Here I draw a Winchester and Western GP9. Drawing develops an eye for detail. GP9s are very basic locomotives, and a great locomotive to practice your skills.
As you draw GP9s for different railroads, you will find them to be virtually identical, however, to catch the true essence of each railroad, your eye for detail will begin to train itself to minor, sometimes major, differences between railroads and eras of the locomotives.
An immediate spotting difference is whether or not the locomotive has dynamic brakes. This Winchester and Western GP9 does not. Railroads such as Lackawanna, Southern Pacific and many others placed some orders with dynamic brakes and some orders without. Dynamic brakes appear as a blister above the engine room doors on the mid-section of the engine.
Late model GP9s have a single fan over each set of grills. GP9s such as this Winchester and Western unit have the dual fans.
Through the years, details change on locomotives. Railroads move horn locations, strobe lights get added, steps get painted in visibility colors. The more you draw, you will begin to spot the era a locomotive is from.
As you draw, you will spot more and more features. Every next time you draw, you will find that you are looking at each detail placement and paint variation even more closely. Enjoy drawing trains.