Transit and passenger rail cars typically employ disk brakes rather than the tread brakes found on freight cars. Disk brakes present their own measurement challenge, as the brake components are mounted beneath the car and are not directly observable from trackside. To address this challenge, IEM has developed a disk brake pad measurement system that mounts a set of cameras and illuminators below the track level. The basic machine vision functions found in our BPMS are duplicated for this system.

Key Features and Benefits:

  • Measures from beneath the car providing a direct, unobstructed view of the disk brake pads and rotor
  • Enhanced immunity to mud, dirt, snow, etc., eliminating false positives.
  • Pad estimation: Enables measurements of pads with limited visibility
  • Dynamic lighting adjustment: Intelligent image enhancement software & state of the art machine vision cameras, allow the disk brake measurement system to operate in all lighting conditions.
  • Long-life Infrared illuminators: IEM’s LED-based illuminators cause no interference with any light-based signaling system.
  • Advanced machine vision cameras: Provides the most accurate image possible for each passing brake pad.


With state-of-the-art machine vision technology, the disk brake measurement system automatically locates and measures the thickness of brake pads on each brake rotor. Automatic inspection, analysis, and reporting of car and wheel to maintenance improves the overall efficiency and safety of operations while reducing the unnecessary labor expense of manual inspections.