Air disc brakes for heavy trucks offer performance advantages to drum brakes

Air disc brakes making slow inroads in North America for use on heavy trucks.


  • CSA is putting more emphasis on brakes for service and reliability.
  • Weight is becoming a factor as larger drum brakes, emissions equipment and pending GHG regulations all shift the focus.
  • Air disc brakes are widely available - a factor that influences choice.
  • An array of safety innovations, such as collision mitigation and lane departure warning, compete for ADB dollars
  • Data sophistication is growing with real-time telematics-based systems.

Looking ahead for the next five years, Meritor believes ADBs will continue moderate growth, but drum brakes will remain the market standard, said Mitts. ADBs and drum brakes are both important and product development investment will continue for both by Meritor with weight, service and reliability being the focus areas to meet the challenges facing its customers.

Major differentiators

Among the major differentiators of ADB vs. drum brakes are feel and safety, Mitts said. As for feel, the ADB's linear output and stability drive the preference.

With regard to safety, the difference is multi-faceted, he said. With better brake feel there is less driver fatigue. Because there is less brake fade, less skill is required, making for safer drivers. In addition, stopping distance is slightly better.

Mitts acknowledged that ADBs cost more than drum brakes but this has to be factored against future truck residual value, maintenance and service savings (pad changes are up to 75 percent faster than drum shoe changes and no periodic lubrication is required) and uptime improvement (adjuster mechanism and pistons are environmentally sealed for life and there are no current "out-of-adjustment" conditions).

Greater adoption of ADBs in North America will continue to progress as vehicle owners and operators become more educated on their benefits and advantages compared to drum brakes. "The right choice is unique for each business," as they say.

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