短語詞組短語teflon piston oil seal 特氟隆活塞油封piston dust seal 活塞防塵罩piston rod seal 活塞桿密封;活塞桿hydrodynamic piston reciprocating seal 液壓缸活塞密封piston head seal 活塞頭密封piston top seal 柱塞頂部密封piston ring seal system 活塞環(huán)密封系統(tǒng)piston ring seal 脹圈密封Piston bar seal 拉桿封 返回 piston seal