单词coach bolt
un.: 方头螺栓；扁圆头带榫螺栓网络: 马车螺栓；止动螺栓；方头螺拴
扁圆头带榫螺栓
方头螺栓
Carriage bolt (coach bolt): Has a domed or countersunk head, and the shank is topped by a short square section under the head.
马车螺栓（螺栓教练）：有一个圆顶或沉头，而小腿是由简短根据头方节突破。