The World Of Rail

Railroad Mugs

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Model Buildings Free Samples

HO Scale model buildings with information about how to build them.

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Static Grass Applicator

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Locomotive Models

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Narrow Gauge Model Track

About gauge and scale related to Ho standard and HO narrow gauge track.

H0m gauge is used to represent metre gauge trains in the HO scale. It runs on 12 mm (0.472 in) gauge tracks (which is the same as TT scale). Modern HOm trains run on realistic-looking two-rail track, which is powered by direct current (varying the voltage applied to the rails to change the speed, and polarity to change direction), or by Digital Command Control (sending commands to a decoder in each locomotive). It is a popular scale in Europe, particularly for trains of Swiss outline.

Ready to run models are widely available from companies like Bemo and D+R Modellbahn, a number of companies including, Lemaco and Ferro-suisse, also produced more detailed handmade brass models.

HOm track is also used in Australia to model the narrow gauge lines in Queensland, South Australia and extensively through out Western Australia where trains run on 3'6" track. See HOn3-1/2 scale.

Related Scales

In the same scale standard gauge trains are modelled on 16.5 mm (0.65 in) gauge track, known as HO. Narrow gauge trains are usually modelled on 9 mm (0.354 in) gauge track which is known as HOe and industrial minimum gauge lines are modelled on 6.5 mm (0.256 in) gauge track known as HOi or HOf. HOn3 is used to model 3 ft (914 mm) gauge railroads in the United States and uses a track gauge of 10.5 mm (0.413 in).

Narrow Gauge???

In case you don't know about Narrow Gauge but were afraid to ask.... In the late 1800s, railroad gauge was standardized to 4 foot, 8 inches between rails. Some US railroads had a six foot gauge back then, and it made transfer from one railroad to the other a problem.

But some railroads had another problem altogether: limited space for a right-of-way. These include logging, mining, and mountain railroads whose routes took them through tight curves, up narrow mountain ledges and through difficult forests. The easiest way to deal with it was to have a narrower gauge track. A large part of the Denver and Rio Grande Railroad was narrow gauge, for instance, because of its routes through the Rocky Mountains and its mining operations. The distance between rails would be anywhere from two to three and a half feet.

In model railroading, there are folks who specialize in narrow gauge. They denote their specialty by first giving the actual scale, and then the track width. Thus, HON3 means HO scale (1/87) using a 3 foot gauge. By coincidence, HON3 gauge is the same as the gauge of N track! And ON3 (O gauge, narrow 3 foot gauge) is the same width as HO track. Thus some narrow gauge is like using larger trains on smaller track.

No, it isn't as simple as buying HON30 trucks for your trains, and then setting up N scale track to run them. Not if you want to be scale, that is! The ties on N track are okay for N scale, but would be too small for HO. Thus, you'd first have to replace the N ties with slightly thicker ones in order to have a true scale appearance. And that's just the beginning.

Why do people get into narrow gauge? They have many reasons, but a lot are the kind of folks who get a thrill in making some things on their own. They have to make or improvise parts, since narrow gauge doesn't have the same wide support as standard gauge. For that reason, narrow gauge layouts tend to be very individual, very unique, and they have a high degree of creativity. (I've never seen a narrow gauge model railroad that was dull.) If you enjoy making your own, you might want to look into narrow gauge. (If you ever need something made and you have a narrow guage fan around, you're in luck).




TYes there is a difference between OO & HO scale,
basicly "OO" = 1/76 scale & HO = 1/87 scale.

But then it gets a bit more complicated.

To start with OO & HO are not actualy scales, they refer to the "GAUGE" of the railway line which is the distance between the rails. 
The 'Scale' is the ratio of how the size relates to reality.
For example in 1/100 scale, a table that is 1 metre high would only by 1cm high in 1/100 scale or one one hundedth of the size.

With model train sets there is a bit of a twist, "HO" refers to 1/87 scale trains and accessories running on HO gauge tracks which are 16.5mm apart. Where as "OO" is 1/76 scale trains and accessories running on HO gauge tracks which are 16.5mm apart.

 "OO" is the common size of model trains in England and "HO" is the most common just about everywhere else, such as Australia, Europe & the USA.

This is why there so much confusion, because you buy HO gauge track & turnouts (intersections) to run your OO gauge trains on, but you want OO gauge or 1/76 scale accessories such as buildings and people to suit the size of the train and carraiges. Unluckily a few of the UK manufacturers, like Hornby & Dublo, decided to market their stuff as HO/OO which is where much of the confusion stems from.

Then to add to the confusion there is 1/100 scale, which many people get confused with OO gauge and then 1/72 scale. 1/72 scale is used by some model Tank & Aeroplane kit manufacturers, such as Airfix, and 1/100 scale is commonly used for Architectural scale models.

To the uneducated eye there is not a lot of difference between these scales. There is about 3 to 6mm difference between the heights of the various scale figures. Trees, grass, plants, lights, road and many other accessories are interchangeable between the scales ( who is to say exactly how tall a tree or a lampost is and how wide a particular road should be). 

Some of the other popular model train scales are;-

TT Scale = 1/120

N Scale = 1/160 rest of world or 1/150 in Japan

O scale  = 1/48 USA 1/43.5 UK & France 1/45 Germany etc.

G scale = 1/120 to 1/25 scale

I won't confuse the situation further by mentioning the different Gauges of railways used throught out the world which give rise to so many other variations like HOe, HOn3 .....

I hope this has helped, for more info please see


What is the difference between OO and HO?

Nothing as far as the gauge of the track is concerned, i.e. gauge refers to the distance apart of the rails and not the scale size. HO and OO gauge is 16.5mm between the rails.

Scale is a different matter altogether, OO scale is 1/76th of true size or 76 times the model length equals one life size item. Another way of referring to OO scale is 4mm to the foot. i.e. 4mm on the model equals a foot in real life so therefore a six foot tall person in model size is 6 times 4mm or 24mm tall. Funny that two different measuring systems are utilized but that’s the way it goes.

HO on the other hand is 1/87th of true size or 3.5mm to the foot. i.e. that six foot person is now 6 times 3.5mm or 21mm tall.

How come two different scales use the same track I hear you say?

The 2 scales are so close that many years ago the manufacturers opted for one gauge for compatibility.

Just as an aside, at standard gauge of 4’ 8 ½” HO scale is more correct being 4.71 times 3.5mm equalling 16.49mm.

OO is actually undersize and strictly speaking should be 4.71 times 4mm equalling 18.84mm.

This actual discrepancy is catered for by people modelling in EM or P4 gauge.

Most often OO scale is off


Model Railway Gauge and Scale Guide

It is important to understand the difference between gauge and scale. Like real-world railways, the
gauge is the distance between the rails, with trains and rolling stock built for each particular
gauge; scale is the proportion that the size of the model is compared to its real-world equivalent.
The scale is normally expressed as a ratio (1:16 or 1/16) or a size (1 inch :1 foot). Sounds simple
enough? Not quite!

When a model train is scaled down the gauge is not necessarily to scale, but to
the nearest standard gauge. This means that you could have two different trains, both with the same
gauge, but a slightly different scale. In practice, this will be hardly noticeable, but it is worth
bearing mind.

In decreasing order of size, the most common model railway gauges are:

G Gauge
Variable scale
45mm gauge

O Gauge
7mm to 1ft, 1:43.5 scale
32mm gauge

OO Gauge
4mm to 1 ft, 1:76 scale
16.5mm gauge
OO is by far the most popular gauge, although the gauge is 15% under scale.

HO Gauge
3.5mm to 1ft, 1:87 scale
16.5mm gauge
The same gauge as OO, but with the smaller scale the gauge is in correct proportion to the scale.

N Gauge
2mm to 1ft, 1:148 scale
9mm gauge
Twice as small as OO gauge scale printing chart