Symbols Used In Helical Spring

a)      l_o= free length of spring

b)      d = Diameter of spring wire

c)       D= Mean diameter of coil

d)      D_o= Outer diameter of coil

e)      D_i= Inner diameter of coil

f)       p = Pitch

g)      i = Number of active coils

h)      i’= Total number of coils

i)        F= load on the spring or Axial force

j)        y= Deflection

k)      G= Modulus of Rigidity

l)        c= Spring index

m)    k= Curvature factor or Wahl's stress factor

n)      K_oor F_o=Stiffness of spring or Rate of spring

o)      a= Clearance, 25% of maximum deflection.

p)      t_y= Torsional yield shear strength (stress)

q)      F.O.S = Factor of safety

r)       F₁= Minimum load

s)       F₂= Maximum load

t)       Y₂= Maximum deflection

u)      Y’= Deflection for the load range

v)      n= Number of additional coils

w)    g= Acceleration due to gravity

x)      V= Volume

y)      m= Mass of the spring

z)       y₁= Initial deflection or initial compression