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Calculations for rack and pinion

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  • Calculations for rack and pinion

    Does anyone know a formula to calculate the max weight that a particular rack and pinion can lift?

  • #2
    I'm not sure this is helpful, but I found this page.

    It provides formulas, but essentially says use trial and error. :-(


    • #3
      Based on past experience, do not forget to consider the load back driving the motor after the power to the motor is turned off...


      • #4
        If you are new to motor torques and speeds, Rev has an excellent document at
        For a rack and pinion, the force on the rack will be the torque operating point of the system divided by the pitch diameter of the pinion.
        If this is for a "lifting" operation, you may want to research worm gears - most designs have high backdrive forces, meaning they don't slip backwards when motor is off.


        • #5
          woops... meant to say "pitch radius" (half of the pitch diameter)


          • #6
            Thank you all for answering! We ending up going to a screw method to lift!


            • #7
              We use a vertical rack and pinion system with a worm gear for lifting. We are using the 4:1 tetrix worm gear. They also sell a 10:1 and 20:1, but the 4:1 works really well for lifting and controlled lowering of our robot. It can hang forever with the power off since it is mechanically held. Our robot is around 15 pounds.