A plain or notched, often wedge-shaped piece of wood or metal designed to hold parts of a machine or structure in place or provide a bearing surface, usually adjusted by a screw or key.

• 扁柱，夹条，凹字形楔一种平的或有凹的经常是一块楔形的木头或金属，用来在一定地方夹住机器或结构的各部分或提供轴承的表面，通常是由螺丝或钥匙来调整