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7 ASSEMBLY DRAWINGS

Assembly drawing shows how the components or parts must be assembled to form the
complete machine or device. The assembly drawing shows the different parts in their relative
positions. An assembly drawing furnishes the following information:
a) One main view to show the best assembly.
b) Selected overall dimensions and important centre to centre distance.
c) Identification of different parts on assembly drawing.
d) Necessary sectional views.
e) Part list, notes, titles, etc.
An assembly drawing is a document, which contains the representation of assembly unit and
other information, necessary for its assembly and control. An assembly drawing must give the
complete information about an article construction, interaction of parts, that belong to it, and there
is a technical document during implementation of assembly operation and acceptance of an article.
An assembly drawing must contain:
А) representation of an assembly unit, which gives an idea of placing and interconnection of
its separate parts;
B) sizes and other parameters and requirements, which are carried out and controlled in the
process of an assembly of an article, pointing about the method of connection of parts of an article;
C) part number of component parts of an article;
D) basic descriptions of an article;
E) overall, setting dimension, conjunctive and reference dimensions (fig.7.1).

7.1 MAKING ASSEMBLY DRAWING

1. Necessary and sufficient amount of representations are determined thus, the external and
internal elements of an article were fully exposed on an assembly drawing.
2. The scale of a drawing is determined depending on complication of an article and its sizes,
a paper format is chosen according to State Standard 2.301-68. A frame and title block are drawn.
3. Overall rectangles or circles are marked for placing of representations and the axes of
symmetry are drawn.
4. Necessary sectional views, sections, additional representations are drawn. If any sectional
view is to be drawn, fix the position of the cutting plane and find out the parts through which
cutting plane passes. Difficult parts are drawn simultaneously on all of representations of an article.
5. Other parts are drawn.
6. The executed drawing is checked up, the lines of visible and invisible contours are drawn,
sectional views and sections are shaded. Change hatching directions in adjacent sectioned
components.
7. Extension and dimension lines are drawn and size numbers are marked.
8. Part numbers of component parts of an assembly unit are marked.
9. A title block is filled in, technical requirements and technical description of an article is
shown in case of necessity.
If an article is designed in a shape of a symmetric figure, it is recommended to combine the
half of view with the half of the proper sectional view. Fixing, keys, connecting rods, axles and
shafts in a longitudinal section are drawn undissected. Such elements, as spokes of fly-wheels,
pulleys, gear-wheels, thin walls as stiffening ribs are cut, but are drawn unshaded, if a cutting plane
passes along an ax or a long side of such element.
Shadings of one part in sectional views on different representations are drawn under one
angle, maintaining the identical interval of shading. Shadings of contiguous parts are drawn in
different directions.

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