Gear Set Design Engine

Spur Gear Set Design Engine

Diametral Pitch · Module · Circular Pitch

Enter Design Requirements Below

Pitch System

The engine will evaluate all three pitch systems and select the best candidate overall.

Center Distance (in) Space Limit / Max OD (in, optional) Pressure Angle

Service Factor

AGMA Service Factor Guide

Uniform Load

Application	1-shift	2-shift	Cont.
Generators, light conveyors	1.00	1.25	1.50
Fans, blowers (uniform)	1.00	1.25	1.50

Moderate Shock

Application	1-shift	2-shift	Cont.
Centrifugal pumps	1.25	1.50	1.75
Mixers, agitators	1.25	1.50	1.75
Bottling machinery	1.25	1.50	1.75
Heavy conveyors	1.50	1.75	2.00
Compressors (centrifugal)	1.25	1.50	1.75

Heavy Shock

Application	1-shift	2-shift	Cont.
Stone / rock crushers	1.75	2.00	2.25
Punch presses	1.75	2.00	2.25
Ball / rod mills	1.75	2.00	2.25
Compressors (reciprocating)	1.75	2.00	2.25
Hoists, cranes	1.75	2.00	2.25

Source: AGMA 2001. Values rounded to nearest 0.25. Verify with AGMA standards for critical applications.

Output Torque

Input Speed (rpm) Output Speed (rpm)

Horsepower (optional — overrides torque when set)

Efficiency (%) Friction Loss (%)

Raw Material

Measurement Over Wires / Pins

Show MOW for each gear with recommended pin diameter

Recommended Gear Set

Enter positive center distance, speeds, and service factor.

Check Inputs

Recommendation Logic

Pitch Systems & Calculation Notes

Diametral Pitch (DP)

Inch standard. DP = teeth / pitch diameter (in). Higher DP = finer, smaller teeth. Standard values: 2, 2.5, 3, 4, 5, 6, 8, 10, 12, 16, 20, 24, 32, 48, 64. Face width limits: 8/DP to 10/DP inches. Face width rounded to nearest 0.25 in for DP ≤ 24; nearest 0.01 in for DP > 24.

Module (m)

Metric standard. m = pitch diameter (mm) / teeth. Higher module = coarser, larger teeth. Standard values: 1, 1.25, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 10, 12, 16, 20. Relationship: m = 25.4 / DP. Face width limits: 8m to 10m mm.

Circular Pitch (p)

Arc distance between adjacent teeth along the pitch circle (inches). p = π / DP = π × m / 25.4. Standard values: 1-1/2", 1-1/4", 1", 3/4", 5/8", 1/2", 3/8", 5/16", 1/4", 3/16", 1/8", 1/10", 1/16", 1/20". Face width limits: 8p/π to 10p/π inches.

Lewis beam equation: Wt = σ × b × Y × Kv / DP (DP equivalent used internally for all systems).

Barth velocity factor: Kv = 600 / (600 + V), where V is pitch-line velocity in ft/min.

Auto-select mode runs all three pitch systems independently, scores every candidate from all systems on the same scale, and picks the single best result regardless of system. The winning system is displayed in the results.

Center-distance tolerance ≤ 8%; ratio error ≤ 8%. ±12 tooth-count offsets tested per pitch value to avoid false "No Fit" results. Face width rounded up to nearest 0.25 in (DP ≤ 24) or nearest 0.01 in (DP > 24), then capped at 10/DP (or equivalent).

Input torque is back-calculated through the combined efficiency and friction loss factor. HP → Torque conversion: T = HP × 5252 / RPM × η × (1 − f).

Profile shift coefficient: x‍_sum = (C‍_required − C‍_actual) × DP. When the pinion tooth count is below the undercutting threshold (18 for 20° PA, 33 for 14.5° PA, 14 for 25° PA), the shift is redistributed to favour the pinion using x‍₁ = x‍_sum × (1 − N‍₁/N‍_min) × 0.5 + 0.5, capped at 80% of x‍_sum. For pinions at or above the threshold the split is equal. The Lewis Y factor correction is applied individually to each gear using its own shift coefficient, giving a more accurate capacity estimate. |x‍_sum| < 0.5 is standard practice; above 0.9 risks tip narrowing.

Measurement Over Wires / Pins (MOW): Standard pin diameter = 1.728 / DP (per Machinery's Handbook). A custom pin can be entered if preferred. φ₁ satisfies: inv(φ₁) = t/d + inv(φ) + d_pin/d_b − π/N, where t = π/(2P) is circular tooth thickness, d = N/P, d_b = d·cos(φ). φ₁ solved by Newton's method. Even teeth: M = d_b/cos(φ₁) + d_pin. Odd teeth: M = d_b·cos(90°/N)/cos(φ₁) + d_pin. Profile shift increases the effective tooth thickness: t → t + 2x·tan(φ)/P.