脱轨器 meaning in Chinese

derailer
derailing apparatus
derailing stop
lifting block derail

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
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