What are motor brushes, and how do they work ?

[jmurray01]

I've always wondered both those things ever since I started collecting Vacuum Cleaners...

Also, how long typically do they last, and what are the signs of them nearing the end of their life ?

 

[kirby519]

Motor brushes are the carbon brushes that make the electrical connection to the motor at the communicator on the armature of the machine.

They can last for several years. Typical signs of failure of the motor carbons are: sparking from the motor, the motor slowing and speeding up, motor failing to start at times to the motor not operating at all.