与公路运输和航空运输的竞争,迫使铁路不断进行新的努力,来改善服务和降低费用。在已往的30年中,恰恰在牵引方面,由于这种努力而取得了可观的成果。直到1950年,铁路牵引动力主要来源于蒸汽机车。蒸汽机车的优点是用起来很皮实,寿命长,但对于燃料的利用不经济,乘务员的劳 Competition with road transport and air transport forces the railways to make new efforts to improve services and reduce costs. In the past 30 years, precisely because of traction, considerable achievements have been made thanks to such efforts. Until 1950, the traction power of railway mainly came from steam locomotive. The advantage of steam locomotive is to use it very leather, long life, but for the use of fuel is not economical, the crew’s labor