短语词组短语back gear shaft 背齿轮轴back axle shaft 后传动轴back drive shaft bushing 后主动轴衬套back shaft scroll 后轴涡轮back -up shaft 支持辊辊轴JMWNY Back shaft 后轴back shaft station 折返式井底车场back shaft bracket 后尾轴架 返回 back shaft