M- mass of the object acting on the spring (kg)

Ms- spring mass (kg)  N- variable load cycle number

  N- spring working circle

  Nz- spring support ring number

  N1- total number of turns of the spring

  P'- Spring single ring stiffness (N/mm)

  R- The middle radius of the coil (mm)

  R1- inner radius of the coil (mm)

  R2- outer radius of the coil (mm)

  R- damping coefficient

  S- safety factor

  T-torque; torque (Nmm)

  T'- torsional stiffness (N-mm /(0))

T- spring moment

Tc- cable pitch (mm)

U- deformation energy (N: mm); (N: mm-rad)

  V-spring volume (mm3)

  V- Impact body speed (mm/s)

  Zm- bending section coefficient (mm3)

  Zt- torsional section coefficient (mm3)

  A- helix angle (°); coefficient

  -- wire rope angle (°); cone half angle (°); coefficient

  Δ- axial clearance of the spring ring (mm)

  Δr- radial clearance of the combined spring ring (mm)

  Ζ- coefficient

  Η- coefficient

  Θ- torsion angle per unit length of the torsion bar (rad)

  K-factor

  -- Poisson's ratio; length factor

V-spring self-vibration frequency (Hz)

  Excitation frequency (Hz) of the variable load applied to the Vr-spring

  Τb- Material shear strength (Mpa)

  Tj- spring working limit shear stress (Mpa)

  Τo- Pulsating torsional fatigue limit of material (Mpa)

  τS- material torsional yield point (Mpa)

  Τ- 1- Symmetrical cyclic torsional fatigue limit of material (Mpa)

  Φ-torsion angle (rad)