FREE TRIAL UPGRADE!
Thank you for investing in EnvironmentalHazmatHuman ResourcesHuman Resources, Hazmat & Environmental related content. Click 'UPGRADE' to continue.
CANCEL
YOU'RE ALL SET!
Enjoy your limited-time access to the Compliance Network!
A confirmation welcome email has been sent to your email address from ComplianceNetwork@t.jjkellercompliancenetwork.com. Please check your spam/junk folder if you can't find it in your inbox.
YOU'RE ALL SET!
Thank you for your interest in EnvironmentalHazmatHuman ResourcesHuman Resources, Hazmat & Environmental related content.
WHOOPS!
You've reached your limit of free access, if you'd like more info, please contact us at 800-327-6868.
Automatic brake adjusters and indicators
  • New CMVs equipped with hydraulic, or air brakes systems must meet the automatic brake adjustment systems requirements of the FMVSS applicable to the vehicle at the time of manufacture.
  • For new CMVs equipped with an air brake system containing an external automatic adjustment mechanism and an exposed pushrod, the condition of service brake under-adjustment must be displayed by a brake adjustment indicator conforming to the requirements of the FMVSS applicable to the vehicle at the time it was manufactured.

Hydraulic brake systems and air brake systems on new commercial motor vehicles (CMVs) must be equipped with automatic brake adjusters (“slack adjusters”) that automatically adjust as the brake linings and drums wear. Air brake systems must also be equipped with a brake system indicator that shows the condition of the service brake under adjustment. If the CMV was built with automatic slack adjusters, they cannot be removed and replaced with manual slack adjusters (see 393.53).

Adjustment systems:

Brake adjustment indicator:

  • Air brake systems — On each CMV manufactured on or after October 20, 1994, and equipped with an air brake system which contains an external automatic adjustment mechanism and an exposed pushrod, the condition of service brake under-adjustment must be displayed by a brake adjustment indicator conforming to the requirements of FMVSS No. 121 (49 CFR 571.121, S5.1.8 or S5.2.2) applicable to the vehicle at the time it was manufactured.