Hello everyone and welcome to Train Talk!
Today, we are going to talk about classifying
steam locomotives into various groups, based
on the number and types of wheels they have,
also called a wheel arrangement.
During the steam era, many manufacturers produced
a wide variety of steam locomotives, most
of which were built specifically for a particular
railroad.
To make things even more complicated, many
railroads had their own systems of classifying
steam locomotives for purposes of keeping
track of them.
So, one of the best ways to organize steam
locomotives was based on their wheel arrangement.
Wheels are grouped into three types: pilot
wheels, driving wheels, and trailing wheels.
The pilot wheels help guide the heavy locomotive
around curves.
Driving wheels are the wheels that actually
move the locomotive and train down the track.
These wheels are powered by taking the pressure
of expanding steam and using it to move the
large connecting rods that are attached to
the drive wheels.
The trailing wheels help support the weight
of the fire box.
Keep in mind, not all steam locomotives have
pilot wheels or trailing wheels, and some
locomotives don’t have either.
Additionally, there are some locomotives that
have two different sets of driving wheels,
but we will get to that in a minute.
Ok, so we’ve grouped our basic types of
wheels, now what do we do?
The most used system of designating wheel
arrangements is known as the Whyte classification
system, named for its creator Frederick Whyte,
a mechanical engineer employed by the New
York Central railroad.
The Whyte system denotes wheel arrangements
by counting the number of a certain type of
wheel on both sides of the locomotive, starting
at the front and working back with different
sets of wheels separated by a hyphen.
For instance, a locomotive with two pilot
wheels, eight driving wheels, and two trailing
wheels would be called a 2-8-2.
It is important to note that when we are counting
the wheels, we are counting what is on both
sids of the engine.
So, while you can only see half the wheels
when looking at one side of the engine or
the other, we are counting wheels on both
sides, which is why this locomotive is called
a 2-8-2 and not a 1-4-1.
This locomotive, which has 2 pilot wheels,
8 driving wheels, and no trailing wheels is
designated as a 2-8-0, the 0 indicating the
lack of trailing wheels.
Well, that’s pretty much the basics of it.
In addition to these number and hyphen designations,
many wheel arrangements were given names.
Let’s go through some of the most common
wheel arrangements now.
The 4-4-0 was one of the most widely and longest
used wheel arrangements of steam locomotives
ever produced.
It was given the name “American”, because
it was really the railroads of America that
pioneered the use of this wheel arrangement.
4-4-0’s were used almost exclusively throughout
the mid 1800’s and they were still being
produced as late as the 1940s.
This is really the locomotive that most people
think of when they imagine the trains of the
old west, often adorned in bright and colorful
paint schemes and plenty of brass.
4-4-0’s were so popular because they were
quite versatile.
They could be used for either passenger or
freight service.
The bigger the diameter of the driving wheels,
the faster they were designed to go.
Today, there are a number of 4-4-0’s that
still run in tourist and museum service, the
oldest of which was built in 1856.
The 2-8-0 wheel arrangement, named the “consolidation”
was developed in the 1860s and was another
of the more common wheel arrangements of steam
locomotives produced.
According to steamlocomotive.com, the name
“consolidation” actually comes from the
consolidation of two different railroads into
the Lehigh Valley Railroad, which happened
around the same time the wheel arrangement
was first produced.
Due to their rather short drive wheels, consolidations
were limited in their top speed, so they were
often used to pull heavy freight trains.
Consolidations were produced well into the
first half of the 1900s and they were used
right up to the end of the steam era in the
United States.
Currently, consolidations are one of the best
preserved wheel arrangements of steam locomotives,
and they are among the most common seen in
operation today.
The 2-8-2 wheel arrangement was developed
in the late 1800’s and was named “Mikado”.
This name comes from one of the first orders
of 2-8-2 locomotives being built for a railway
in Japan.
“Mikado” was the english word for the
Japanese Emperor at the time.
Mikados were well balanced, multipurpose locomotives
used by many different railroads throughout
the 1900’s.
While they were primarily used for freight
service, they could be seen pulling passenger
trains from time to time as well.
Mikados, like consolidations, are a well preserved
type of locomotive and there are several examples
that still operate today everywhere from tourist
railroads to mainline excursion trains.
4-6-2 locomotives, called the Pacific, were
primarily used for high speed passenger trains
from the early 1900’s through the end of
steam in the mid to late 1950s.
It is believed that the name “Pacific”
comes from the first operator of this type
of locomotive, the Missouri Pacific, which
purchased its first Pacific locomotives in
1902.
Today, a number of Pacifics remain in preservation,
but very few of them still operate.
4-8-4s were one of the most popular wheel
arrangement of big steam locomotives.
They were named “Northern” because they
were first built for the Northern Pacific
Railroad in 1927.
These were powerful locomotives that were
built to reach speeds as high as 110 miles
per hour.
Northerns were often used as passenger locomotives,
but they also saw service on high priority
fast freight trains.
There are a number of preserved northern type
locomotives today, but very few of them still
operate.
Of the ones that do, they are primarily used
for excursion service out on the main line.
Locomotives that did not have pilot wheels
or trailing wheels were called switchers and
they were typically only used for moving cars
short distances.
Switchers came with either 4, 6, or 8 driving
wheels and were designated as 0-4-0, 0-6-0,
or 0-8-0.
In addition to standard tender engines, tank
engines also use this same classification
system.
Tank engines are noted by putting a capital
letter “T” right next to the number of
trailing wheels.
For instance, this locomotive would be classified
as a 2-8-2T.
There is one final addition to the wheel arrangement
naming system, and that is for locomotives
that have multiple sets of driving wheels,
called “mallets” and “articulateds".
These types of locomotives are complicated
enough that I want to do an entire episode
on them, so for this episode, we will just
focus on the wheel arrangements.
Basically, they follow the same system of
designating wheel arrangements except the
multiple sets of driving wheels are separated
with a hyphen.
For example, the Union Pacific’s articulated
locomotive “Big Boy” has 4 pilot wheels,
one set of 8 driving wheels, another set of
8 driving wheels, and then 4 trailing wheels,
so it would be called a “4-8-8-4”.
And this locomotive, a tank engine with 2
pilot wheels, 6 driving wheels, one more set
of 6 driving wheels, and then 2 trailing wheels
would be called a “2-6-6-2T"
Well, that covers pretty much everything.
Now let’s try to figure out what these wheel
arrangements are, and learn a few new names
too!
4-4-0 “American"
2-6-0 “Mogul”
2-6-2 “Prairie”
2-8-0 “Consolidation”
4-6-0 “Ten Wheeler”
2-8-2 “Mikado”
4-6-2 “Pacific”
4-6-4 “Hudson”
4-8-4 “Northern”
2-8-4 “Berkshire”
2-6-6-2T “Mallet” tank engine
4-6-6-4 “Challenger” Articulated
Well, we’ve covered a lot in this episode.
I hope you had fun!
There are some other types of steam locomotives
that don’t follow the whyte classification
system at all including “geared locomotives”
and cog locomotives, but we will cover those
in future episodes.
If you enjoyed the video, let me know by liking
it and leaving a comment below.
And if you’re not already, be sure to subscribe
to the channel for new videos every week.
Until next time, I’m Mike Armstrong.
I’ll see you down the line!
Thanks for watching.
