Do you have any basic rules or formulas that will help identify what my spur gear is?

Please refer to the tables below for spur gear calculations:

DIAMETRAL PITCH (IMPERIAL)
Diametral Pitch is the Number of Teeth to each Inch of the Pitch Diameter.

To obtain the	If you have the...	Formula
Diametral Pitch	Circular Pitch	DP = 3.1416 CP
Diametral Pitch	Pitch Diameter and the Number of Teeth	DP = N PD
Diametral Pitch	Outside Diameter and Number of Teeth	DP = N+2 OD
Diametral Pitch	Module	DP = 25.4 MOD
Pitch Diameter	Number of Teeth and the Diametral Pitch	PD = N DP
Pitch Diameter	Number of Teeth and the Outside Diameter	PD = (OD) (N) N+2
Pitch Diameter	Outside Diameter and the Diametral Pitch	PD = OD – 2 DP
Outside Diameter	Number of Teeth and the Diametral Pitch	OD = N+2 DP
Outside Diameter	Pitch Diameter and the Diametral Pitch	OD = PD + 2 DP
Outside Diameter	Pitch Diameter and the Number of Teeth	OD = N+2 N÷PD
Number of Teeth	Pitch Diameter and the Diametral Pitch	N = (PD) x (DP)
Number of Teeth	Outside Diameter and the Diametral Pitch	N = (OD) x (DP) – 2
Module	Diametral Pitch	MOD = 25.4 DP

Please note: the above formulae relates to standard outside diameters and pitch diameters.

MODULE (METRIC)
Module represents the amount of Pitch Diameter (mm) per tooth

To obtain the	If you have the...	Formula
Module	Pitch Diameter and the Number of Teeth	MOD = PD N
Module	Circular Pitch	MOD = CP 3.1416
Module	Diametral Pitch	MOD = 25.4 DP
Module	Outside Diameter and the Number of Teeth	MOD = OD N+2
Pitch Diameter	Module and the Number of Teeth	PD = MOD x N
Pitch Diameter	Number of Teeth and the Outside Diameter	PD = OD x N N+2
Pitch Diameter	Outside Diameter and the Module	PD = OD – 2MOD
Outside Diameter	Module and the Number of Teeth	OD = (N+2) x MOD
Diametral Pitch	Module	DP = 25.4 MOD

Please note: the above formulae relates to standard outside diameters and pitch diameters.

For bevels, worm gears and helicals we suggest you have these drawn up and send the drawing to Ronson Gears for quotation.

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	Email Address: enquiries@ronsongears.com.au

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Do you have any basic rules or formulas that will help identify what my spur gear is?