By coupling the strength design of gear based on EHL central stress fitting formula and the gear lubrication design based on D-H formula, a non Hertz contact gear design formula which can meet the requirements of tooth surface contact strength and elastohydrodynamic lubrication can be obtained

Where, the diameter of dividing circle designed by DNH non Hertz contact theory, mm.

The circular speed V of the gear in the formula is transformed into the speed n1 of the driving gear

The formula is the non Hertz contact strength design formula of involute spur gear.

Similarly, the non Hertz contact strength design formula of helical gears can be obtained.

The circular speed V of the gear in the formula is transformed into the speed n1 of the driving gear