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what kind of motor has the most torque? — Parallax Forums

what kind of motor has the most torque?

ArchiverArchiver Posts: 46,084
edited 2002-05-13 02:56 in General Discussion
hello there.

I know that every motor is different, but I'm wondering what's the torque
comparison of a generic dc brush motor, stepper motor and servo motor.

Thanks

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2002-05-02 05:14
    I'd guess the servo due to the gearing.

    Original Message
    From: raoul vaneigem [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=nDfKFx1H2rxiNOzAJ6Dy5z7KRrrhC-DxsJxYckebefdJ6k6fDulHLDwlo_UATUO0l6OU30Pmng]raoul@c...[/url
    Sent: Wednesday, May 01, 2002 10:52 PM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] what kind of motor has the most torque?

    hello there.

    I know that every motor is different, but I'm wondering what's the torque
    comparison of a generic dc brush motor, stepper motor and servo motor.

    Thanks


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  • ArchiverArchiver Posts: 46,084
    edited 2002-05-04 11:24
    Of a gear head motor
    Ben
    Dennie Bishop <dbishop@e...> wrote: I'd guess the servo
    due to the gearing.

    Original Message
    From: raoul vaneigem [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=1UkGRhXNmJqYNb4iV9lEtrKG2aTMdC3qQuqmnqqD-lCqs4hVIDh2ckVNOz7rxBQeWXYqN58lxw]raoul@c...[/url
    Sent: Wednesday, May 01, 2002 10:52 PM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] what kind of motor has the most torque?

    hello there.

    I know that every motor is different, but I'm wondering what's the torque
    comparison of a generic dc brush motor, stepper motor and servo motor.

    Thanks


    To UNSUBSCRIBE, just send mail to:
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    BEN (TEAM DBR)
    http://www.geocities.com/temdbr



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    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2002-05-04 12:19
    Well that is a very general question...
    If we assume the magnets, armature, and voltage/current is the same. Then
    all three would be about equal. They are all electric motors of one type or
    another.
    Now if we add a gear set to a motor to gear it down, then we can increase
    it's torque output but at the expense of lower RPM's out the output shaft.

    A DC motor is designed to turn in one direction well, and deliver maximum
    performance at a certain voltage and RPM. But on more generic ones that
    don't turn really high RPM's you can run them forward and backwards quite
    well by reversing the voltage on the motor. High RPM motors typically have
    the commutator timed so that they can run their best in one direction. AC
    motors have a similar timing relationship as well, otherwise they might
    startup and run backwards, which might be bad if it is a airconditioner
    motor or something.
    A Stepper motor is designed to "step" once for every pulse train sequence
    that is applied to it (some motors can do 1/8, 1/4, 1/2 steps too). They can
    arrange the coils and magnets so that the motor can have larger or smaller
    or even micro steps.
    The stepper works well for more precise control over positioning and knowing
    where you are. For example, 100 pulse or 100 steps out, and 50 steps back,
    and you know your still 50 steps out from the start. Plus you can get
    precise control over RPM's too, thus steppers work well in some devices like
    hard disk drivers and printers, etc.
    A real servo motor has a complementary but smaller motor feedback unit
    hooked up to it, if the feedback motor unit turns, the big servo motor turns
    to match the smaller one. You can remove the feedback motor and replace it
    with a electronic feedback unit to simulate the movements as well. The servo
    motor gets it's advantage from the fact that a little itty bitty feedback
    motor can drive a huge monster servo motor (they do use amplifiers here
    too).
    The little R/C hobby servo units you see all over are actually a little DC
    motor geared way down to increase torque at the output. They use a little IC
    chip and a little H-bridge driver circuit to control the motor so they can
    run it forward and backwards. There is a little feedback potentiometer that
    tells the IC chip how far the motor has moved the output shaft. When they
    apply a PWM signal to the input line, a 1.0 ms pulse is full travel one
    direction, a 2.0 ms pulse is full travel the other way, a 1.5ms pulse is the
    center position. The IC chip will power the motor until the feedback pot
    returns a commensurate result and then it stops.

    As for power, it's all relative to what you want to do.
    For example: the Space needle restaurants usually have a rotating top
    portion.
    They typically use a little 1/2 to 1 hp AC motor, geared way down, to
    provide the rotating power.

    Original Message
    From: raoul vaneigem [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=FLmPawWmor-kBqvN5x1qalynPL_ERppPbI2fvkn7-1DueB0t5KxslOwwOoS0QjTRD9AVROf_iiKdghs]raoul@c...[/url
    Sent: Wednesday, May 01, 2002 10:52 PM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] what kind of motor has the most torque?

    hello there.

    I know that every motor is different, but I'm wondering what's the torque
    comparison of a generic dc brush motor, stepper motor and servo motor.

    Thanks


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    BEN (TEAM DBR)
    http://www.geocities.com/temdbr



    Do You Yahoo!?
    Get personalised at My Yahoo!.

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  • ArchiverArchiver Posts: 46,084
    edited 2002-05-04 16:25
    DC Series wound motor are strongest -- these are used in the an
    automotive starter motor.

    DC Compound or parallel winding motors are next also called universal
    motors

    Then we have have three phase motors

    Servo motor does not indicate the type of motor, it indicates the power
    arrangement to the motor.


    Seems like this is correct, now that a statement has been made, I am
    sure someone will correct it :-))))))))))))

    I am talking here of startup torque and not running torque, because once
    it gets going all bets are off because of RPM ranges and a bunch of
    other factors,


    HTH,

    Leroy
  • ArchiverArchiver Posts: 46,084
    edited 2002-05-13 02:56
    --- In basicstamps@y..., raoul vaneigem <raoul@c...> wrote:
    > hello there.
    >
    > I know that every motor is different, but I'm wondering what's the
    torque
    > comparison of a generic dc brush motor, stepper motor and servo
    motor.
    >
    > Thanks

    Of the three types indicated I would have to say the DC brush motor
    will give the most torque. Particularly if you have the variety that
    has an electromagnetic field instead of permanent magnets. If you
    then wire the field in series with the armature you have the very
    powerful series motor, like the starter motor in your car. Under a
    heavy load, as armature speed decreases the magnetic fields increase
    and so does the the torque. In theory, if these motors are allowed
    to run without a load they will overspeed to the point of self
    destruction.
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