The Run-Time Behaviour Of Coupler/Draft Gear Systems On Heavy Haul Locomotives

As a key system in train, coupler/draft gear systems have been proven to greatly affect the train dynamics by their run-time behaviour. This truth has been validated in a large volume of published papers and derailment reports. However, accurate predictions and systematic researches are remain unsolved due to the disadvantages of field tests and lack of availability of rational simulation models.In this paper, readers will be convinced of the influence of coupler/draft gear systems on train dynamics by the listed literature and analyses of derailment accidents. Afterwards, literature research will also be orientated to the modelling of coupler/draft gear systems, merits and demerits of those models will be analysed to serve the subsequent modelling. Nonlinear draft gear models and universal system structure models will be presented in this paper. Integrating frictional pairs and aligning shoulders or stops, detail coupler/draft gear system models will be accomplished.Systems’run-time behaviour were simulated in train, and all simulations were aware of track geometry and irregularity. Based on the analyses of influence of run-time behaviour on train dynamics, several unexpected phenomena were studied quantitatively and qualitatively.Study results show that:Frictional pairs of flat-pin-system were shown to be the critical elements in control of systems’ run-time behaviour. With frictional pairs flat-pin-system can achieve more stable performance and result in better running safety. Though frictional pairs can be of assistance in reduction of wheel/rail wear on tangent track, little improvement was detected on curved track.With the joint effects of primary and secondary suspensions, carbodies were found possess certain of coupler-stabilize-ability. The stability of quasi-calculation and dynamic simulation are in close agreement with the field tests. From the perspective of enhancement of train dynamics and protection of coupler systems, it is better for round-pin-system to adapt draft gear with stiffer characteristics. The angling directions of couplers in round-pin-system are random events which will not be affected by the directions of curvature. But the directions of curvature have conspicuous effects on systems’ curving behaviour as well as the running safety of longitudinal compressed locomotives. In comparison, the angling directions of flat-pin-system have strong relevance with the directions of curvature, but their behaviour will not be affect by different directions.