Which Gauge

If you have any comments on this page please feel free to add them in the comments below.It could be you are looking to build or buy a locomotive, but don’t know which gauge would suit you. If that is the case, there are a few considerations. Most common gauges are 3.5” and and 5”, however 2.5” and 7.25” gauge are also used all over the country. This article refers to gauges used primarily in the UK.

What does my local Model Engineering Society (MES) use?
There is no point in building yourself a 7.25” locomotive only to find your nearest useable track is a five hour drive away (unless you are very dedicated!). A bit of googling will soon find your local MES, most of which have a couple of different gauges of track to enjoy. Most common are the 5” and 3.5” gauges, however both the larger and smaller sizes have a devoted following. What matters most is how far you are willing to travel. Some tracks are raised, and some are ground level. You will need a suitable driving truck to suit. Some are available that can be quickly converted to run on either.

Can I transport it?
Some MES have local storage which allows you to keep your engine onsite (which when you get above 5” gauge becomes a very attractive proposition). However most will require you to transport your locomotive and often a riding trolley to the track. If this is the case you will need to consider your transport. Very broadly, most 3.5” gauge will fit in the boot of a standard sized saloons, a small 5” gauge will probably require an estate or van. Something the size of a 5” Britannia will almost certainly need a van or similar. However you have other things you may need to consider as well, such as the transport of your riding truck, tools, coal, and for some tracks even water supply. This soon takes up space. A transport box is handy to prevent your locomotive from rolling around. And getting damaged in transit. Some people fit a board with rails inside their vehicles to help assist with the security while on the move. Don’t forget enough space for wet weather clothing and a flask of tea!

Can I lift it?
A smaller 3.5” gauge locomotive will almost certainly be a one person lift (although you should still take care not to exceed your abilities, especially if you have any health conditions). If you are considering a larger gauge you will need to ensure you have assistance to lift it into and out of your vehicle at both ends of your journey. This can either be another person, or even more safely, suitable lifting equipment. Some MES have the ability to offload your locomotive straight onto a steaming bay or transport platform. At home you will need the ability to transport your locomotive from your storage or workshop. If access to your workshop is restricted then it may be a good idea to consider a smaller gauge.

Can I afford it?
Whether building or buying the general, obvious, rule is that the larger the locomotive the higher the cost to buy. Running costs do not differ greatly between locomotives (for example the increased coal use of a larger locomotive does not represent a vast increase in cash outlay) but a bigger boiler, and therefore a bigger lump of copper, can drastically increase purchase or manufacture costs. Generally the more complicated the locomotive the more costly the castings.

What do I want to use it for?
If you wish to pull multiple passengers 5” gauge is probably the smallest you should consider. Smaller gauges are usually perfectly capable of pulling one or two passengers, sometimes more if built and driven well. A Narrow gauge locomotive such as a Sweetpea may be more suitable as they tend to have more power for a given gauge due to the increased size of their firebox, boiler and cylinders.

Do I have the tools?
If you are building a locomotive you need to consider that larger gauges will have larger castings (specifically wheels). The throw of your lathe chuck will dictate the size of the castings you can turn. A lathe such as a Myford ML7 can just about turn a 10” diameter. Anything beyond this size will require outsourcing. The largest wheels you will find in 5” gauge are probably the Stirling Single, with a diameter just under 9”. Once completed most components are much smaller, and a larger lathe is seldom required. A locomotive will need regular maintenance and misbehaving components may need servicing or repairing, however this can usually be achieved using modest tools (although a lathe is almost essential for some tasks).

Ease of operation
Although the larger the gauge the greater the difficulty in transporting it, the inverse is often true with regards to running and manufacture. A smaller locomotive means more fiddly valve-gear to make. Smaller controls in the cab can be more difficult to see and operate, especially at speed! A smaller firebox means smaller shovel and coal, with the associated difficulties that raises. When you are leaning over a long tender this can become even more of an issue.

Storage
You locomotive will need somewhere dry with good airflow to store it. Although a heated area is nice, most important is the ability to prevent moisture build up. Rapid changes of temperature encourage moisture to form and thus the dreaded rust. Some people put a filament lightbulb into the firebox, as a modest wattage keeps the temperature gently warmed and stable. Covering with a blanket can slow down temperature changes. A larger locomotive will need more space to store, and if you choose a smaller gauge you can store more of them…. It also makes them easier to sneak past your spouse when the collection gets larger.

Narrow Gauges
If you wish to have a larger locomotive but are limited in available tracks it could be worth considering a Narrow Gauge locomotive. A narrow gauge locomotive in 5” gauge is larger than a standard gauge locomotive modelled in 5” as it is scaled down less. For example a Standard Gauge GWR Pannier Tank in 5”, such as LBSC’s Pansy, is roughly 1:11.3 scale. A Narrow Gauge Sweet Pea in 5” Gauge, scaled as if from the common 2 foot narrow gauge, is roughly 1:4.8. This means the boiler and firebox can be larger, which makes for an easier to run and more powerful locomotive.