This second device is placed on a locomotive wheel that is on the opposite side. The wheels will start to turn and the brushes (or brush and scraper)will remove the dirt from the wheels. Wheel Cleaning Brush.
66623 Minitrix Trix Wheel Cleaner N Gauge Conductive Loco Wheel Cleaning Brush
66602 Trix Wheel Cleaner OO HO Gauge Conductive Loco Wheel Cleaning Brush
Trix M66623 N Gauge Conductive Loco Wheel Cleaning Brush
Trix M66602 OO Gauge Conductive Loco Wheel Cleaning Brush
GAUGEMASTER OO/HO Scale Wheel Cleaning Brush GM60
Gaugemaster GM60 OO/HO Scale Wheel Cleaning Brush