Engineering Calculators

Contact Ratio Calculation For Spur Gears With Calculators

Contact ratio is a very important parameter for spur gear designs. When all the parameters are calculated for mating spur gears, you need to be also sure about the contact ratio of mating spur gears are inside the acceptable range.

The minimum acceptable contact ratio that recommended by spur gear manufacturers is 1.2. In general applications, contact ratios of spur gear systems around 1.5.

You can use the calculator below to see the contact ratio of your spur gear mates.

Contact Ratio Calculator For Spur Gear Mates
















How To Use Contact Ratio Calculator For Spur Gears?

As you see above, the use of contact ratio calculator is very simple. You need to have some information about your spur gear mate system;

  • Np is the number teeth at your pinion gear.
  • Ng is the number of teeth at your bigger gear.
  • Pd is the diametral pitch value of your gear. If you gave metric module, value you can convert this metric module into diametral pitch value.
  • θ is the pressure angle value of your gear tooth. In most applications, this value is 20 degrees. But you need to take a look at the catalogues of gear manufacturer.

Enter the required data above at contact ratio calculator, then click on ‘Calculate!’ button to see contact ratio.

Also you can use MB-Unit Converter tool to convert your units into another unit sets.

If you want to do another calculation, click on ‘Reset’ button then re-enter the values again.

Conclusion For Contact Ratio Calculator For Spur Gear Mates

This calculator can be very good companion of you to use it in the phase of spur gear system design.

All the responsibilities of calculations that done with these calculators is on the users.

Do not forget to take a look at the other engineering calculators avaliable in Mechanical Base!

Do not forget to leave your comments and questions about the contact ratio calculator for spur gear mates below.

Your precious feedbacks are very important for us.

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2 Comments

  1. The contact ratio didn’t work correctly for a pinion with 16 teeth, gear of 44 teeth, diametral pitch of 6 teeth/in, and 20-degree pressure angle, it should be 1.615. A student of mine used your website and submitted the incorrect answer.

    1. Hi Ted. We are very thankful for your feedback. Feedbacks like yours are very important for us. Actually, contact ratio formulations changes according to different types of gear meshes. This calculator is made for the standard spur gear meshes. Your spur gear type is rack and pinion. Could you please check the formulations stated in this topic, for different types of spur gear meshes?

      https://www.sdp-si.com/resources/elements-of-metric-gear-technology/page6.php#:~:text=A%20contact%20ratio%20between%201,teeth%20are%20always%20in%20contact.

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