利用摩擦前進的「黏著驅動」
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鐵道的軌道與車輪基本上都是鐵做的。使用在汽車車輪的橡膠輪胎接地面，刻有所謂胎紋的凹槽，而使用在鐵道上的車輪踏面並不會凹凸不平，而是表面光滑。可能有人會想：「這樣車輪不會滑嗎？」沒錯，答案是會。和行駛在鋪設道路上的汽車相比就會很清楚了。
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汽車是以動力讓橡膠輪胎轉動，利用接地面所產生的摩擦，像是橡膠輪胎要把鋪設路線往後踢般往前推進。所以，當下雨或下雪這種路面容易滑的時候，產生的摩擦就會變小，一想要加速、車輪就會空轉，一踩煞車，車輪就會被鎖死而滑動。
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有一個名詞叫作「摩擦係數」，是表示容易產生摩擦程度的數值，而鐵道車輪與軌道之間的摩擦係數，是汽車的橡膠輪胎車輪與鋪設路線之間摩擦係數的約二分之一到四分之一。正因如此，鐵道的車輪很容易打滑。某個電車駕駛表示，駕駛電車就像是如履薄冰，也像是在駕駛拆下正常輪胎的汽車一樣。
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提到鐵道，車輪和軌道之間作用的摩擦叫作黏著，因此使用摩擦來推進就叫作黏著驅動。黏著驅動有著容易讓車輪空轉或打滑的缺點，但自從蒸汽機關車誕生以來，還是使用了200年以上。現在上下班用的電車或新幹線電車也是藉由黏著驅動來行駛的。
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摩擦小，就衍生出其他優點來。那是因為防礙推進的摩擦排斥較少、效能良好之故。（更多鐵道小知識請見《鐵道的科學：認識鐵道的運行技術與原理，更快速、更便捷、更舒適的祕訣是什麼？》，晨星出版）
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