N scale dumper - old style 

Coal dumper, old style. The mechanism is from a State Street Models kit. A loco pushes cars up the ramp where they are uncoupled and dumped. The empty is shoved down a kickback ramp and returned to the yard by gravity. This dumper has since been upgraded to include a barney for shoving up the ramp, and the kickback's "spring switch" is now thrown automatically using optical sensors and a solenoid switch.