Temperature Capabilitites

High temperatures in wheel ends can result from damaged bearings, brake issues, prolonged braking, tire anomalies, and environmental factors

This article aims to explain how the TraX sensor measures, and broadcasts temperature data. It applies to sensors operating with firmware version BSS10.

The definitive guide to the sensor's behavior is detailed in the SKF TraX Technical Specification - Connected version document.

How the TraX Sensor Measures and Broadcasts Temperature Data

With rising temperatures, the frequency of temperature measurement sampling and broadcasting intensifies. The TraX sensor has a temperature measurement accuracy of +-3 °C.

TraX sensor behavior according to temperature ranges:

• Under normal operating conditions, where temperatures do not exceed 70°C (150°F), the vehicle must maintain a speed of at least 60 km/h (40 mph) for a minimum of 30 minutes for the TraX sensor to broadcast data.
• Should the temperature rise above 70 °C (150 °F), whether the vehicle is stationary or moving, the sampling frequency will escalate, and the sensor will broadcast data every minute.
• In extreme events, when the temperature is above 100 °C (212 °F), the sampling frequency increases even further, and broadcasts are transmitted every 10 seconds.

The table below summarizes how the TraX sensor behaves in three different temperature ranges.

Temperature range	Sampling frequency	Temperature in Celcius	Temperature in Fahrenheit	Data Broadcast: Vehicle at a Standstill	Data broadcast: Vehicle is  moving
Normal	Every 5 minutes	-40¹ to 69	-40¹ to 149	None	Every 30 minutes
Heightened	Every 10 seconds	70 to 99	150 to 211	Every 1 minute
Extreme ²	Every 5 seconds	100 and above	212 and above	Every 10 seconds

¹	The minimum acceptable limit to use the product.
²	Should the temperature surpass 105 °C (221 °F), the sensor will still measure and relay data, but its precision may not be assured. It is advisable to replace the sensor if such temperatures have been reached.

Temperature Alarms

The TraX sensor is designed for long-term monitoring rather than immediate alerts. It will activate a temperature alarm if the measured temperature exceeds 95 °C (203 °F) for more than 30 minutes.

To build upon the temperature measurement capabilities of the TraX sensor, the TSP can integrate controls into its platform that generate alerts for rapid thermal events.

Rapid thermal events can be identified by analyzing sensor data, collected during brief temperature spikes. As previously mentioned, the TraX sensor escalates its broadcasting frequency with fresh temperature readings as the temperature rises, depending on the temperature range. Therefore, it is essential that the TSP can capture and process all TraX sensor data broadcasts, not just those triggering an alarm.

The TSP can also compare the temperature values coming from all the sensors mounted on the vehicle to better detect unexpected thermal event.

The table below outlines general guidelines for three severity levels of rapid thermal event alarms: Caution, Warning, and Critical. It may be necessary to adjust the temperature thresholds for each fleet according to its tolerance for false alarms, as the risk of false alarms increases with lower threshold settings.

Alarm severity	Alarm rule	Duration	Temperature threshold in Celcius	Temperature threshold in Fahrenheit
Caution	Crosses temperature threshold once	n/a	95	203
Warning	Crosses temperature threshold three times	5 minutes	95	203
Critical	Temperature is above the threshold	30 minutes	95	203