推荐回答（2个）
道岔(Turnout)是铁路机车车辆从一轨道转入另一轨道的线路间连接与交叉设备总称。
但比较特殊的地方是台铁前辈出版的书籍把道岔作为转辙器的俗称，众多资料也将电动转辙机(electric switch machine)误称为转辙器。
轨道线路连接有各种类型的单式道岔和复式道岔；交叉有垂直交叉和菱形交叉；连接道岔与交叉的组合又有渡线 、交叉渡线和梯线等，这些设备在铁路工程学中都称为特殊轨道(special trackwork）。
最常见的是单式道岔和复式道岔，它是允许轨道在同时交叉将一个轨道分为两个和三个轨道的设备。
单式道岔组装时分三个部分，经由焊接或鱼尾钣接合而成；分别是转辙器(Switch or points panel)部分、岔心或辙叉(Crossing panel)部分与其连接部分(Closure panel)。
构造
1、转辙器
转辙器包括基本轨(Stock rail)、尖轨(switch blades)和转辙机械(switch motor或switch machine)
是主要控制列车在道岔上行驶方向的活动部件。通常由人工或电信号控制。
2、辙叉部分
辙叉部分包括固定或可动岔心(Crossing nose或frog)、翼轨(Wing rail)及护轨(Check rail)。设置于定位与反位交叉处的特殊轨道，轮缘槽可使车辆行于一股道顺利通过至另外一股道。
3、可动心道岔
根据岔心的种类可将道岔分为固定道岔和可动心道岔。前者岔心处四条钢轨用铆钉被固定在枕木上，后者岔心根据行驶方向小幅移动岔心以消除某一方向的“有害空间”。
4、连接部分
连接部分主要由四根称为导轨或连接轨构成，材质及形状皆与一般轨条相同。
对称道岔产品组成
道岔是个大家族，最常见的是普通单开道岔。它由转辙器、连接部分、辙叉及护轨三个单元组成。转辙器包括基本轨、尖轨和转辙机械。当机车车辆要从A股道转入B股道时，操纵转辙机械使尖轨移动位置，尖轨1密贴基本轨1，尖轨2脱离基本轨2，这样就开通了B股道，关闭了A股道，机车车辆进入连接部分沿着导曲线轨
过渡到tdaf002辙叉和护轨单元。这个单元包括固定辙叉心、翼轨及护轨，作用是保护车轮安全通过两股轨线的交叉之处。
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