As large-scale rotating machines develop toward high rotating speed and high power–weight ratio, skidding damage has become one of the major initial failure modes of cylindrical roller bearings. Therefore, understanding the skidding damage law is an effective way to ensure the safety of machines supported by cylindrical roller bearings. To realize the skidding damage, a high-speed rolling bearing test rig that can simulate the actual operating conditions of aviation bearings was used in this paper, and the skidding damage dynamic behaviors of cylindrical roller bearings were investigated. In addition, to ensure the accuracy of the obtained skidding damage mechanism, the cylindrical roller bearing was carefully inspected by microscopic analysis when the skidding damage occurred. Out results show that instantaneous increases in friction torque, vibration acceleration, and temperature are clearly observed when the skidding damage occurs in the cylindrical roller bearing. Furthermore, under the conditions of inadequate lubrication and light load, the critical speed of skidding damage is rather low. The major wear mechanisms of skidding damage include oxidation wear, abrasive wear, and delamination wear. The white layers are found locally in the inner ring and rollers under the actions of friction heat and shear force.

Although Kolmogorov-Smirnov (KS) statistic is a widely used method, some weaknesses exist in investigating abrupt Change Point (CP) problems, e.g. it is time-consuming and invalid sometimes. To detect abrupt change from time series fast, a novel method is proposed based on Haar Wavelet (HW) and KS statistic (HWKS). First, the two Binary Search Trees (BSTs), termed TcA and TcD, are constructed by multi-level HW from a diagnosed time series; the framework of HWKS method is implemented by introducing a modified KS statistic and two search rules based on the two BSTs; and then fast CP detection is implemented by two HWKS-based algorithms. Second, the performance of HWKS is evaluated by simulated time series dataset. The simulations show that HWKS is faster, more sensitive and efficient than KS, HW, and T methods. Last, HWKS is applied to analyze the electrocardiogram (ECG) time series, the experiment results show that the proposed method can find abrupt change from ECG segment with maximal data fluctuation more quickly and efficiently, and it is very helpful to inspect and diagnose the different state of health from a patient's ECG signal.

Surface wear caused by contact between crane wire rope and a pulley seriously affects the mechanical properties of the wire rope. In this study, the tribological behavior of wire rope was investigated using a homemade rope–pulley sliding friction test rig. Then, the influence of different surface wear on the bending fatigue life of the rope samples was analyzed. The results show that the friction coefficient (COF) decreases with the increasing sliding distance. It reaches a minimum of approximately 0.52 when the contact load is 700 N. The surface temperature of the wire rope rises rapidly and then gradually stabilizes. The maximum temperature rise fluctuates in the range of 50 °C to 60 °C with increasing contact load. The wear scar of the wire rope is irregular, and the maximum wear width increases from approximately 1.94 mm to 2.45 mm with the contact load. Additionally, increased contact load leads to smoother wear surface of wire rope, and the wear mechanisms are mainly abrasive wear and adhesive wear. Additionally, surface wear leads to a decrease in the bending fatigue life of wire ropes, and degradation of anti-bending fatigue is more serious under a larger sliding contact load.

In view of the serious friction and wear on the surface of a hoisting wire rope caused by the failure of lubrication under severe hoisting conditions, a study on the tribological characteristics of lanthanum stearate modified lubricating oil (LSMLO) was carried out. First, lanthanum stearate was prepared by the saponification reaction, and its surface morphology, chemical structure, thermal stability, and dispersion stability in IRIS-550A lubricating oil (IRIS) for wire rope were analyzed. Then, the tribological properties of LSMLO were investigated through four-ball friction tests and sliding wear tests of wire ropes. The results show that stearic acid almost completely reacts to produce lanthanum stearate, which has good thermal stability and a disordered layered structure. With the help of oleic acid, the dispersion stability of lanthanum stearate in IRIS can be significantly improved. The four-ball friction tests show that the optimal addition amount of lanthanum stearate in IRIS is 0.2 wt.%, and the CoF and wear scar diameter are reduced by about 35% and 25% respectively when lubricated with LSMLO compared to that with IRIS. LSMLO can better reduce the wear of the wire rope under different sliding speeds and contact loads than IRIS, and it exhibits improved anti-friction and anti-wear properties under high speed and low load.

A winding hoist is a key equipment for ultra-deep mine hoisting. The inter-circle transition in the winding process of the hoisting wire rope causes vibration, impact, extrusion, wear, and other negative phenomena, which seriously affect the service life of the rope. In order to explore the effect of inter-circle transition on the friction and wear performance of wire ropes, the present study adopts the principle of equal ratio scaling to build a test rig for an inter-circle transition of wire ropes, and the evolutions of coefficient of friction and maximum friction temperature with increasing the tensioning force and rope speed under dry friction were investigated by the test rig, and the major wear mechanisms under different working conditions were investigated in combination with the wear morphologies. The results show that the coefficient of friction decreases first and then increases with an increase in the tensioning force, and decreases linearly with increasing the rope speed. The evolution of maximum temperature over time under different tensioning forces and rope speeds are all mainly divided into three stages: The rapid growth phase, the slow growth phase, and the stable phase. The influence of the rope speed on the temperature of the wire rope is greater than that of the tensioning force. Moreover, in the process of inter-circle transition, the major wear mechanism is abrasive wear. Furthermore, larger tensioning force and rope speed may cause the steel wires on the contact surface of the wire rope to break.