How a steam locomotive works

Recently I found this very nice and descriptive article written by Robert S. McGonigal

Unlike modern machines, the steam locomotive - which underwent few fundamental changes in 125 years of development - openly displays many of its parts. This mechanical honesty has long captivated onlookers and invited study, but many still wonder just how it all works. In fact, entire books have been devoted to the subject.
There are two basic areas of activity on a steam locomotive: the boiler where steam is made, and the engine (cylinders, rods, and driving wheels) where steam is used. The essential action of any steam engine, stationary or mobile, is that of steam under pressure (200-300 PSI for most locomotives) entering a cylinder-piston assembly and pushing against the piston as it expands in an effort to reach normal atmospheric pressure.

Making steam
The production of steam begins with the fire, which rests on grates at the bottom of the firebox. Hot gases rise from the firebed to the upper portion of the firebox, or combustion chamber. On a coal-burning locomotive, the build-up of ash is controlled by shaking the grates so the ashes fall to the ashpan below. At the end of the run, the ashes are dumped from the ashpan hopper.

The gases move from the firebox forward through an array of pipes called flues, or tubes, in the main part of the boiler, which is filled with water. The best way to envision how the inside of a cylindrical boiler looks is to imagine a bundle of drinking straws in a glass (only the glass would be resting on its side, not upright).

Heat from the gases in the flues brings the water to a boil, making steam. The steam rises to the top of the boiler and is collected in the dome, where the throttle regulating the flow of steam to the cylinders is typically located. (More modern locomotives had their throttles located in the smokebox.)

The dry pipe carries the steam from the dome forward to the superheater, an improvement that came into wide use around 1910. The superheater is simply an arrangement of tubing that conducts the steam back through extra-large flues, where it is heated to a higher temperature, before returning it to the steam delivery pipes leading toward the cylinders. The use of superheated, as opposed to saturated, steam brought a 25-30% increase in the efficiency of the steam locomotive.

As a pressure vessel, the boiler must be carefully managed, lest it blow up. Safety valves are designed to automatically let steam escape if the boiler pressure gets too high. The top of the firebox, called the crown sheet, must be covered with water at all times. If the water level falls below the crown sheet, the fire's heat can weaken it, causing the pressurized boiler to explode. Devices like the water gauge, or glass, are provided in the cab for the crew to monitor water level. Low-water alarms are found on newer locomotives.

Using steam
From the steam delivery pipes, the steam enters the valve chests (one on each side). The valves, by moving back and forth, allow the steam to enter the cylinders at times when it can usefully push the pistons. When the steam has done its work, the valve has moved to let it escape, at considerably diminished pressure, to the blast pipe in the smokebox.

The motion of the valves is derived from the crosshead, which moves according to the rotation of the driving wheels and also is connected to the valve gear. The engineer works the valve gear with the reverse lever, so named because it is used to control the locomotive's direction of travel as well as the timing of valve events.

Once the steam has pushed the piston, a series of linkages - piston rod to main rod, main rod to side rod, side rod to driving wheels - converts the piston's back-and-forth motion to the rotational motion of the wheels. Counterweights placed opposite the point of attachment of the rods keep the driving wheels balanced.

The earliest locomotives had one pair of drivers, while the largest number of wheels driven from a single set of cylinders was six pairs. Because of their great size or the need for flexibility, many locomotives had two engines - two sets of driving wheels, each powered by a set of cylinders.

To help guide it into curves, many locomotives also had a small set of wheels (either one pair or two) in front beneath the smokebox called a lead or pony truck. Similarly, a two- or four-wheel trailing truck was placed at the rear of the locomotive to support the firebox.

There were many variations of wheel arrangements depending on a locomotive's intended service and the era of its construction.

Exhausting smoke and steam
After the steam is used in the cylinders, it enters the smokebox via the blast pipe. As the exhaust steam blasts upward toward the stack, it provides draft for the fire by drawing the gases through the flues and into the smokebox. (Fresh air enters the locomotive through open spaces at the base of the firebox.) The mingled exhaust steam and gases then leave the locomotive through the stack. It's the relatively violent escape of steam from the cylinders that produces the familiar chuff-chuff sound.

As the exhaust is dependent on spent steam leaving the cylinders, provision must be made for exhausting the hot gases, or smoke, when the engineer has the throttle closed. A group of small steam jets called the blower is located in the smokebox for this purpose.

The smokebox also serves to collect partially burned particles of coal from the fire that have passed through the flues. When these accumulate to a depth sufficient to obstruct the flow of gases, some are picked up by the swirling exhaust and thrown out the stack as cinders.

Fuel, water, incidentals
Fuel (coal for most steam locomotives, oil for some, wood in the early days) and water are carried in the tender, a separate car semi-permanently coupled to the locomotive.

Coal was originally fed to the firebox by the fireman with a shovel, but locomotives of any size or modernity are fitted with mechanical stokers. Some locomotives intended for short-haul use were built without tenders; they carry a limited amount of their own supplies and are known as tank engines.

Water is added to the boiler by two injectors (one for the engineer, one for the fireman), or an injector and a feedwater heater. An injector uses steam to force water into the boiler, heating the water as it does so. Water from the injector is still cold compared to that in the boiler, so the check valve where it enters the boiler is placed forward, so as not to cool the water near the firebox. More efficient feedwater heaters, fitted to most big steamers after the mid-1930's, use exhaust steam to preheat the water.

Other accessories found on steam locomotives are safety features that have been carried over, albeit in altered form, as standard equipment on today's diesels.

The headlight - and other electrical appliances such as marker lights and cab lights - is powered by a small steam-driven turbo-generator. Earlier headlights were oil-burning.

The pilot, which was gradually reduced in size from the "cowcatchers" of the mid-19th century, pushes aside obstructions. To accommodate brakemen, locomotives engaged in lots of switching often had footboards instead of pilots, but these have been outlawed on diesels for safety reasons.

Sand for traction is stored in one or more sand domes, or sand boxes as they're sometimes called.

The whistle, mounted on the dome of many locomotives, could be placed in several different spots. Mechanical bell ringers replaced the simple action of a crewman pulling on a cord attached to the bell.

Scales in Model Railroad

Scales in model railroad are described by letters N, HO, S, and O. Each letter describes the ratio of the model's size to its prototype, which is what model railroaders call the real thing a model is based on.

Following six scales are currently manufactured in the market. Most popular is HO (pronounced aitch-oh). HO scale models are 1:87 proportioned, which means one foot on the model represents 87 actual feet. An HO scale 40-foot boxcar is about six actual inches long.

Scale Proportion
Z 1:220
N 1:160
HO 1:87.1
S 1:64
O 1:48
Gn3 1:22.5

The second popular modeling scale is N scale with a ratio of 1:160, it's a little more than half the size of HO scale. An N scale 40-foot boxcar measures just over three actual inches long.

Many model railroaders use the terms "scale" and "gauge" interchangeably, but they really mean different things. Scale, as we already learned, is the ratio of the model to the prototype. Gauge is the distance between the rail tracks. Standard gauge on North American railroads is 4'-8½", but many railroads, especially in the 1800s, were built to narrower gauges. Three feet between the rails was the most common narrow gauge in the United States. To indicate narrow gauge models we use a small "n" and the gauge of the track prefaced by the scale. For example, an HOn3 layout is one where the buildings, figures, and trains are HO scale, but the rails are spaced three (scale) feet apart.

Indian Railway

The first railway on Indian sub-continent ran over a stretch of 21 miles from Mumbai (former Bombay) to Thane.

Image courtsey: Indian Railways official website

However, the formal inauguration ceremony was performed on 16th April 1853. 14 railway carriages carrying about 400 guests left Mumbai's CST (then called as Victoria Terminus aka V.T.) station at 3.30 pm "amidst the loud applause of a vast multitude and to the salute of 21 guns."

Today, Indian Railways runs around 11,000 trains everyday, of which about 7,000 are passenger trains.



Indian Railways is a multi-gauge, multi-traction system.
Broad Gauge (1676 mm)
Metre Gauge (1000 mm)
Narrow Gauge (762/610 mm)

Train Terminology

· Couplers: The knuckle-shaped devices at the ends of locomotives and cars. The "horn-hook" style was developed several decades ago by the National Model Railroad Association to encourage mass-produced HO scale equipment. The "Rapido-style" coupler is the de facto standard for N scale. In recent years, however, more manufacturers have been offering their stock equipment with more-prototypical looking "knuckle"-style couplers, such as those first made popular by Kadee.
· Drivers: The large wheels on a steam locomotive connected by side rods.
· Flywheel: A turned, solid-metal cylinder mounted in line with a model locomotive's motor that smooths out the motor's rotating motion to the drive train.
· Rail joiner: A small metal clip that joins two sections of rail together.
· Rerailer: Section of track that guides wheels onto the rails.
· Scale: The proportion of a model in relation to its real-life counterpart.
HO ("aitch-oh") scale is the most popular model railroading scale, with a proportion of 1:87, or 1/87th of actual size.
The second-most popular scale is N (1:160).
Large scale can range from 1:32 to 1:20.3, with 1:22.5 the most popular. All large scale trains use the same track gauge.
Other common scales in North America are O (1:48), S (1:64), and Z (1:220).
· Tender: The car immediately behind a steam locomotive that carries fuel for the firebox and water for the boiler.
· Throttle: The speed control of the locomotive; in the model world, a potentiometer controlling a voltage regulator.
· Truck: The frame assembly under each end of a car or diesel locomotive that holds the wheelsets.
· Wheelset: The wheel-axle assembly that fits into the truck. Most trucks have two or three wheelsets, depending on the type of car.

Model Trains

Model Trains have been around for years and it is called as world's greatest hobby. As with any hobby, the obvious answer is because it's fun! It is also a hobby that can last a life-time. Many people in the hobby started when they were kids and it stayed with them.

Following is what I read on website of National Model Railroad Association

History
Railroads reflect the times they operated in, and vice versa. Building a model railroad leads to learning about the real things. Railroads embraced the full range of history. In the United States, railroads were major factors in, and were greatly affected by, the labor movement, race relations, the rise and fall of the Guilded Age and its robber barons, and so on. Railroads were, and are, equally important in the histories of other countries.
Basic Carpentry and Electrical Skills
If you've never sawed wood or stripped some wire, You Will! Building a model railroad requires these skills. You might think that they are "hard" -- they aren't, you just need to start down the path. You'll be surprised how easy it is to pick them up!
Economics
Railroads are economic entities. They move raw materials and manufactured goods from place to place. The patterns of these movements are all driven by economics.
Modelbuilding
This is pretty straight forward! After all, we are building a Model Railroad. There are a whole range of skills that you'll develop over time.
Artistic Techniques
Building scenery and weathering cars, among

others, all require a bit of an artistic touch. We can learn that "less is more" (for instance, sometimes just a bit of weathering on a car is all that's really needed). we can learn that we don't always need a perfect rendition of something, sometimes all we really need is to give the impression.

How To Research
As you get more interested in model railroading, you might decide to build more accurate models. To do this you will need to research "the real things". You'll want to know exactly how something was built or used. To do that you'd need to locate documents or pictures. All of this takes research.
Logical Thought and Planning
From novice model railroader to Master Model Railroader (MMR), logical thought and planning are important. Everything from figuring out the right steps for building a kit to designing a layout to developing an operating plan for your railroad all require logical thought and planning.
3D and Spatial Visualization
When you decide to take on scratch-building and kit-bashing, you'll quickly learn some of these skills. We often have to visualize how things will finally look, or how they will go together, long before they are done.
Develops Manual Skills
This is pretty self-evident. To build a model railroad requires some manual dexterity and skills. You can't be "all thumbs" to build one. And if you think you are all-thumbs, you'll quickly discover that you are not all thumbs.
Basic Engineering
Model Railroads themselves require a bit of engineering to construct. We don't want the benchwork to collapse or the electrical wiring to burst into flames! This is self-evident. But we can also learn a bit of engineering by studying the prototypes for the models we are building; Why are bridges build this way and not that? Why did the railroad go this way instead of that way? How does an engine work?
Geography
Railroads don't exist in a vacuum. They go through the landscape. There are mountains and plains, forests and rivers, towns and cities. Model railroading can develop basic undstandings of all of these geographic features. Furthermore, if you decided to research and model a specific real railroad you can learn a lot about the specific geographic regions where that railroad operated.
The Internet and The Web
You can even learn a lot about The Internet and how to make and run web sites. After all, we put together this web site! But the best part of it all is that you are not forced to learn much. You can derive as much, or as little, education from the hobby as you want. After all, sometimes we just want to have fun!
Social Aspects
Model Railroading can be a very social hobby.
It's a great way to meet new people.
There are clubs and associations (such as the NMRA) that you can join. These clubs run the whole range, from swapping stories to teaching skills to each other, to actually building and running a permanent model railroad.
There are model building contests.
It's also a great excuse to travel! You can go on rail-fanning trips, go to conventions and shows, or to visit people you've met.
Model railroading appeals to people in all walks of life. If you find a group of model railroaders, you'll find doctors and lawyers, engineers, shop keepers, business people, military folks, mechanics, carpenters, artists, atheletes, and politicians. Young and old, rich and poor. And it is fun.
It Takes Time
One of the big concerns today is that we're a culture of "instant gratification". Model Railroading is anything but instant gratification. You can get things up and running quickly, as we hope to show you in these pages.
But you can also then go back and work on things some more, spend more time. You can perfect your skills over the course of years. And as you perfect your skills, you go back and look at the things you did in the past and say "it was good then, but I know I can do better now"; what was great two years ago is barely acceptable last year, and this year it's sub-standard.
Model railroading is an activity of constant improvement and learning. From that, we often learn that the true gratification is not in attaining the goal, but the journey we take to get there.
Model Railroading Is Not Just For Men!
Some folks think that model-railroading is a "guy thing". Perhaps a long time ago it was. But this is the twenty-first century and those stereotypes are pretty much gone. Or at least they should be!
One NMRA division holds a "build a kit" clinic at its yearly show. This clinic is aimed at young children and their parents. The idea is to show them that "it's not hard". Someplace between 1/3 and 1/2 of the attendees are girls, mothers, or grandmothers. So it's obvious that you don't have to be male to be interested in model railroading!
The NMRA has a Master Model Railroader (MMR) program. It takes dedication and a lot of hard work to become an MMR. To become an MMR requires demonstrating skills across the entire spectrum of the hobby. There are 4 women MMRs (here's an interview with Mary Miller, one of the NMRA's MMR's).
Model Railroading is not just for Geeks
Finally, some people may be a bit uncomfortable about "adults playing with toy trains" or may be worried about what their friends and relatives might say. Who cares what they think? But just to set your mind at ease, there are many celebrities who are (or were) also model railrailroaders, such as
Winston Churchill
Tom Brokaw
Phil Collins
Joe DiMaggio
Walt Disney
Michael Gross, the actor
Ed Dougherty, the professional golfer
Merle Haggard
Tom Hanks
Elton John
Michael Jordan
Ricardo Patrese, the Formula-1 race car driver
Frank Sinatra
Joe Regalbutto, the actor
Bruce Springsteen
Rod Stewart
Donald Sutherland
Mel Torme
Neil Young, the rock star. He's also a part-owner of Lionel...

It's Fun!
In case you missed it, it's fun!