What does the designation 2-4-4-2 on a train engine mean?

Question

What does the designation 2-4-4-2 on a train engine mean?

Answer 1

It's the number of wheels on each truck.  So a 2-4-4-2 engine has two front wheels on an axle, then two axles with two wheels each pivoting together on a truck, then four more wheels on another truck, and finally two trailing wheels on a single-axle truck at the rear.

Answer 2

Wheel arrangement.

2-4-4-2 refers to a two wheel 'pony' truck, or leading truck, a set of four drivers, then another set of four drivers, then a two wheel trailing truck.

This was not a common wheel arrangement.  Usually, locomotives with two 'engines' under one boiler were 'articulated', with the engines able to swivel on a pivot point so that they could better traverse curvature.  The 2-4-4-2s built by the Baldwin Locomotive Works were not articulated, however, but were two 'rigid' engines under one boiler.  This is called a "duplex."

There is detailed information on this subject in my 360 blog post of March 10, 07.  Just click on HOGHEAD and follow the trail.............

Answer 3

two small wheels right behind the cow-catcher (known as "pilot wheels"), four driving wheels - four more driving wheels and two trailing wheels behind the last drivers.  The designation refers to the type engine, in this case, it would be a "Mallet" -type locomotive.

Answer 4

This is part of The Whyte System of locomotive classification.  Whyte originally had a 2-number system, the first digit was for unpowered leading wheels, and the second digit was for powered axles.  So, a 2-4 engine had 2 leading wheels and 4 big powered wheels.  As engines got bigger, a set of unpowered wheels had to be added to the rear to support the firebox, so a third digit had to be added.  For example, a 2-10-4 engine had 2 leading wheels behind the cowcatcher, 10 big powered wheels, and 4 trailing wheels.

The 2-4-4-2 means that there are two sets of powered wheels, powered by separate steam cylinders.  This engine would be articulated, meaning that the front set of wheels could pivot independently from the rear wheels, so the huge engine could negotiate curves.  This engine has 2 leading wheels and 4 powered wheels in front, and then another set of 4 powered wheels, followed by 2 trailing wheels supporting the rear of the engine.  Most US steam locos had sets of 6 or 8 powered axles, so maybe this is a European engine - I'm afraid I am more of a diesel guy than steam.

Answer 5

Alex B is correct as far as he goes. The first axle designation of 2 is a "steering" axle and for additional weight support of the engine. The next two numbers -4-4- are indeed four axles but are not on trucks, they are the drive wheels powered by the engines power plant. The last number -2 is again an additional truck supporting the weight of the engine and acting as a "steering" axle

Answer 6

That the # of the engine , If you will notice on another train It will have 4 different # good luck