简述YJ19卷烟机导纸轮的作用及保养。
ZK3-A型电空转辙机的电磁阀铁心行程为（）mm。 ["1.8±0.3","1.8±0.5","1.5±0.3","1.5±0.5"]
刚性联轴器有那些优缺点？
ZK3-A型电空转辙机的电磁阀线圈（线径0.38mm）电阻为（）。 ["65Ω±3.25Ω","65Ω±5Ω","85Ω±5Ω","85Ω±8.5Ω"]
舵叶轴承孔与舵杆工作轴颈的同轴度偏差不得大于（）倍的舵承安装间隙。 ["0.7","1.0","1.25","1.5"]
简述YJ19卷烟机导纸器的保养。
