Railroad terminology

Tortoise - The Tortoise, a brand name of Circuitron Inc., is an under the table mounted, slow motion switch machine that employs a stall motor design, meaning that when the motor reaches the end of travel it "stalls" and holds that position until the circuit is broken or the device is switched in the other direction.

Bus Wire - is a typically larger gauge conductor or wire that carries track power around a layout.  Short feeder wires of smaller gauge connect between the bus wire and track.  The bus wire can be as heavy as 14 gauge or even 12 gauge stranded or solid, and is sized according to the current carrying capacity needed based on the load and length of run.  Feeder wires need to be of a smaller gauge to allow easy connection to the track without being to cumbersome.  Because the feeders run is very short, often 12-18 inches or less the gauge need not be as heavy to handle the load.

Taps and dies - are cutting tools used to create screw threads in solid substances including, but not limited to, metal, wood, and plastic. A tap is used to cut the female portion of the mating pair (e.g. a nut). A die is used to cut the male portion of the mating pair (e.g. a bolt). The process of cutting the threads in a hole is called "tapping" the hole. The process of cutting with a die is called "threading" (or sometimes "chasing", although "chasing" as a technical term can have restricted meanings)

Wetting Agent - A wetting agent is a substance that lowers the surface tension of a liquid.  In Model Railroading a wetting agent is commonly used when applying a glue and water mixture to track ballast to cement the ballast in place.  Without the wetting agent, the water and glue mixture will bead up on top of the ballast pile rather than soaking in to saturate it throughout.  If the glue mixture fails to penetrate through the ballast the ballast will be loose and cause problems later.  Drops of dishwashing detergent or some isopropyl alcohol are common wetting agents in modeling.

Track ballast - forms the track bed upon which railroad ties are laid. It is packed between, below, and around the ties.  It is used to facilitate drainage of water, to distribute the load from the railroad ties, and also to keep down vegetation that might interfere with the track structure.  This also serves to hold the track in place as the trains roll by. It is typically made of crushed stone.

The model railroading community is divided up into different scales (think neighborhoods) and gauges, which describe not only the size of the equipment (compared to the prototype) they run, but also how wide the track would be if it were a full sized railroad.

Wikipedia has a nice graph explaining the different scales & gauges here.

Common scales & gauges include:

"G Gauge" - a collection of scales including  1/20, 1/20.5, 1/22.5, 1/24, 1/29 and 1/32 designed to run on the the track originally created by the LGB company in Germany. The track width itself is the same for all the scales, with the differing width representing either normal gauge (1/32nd or #1 scale) or some form of narrow gauge track width (20in, 2ft, 30in, 3ft...). These are the scales normally seen in Garden Railways. Several of the above scales are being formalized with their own letters, the most common of which is "F" at 1/20.32.

O scale - 1/48th scale (1/4 inch to the foot). Originally the scale of Lionel & American Flyer with it's three rail AC power "tinplate" track, O scale is making a rennaisance as the baby boomers age and discover that larger can be easier to handle. Companies such as Atlas O and MTH are producing high-quality O Scale locomotives and equipment that generally comes in two versions - three rail AC and two rail DC. 

S scale - 1/64th scale. Formerly home only to the American Flyer tinplate collectors, S scale, like O scale, has been making a rennaisance recently, and probably for the same same reasons - HO just seems a little small for some people.  S Scale is fortunate in that many of the diecast automobiles you can buy at stores like Wal-Mart are 1/64th scale. Accurate and detailed S scale equipment is now being produced by companies such as Des Plaines Hobbies.

HO Scale - 1/87th scale. The most popular (by a lot) model railroad scale, HO scale has been around since just after WWII.  The "HO" originally stood for "Half-O" although it isn't quite that.  It is generally the easiest scale for which to find anything you are looking for.  A recent development in HO scale is that of the Free-mo modular system, which allows large, interesting layouts to be assembled by many indviduals.

N Scale - 1/160th scale. Showing up in the late 1960s/early 1970s, N Scale is approximately half the size of HO scale, which made it popular among people who either had a limited amount of space or wanted to run prototypical length trains without having to build their layouts in an aircraft hanger. Like HO, there are many many manufacturers of quality train and scenery components in this scale. N scale was popularized by the introduction of the N-Trak modular standards, which allowed different people around the world to build small sections of railroads and then hook them all together at a meet. Fantastically large layouts are able to be assembled, temporarily, in this manner.

Z Scale - 1/220th scale. A recent newcomer, manufacuturers such as Micro-Trains, American Z Trains and Marklin are introducing new locomotives and cars at regular intervals. Within the last two years Micro-Trains has produced US prototype "hood" style diesels such as the GP35 and the GP9 - and an SD40-2 model is on it's way as well. People have created entire Z scale layouts inside of briefcases. Like HO and N scale, Z scale also has a modular standard known as Z-Bend. There were multiple Z-Bend layouts at the 2008 National Train Show.

Now we've gotten scale out of the way, let's talk "gauge."

Often, when talking about model trains, people will say that they model in something like "HOn3" or "On30"  or such. What the "nXX" defines is the gauge they model within that scale - normally narrow guage. Narrow gauge prototypes were normally (but not exclusively) set up in rugged regions where the ability to take up less space and turn tighter curves were prized. Common narrow gauge widths included 24 inches (such as the Maine "two footers"),  and 36 inches (or 3 feet, common out west). Since HO scale track is nearly a perfect 30 inches in O scale, it is now being commonly used in On30 (narrow gauge, 30 inches) modeling - a quickly growing scale and gauge. If you see a single digit, like a 2 or 3, it indicates feet, where two digits, such as 24 or 30, indicate inches.

Fn3 is 1:20.32 scale equipment being run on G gauge track, to emulate 3 foot narrow gauage. It is somewhat unique in that it's a scale that generally does not have a standard gauge - only narrow gauge.

What happened to this thread?  I was just noodling around today and found this old post by Joe.  Only two replies?  I wish more could have been contributed since I'm an old newbie and want to learn and know more about our hobby.  I have questions about a lot of stuff but to find out, I have to do research on-line, in books, in magazines, etc.  It would be nice to be able to go to one location and find a comperhensive glossary to learn "everything I ever wanted to know about prototypical railroading as well as model railroading.  Many terms/words I may not even know how to spell so it might be difficult/time consuming to research them on-line, in books, or in magazines.  Some of us might not have the expertise or wherewithal to research what's needed or desired. 

Since I'm helping my 14 year-old grandson enjoy his budding interest in the hobby, I need to be able to answer or explain many of the already mentioned terms and more satisfactorily.  As you can imagine, he is very observant and inquisative.  So here are my tuppence worth of questions and terms I like and need defined and/or described and that will be of help to other newbies:

MU - both in the prototype and what issues are encountered or must be considered in modeling?

Hostler

Roller bearings

Dreadnought ends

Dead man switch

Steam dome

Frog

I realize that it's for safety but why do trains blow their whistle/horn long, long, short, long at every grade crossing?  Is it for the letter Q (dah dah dit dah) in morse code?  And if yes, why Q?  What about other signals?

Why do steam engines emit large amounts of steam from both cylinders as they begin rolling from a stop?

More should respond to this informational thread.

I realize that it's for safety but why do trains blow their whistle/horn long, long, short, long at every grade crossing?  Is it for the letter Q (dah dah dit dah) in morse code?  And if yes, why Q?  What about other signals?

Here's what I found on Wikipedia.

– – o – 1. Trains or engines approaching public highway grade crossings shall sound the horn for at least 15 seconds, but no more than 20 seconds before the lead engine enters the crossing. Trains or engines travelling at speeds greater than 45 mph shall begin sounding the horn at or about, but not more than, one-quarter mile (1,320 feet) in advance of the nearest public crossing. Even if the advance warning provided by the horn will be less than 15 seconds in duration. This signal is to be prolonged or repeated until the engine or train occupies the crossing; or, where multiple crossing are involved, until the last crossing is occupied. 2. Approaching tunnels, yards, or other points where railroad workers may be at work. 3. Passing standing trains.

1. MU is an acronym for multiple unit.  One of the big advantages of diesel over steam is that since diesels are actually diesel-electrics (exception being the diesel-hydraulic units), multiple engines can be plugged in to each other to function as one locomotive with a single crew.  In the days of steam, it was necessary to have a separate crew for each steam engine in the train.

2. Hostler is a person whose job is to move locomotives around the engine facility.

3. Roller bearings are bearings that have an inner and outer polished "race" with round polished rods or "rollers" between the races.  he front wheel bearnigs on your car are probably tapered roller bearings.

4. I know what a "dreadnought end" is but I'm not sure how to define it or post a pic to illustrate it.

5. "Dead man switch" is an electrical switch that is spring loaded off.  The operator has to maintain pressure on the switch to keep it energized.  If the operator dies, faints, or is otherwise incapacitated so that pressure is off of the switch, the machine will stop.  These are often used on machinery where an operator could loose a hand or finger, or be crushed.  They will be located so that the operator has to have both arms clear of the machinery to make it work.  In the case of the modern locomotive, they will have a button that needs to be pressed every few minutes or so to keep from turning on an alarm.  It is designed to make sure the operator has not fallen asleep while the train is in motion.

6. Steam dome is one of the domes on top of the boiler of a steam engine.  As water is boiled to make steam, the steam will rise above the level of the water in the boiler.  The steam collects in the steam dome, and the valving in the locomotive will take steam off the top of the steam dome and send it to the cylinders to operate the locomotive.

7. Frog- is part of a switch or as model railroaders also call them turnouts to diferentiate them from an electrical switch.  If you look at a switch or turnout from above, you will see a casting at the point where the two or in the case of a threeway switch three routes diverge.  If you look closely at it, it looks kind of like a frogs foot or foot print.  Therefore it is called a "frog."

Why do steam engines emit large amounts of steam from both cylinders as they begin rolling from a stop?

When steam locomotives start out after sitting for some time, the residual steam in the cylinders and steam lines cools and condenses into liquid water.  Since water is an incompressible liquid, cylinder cocks are provided to allow the water out of the cylinder as the piston moves to the end of its travel in the cylinder, to prevent damage to any of the metal parts of the engine:  cylinder, cylinder head, piston, or any of the drive or valve gear.

Typically, the engineer controls the cylinder cocks from the engine cab, usally by steam operated controls.  So it's his discretion whether they should be opened.  If he has made short stop after running, and it's not a cold day, he will probably leave the cocks closed.  If there is any question, he'll open them to preserve his machine.

When the cylinder cocks are open, part of the power of the expanding steam is exhausted through them instead of contributing to the power stroke.

It's not just for newbies either. I have been in the hobby for about 35 years and I still have to ask every once in while when a "railroad" term comes up in operations. I give a strange look and ask, "whadda ya want me to do??"  Guess the point here is never be afraid to ask a supposed simple question. 

Steve   

Thanks Don and everyone else who contributed. 

Great explanations and help.  The reason I ask is that my grandson and I want to model the SP in late 40s early 50s.  We've watched videos on YouTube or 4449 and we went to the Train Festival in Owosso last July and he asked me about the steam blasting from each side as the Daylight engine begins to move.  I had no idea but now I do. 

Thanks again and please continue asking and answering.  I'm sure I will have some more very soon.

George - L.A. General Shops