Experimental study on the relationship between freight train wheel brake temperature and slope gradient

• First quantification of slope gradient’s direct impact on tread braking temperature. • Conducted 1:1 test bench experiments simulating real-world operational conditions. • Revealed nonlinear temperature rise with slope gradients increase using infrared thermography. • Advanced tread temperature > 150°C by 250 s and 480 s and increased high-T area by 0.2% and 10.7% at 10–18‰ slope. Advanced tread temperature > 200°C by 65 s and 40 s and increased high-T area by 1.7% and 2.3% at 22–30‰ slope. • Provided basis for sustained braking on steep gradient road sections. Under extreme conditions such as sustained braking on long, steep slopes, freight train wheels are prone to thermal loads that can affect their lifespan. This study, based on a 1:1 brake test rig and infrared thermography, investigates the temperature distribution characteristics of wheel treads in the 1030‰ slope range under braking conditions of 50 km/h speed, 4kN braking pressure, and 600 s continuous braking. Results indicate that as slope increases, the time to reach high temperatures on the tread surface, duration of elevated temperatures, and temperature gradients exhibit non-linear increases. When the slope increases from 10‰ to 30‰, the maximum wheel tread temperature rises from 147°C to 365°C. The maximum lateral temperature difference of the tread increases by 89% to 298% and the maximum temperature gradient increases from 8 to 12°C·mm −1 to 2428°C·mm⁻1. The duration of temperatures above 200°C increases from 225 s to 360 s, while the time to reach 200°C decreases from 345 s to 280 s and 240 s. This study establishes a quantitative relationship between slope and wheel tread thermal load, providing important insights for wheel thermal management and braking strategy optimisation during slope braking.