Contact Ratio Formula

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The contact ratio represents the average number of teeth meshing at the same time. Check FAQs
CR=PPc
CR - Contact Ratio?P - Path of Contact?Pc - Circular Pitch?

Contact Ratio Example

With values
With units
Only example

Here is how the Contact Ratio equation looks like with Values.

Here is how the Contact Ratio equation looks like with Units.

Here is how the Contact Ratio equation looks like.

1.125Edit=18Edit16Edit
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Contact Ratio Solution

Follow our step by step solution on how to calculate Contact Ratio?

FIRST Step Consider the formula
CR=PPc
Next Step Substitute values of Variables
CR=18mm16mm
Next Step Convert Units
CR=0.018m0.016m
Next Step Prepare to Evaluate
CR=0.0180.016
LAST Step Evaluate
CR=1.125

Contact Ratio Formula Elements

Variables
Contact Ratio
The contact ratio represents the average number of teeth meshing at the same time.
Symbol: CR
Measurement: NAUnit: Unitless
Note: Value can be positive or negative.
Path of Contact
The path of contact is the path traced by the contact point of a pair of tooth profiles.
Symbol: P
Measurement: LengthUnit: mm
Note: Value should be greater than 0.
Circular Pitch
A circular pitch is the distance along the pitch circle or pitch line between corresponding profiles of adjacent teeth.
Symbol: Pc
Measurement: LengthUnit: mm
Note: Value should be greater than 0.

Other formulas in Toothed Gear Terminologies category

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​Go Work Output on Driver
w=Rcos(α1-Φ)πd1N1
​Go Addendum of Pinion
Ap=Zp2(1+TZp(TZp+2)(sin(Φgear))2-1)

How to Evaluate Contact Ratio?

Contact Ratio evaluator uses Contact Ratio = Path of Contact/Circular Pitch to evaluate the Contact Ratio, Contact Ratio formula is defined as a dimensionless quantity that characterizes the tooth overlap in a gear mesh, providing a measure of the extent to which the teeth of one gear overlap with those of another gear in a toothed gear system. Contact Ratio is denoted by CR symbol.

How to evaluate Contact Ratio using this online evaluator? To use this online evaluator for Contact Ratio, enter Path of Contact (P) & Circular Pitch (Pc) and hit the calculate button.

FAQs on Contact Ratio

What is the formula to find Contact Ratio?
The formula of Contact Ratio is expressed as Contact Ratio = Path of Contact/Circular Pitch. Here is an example- 1.125 = 0.018/0.016.
How to calculate Contact Ratio?
With Path of Contact (P) & Circular Pitch (Pc) we can find Contact Ratio using the formula - Contact Ratio = Path of Contact/Circular Pitch.
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