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IR Temperature Measurement

Technical Bulletins

Jun 02, 2022

Bendix Infrared Thermometer in use

With the advent of non-contact infra-red (IR) heat measurement technology IR Temperature Guns are now an affordable technology that can help you determine if your vehicle has any potential braking issues.

The IR Heat gun is a useful tool for diagnosing brake issues quickly without the need for brake tear down.

Before we discuss brakes, there are a couple of measurement topics:

IR Temperature Gun

Most commercial units are calibrated and operate with a simple point and click temperature measurement. Ensure the unit is capable of measuring in the range of 0-500°C, this will cover most automotive applications.

Temperature Measurement

Confirm the distance from the item you are measuring is within the range of the device and keep this consistent if measuring multiple items for comparative purposes, ie. brake assemblies.

As a guide 15-20cm is ideal – confirm with the manual for your unit.

Bendix Infrared Thermometer measuring temperature

Brake Check Techniques

The most important part about brakes in commercial vehicles is distributing the brake load evenly across all axles within the combination, this allows each of the brake assemblies to “do their share of work” and prevent overloading of the other brakes which can lead to excessive heat, brake wear and excess mechanical stress.

A general guide to checking your combination is operating at its optimal condition:

Drive the vehicle (preferably loaded) and perform approximately 10 stops from 80-60 km/h to warm up the brakes.

Stop the vehicle and measure and record the brake temperature at the brake drum/disc, usually the center of the drum or disc face ensuring the same location for all brakes.

Compare the temperatures across the brakes, if the temperature between brake varies >approx. 50°C then inspect the brake operation, adjustment wear etc.

Tips for Measurement

When “heating the brakes” the ideal temperature is 100-200°C this will clearly show any differences in operating performance.

Measure the brake temperatures on one side of the vehicle at a time, brakes by nature cool quickly by measuring brakes close to each will give best results.

Note – it is not the absolute temperature we are interested in but the difference between brakes.

Measurement example:

Measurement example


In this example a tri-axle trailer, measurements were taken on each side, so we need to compare each wheel side, ie. LHS Axle 1,2,3.


Temperatures show some variation, can be attributed to mechanical variation and measurement technique, no action required.


Axle 2, 70°C is significantly lower than Axles 1 and 3 (125°C, 115°C), further investigation is needed on this brake.

Bendix Infrared Thermometer

Measure the temperature of hot, hazardous or hard-to-reach objects without contact safely and quickly.


  • Temperature range: -50~500°C (-58~1022°F)
  • Repeatability: 1% of reading or 1°C
  • Response time: 500 mSec, 95% response
  • Emissivity: 0.10~1.00 Adjustable (0.95 Preset)
  • Distance to Spot size: 12:1
  • Typical battery life: 12 hours
  • Accuracy: 0~500°C: ±1.5°C, -50~0°C: ±3°C
Bendix Infrared Thermometer


  • Technical Bulletin Bendix Infrared Thermometer PRJ 08165 June 2022
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