2 replies to this topic

[Dave_12]

Why do some motor builders use a different make of brushes for the positive and negative brush?

[zipper]

The front brush on hotter motors wears more. Re Mike: When we ran 40 minute one-motor G7 races in the Midwest USRA, the front brush always was the one that wore out first.

Stu explained it as the direction of the current flow and more arcing on that brush.

Conversly the braid that wore more (again due to arcing) is the one connected to the opposite buss bar (looking at the car from the bottom pointing forward, the right one) or in 1/1 American car terms, the "drivers" side.

[Bill Seitz]

Addendum to what Pekka provided:

 

It's the positive side brush and pickup braid that wears faster, and does so on all motors/cars. The usual track wiring places the positive side on the right side of the slot (looking in direction of travel). The positive side is usually the front-facing motor brush (in an anglewinder), the one on the short buss bar side. However, not always. Depending on how the arm is wound or the orientation of the magnets in the can, the polarities on the motor can be swapped.