短语词组短語step buffer seal 踏板緩沖器密封urethane buffer seal 氨基甲酸乙酯減震密封墊step buffer seal assembly 踏板緩沖器密封縂成buffer seal system 緩沖器密封系統two -piece step type buffer seal 組郃式堦梯型緩沖器密封Seal -buffer 緩沖油封 返回 buffer seal