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How to Calculate Motor Torque?

Discussion in 'DIY Motion Simulator Building Q&A / FAQ' started by Eliseu, May 23, 2020.

  1. Eliseu

    Eliseu New Member

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    How to know the Motor Torque output?

    upload_2020-5-23_19-56-43.png

    IMG_20200429_160159.jpg IMG_20200429_160352.jpg
  2. Ads Master

    Ads Master

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  3. Gadget999

    Gadget999 Well-Known Member

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    My Motion Simulator:
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    you cant - but you can measure it - use a set of scales and a arm attached to the motor
  4. adgun

    adgun Active Member

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    He can
    One watt is one newton with a speed of one meter a second, and you can make NM from it.
    Calculate rpm to meter/second, with a 1 meter lever
    above one meter a second devide it with motor watage, below one meter a second multiply it
    This gives motor torque multiply it with gearbox ratio and take gearbox efficienty
    a 25 ratio wormgearbox got a 70% efficentie
    regards Ad
  5. Gadget999

    Gadget999 Well-Known Member

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    You dont know how many turns theee are in the armature and the diameter of the armature

    I have tested 2 x 400w motors one of them needed 10 amp to lift a load and the other needed 18 amps to do the same weight.

    Best to use the manufacturer stall torque if you can find it
  6. adgun

    adgun Active Member

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    the motor label gives 1/4 HP and 1750 rpm you dont need more
  7. Eliseu

    Eliseu New Member

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    @adgun Do you confirm the following values?

    [​IMG] [​IMG]

    Motor:
    HP: 1/4
    rpm: 1750 r/min
    η = 72%

    Gear:
    i=25

    -------------------------------

    ω= rpm.2.π/60

    Pout=Pin.η

    1 hp = 745.699872 W
    1/4= 186,5W

    Pout=Pin.η
    Pout= 186.5*0.72=134.226W

    ω= rpm.2.π/60
    ω= 1750.2.π/60 =183rad/s

    Pout=T.ω
    Tmotor=Pout/ω
    Tmotor=134.226/183 = 0.733Nm

    Tgearmotor= Tmotor. i
    Tgearmotor=0.733*25= 18.33Nm

    Tgearmotor= 18.33Nm

  8. adgun

    adgun Active Member

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    motor 186.5 watt/rpm 1750 gearbox ratio 25 gearbox eff 70%
    1750/25\=70rpm /60\=1.1666 rounds second
    1.166x2xpi=7.33 meter second
    186.5/7.33\=25.44NMx70%=17.81NM
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  9. Eliseu

    Eliseu New Member

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    Thanks to validate the logic...
    The efficiency is 72%...
  10. adgun

    adgun Active Member

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    You must have gearbox eff. not motor eff.
    The motor delivers 1/4 hp but ask more current doing that.
    Wormgearboxes with a 25 ratio are about 70% with smal brand differinces
    sorry for the bad english
    regards Ad
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