I once owned a couple of the Paya steamers I believe green and also blue 2-6-2's. The engines had a resistance type heater coil and a bellows that was mechanically driven to puff the smoke. As MIKETG indicated, the casting both wheels and passenger car vestibules, suffered from the dreaded zinc pest. The plating was flaking off the wheels as they expanded.
Eric Hofberg
TCA, LCCA