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Spur Gears

Rate a steel spur gear pair by the AGMA method: tooth bending and surface pitting for the pinion and the gear, the factors behind them, and the power the pair can carry at your target. Updates as you type.

Why gear teeth break at the root and pit at the pitch line: spur gears, explained.

Teeth and mounting

Module m(mm)Pinion teeth N_PGear teeth N_GFace width b(mm)Pinion positionTooth profile

20° pressure angle, full-depth involute teeth. Module is pitch diameter per tooth; 10 teeth per inch is 2.54 mm.

Duty

Power(kW)Pinion speed(rev/min)Pinion life(million cycles)Overload factor K_oReliabilityTarget load factor

Steel and accuracy

Through-hardened steelPinion hardness(HB)Gear hardness(HB)Quality number Q_vGeometry factor J, pinionGeometry factor J, gear

Read J from AGMA 908 or Shigley Fig. 14-6 for the tooth counts; left blank, the Lewis form factor stands in for it.