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10 LABORATORY WORK №7
CONTROL, TESTING AND DEFECT SPRINGS

10.1 Goal of the work. Purpose of the work is to get
acquainted with the causes causing the loss of elasticity and the
change in the linear dimensions of the springs.
10.2 Knowledge and skills. In the course of the
laboratory work, the student must obtain the characteristics of
the springs and their defects.
10.3 General Terms and Conditions. Cylindrical
twisted springs (figure 10.1) are wound from a spring wire with
a diameter d. One of the characteristic parameters is the spring
index:
d
C  c , (10.1)
d
where d c – average diameter of the spring, which is determined
by the formula:
d  d
d  2 1 , (10.2)
c
2
where d 2 і d 1 – outer and inner diameters of the spring.
For compressed springs, an important parameter is the
step of an unloaded spring P (Fig. 10.1, а). Springs acting on
tension (Fig. 10.1, b) have a mostly closed capillary (P = d)
with an initial tension (pressure) between the turns.
The relationship between the force and deformation of
the spring is called the spring characteristic. Figure 10.2. a -
shows the characteristics of the compression spring, and in
Figure 10.2, b - is the tension spring.

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