联结环 meaning in Chinese

coupling link
draw bar ring
draw-bar ring
hitch law
towing ring

U - link u
形联结环
Coupling devices for trucks and trailers ; trailer coupling ring 40 without socket , dimensions
汽车和挂车的挂结装置.不带套筒的挂车联结环40 .尺寸
Industrial pipework . bracing rings for flanges with female groove or spigot , or male tongue or spigot faces . iso pn 2 , 5 to iso pn 50
工业管道.与凹面槽或插口或凸面舌键或插头配用的法兰盘的联结环.标准压力为pn至pn