • § 393.41
    Parking brake system.
  • § 393.42
    Brakes required on all wheels.
  • § 393.43
    Breakaway and emergency braking.
  • § 393.44
    Front brake lines, protection.
  • § 393.48
    Brakes to be operative.
  • § 393.51
    Warning signals, air pressure and vacuum gauges.
  • § 393.52
    Brake performance.
  • § 393.60
    Glazing in specified openings.
  • § 393.61
    Truck and truck tractor window construction.
  • § 393.62
    Emergency exits for buses.
  • § 393.65
    All fuel systems.
  • § 393.67
    Liquid fuel tanks.
  • § 393.70
    Coupling devices and towing methods, except for driveaway-towaway operations.
  • § 393.71
    Coupling devices and towing methods, driveaway-towaway operations.
  • § 393.75
    Tires.
  • § 393.76
    Sleeper berths.
  • § 393.81
    Horn.
  • § 393.82
    Speedometer.
  • § 393.83
    Exhaust systems.
  • § 393.87
    Warning flags on projecting loads.
  • § 393.88
    Television receivers.
  • § 393.89
    Buses, driveshaft protection.
  • § 393.92
  • § 393.93
    Seats, seat belt assemblies, and seat belt assembly anchorages.
  • § 393.100
    Which types of commercial motor vehicles are subject to the cargo securement standards of this subpart, and what general requirements apply?
  • § 393.102
    What are the minimum performance criteria for cargo securement devices and systems?
  • § 393.106
    What are the general requirements for securing articles of cargo?
  • § 393.201
    Frames.

Part 393

Section § 393.42: Brakes required on all wheels.

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The regulations text of the section can be found on the eCFR website. To view the regulations text, use the link below. For assistance, please send an email to FMCSA.Webmaster@dot.gov.
View regulations for Part 393

Question 1: Do retractable or lift axles have to be equipped with brakes?

Guidance: Yes, when the wheels are in contact with the roadway.

Question 2: Are unladen converter dollies covered by the exemption in §393.42(b)(3)?

Guidance: Yes. However, if the converter dolly is laden, the brakes must be operable.

Question 3: §393.42(b)(3) of the Federal Motor Carrier Safety Regulations FMCSRs states that any full trailer, any semitrailer, or any pole trailer having a Gross Vehicle Weight Rating (GVWR) of 3,000 pounds or less must be equipped with brakes if the weight of the towed vehicle resting on the towing vehicle exceeds 40 percent of the Gross Vehicle Weight Rating (GVWR) of the towing vehicle. Is the manufacturer of the trailer responsible for ensuring that the trailer is equipped with brakes when required?

Guidance: No. The motor carrier pulling the trailer is responsible for ensuring that the trailer is in compliance with all applicable Federal Motor Carrier Safety Regulations (FMCSRs).


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