Mechanical drawing learned in college is useful for future work, which can help you understand drawings quickly and is the foundation of construction machinery specialty.

Mechanical drawing is a subject that accurately expresses the structural shape, size, working principle and technical requirements of machinery with drawings. Drawings are composed of figures, symbols, words and numbers. They are technical documents that express design intentions and manufacturing requirements and exchange experiences. They are often called engineering languages.

In order to make people have a consistent understanding of the format, characters, lines, graphics simplification and symbol meaning involved in drawing, a unified specification has been gradually formulated and developed into a mechanical drawing standard. Countries generally have their own national standards, and there are also standards formulated by the International Organization for Standardization in the world.

China's national standard for mechanical drawing was formulated in 1959 and revised twice in 1974 and 1984. The items specified in the mechanical drawing standard include: drawing width and format, scale, font and drawing lines, etc. In the drawing format and format, the size of the standard drawing format and the corresponding frame size are specified. Proportion refers to the ratio of the dimension length in the drawing to the actual dimension of the machine parts. Except drawing with the scale of 1: 1, only the reduction scale and enlargement scale specified in the standard are allowed.