Yes, the mechanism is noisier than the Atlantics (same chassis) and I assume it has to do with the boiler shell somehow amplifying the gear and motor noise. Maybe (just now thought of this) it's the bracket to the cab roof, acting like a sound board? Will have to experiment on one to see if isolating it helps. The shell doesn't seem to amplify the smoke unit's choo-choo feature! Franklinstein
Because ACG used existing tooling to make these engines, they are more O or larger Scale, as are the cars. The sets were really designed to be marketed by themselves, not as part of the ACG scale line. Early railroad engines and cars were really small compared to the later stuff.
I notice the one Mark pictured has dummy coupler on it, or the weight has fallen off. I wish someone would photograph how they made the cab roof bracket fit the chassis without a motor in it.