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The wheel–rail contact force is a crucial indicator for ensuring the secure operation of a heavy-load train. However, obtaining the real-time wheel–rail contact force of a heavy-load train is a challenging task as, due to safety considerations, it is not possible to install instrumented wheelsets on heavy-load trains. This work presents a novel approach to quantify the wheel–rail contact force of a heavy-load train, utilizing a cooperative calibration methodology. First, a ground measurement platform for the wheel–rail contact force of a heavy-load train is constructed on a selected rail section. The railway inspection car’s wheel–rail contact force measurement system is fine-tuned using a multilayer perceptron calibration approach, and the ground platform then uses the results to fine-tune the railway inspection car’s examined wheelset. Second, based on actual measured data on the wheel–rail contact force of a heavy-load train, and using the golden jackal optimization algorithm, the multilayer perceptron correction approach is employed to create a data relationship mapping model. This model correlates the corrected data on the wheel–rail contact force obtained from the railway inspection car with the wheel–rail contact force of a heavy-haul train with an axle load of 25 tons, and the precision of the mapping is guaranteed. Finally, by combining the wheel–rail contact force correction method for the railway inspection car and the contact force mapping model between the railway inspection car and the heavy-load train, collaborative calibration of the wheel–rail contact force of the heavy-load train is realized. The experimental results under two working conditions show that this method can realize high-precision, real-time measurement of the wheel–rail contact force of a heavy-load train. For the working condition of a straight-line section, the calibration error was within 1.593 kN, and the MAPE was 0.105%; for the working condition of a curved-line section, the calibration error was 2.344 kN, and the RMSE was 184.72 N.

This paper addresses the issue of abnormal fluctuations in brake pipe pressure causing variations in braking force, or even forced stops, in heavy-haul trains. A multi-parameter synchronous acquisition monitoring device has been designed to collect relevant operational parameters during train movement. Integrating train traction calculation methods, algorithmic reasoning is conducted to assess the impact of abnormal pipe pressure fluctuations on braking force. Utilising the derived computational approach, the effect of such pressure anomalies on train braking force is calculated. Train braking force is regulated through control of the train pipe pressure reduction. Both train pipe pressure and pressure reduction are managed by the locomotive via the equalising air chamber. Traditional detection methods focus on pressure reduction and air charging/discharging times, making it difficult to analyse fluctuation causes in-depth. This study installs pressure sensors on the locomotive brake’s equalising air chamber and the train pipe inspection port to collect pressure data. It simultaneously records parameters such as ambient temperature and atmospheric pressure. Utilising the monitoring data, it calculates the impact of pipe pressure fluctuations on train air braking force, thereby supporting improvements in braking system stability and operational safety.

When maximum speed of 160 km/h is reached and the axle load reaches 25–30 tons, the train wheels need to have high strength and toughness. The main chemical elements affecting the strength and toughness of the wheel were determined by the mechanical features of the samples with different chemical compositions. Through analysis of the impact fracture of typical specimens, the difference of wheel toughness was mainly reflected in the dimple band, crack source, and cleavage pattern. By SEM analysis of fracture cracks, the critical size difference was found to exist between the grains during brittle fracture, where the intergranular fracture between grains of different sizes is mainly due to the different interfacial stresses between grains of different sizes.

As a vital component in the valve train of internal combustion engines (ICEs), the cam/tappet pair undergoes high mechanical and thermal loads and usually works in a mixed and boundary lubrication regime. This leads to considerable friction loss and severe surface wear. Currently, the applications of diamond-like carbon (DLC) coatings for automotive components are becoming a promising strategy to reduce the friction and lower the wear. However, the practical performance of the coating is related to many factors, including friction coefficient, thermal properties, load conditions, and surface topography. In order to investigate these factors and successively improve the fuel efficiency and durability of the cam/tappet pair, a comprehensive multi-physics analytical model considering the mechanical, thermal and tribological properties of DLC coatings is established in this paper. Simulations are carried out for the coated as well as the uncoated cam/tappet conjunctions with different roughness at various ambient temperatures. The results show that both the fluid and asperity contact friction for the coated cam/tappet conjunction are significantly reduced due to their favourable characteristics. As a result, the friction loss of the coated cam/tappet pair is noticeably lower by almost 40% than that of the uncoated, despite a slightly higher asperity contact. In addition, the wear resistance of DLC coatings is also impressive, although the wear condition becomes progressively more severe with the increasing ambient temperature. Moreover, the roughness has complex effects on the friction and wear under different conditions.