Helical Gear Calculator

Inputs

View results
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
Edit inputs
Center distance(a)
63.85mm
Pass

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)2.128mm

mt = mn / cos(beta).

Transverse pressure angle(alpha_t)21.17°

Pinion pitch diameter(d1)42.57mm

Gear pitch diameter(d2)85.13mm

Axial pitch(px)18.37mm

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.

Powered by MachineCalcs ↗