ENGINEERING TOOLS
Spring Calculators
Online design calculations for compression, extension, torsion, disc and leaf springs
Torsion Spring Calculator
Inputs
Results
Bending stress is within the allowable value.
Torque–angle
Rate T/φ = E·d⁴/(64·D·nₑ) with nₑ = n + (a₁+a₂)/(3πD) for leg deflection; σ = K_b·32T/(πd³), allowable 0.625·Rm. Loaded in the winding direction — the coil diameter shrinks under load, so leave clearance on the arbor. For reference only.
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View related products →Formulas
Torsional rate
T/φ = E·d⁴ / (64·D·nₑ)
φ in radians; × π/180 per degree
Equivalent coils
nₑ = n + (a₁ + a₂)/(3πD)
Includes leg bending
Handbook form
k′ = E·d⁴ / (3667·D·n + 389·(a₁+a₂))
N·mm/°, identical result
Bending stress
σ = K_b·32T/(πd³)
K_b = (4C²−C−1)/(4C(C−1)), inner fibre
Loaded diameter
D′ = D·n / (n + φ/360)
Coil closes in the winding direction; arbor ≤ 0.9(D′ − d)
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