Installation design technical specification for electric derailer and singnal protective equipment of train inspection and repairing 列检电动脱轨器及信号防护装置安装设计技术条件
2.
A device for shifting gears on a bicycle by moving the chain between sprocket wheels of different sizes 脱轨器,转撤器通过在不同大小的扣链齿轮间移动链条而转换自行车齿轮(换档)的装置