If anyone wishes to reproduce this in whole or part, would they please ask me first. G.F.

SOUTH DOWNS LIGHT RAILWAY

MINIATURE STEAM LOCOMOTIVE MANAGEMENT

• Basic Principles
• Inspection
• Lubrication
• Lighting up
• Driving
• Disposal

BASIC PRINCIPLES

It is important that all those who have the responsibility of a steam loco have a thorough understanding of the machine in their care. It is a valuable machine, it may not even belong to them, it is easily damaged through ignorance or inattention, and most importantly is only safe when handled competently. As with all machines, things go wrong with steam locos, and it is vital that the Driver knows what action to take to prevent an accident or cause further damage.

Boilers

The only thing that stops the fire from burning the copper or steel of the firebox and causing an explosion, is the water above it. It is VITAL that the water level is never allowed to drop to the point where it no longer covers the firebox crown.

On locos of 7.25 gauge or less, copper boilers are the most common, whereas 10.25 gauge and above, steel is more often used.
Copper boilers are expensive in materials - but they can out-live their steel counterparts. A typical copper boiler has flanged plates with (often) threaded stays, the whole of which is silver soldered. Fire tubes are also silver soldered in place.
Steel boilers are cheaper to build, and are (nowadays) usually welded construction of profiled plates for economy - only occasionally will a new steel boiler be made with flanged components. The steel used should always be of boiler quality, and should be stamped with identification numbers with matching certificates. For most purposes, all pressure vessels (including our locomotive boilers) should be welded by appropriately coded welders. This makes certification and insurance much easier - as well as giving the reassurance that the boiler is safe and fit for purpose. Plate Thickness used in steel boilers tends to be between 6 and 12mm - depending on the particular component. This allows for sufficient strength to withstand the pressure, and very importantly, an allowance for corrosion. Tubes are usually steel and expanded in to allow for easier renewal (again because of corrosion). Unlike normal steels, boiler steel has a very low carbon content, which promotes heat conduction - making for a free steaming boiler. In order to protect and extend the life of a steel boiler, it is common to add chemical treatments to the water (often a measure poured directly into the tender) to inhibit corrosion and promote good steaming characteristics. This may require the supply water to be analyzed from time to time to ensure the optimum chemical composition, and will vary from region to region.

The corrosion factor aside, all boilers suffer over time, and this is largely due to differential expansion. At typical working pressures, the water temperature (and therefore that of the boiler barrel) will be in the region of 150 degrees centigrade, whilst the fire can work to temperatures of around 2000 degrees. This can give you a very sharp temperature gradient on the same piece of firebox plate whilst coping with a pressure of 150psi.

With all these stresses involved, it is very understandable that insurance companies insist on a strict inspection and testing regime to ensure our boilers remain safe. Copper boilers require inspection and testing every two years, while steel boilers require the same every year. The test consists of a Hydraulic test (cold) which will normally be to 11/2 times working pressure, followed by a Steam test to full working pressure. These inspections and tests are made by an independent examiner.

There are five types of boiler in large scale locos you may come across.
1. Locomotive Type
2. Marine
3. Vertical
4. Flash
5. Briggs
By far the most common is the locomotive type. This has a conventional firebox with grate and ashpan beneath, with fire tubes to the smokebox.
The Marine boiler is also a horizontal boiler, but has a round firebox within the barrel - this means that there is not a conventional ashpan as found in the locomotive type. As in other types, fire bars are prevented from being melted from the white-hot fire on top of them by drawing cold air up through them. If ash is allowed to build up it will clog up the air passage and allow the bars to burn out. Marine boilers are particularly vulnerable to this, and so the ash must be cleared frequently to avoid this build up.
Vertical boilers were mostly used by Sentinel and DeWinton, are simpler in construction than locomotive types - and have the added advantage that they are harder to run out of water!
Flash steam or mono tube boilers are a completely different beast, and consist (often) of a single tube passing through a furnace (the fire) which has a small volume of water fed into it. Because of the massive amount of heat thrown at it, the water then flashes to steam which is used in the conventional manner. It’s a bit like a superheater but without the boiler! Most traditional Flash steam boilers require water in them all the time to protect them, but a variant being pushed recently has the tube encased in a mild steel casement which apparently prevents the tube from overheating and burning out.
The Briggs boiler is a model engineering variant of the locomotive type, not having a wet firebox, but instead having a thick flat plate crown running full from the backhead to the tube plate, with the sides, front and backplates of the firebox being dry with fire clay lining. This, in theory at least, is less efficient than the loco type, as there is significantly less heating surface area, though the Briggs boiler usually has syphons or 'water walls' fitted to protect the crown from overheating which increase the heated area over the basic design.

Safety Valves

The function of the safety valves are to protect the boiler (and therefore us) from the over-pressurising and resultant failure of the boiler. Each boiler has a rated pressure at which it has been tested and certified which must not be exceeded.
The safety Valve therefore has to vent all the excess steam the boiler is capable of generating - which when you think the boiler creates enough steam for the loco to hammer along with a heavy load almost indefinitely- is a lot of steam! Valves that are too small or failed would not be able to do this, and would allow the pressure to build until catastrophic failure occurred.
In consequence, safety valves form part of the boiler test, and should not be tampered with other than by competent persons.
There are a number of different types of valves in use from Ramsbottom type through to ‘Pop’ valves- some of which have a tapered seat and others a stainless steel ball. They all have slightly different characteristics, but all share the ability to vent all excess steam at a given pressure (working pressure) without undue rise (maximum permitted 15% over pressure) and then to re-seat.

Blowdown Valve/Cock

To keep the boiler as clean as possible and to minimise priming, it is necessary to ‘blowdown’ preferably every day of steaming. This involves getting a full glass of water, starting both injectors, and opening the blowdown valve (which is just above the Foundation Ring of the firebox) and venting the water out of the boiler at working pressure to get rid of all the sediment and rust that accumulates in the bottom of the boiler.
There are two nastynesses with this. One is that the direct venting of the boiler water at high pressure has to be seen to be believed. It should be done well away from the public (on shed) with no-one anywhere near it. The other problem is that the water level in the glass drops very rapidly - and you have to close the valve before the water disappears out of the glass.
Most blowdown valves point straight down towards the trackbed (which shoots ballast everywhere), but some locos have a horizontal discharge which could cause severe injury if it was let off by accident or the valve failed. These should have a safety cap on the discharge pipe to avoid accidents.
Some locos have a continuous blowdown fitted. This is a valve that opens when the regulator is opened, and allows a small amount of water to drain out of the boiler until the regulator is closed. This helps prevent a build up of salts and solubles that occurs when you deliver impure water into the boiler and draw off pure steam, leaving the impurities to concentrate.

Injectors

The injector is a brilliant device for using steam from the boiler to inject cold water into the boiler to keep the water level up. Logically it shouldn’t work, but it does. By using a series of very delicate and accurate cones, it exchanges temperature and velocity for pressure. They normally work from about 40psi up to about 110psi., although high pressure injectors are available that work to 150psi. Injectors must always be tested before moving off shed. They sometimes get a bit of debris in them, which will stop them from working. If this happens, run the cold water through them for a while (because you’ve just heated them up with steam) and then carefully take the cones out and blow them clean. Do not poke or prod them - the ends of the cone are wafer thin, very easily damaged, and it will not work if you bend them.
Injectors will not work if they get too hot, so if it won’t pick up, run the water alone for a couple of minutes to cool it down and then try again.
A fairly common problem - particularly with saddle tank locos- is that the injectors won’t work if the feed water gets warm, as the process relies on a temperature differential. Therefore boiler lagging is important, and the ability to drain down your tank easily to refill with cold.

Gauge Glasses

Having water ‘in the glass’ refers to the water level in the gauge glasses. These are glass (or pyrex) tubes which sit in gunmetal boiler fittings on the backhead. The tubes are held captive by finger tight nuts -top and bottom- with short sections of rubber or silicon tube for seals. The glass can crack and blow through age, shock, over-tightening or direct contact with the gunmetal seat (hence the soft rubber seals). Having a face full of steam from the boiler is most unpleasant, and so most locos are fitted with gauge glass protectors - toughened glass surrounding the tube - which contains the worst of the discharge. Locos of our size also often have cocks on the top and bottom fitting so you can shut a broken glass off. These frequently sieze through lack of use. It is therefore good practice to operate (and check) the cocks as part of your preparation procedure. That way you know it will work when you need it.
To avoid accidents, whenever you have steam/pressure in the boiler, you should always shut off the cocks and drain down the glass before removing the protectors for cleaning etc..
It should be noted that the bottom cock (that opens into the water space) should be shut off first (in an emergency) followed by the top cock (that opens into the steam space).

Blower

The blower is used to create a draught within the boiler to pull oxygen through the fire whilst raising steam, or when the loco is stationery with the blast pipe inactive.

The basic blower is a small diameter jet fed by boiler steam via a valve in the cab. The jet is positioned close to the blast pipe and pointing up the centre of the chimney. This entrains the surrounding air, inducing a draught up the chimney (and therefore through the fire tubes and fire box) which pulls air through the fire thus feeding it with oxygen and creating a hot bright fire. A typical jet will have a hole between 0.8mm and 1.5mm diameter. ‘ALICE’ has a single jet of approx 1.00mm which is quite sufficient to get the fire roaring (she is helped by her tall chimney) whereas the standard 4 has a blower ring of 4 jets of about 1.5mm. Both systems work well. Occasionally the blower jet becomes blocked with a small piece of carbon, and then needs pricking out with a piece of wire or similar (multi-jet systems seem slightly more prone to this). If a blower is working but doesn’t seem to be doing its job properly, DON’T enlarge the hole. It is much more likely that the pipe has been knocked and is not pointing perfectly to the centre of the chimney.
In future locos I shall use MIG welder tips (holes of 0.6, 0.8. or 1.0mm) for the blower jets - these are made from copper, and will unscrew for cleaning/replacement and cost pennies.

Regulator

On many locos, the regulator is a smaller version of their full size counterparts - often a slide valve in the dome operated by an internal linkage. The valve is held onto the face by a light spring and by positive steam pressure. The problem occurs when a bit of grit gets underneath the valve, preventing it from seating, when it wears to a poor surface, or when the operating linkage gets badly worn. In any of these cases, the result is the regulator ‘blowing by’ - when steam gets through even though the regulator is in the closed position. The cure is to remove the steam dome, and clean / reface the valve.
The regulator valve itself is, of course, un-lubricated in miniature locos, and in consequence is susceptible to wear.
The modern solution to this is to use Ball valves, which are available in a variety of sizes (1/2”BSP is good for a regulator) and provide a smooth, reliable and cheap regulator straight off the shelf. You must ensure that any valve you use is rated for steam - these have red or purple handles normally, and not a gas valve (which has a yellow handle). Different valves will cope differently with pressure and temperature etc..

Blast Pipe

The blast pipe is located in the smokebox, and is the nozzle through which the exhaust steam escapes to the chimney. It is a critical item, as the correct size and position of the pipe dictates the ‘Draughting’ - how well the boiler generates steam. It is positioned at a fixed point directly beneath the centre of the chimney or petticoat pipe (often giving a one-in-three angle to the chimney base) with a hole sized to give a slight constriction (and therefore back-pressure) to the escaping steam. This increases the velocity of the steam, which then entrains the surrounding air (just like the blower) creating a vacuum and pulling air through the fire again! An exhaust beat that sounds very very sharp, may well be entraining so much air that it starts to pull the fire out through the chimney, whereas a very soft beat may not be creating much of a draught at all. The smaller the blast pipe nozzle, the sharper the beat, and the larger the nozzle, the softer the beat.
Incidentally, If the smokebox door doesn’t seal properly, or there is an unfilled gap around the base of the blast pipe, neither the blower nor the blast pipe will be able to create sufficient vacuum for the loco to steam properly. Chimney aside, the smokebox should be air-tight.

A problem that has occasionally come to light is that the build-up of oil and soot on the inside of the chimney (a good sign as it demonstrates adequate lubrication) can reduce the internal diameter beyond the critical point to which the loco will not steam. This is easily cured be reaming the soot off the inside using a piece of pipe or similar, but the blast pipe should be plugged or covered to prevent rubbish from falling in and getting sucked back through the cylinders.

Valves

The steam flowing through the regulator passes down the main steam pipe or pipes, and then into the valve chests. The movement of the valve (defined by the valve gear) then allows steam into one side of the piston, whilst allowing the spent steam to exhaust out of the opposite end, and then into the blast pipe. As the piston in the cylinder moves, rotating the wheels, the valve then alters its position to control the amount and timing of steam allowed to the cylinder, finally to reverse its position allowing the piston to return in the opposite direction (thus completing one rotation of the wheel).
There are two common types of valves in our scales - slide valves, and piston valves (both inside and outside emission)
Slide valves are simpler and are more typical of industrial and narrow gauge locos. The valves themselves are usually gunmetal, slide upon the flat valve face, exposing and covering steam ports within the face, and are held tightly against the face by positive steam pressure. When you are driving a loco with outside cylinders and inside valves (so the valves are vertical and not horizontal) there is a ‘clunk’ when you open the regulator, as the valve is forced against the face. When you close the regulator, it will fall away from the face. Valves are adjusted by nuts either side, threaded onto the stainless steel valve spindle, and are set to give equal travel across the ports when moved through the valve gear cycle.
A Piston valve is made up from two pistons on one spindle travelling in unison, which pass over steam ports machined into the piston bore. The valve pistons are machined or ground to close tolerances, and are fitted with rings (often of the Clupit type) to ensure steam tightness.

Both forms of valve rely on adequate and reliable lubrication.

Cylinders

Most cylinders in our size are cast in a grey iron, which is perfectly adequate in performance, although the crust on a casting is very hard and has to be machined off requiring tungsten carbide tools. On full size locos the bores are often fitted with separate liners which are shrunk in. In our size you would probably only use liners to restore a worn bore back to specification. Cylinder covers are bolted on at both ends (the piston rod end also carries the slide bars) and these are also castings. It is these covers that are most prone to breaking in the event of a ‘carry over’ i.e. when a large slug of water gets carried into the steam pipe and fed to the cylinders. Since water is not compressible, this then tends to break out the casting as the piston travels forwards or backwards. Expensive and embarrassing. Some locos (like our King Arthur Class) have pressure relieve valves, which will vent the water out the front cover when it reaches a high pressure (like a safety valve), but before it damages the piston or cylinder.
In most instances, piston rings tend to be of the Clupit type (like car piston rings) although in smaller scales graphite packing or PTFE is often used. Again the importance of lubrication cannot be overstated. Particularly in the smaller scales, Cylinders and covers are usually cast in gunmetal. This material machines well, has good wear characteristics and doesn’t rust!

Draincocks

On the underside of the cylinders, front and back, draincocks are fitted, controlled from the cab via a lever and linkage, or steam operated. These cocks open the cylinder to atmosphere to allow the condensed steam in the cylinders that have cooled whilst stationery, to drain out - thereby preventing damage through waters’ non compressibility.
They can fairly frequently get blocked by bits of boiler scale, and may need pricking out with wire, or even removal and dismantling to clean. On a two cylinder loco, with the draincocks open, you should get four jets of steam/water per revolution of the wheels - if you don’t, the chances are that one or more is blocked, and while it is blocked, it is not protecting the cylinder.

Snifting Valves

When you are drifting with the steam shut off, the piston can tend to suck air back down the blast pipe to fill the cylinder. This is undesirable, as it may also suck ash and other debris in - which will damage valve seats and cylinder bores. Therefore some locos with piston valves are fitted with snifting or vacuum relief valves. The idea is that uncontaminated air is sucked in through these valves, in preference to ‘dirty’ air drawn in down the blast pipe.
On some locos, the valve is fitted so that gravity keeps it open, with the internal ball at the bottom. This needs a considerable whiff of steam initially, to lift the ball, and then hold it tight against its seat. Slow speed shunting is thereby made more difficult, as you need to open the regulator wider than normal to get the thing moving, and then you have to shut it quickly to stop the loco from racing off! JOHN TERRANCE has this arrangement.

INSPECTION

Before considering Lighting Up a loco, a basic safety inspection should be undertaken - the most important aspect of which is the boiler. Since the boiler contains water and steam at pressures over 100psi, failure of the vessel must not be allowed to become even a remote possibility. To this end, you should take a torch (having ensured that there is water in the glass) and make a visual inspection of the smokebox tube plate and the inner firebox, particularly all stays, tubes and fusible plugs. If any dampness or beading is found, the fire should not be lit until the boiler has been checked by a competent person. If in doubt, play safe and do not light up.
Boiler fittings should operate properly, especially shut off cocks on gauge glasses, as a glass blowing can be exceedingly unpleasant and needs to be stopped quickly.
Wheels should also be checked to ensure that flanges are not unduly worn or chipped, that wheels are not loose on axles (the paint cracks around the axle in this instance) and that spokes are not cracked. All pins, bolts and oil pots should be present and correct (particularly look at the brake gear which is often over-looked), and an eye kept out for any signs of rubbing or wear on the motion, wheels or frames.

LUBRICATION

By definition, all moving parts are susceptible to wear and tear through friction, and therefore all moving parts must either be made to withstand wear as much as possible, or must be protected by means of lubrication according to bearing type and situation.

On a steam locomotive of whatever size, there are three general types of lubrication:
Grease - normally applied via Grease Nipples, and generally found on plain bearings like Brake Cross Shafts, Bogie or Pony truck pivots etc., but on some locos also used on Main Axle Bearings, and even Valve Gear Motion.
Lubricating Oil - with a viscosity similar to that of car engine oil, this is used in the majority of areas, particularly Valve Gear Motion and Axle Bearings, and is usually applied through oiling holes leading to the bearing surfaces, or via oil boxes (or pots) flowing through small-bore copper pipe to the bearing.
Steam Oil - a very thick oil which flows very slowly (when cold) is used whenever exposure to the higher temperature of steam spaces is required. At steam temperatures other oils (like lubricating oil) get so thin and runny that they run out of the bearing very quickly, thus rendering it unprotected and causing the bearing to overheat, ‘pick up’ or wear, whereas steam oil retains a useful viscosity at these temperatures. More importantly, Steam Oil emulsifies (with the steam) so that as it passes through the valves and cylinders, it still lubricates without leaving any deposits to carbonize. In short, whereas at a pinch you can use other oils for lubricating motion for short periods, steam oil has unique properties which mean it is the only oil you can use for lubricating steam cylinders.
Steam oil is fed by one of three methods. Mechanical lubricator (usually mounted on the running plate) driven by the motion and serving the Valve Chests and Cylinders. Displacement Lubricators, most commonly used for lubricating steam brakes, but used for main lubrication on smaller scale locos. Boxes or pots - usually on motion, valve and piston rod glands.

The loco must be oiled up before going into service - most conveniently whilst steam is being raised

Mechanical Lubricator

Consists of a reservoir holding steam oil with (normally) a single or double cylinder pump immersed, which is driven via a ratchet and pawl or clutch from the valve gear motion. It is usually possible to vary the delivery of these pumps by using different holes on the operating lever. The ideal adjustment should deliver enough to leave a light film of oil on the inside of the chimney after use. Obviously it is much better to deliver too much oil than too little.
The pump feeds through a one-way valve on the bottom of the pump into the oil pipe, and then through a final one-way valve into the valve chest or into the main steam pipe just before the valve chest. The pipe should not be routed through the smokebox, as this can lead to the oil over-heating and carbonising within the pipe, thus stopping the oil flow.
The oil used for topping up the reservoir must be clean - and to this end there is often a mesh in the top of the lubricator to filter out unwanted and damaging particles.

It is always good practice to wind the mechanical lubricator 30 or 40 turns by hand prior to use, which should ensure that the valves and cylinders are lubricated from the first movement.

Displacement Lubricators

Often used as the primary oil source on smaller locos, it is more commonly used for steam brakes in 7.25” and above. This is a sealed (pressurised) vessel containing oil, with a very fine steam pipe (often with an adjusting screw) leading into the top half of the pot. The principle is that a small quantity of steam is allowed into the lubricator, which then condenses into water. The water then sinks to the bottom (being denser than oil) thus displacing a small quantity of oil that then passes down the steam pipe into the cylinder.
The lubricator will usually need refilling during the day, and great care must be taken to close off the steam supply and relieve the pressure before unscrewing the top as steam heated oil sprayed over you will burn very badly indeed.
You should open the drain tap on the bottom before unscrewing the top, unscrew the top at which point the collected water will run out, close the drain tap and then refill with steam oil before replacing the top securely.

BEARINGS

Steam locomotives use a variety of bearings, and the engineman needs to recognise the different types and know what sort of lubrication (and frequency of lubrication) they will need. . It goes without saying that bearings and water do not mix - water is a very poor lubricant! Any contamination should be removed, and the bearing then re-lubricated or grease packed.

Roller Bearings / Ball Races

On a loco built for commercial day in - day use out like our Black Five, you will often find grease nipples on almost everything, with the intention that the bearing gets a shot of grease just at the beginning of the days work instead of being oiled every hour. With this minimum maintenance in mind, commercially made Roller bearing and needle bearings are used wherever possible - particularly in high wear areas like Coupling and Con rods. One drawback with building scale loco parts with Commercial bearings is that they are over scale, making them difficult to use in all the places that one would wish without spoiling the proportions on the rod or whatever. When you feel round the motion, you should feel no play or movement in these bearings, and any movement found should be investigated.
Another drawback in practice is that grease points that only need greasing occasionally run the risk of them not being greased at all - particularly when we have different drivers every day. If in doubt, GREASE IT - at any rate there should always be visible signs of fresh grease on the bearing or joint. Loose or blocked grease nipples should be tightened or replaced to ensure that damage does not occur due to drying out.

Bushed Bearings

Steel rods running on steel pins will quickly destroy themselves, so the most common solution is to bush them with Gunmetal or Phosphor Bronze. Although sometimes referred to as ‘brasses’, brass is not suitable for bearings, and will wear out very quickly. When fitted, bushes should be an easy sliding fit, with no discernible sideways movement. Thus, any side play felt is wear either in the bush, or the pin, or quite commonly, both. Of course there must be a clear drilled oilway through the bearing to allow the bearing surface to be oiled. Very occasionally, you may find that the bush has rotated, thus blocking the oilway. Bushes are sometimes pinned to prevent this from happening.
These bearings should be lubricated approximately hourly throughout the day.

Sintered or Oil-Lite Bearings

Very similar to the above bearings, the material itself is slightly different - instead of being ‘solid’ gunmetal, these are formed out of little spheres partially fused together. The function of this is to retain oil in the gaps - thus lubricating for longer. If for any reason these get hot, they tend to leech out their oil, and will need plenty of lubrication afterwards to replace it.
These bearings should be lubricated approximately hourly throughout the day.

Plain Bearings
Where bearings appear not to be bushed at all, it may very well be that the pin (probably) has been case-hardened - thus preventing wear (as long as it is lubricated regularly). Again, there should be no discernible play.
These bearings should be lubricated approximately hourly throughout the day.

White Metal Bearings

White metal bearings are conventionally used for axle bearings and cross heads on full size locos, as well as the major rods. The bearing assemblies themselves are usually gunmetal, with a white metal inner cast in to form the actual bearing surface, which is then machined to give the required fit to the pin or axle. The principle works well until it runs out of oil, at which time it over-heats, picks up, and melts. A ‘Hot Box’ refers to an axle bearing with has overheated (it will become too hot to touch) and you will find that the axle and wheel centre is substantially warmer than the others. Draining the remaining oil and feeding it with castor oil was supposed to be a standard procedure on BR to try and cure it, but otherwise, it will need removing and re-metalling.
When oiling round, it is good practice to feel the wheel centres for heat to ensure the bearings are ok.

LIGHTING UP

After the initial inspection, there are five checks you should make with any loco before putting a fire in:
• Handbrake on
• Draincocks open
• Regulator closed
• Water in the glass
• Visual inspection of firebox and smokebox tubeplate

Additionally, check that the smokebox door is properly shut and sealing, and that the ashpan is clear.
When you are sure that the loco is fit to be steamed, place a good layer of paraffin soaked wood in the fire box, together with a ring of coal around the edges. Never even think of soaking the wood in petrol! Always use either paraffin or diesel. Put the mechanical blower on to the chimney, turn it on 6volts (slow speed) if you have the option, and put a lighted rag into the firebox, shutting the door. If the draught induced by the blower is too fierce, it will put the fire out when first lighting up on wood. Wait till it is well established before turning the blower up. The fire will consume quite a lot of timber at this point, and needs to be fed until it is hot enough to take coal. Do not rush the boiler in this process, as changing temperature too quickly puts unnecessary stress onto the firebox and tubes that can expand faster than the barrel.
If the loco has a manifold shut off valve, ensure it is open, together with any valves to the pressure gauge.
Assuming that you have all other valves on the boiler closed (including the locos own blower) you will start to make steam in 15 - 25 minutes, during which time you can take the opportunity to oil up the loco.
When pressure reaches around 40psi, turn on the loco blower and remove the mechanical blower, as the loco should now be well able to look after itself. Steam Pressure will now keep climbing (assuming you are looking after the fire) allowing you to test both injectors at around 50psi. If an injector fails, it should be rectified before the loco goes into traffic. Standard injectors have an operating range of between 50 and 100psi (although good ones will perform better than this), but some locos (the Bagnall ‘Alice’ and ‘Britannia’) run at higher pressures and so their injectors work between 75 - 150psi.

In short, to be safe, all the equipment on the loco should be working properly, and be checked before going into service. If something doesn’t work, or doesn’t work properly, the loco should only be used if a competent person judges that it is safe to do so. We have the Hymek to pull passengers if there is a problem, so the inconvenience is small.

DRIVING

Assuming the locomotive is fully prepared, and you have checked water levels, fire etc., you may get ready to pull away. You must first check you have been given the staff or token, make sure you have the road, and are given the ‘Right Away’ before taking the brakes off. Always check behind you to make sure your train is ready.
In Full Gear with the draincocks open (until the cylinders are warmed through) open the regulator gently until the loco starts to move off, being ready to close it quickly if it starts slipping. Locos with superheat are deceptive, as the steam carries on heating and expanding post regulator - so even after you close the regulator the loco will drive away for a short while before using the steam already in the passages - therefore even more caution is required when pulling away, or you will do an imitation of ‘Blue Peter’!
When you have picked the train up, you can then continue to open the regulator to pick up speed, notching up the reverser as appropriate. ‘Notching up’ cuts off the steam to the cylinders earlier and earlier in the piston travel - the advantage being that you use less steam (because the steam that is allowed into the cylinders is able to expand as the pressure drops), and the loco is able to run smoother and faster. Less power is transmitted to the wheels when notched up (just like a high gear in a car) and therefore when pulling onto a gradient you may need to put the loco back into full gear to get to the train up!

When driving, you must always bear in mind that you may need to stop quickly, and therefore you must remember that although a light engine can come to a halt rapidly, a loaded train may simply push the loco a long distance - particularly whilst going down a gradient or when the rails are wet.

In the same way that the cylinders start off cold and require warming up before they work normally, the steam brake cylinder is also not very efficient when cold, and may need ‘feathering’ to warm it before hurtling into the station.

When coasting or ‘drifting’ it is good practice to have the regulator open a crack to let a wisp of steam into the cylinder at each stroke. This prevents a vacuum forming in the cylinders (see snifting valves) and debris / cold air being drawn down the blast pipe.

When coming to a stand, always leave plenty of room or come in slowly as you are bound to misjudge it occasionally, and running into the back of another train or the buffers is as unacceptable in 10.25 gauge as it is on the full size.

NEVER LEAVE A STEAM ENGINE UNATTENDED. If you need to go to breakfast, or go to the loo, ask someone (appropriate) to supervise it. Never walk away and leave a loco to look after itself.

Priming

Priming is the phenomenon that takes place when water is ‘carried over’ from the boiler into the cylinders. The first indication that the Driver gets is when the exhaust beat of the engine softens and it starts to rain! Apart from the drop in power when this happens, water can cause serious damage to an engine and must be avoided.
At the first sign, the drivers should open the draincocks and close the regulator till the normal harder exhaust beat returns.

Priming is caused by a number of factors:
• Impurities in the water - often seen as dirty water, scum or foam in the glass. Regular blowing down, boiler washouts and water treatment will help prevent this.
• Having the water level too high in the boiler
• Opening the regulator too much too quickly
• Opening the regulator whilst the safety valves are ‘blowing off’.

The last three causes are because there is insufficient ‘steam space’ (and therefore too great a pressure drop) to allow conversion from water to steam at a sufficiently fast rate - leading to ‘unconverted’ water passing through the regulator. You are letting out steam faster than the water can turn into steam to replace it.

………..very similar to pouring coca-cola too quickly - it all frothes up, whereas if you pour it a little slower, it remains calm……

DISPOSAL

At the end of the day comes the task of disposing. On a full size loco it is a hard, dirty and tedious finish to the shift. Many of the jobs are identical on 10.25, but made much quicker and more bearable by the smaller size.
First, the boiler should be topped up with water- either to the top nut (if it is being steamed the next day for instance), or ‘hydraulicked’ - filling until the injector drops off by itself (this helps prevent corrosion, and also allows for leakage).
If the fire is being shovelled out at all, this should be done. It is good practice to leave at least some fire in so that the boiler cools down more slowly, thereby reducing the stresses involved. At least, the fire should be raked through, which will drop a fair amount down into the ashpan.
The ashpan itself is next, and that should be completely cleared, remembering to damp down the hot ashes if there is any risk of fire. The Dampers must then be closed so as to discourage any cooling airflow through the boiler. Again, the idea is to allow the boiler to cool down as slowly as possible.
With the blower cracked on (so as not to get covered), the smokebox should be shovelled and brushed clean. The combination of water and ash create a strong acid, which will badly corrode the steel of the smokebox if left.
On a full size loco, trimmings are removed from syphon oil boxes (so as not to waste oil lubricating a static engine), and a lid is put over the chimney (again to discourage air-flow through the boiler). The engine should then be left with dampers and firehole door closed, with the gauge glasses shut off and drained down, and with the steam manifold and blower shut off. Similarly, the draincocks must be left open, the loco in mid gear, the handbrake applied, and the foot plate swept down.

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