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Can multiple motors drive single axle (water pump here)

  1. Apr 19, 2016 #1
    I have a dilemma with the design of a device I want to build which is acquiring the correct size motor (shape & power) in my price range (even finding one within specs). I have found that the motors from cordless drills are ideal for this application (due to size, price and availability) so they meet all my requirements as long as I can use multiple motors to turn one shaft.

    I need 3-6 motors to drive the axle of a water pump. I can easily fit 6-8 in my design if I need the power and battery capacity is not a concern at all.

    If I use multiple motors I will use all the same models so they are identical.

    If multiple motors are used, let's say 18v brushless DC, can I run them in series (would there be any benefit to this)? I can make the battery bank 18-20v or multiples there-of. I can easily run a heavy bus bar if running in parallel so current isn't an issue here. Is one better than the other?

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  3. Apr 20, 2016 #2

    Simon Bridge

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  4. Apr 20, 2016 #3


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    Won't using multiple brushless motors complicate the speed controller? You can't use one controller to drive them all. Might be simpler to use brushed motors.
  5. Apr 20, 2016 #4
  6. Apr 21, 2016 #5
    If the motors are all the same and they are wired in parallel, wouldn't they all run at the same speed? I'm not sure why brushed (universal??) motors would be better.

    I was trying to design the motor layout for using multiples and it seems to get complicated (in my arraingement) when figuring out the path of the belt/chain. I'm wondering if there are problems with using 2 chains or belts so I would have 2 sprockets or pullies on the axle to be driven and I would have 2-3 motors on each belt/chain. I'm a little more concerned with using chains in this situation.
  7. Apr 21, 2016 #6


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    On a brushless motor the speed controller also does the comutation. It switches power to each winding in turn based on the rotor position. The rotor position is typically sensed by monitoring the voltage on an un powered winding.

    So its not enough that they run at the same speed. They also have to be in phase....or use one controller per motor.
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