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Figure 4.14 – Hexagonal headed bolt (type 1)

Example of conventional denotation of a bolt of normal accuracy, type 1, with the diameter
of a thread 20 mm, a fine pitch 2 mm, by the tolerance zone 6g, a working length 100 mm, a
strength class 5.8, without coverage according to State Standard 7798:2008:
BOLT M202-6g 100.58 State Standard 7798:2008.

Bolts of types 2 and 3 are used for the connection of machines parts which are vibrating. It
results in unscrewing of nuts and bolts. In fig. 4.15 the bolt of type 2 is shown - with opening for a
split-pin and type 3 - with two openings in the head of bolt for wired connection of bolts group.

Figure 4.15 – Hexagonal headed bolt (type 2 and type 3)

Three verges of hexahedrons are shown on the front view of bolts and nuts. The drawings of
a nut and a head of the bolt are started from the construction of the correct inscribed hexagon. The
stage-by-stage construction of crossing lines of verges of a bolt head with the conical surface of
chamfer on its face is shown in fig.4.16. At such construction the hyperbolical curves of crossing
are simply drawn by the arcs of circles.

1 step 2 step 3 step

Figure 4.16 – The stage-by-stage construction of hexagonal headed bolt

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