Helical Gear Calculator

Inputs

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Tooth count on the driving helical pinion.
Tooth count on the driven helical gear.
Tooth size measured normal to the helix. Pitch diameters use mt = mn/cos(beta).
mm
Helix angle at the pitch cylinder.
°
Pressure angle in the normal plane. 20 degrees is common.
°
Pinion input speed.
rpm
Pinion input torque.
N·m
Torque multiplier efficiency allowance.
%

Results

Default result
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Center distance (a)
63.85 mm
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Computed from pitch diameters using transverse module.

a = (d1 + d2)/2 for standard parallel-shaft mesh.

Also computed

Gear ratio (i) 2

Driven teeth / pinion teeth.

Transverse module (mt) 2.128 mm

mt = mn / cos(beta).

Transverse pressure angle (alpha_t) 21.17 °

Pinion pitch diameter (d1) 42.57 mm

Gear pitch diameter (d2) 85.13 mm

Axial pitch (px) 18.37 mm

px = pi*mn/sin(beta).

Method notes 3 notes
  • Normal-system helical gears use mt = mn/cos(beta), so d = z*mn/cos(beta) and a = (d1+d2)/2.
  • Transverse pressure angle is alpha_t = atan(tan(alpha_n)/cos(beta)). Axial pitch is pi*mn/sin(beta).
  • This is layout geometry only. It does not rate tooth bending, pitting/contact stress, thrust bearing load, backlash, profile shift, lubrication or gearbox housing stiffness.

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