Research On The Influence Of Brake Mode To Abnormal Wear Of Wheelset Tread On Urban Mass Transit

Wheelset tread abnormal wear of urban mass transit is a significant spoil to train operation and if it is neglected, it may cause wheel-rail contract surface spalling, rail corrugations and partical wear and so on, which makes dynamic behavior of vehicles worse, decreases riding comfort, and increases the maintenance activities and the operation expenses.At first, the analysis ofwheelset tread abnormal wear in the thesis is based on the statistics of initial three months operation of Nanjing metro, and together with the same problem of other cities' urban mass transit, according to the investigation analysis, if the unreasonable hardness matching of wheel-rail contract surface is excluded, the too high brake pressure of wheelset is the vital reason, especially if it happens on the the trailer, at meanwhile, brake mode is also an important factor.And then, depending on the established finite element model ofwheelset tread on emergency brake mode, the temperature field of wheelset tread on emergency brake mode is simulated by using ANSYS software. The simulation result shows that the influence of emergency brake mode to wheelset tread abnormal wear is negligible, then pneumatic brake on service brake mode and fast brake mode is further proved to be the main factor which results in wheelset tread abnormal wear.At last, the relationship between antiskip control system and "micro slides" of wheelset is discussed in details. Electro-pneumatic brake mode is commonly adopted at vehicles braking system of urban mass transit, and electrical brake mode is preferred, but when electrical brake is insufficient, pneumatic brake is complement. When required complement pneumatic brake force is distributed unbalance to the wheelset of motor and trailer, especially the brake force of trailer is too high, to which exceeds the adhesion limitation, then "micro slides" phenomenon appears. The "micro slides" phenomenon happens repeatedly during one brake cycle makes the temperature of wheelset tread rise rapidly, and would break the temperature of transformation, then lead to the occurrence of abnormal wear of wheelset tread. It is concluded that the sensitivity of antiskip control system is related with wheelset tread abnormal wear tightly.The distribution of brake force of urban mass transit on service brake mode and fast brake mode plays an important role to wheelset tread abnormal wear. In addition, if the antiskip system could detect the slide status in time and take relevant measures, the wheelset tread abnormal wear would be improved. According to the research conclusion of this thesis, it is suggested that the braking system control should be strengthened for researching the reasonable distribution of brake force and appling the practice of urban mass transit vehicles in the future, by improving response time and precision control of braking system, the abnormal wear of wheelset tread would be decreased.