Number of Turns in Torsion Springs

• Torsion Spring Design Resources – Spring Design

The number of active turns in a torsion spring is equal to the number of body turns, plus a contribution from the ends. For straight torsion ends, this contribution is equal to 1/3 of the moment arms and is usually expressed as an equivalent number of turns:

N_e = (L₁ + L₂) / 3∏D

L₁ = length of the moment arm of the first end

L₂ = length of the moment arm of the second end

N_a = N_b + N_e

N_b = number of body turns

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