High temperatures in wheel ends may result from damaged bearings, brake system issues, prolonged braking, tire anomalies, or environmental factors. This article explains how the TraX device measures and broadcasts temperature data. It applies to devices operating with firmware version BSS11 and later.
For the authoritative description of device behavior, see the article Technical Specifications, which includes the PDFs for both the Connected and Standalone versions of the SKF TraX technical specification.
Measuring and broadcasting temperature data
As temperature increases, the device automatically increases its sampling and broadcasting frequency. The temperature measurement accuracy is ±3 °C.
The device broadcasts three temperature values:
- Maximum temperature: Highest recorded temperature since commissioning or last reset.
- Minimum temperature: Lowest recorded temperature since commissioning or last reset.
- Current temperature: Most recent temperature reading (updated every five minutes under normal conditions).
Only the current temperature value is expected to change regularly. If the current temperature exceeds previously recorded limits, the maximum or minimum values are updated accordingly.
Device behavior by temperature range
The table below summarizes how the device behaves across different temperature ranges.
| Range | Sampling frequency | Temperature (°C) | Temperature (°F) | Broadcast – standstill | Broadcast – 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 | |
| Extreme² | Every 5 seconds | 100 and above | 212 and above | Every 10 seconds | |
Notes:
- ¹ Minimum acceptable operating temperature.
- ² If temperature exceeds 105 °C (221 °F), the device continues measuring and transmitting data, but accuracy may be reduced. Sensor replacement is recommended if such temperatures are reached.
Operational explanation
- Normal conditions: At temperatures ≤70 °C (150 °F), the vehicle must travel at least 60 km/h (40 mph) for a minimum of 30 minutes for the device to broadcast data. If the vehicle is stationary or moving below this threshold, no broadcast occurs.
- Heightened conditions: When temperature exceeds 70 °C (150 °F), sampling increases and data is broadcast every minute, regardless of vehicle movement.
- Extreme conditions: Above 100 °C (212 °F), sampling increases further, and broadcasts occur every 10 seconds.
Rapid thermal event detection
The device is designed for continuous temperature monitoring. Detection of rapid thermal events requires additional logic implemented by the Telematics Service Provider (TSP) within its platform.
Rapid thermal events can be identified by analyzing high-frequency broadcasts during short temperature spikes. Because the device automatically increases its sampling and broadcast frequency as temperature rises, it is essential that the TSP captures and processes all transmitted data.
Detection accuracy can be further improved by comparing temperature data from multiple TraX devices installed on the same vehicle to identify abnormal deviations between wheel ends.
The table below provides general guideline thresholds for TSP-implemented rapid thermal event alerts. Thresholds may need to be adjusted based on fleet-specific operating conditions and tolerance for false positives.
| Alarm severity | Trigger condition | Duration | Threshold (°C) | Threshold (°F) |
|---|---|---|---|---|
| Caution | Temperature crosses the threshold once | — | 95 | 203 |
| Warning | Temperature crosses the threshold three times | Within 5 minutes | 95 | 203 |
| Critical | Temperature remains above the threshold | 30 minutes | 95 | 203 |