德国车轮轮辋超声应力检测技术

超声应力检测与其他应力检测方法相比,有其不可替代的优越性,但这种方法对被检材料均匀性要求高,必须提前对试样进行标定,而且需要耦合剂,在应用上有局限性。介绍一种基于声弹性双折射的超声波应力检测技术工作原理,通过采用德国Fraunhofer的IZFP机构基于声双折射效应研发的UER设备,分别对未加热处理的新车轮和加热处理后的新车轮进行应力检测比较,得出影响车轮轮辋应力检测的因素。     

移动式整车称重系统的研制

移动式整车称重台的安装简便,节省秤重时机车运行时间和费用.利用车辆轮缘进行秤量重力点,取下条形承载板,机车可正常在线路行驶.研制过程中应着重解决称重传感器选择、标定和承载板材料的选择等三项关键技术.     

轮轨非对称接触及其对车辆动力学性能的影响

随着速度的不断提高,轮轨接触关系对列车运行安全性的影响越来越大。当轮轨型面发生损伤后,轮轨非对称接触现象就会产生。轮轨非对称接触现象不仅影响车辆运行的安全性,同时与车轮型面损伤问题也有着密不可分的关系。文章以SS3B型机车为例,建立了由轮轨型面磨耗和轮径差导致的轮轨非对称接触的模型。仿真结果表明当轮轨非对称现象发生后,机车的抗蛇行运动临界速度就会降低,同时,曲线通过的脱轨风险性也会显著增大。     

改善轮/轨接触特性提高铁道车辆曲线通过性能

针对现有转向架车轮踏面形状,通过加宽轨距、改变内轨垫板角和内轨顶面的非对称削正3项措施,达到扩大内外轨轮径差,提高曲线通过性能的目的.     

浅谈不落轮旋车床的常见故障及处理方式

介绍了动车组检修关键设备不落轮旋车床在使用过程中出现的几种常见故障,分析了产生故障的原因,并提出一些常用故障的处理方法。     

Dynamic model and validation of an articulated steering wheel loader on slopes and over obstacles

This paper devotes both analytical and experimental efforts in developing a comprehensive dynamic model for an articulated steering wheel loader. The general motion of a wheel loader without suspension is described by seven degrees of freedom (DOF) (three for translation and four for rotation) in this model, which can be used to study the problem of wheel loader dynamics on slopes and over obstacles. A scale wheel loader was designed and manufactured to validate the dynamic model in three conditions (turning on level ground, turning on slopes, and passing over obstacles). The test results reasonably agree with the simulation results. The developed dynamic model was found to be useful and could serve as an important tool for analysing the stability of wheel loaders.     

120型控制阀造成行车抱闸的原因分析

结合近期铁路货车运用制动抱闸故障发生频繁情况深入分析,并提出改进建议。     

The role of the contact geometry in wheel–rail impact due to wheel flats

A thorough investigation of wheel–rail impact due to wheel flats is presented, together with a quantitative characterization of the main mechanisms and parameters. A criterion for the speed with respect to contact loss between wheel and rail is derived. In the subcritical speed regime, the magnitude of the impact force is shown to be directly related to the geometry of the flat, whereas in the transcritical speed regime a fictitious or effective flat depth exists, which decreases with the second order of the speed. In this domain, the position of impact shifts towards the end of the flat with increasing speed. The impact force increases with the second order of the speed in the subcritical speed regime and approximately the first order of the speed in the transcritical speed regime. The magnitude of the impact force is inversely proportional to the minimum circumferential curvature of the wheel tread defect in the subcritical speed regime, and to the effective minimum curvature in the transcritical case. The variation with the flat depth is less; the impact varies with the square root of the flat depth. The presented theory is in accordance with measurements reported in the literature and explains characteristic features in them.     

Minimum-time manoeuvring in electric vehicles with four wheel-individual-motors

The coordinated control of vehicle actuators is gaining more and more importance as new platforms are becoming available, with chassis endowed with many different actuators that may help controlling the vehicle motion. Furthermore, wheel individual motors allow using a single system to apply both positive and negative torques at the wheels, which can be actuated independently one from the other. In electric vehicles (EVs), moreover, such a freedom in the actuation mechanisms opens the way to the combined optimisation of performance and energy consumption issues. In this paper, the problem of minimum-time manoeuvring in EVs is addressed, and the proposed strategy is compared against a benchmark, a-causal optimal solution showing that only a negligible loss of performance is experienced.     

A method for testing railway wheel sets on a full-scale roller rig

Full-scale roller rigs for tests on a single axle enable the investigation of several dynamics and durability problems related with the design and operation of the railway rolling stock. In order to exploit the best potential of this test equipment, appropriate test procedures need to be defined, particularly in terms of actuators’ references, to make sure that meaningful wheel –rail contact conditions can be reproduced. The aim of this paper is to propose a new methodology to define the forces to be generated by the actuators in the rig in order to best reproduce the behaviour of a wheel set and especially the wheel –rail contact forces in a running condition of interest as obtained either from multi-body system (MBS) simulation or from on-track measurements. The method is supported by the use of a mathematical model of the roller rig and uses an iterative correction scheme, comparing the time histories of the contact force components from the roller rig test as predicted by the mathematical model to a set of target contact force time histories. Two methods are introduced, the first one considering a standard arrangement of the roller rig, the second one assuming that a differential gear is introduced in the rig, allowing different rolling speeds of the two rollers. Results are presented showing that the deviation of the roller rig test results from the considered targets can be kept within low tolerances (1% approximately) as far as the vertical and lateral contact forces on both wheels are concerned. For the longitudinal forces, larger deviations are obtained except in the case where a differential gear is introduced.