制轮楔;轮辖
lynchpin n 1: a central cohesive source of support and stability; "faith is his anchor"; "the keystone of campaign reform was the ban on soft money"; "he is the linchpin of this firm" [syn: {anchor}, {mainstay}, {keystone}, {backbone}, {linchpin}] 2: pin inserted through an axletree to hold a wheel on [syn: {linchpin}]