Re: [CAD_CAM_EDM_DRO] What is 2nd set of brushes for on a servo

cnc_4_me wrote:

>One of the differences between DC servos and DC motors is the number of
>brushes. What exactly does a second set of brushes do for you?
>
>

It depends. Some motors are 4-pole. These are often optimized for lower
speed operation, ideal for a CNC servo.

If the two sets of brushes are evenly spaced around one commutator, that
would
be a 4-pole motor. If they are on different commutators (different
axial position
on motor) then the 2nd set is for a tachometer. You should not run any
current
through the tachometer brushes.

>Does the current draw stay the same?
>
>Would a second set of brushes make a DC motor run smoother?
>
>

no.

>Could a second set of brushes be added to a treadmill motor?
>
>

Only if you add 2 more poles to the field structure.

Jon