What is it that defines a Pacific locomotive from an Atlantic locomotive Is it wheel arrangement cylinder arrangement or something else.?

Answer 1

Steam locomotives are classified by wheel arrangement. the type known as an Atlantic had the wheel arrangement 4-4-2 Four inthe front, Four drive wheels (powered) and one trailoing rear axle (tenders are not counted in the Whyte system, as it is called) . the Pacific (probably so-called as it is larger, in keeping withthe ocean code thing, is a 4-6-2, Two front axles, Six drive wheels, and one rear axle which may or may not be (Boosted) with a rear axle booster. the famous (Blue Comet) of the CNJ and the British Mallard (clocked once at l27MPH) were of this type. both the Atlantics (coded as E-6 on the PRR) and the Pacifics ( Class K on the PRR) were primairoy Passenger locomotives and hence high-geared. The Hudson class of locomotive was a 4-6-4 and these were big time on the NYC not used on the Pennsy.