要使几百万辆的货车和数千辆机车维持运行是一项巨大的任务，功不可设的当数铁路公司和一些承包工厂。在过去的几年中，车辆与机车的总数目一直在逐年减少，但货运量却是在一直增长。尽可能让车辆在线运行而不送厂检修是考验铁路公司承运能力的一个重大因素。为了了解哪些公司 It is a huge task to keep millions of trucks and thousands of locomotives running and can not afford to be a Dangdang railway company and some contracted factories. In the past few years, the total number of vehicles and locomotives has been decreasing year by year, but the volume of freight traffic has been increasing. It is a major factor that tests the ability of the railway company to carry as much as possible to let the vehicle run online without sending overhaul. In order to know which companies