Additional equations for extension springs
1.
work/application
1 W = · (F
+
F
0
) · s
2
2.
load
G d
4
· s
F = ·
8 D
3
· n
replace "F" with the difference
F – F
0
for prestressed extension
springs
3.
spring deflection
8 D
3
· n
s = ·
· F
G d
4
4.
spring rate
G d
4
D
F F
R = ·
= =
8 D
3
· n
D
s s
without prestress
with prestress
G d
4
D
F F F
−
F
0
R = ·
= = =
8 D
3
· n
D
s s s
5.
shear strains
8 D
τ
= ·
· F
π
d
3
dynamic
τ
k
= k ·
τ
6.
diameter of wire
3
8 F · D
d =
√
·
π τ
zul
7.
number
of active coils
G d
4
· s
n = ·
8 D
3
· F
8.
total number of coils
(reference)
Lk n
t
=
−
1
d
9.
internal prestress
F
0
= F
−
s · R
G d
4
· s
= F
−
·
8 D
3
· n
12.2
Selecting springs
replace "F" with the difference
F – F
0
for prestressed extension
springs
replace "F" with the difference
F – F
0
for prestressed extension
springs
shear strain Tizul in N/mm²
permitted shear strain
τ
izul for compression
springs according to no. 1.4310
wire diameter d in mm
KL SH
permitted shear strain
τ
izul for compression
springs according to EN 10270-1
KL DH
