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F 2 – the greatest workload at which the maximum
torsion stress in the transverse sieve of the spring wire is equal
to the permissible value. Bending stress occurs in the wire,
which is insignificant and is taken into account when
calculating for:
 [ ]d 3
F  , (10.3)
2
8kd
c
where [] – he permissible stress of the torsion of the material
of the spring wire, the magnitude of which is tentative []=392
MPa;
k – a coefficient that takes into account the curvature of
the turns,
4 c 2
k  .
4 c 3
l 2 and l 2 – length and deformation of the spring under
the influence of the workload F 2.
F 3 – the limiting load, which for a spring, working on
compression is equal:
l  Gd 4
F  3 . (10.4)
3 3
d 8 n
c
For springs working on tension:
F 3=(1,05...1,2)F 2, (10.5)
where l 3 – deformation of the spring, which works on
compression before the torsion of the turns (for a spring, which
works on tension deformation under load F 3).
l 3=l 0-l 3=l 0-(n 1-0,5)d,
where l 3 – The length of the spring, which works on
compression, deformed to the tangles;
n 1 – total number of turns of the spring;
n 1=n+n 2,
where n 1 і n 2 – number of support ("dead") turns, pressed at the
ends of the spring to the adjacent turns and polished
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