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Gear motor specs

Discussion in 'DIY Motion Simulator Building Q&A / FAQ' started by Trent Robinson, Dec 26, 2023.

  1. Trent Robinson

    Trent Robinson Member

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    My Motion Simulator:
    2DOF, DC motor, Arduino, Motion platform
    Has anybody actually measured the torque and or stall current of the commonly used eBay Crab Pot motor? The specs are contradictory (unless I'm missing something).

    Gearbox: 50:1
    Power: 180W
    Rated output speed: 75 RPM
    Rated torque: 50-60 NM

    Inferred motor speed: 3750 RPM
    Calculated torque of motor .46 NM
    Calculated torque of gearbox output 23 NM

    If the crab pot really is getting 50-60NM, I calculate the motor should be closer to 430W not 180W. I have found similar contradictions from the myriad of tarp motors available. I know the specs are marketing lies but how does one design and choose when everything is of questionable validity?
    Trent Robinson, Dec 26, 2023
    #1
  2. Trent Robinson

    Trent Robinson Member

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    My Motion Simulator:
    2DOF, DC motor, Arduino, Motion platform
    Well, I bought a "600w" 60:1 tarp motor off of eBay.

    It consumed 22 amps running no load and 220 amps at stall! I'm blown away. That's 2640watts! I realize it won't run at stall but this seems a bit insane. I really wonder how they rated this motor. I'm thinking I should return it and regroup or am I missing something?
    Trent Robinson, Jan 7, 2024
    #2
  3. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
    3DOF, DC motor, JRK
    This is the retailer specs, including the current draw @ rated torque: https://tarpingusa.com/products/presale-600w-60-1-gear-ratio-8hp-electric-tarp-motor-eagle

    Specifications:
    • Output Shaft: 3/4" x 3-3/4", with two 5/16" through-holes
    • Operating torque: 32 NM
    • Current Draw @ rated torque: 33 Amps
    • RPM: 60
    • Wattage: 600W
    • Gear: Worm to Wheel
    • Mounting: Three 5/16"-18 bolts
    • Dimensions: L: 10.5", W: 5.75", H: 6.25"
    You could try contacting them directly regarding any specific questions you may have: https://tarpingusa.com/pages/contact-us
    noorbeast, Jan 7, 2024
    #3
  4. Trent Robinson

    Trent Robinson Member

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    My Motion Simulator:
    2DOF, DC motor, Arduino, Motion platform
    It's actually these ones: Dump Truck Tarp Motor 600W 60:1 1pc US Stock | eBay I think they are basically the same with slight differences in stated specs.

    Perhaps I shouldn't concern myself with stall torque and just focus on the rated torque ~33-50A. I was just trying to size my power supply and thought max current was the way to do it.
    • Optimistic Optimistic x 1
    Trent Robinson, Jan 7, 2024
    #4
  5. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    My Motion Simulator:
    3DOF, DC motor, JRK
    I used the Ebay info as a way to search for the actual retailer, to check specs, as Ebay sellers tend to be inaccurate.

    While published specs can be dubious, if not from a reputable retailer/manufacture, they are likely a better indicator of current draw for stated torque than stall current.

    That being said, when it comes to PSU selection it is wise to allow significant overhead in PSU specs, as a motion rig generates significant power spikes in fast reversals. For example I use a 575W PSU for each of my 200w motors on my 3DOF compact rig: https://www.xsimulator.net/community/threads/dx-compact-simulator.5866/
    • Like Like x 1
    noorbeast, Jan 7, 2024
    #5
  6. Trent Robinson

    Trent Robinson Member

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    My Motion Simulator:
    2DOF, DC motor, Arduino, Motion platform
    Ah, understood and thank you!

    I have certainly been planning to oversize the power supplies, that was part of this exercise. I will wait for my motor controllers to arrive and do some bench tests.
    Trent Robinson, Jan 7, 2024
    #6