Driving tips for a miniature steam locomotive

Driving

Stafford steam engine Gentoo running at about 4 mph

'Gentoo' running at about 4 mph. Photo taken at the Pinewood (Wokingham) track by Mike Palmer of Station Road Steam.

If you have completed the firing up process as detailed on this website your Stafford will have a fully banked fire burning brightly in the firebox, plenty of water in the boiler, between 90 and 120 psi showing on the pressure gauge, and you will know that everything is ready for your first drive around your chosen track. However, if you are like me, you may be a little bit nervous about your first run so here are four tips to consider before you set off:

1) Always wear safety glasses when driving to prevent hot smuts or ash from the funnel getting into your eyes. I personally know of two people who ended up at the hospital and narrowly avoided quite serious damage to their eye as a result of not wearing any eye protection.

2) Don't fixate on the Stafford's controls. Always keep looking ahead at the track as depending on where you are running there may be all sorts of hazards to watch out for. You don't want to run into something or go too fast and end up derailing your loco.

3) If you start out with a good fire, water, and steam levels the Stafford will easily manage 1/2 a mile pulling a loaded passenger train without needing any coal or water to be added. So if you are sensible and starting your first run without any form of train behind you the Stafford will probably be able to go right around your track and back into the station, where you can then stop and sort out the coal and water again.
With practice at driving will come the confidence to take care of the loco's coal and water needs whilst "on the move".

4) Despite anything you may have read elsewhere the controls of the Stafford still get too hot to hold after a few hours of running, so I would advise using a small piece of rag in your hand to insulate you from the hot metal controls while driving. You could use a glove, but it's hard to find one thin enough to let you work the controls and a piece of rag is much cheaper to throw away when it gets dirty.

The next section is all about driving the Stafford class of locomotive, but if you only want to see the summary of my driving tips at the end of this page then please click here.

Basic Driving Skills.

With the Stafford ready to start driving take a last look around to make sure that everything you want is safely onboard and that the track is clear. Make sure that the regulator lever is in the closed position (fully to the right), the cylinder drain cocks are open (lever fully forwards towards the boiler), move the reversing lever fully forwards, and then release the handbrake. Have another quick check that the track ahead is clear and that no one is about to try to climb aboard your train, and then if you have a whistle fitted give a short toot to warn anyone nearby that your train is about to move. Now gently open the regulator (moving the lever towards the left) and your Stafford should start to move forwards. If you have a calibrated speedometer fitted to your driving truck you can take a quick look to see how fast you are going, but if not you will need to relate your locos speed to that when you are walking. For your first runs a "safe" 4 to 5 mph will probably suffice, which is about a fast walking pace.
With the loco moving steadily you will be able to keep the regulator in a fixed position and then move the reversing lever back two notches on its quadrant, "notching back", which will stop the steam from entering the cylinders well before the pistons reach the end of their strokes and save the amount of steam (and thus water and coal) that the loco is using. You probably won't notice any difference in the way the Stafford moves when you notch back because the steam will continue to expand in the cylinders and push them throughout their full stroke. You will also be able to fully close the steam blower control valve because now that the loco is moving the exhaust steam blasting up the funnel will provide ample draught to keep the bright fire burning. Finally, after about thirty seconds to a minute of running you can close the cylinder drain cocks (lever fully back) as the cylinders will have been heated enough by the steam to prevent more condensation forming inside them. Try to do all of these actions smoothly, and don't forget to keep looking at the track ahead. You should only need a quick glance downwards to find each control, and then return to looking for any hazards that may be about to get in your way.
As the saying goes "sit back and enjoy the ride" as you are at last driving your steam locomotive, but don't forget that it takes quite a distance to slow up or stop so you need to plan well ahead. Every so often take a look at the sight glass to see what the boiler water level is doing, although you will probably see the level sloshing up and down so that you need to "take an average position" to decide what the level really is. You don't need to do anything about the water level unless it is well below 1/2 full, so you will probably be able to complete a lap of your track without needing to add water. When you are on a straight section of track try opening the regulator a little bit to increase speed, and then close it a little to feel how quickly the loco slows down again (later you will find that it takes very much longer to react if you have a loaded train attached). All too soon you will probably be back at the station and you will need to stop and sort out the fire and water.
To stop the Stafford all you need to do is fully close the regulator, and then wait. Eventually the loco will coast to stop; the skill comes in stopping in the right place every time regardless of the load you are pulling. As the loco slows down to about 2 mph you may consider moving the reverser fully forward again as this will give you more (and smoother) power if you find yourself stopping early and need to open the regulator a bit to reach the point where you want to stop. Once stopped, make sure that the regulator is fully shut, then move the reverser back to the centre (stop) position and wind the handbrake on. You can now attend to the fire and water without having to concentrate on driving the loco.
Having just completed a lap of the track the fire should be burning very brightly and producing lots of steam, so you will find that the boiler pressure will start to rise because the loco is no longer using the steam to move. To stop the boiler pressure rising so far that the safety valve opens you should use an injector to add water to the boiler until the level is once again between 1/2 and 3/4's full. The operation of the injector is covered in the controls section of this website; but don't forget that the sequence is, water on, steam on, fill boiler, then steam off, water off. You will see that as the water fills the boiler the boiler pressure will start to drop because the fresh cold water is cooling the boiler and thus the boiler is making less steam. As the boiler is filling you can add more coal evenly across the fire, and if you need to add a lot of coal you should probably open the steam blower slightly to create enough draught to start the new coal burning. While adding the coal keep an eye on the water level if you are still using the injector as you don't want to overfill the boiler with water. With coal and water added all you need do is wait a couple of minutes until the boiler pressure is about 90 psi again and the fire is banked up and burning brightly and then you can set off for another lap of the track. That's pretty much all there is to basic driving, so just enjoy yourself until you feel confident enough to start tending the water and fire whilst on the move.
For the first few laps just keep an eye on the water level; as if the fire goes out it's just an inconvenience, but if the water level gets too low it's potentially dangerous. If you aren't sure about the water level just stop the Stafford and sort things out while you are stationary (and if other drivers have to wait a few minutes they'll understand that you are still learning to drive your loco). While driving you can also practise using the regulator, especially if you have hills on the track. Always try to build up the speed a bit before you start climbing the hill and then let the speed reduce as you climb so that, if you get it right, you arrive at the top of the hill at the speed you want for the next bit of track. Speed control is a very useful skill to gain, especially if you intend to pull heavy passenger trains as you can very easily start spinning the Stafford's wheels (and probably end up getting stuck) if you try to increase the speed of a train significantly whilst on a hill. Likewise on downhill sections you will need to close the regulator a bit (or even fully when you have a heavy train behind you) to stop the Stafford from picking up excessive speed. As you practice the aim is to be very smooth on the regulator; and to always try to conserve energy by accelerating smoothly and gently, letting the speed drop back steadily as you climb hills, and most importantly anticipating any downhill section or stops so that you don't go too fast or fail to stop in the correct place. Another point to make about speed is that industrial 4 wheeled steam engines, on which the Stafford is based, were never intended to run at high speeds. They were designed to pull loads slowly, and to help them to go round very tight curves they had short wheelbases. You will notice that when driving your Stafford it may pitch (the front and back bounce up and down) quite a lot if the track is bumpy, something that the "main line" steam locomotives multiple wheels helped to prevent. Driving slowly will give the Stafford a safe ride across uneven track, so learn where the bumps are on your track before you start to increase your speed. I find that the Stafford is very happy pulling passenger trains on smooth sections of track at about 6 to 8 mph, and running light engine I've even seen 11.5 mph on a long smooth straight but that seems rather scary and too fast for comfort.
If while driving the Stafford "light engine" (only the loco and you on your driving truck) you find the boiler pressure starting to drop don't worry, just open the steam blower valve a little bit to get the fire burning brighter. Running light engine does not make the Stafford work very hard at all, so you won't use much regulator (and thus steam) with the result that there may not be enough exhaust steam going up the funnel to keep the fire burning brightly. Once you start pulling heavy passenger trains the Stafford will start to work harder and you will only be using the steam blower while stopped in the station.
Don't forget to take the opportunity while stopped in the station to top up the water level in the saddle tank (adding the water treatment as necessary), to add some more oil to all the moving parts, and to add more steam oil to the mechanical lubricator if the level is getting low.

The Stafford steam locomotives fire grate.

The next thing to get comfortable with is firing. As said before the ideal fire is one that evenly covers the entire grate area to a depth where the top of the coal is just a little above the bottom of the firebox door sill. If you look at the photo here you can see that the Stafford grate assembly also has a backplate fitted with its top level with the centre of the firebox door (the door is visible as the opening in the large cover plate on the right). If you also remember the photo at the top of the controls section of this website you will know that the firebox door is less than half the width of the grate. So when you add coal to the fire you will need to push it about in the firebox with your shovel to ensure that the entire grate area is evenly covered with coal (and thus the fire). This is not as easy as you may think for two reasons. First because you cannot see into the firebox very well (if at all when driving the loco), and second it is easy to push coal over the grate backplate.
If you fail to keep the grate evenly covered with coal you can end up with it all burning away where it was thinnest, which easily happens in the hard to reach corners. You will now have a hole in the fire which lets the cold air from under the grate flow very easily past the fire and into the fire tubes to the funnel. This cold air will not heat the boiler water, and you will probably quickly run out of steam. The answer is to make sure that you use the shovel to spread the coal all over the fire, but sometimes this problem may occur (especially if you let inexperienced drivers borrow your loco). If the problem does occur the first indication is often audible as you will hear an almost musical "low note" as every cylinder stroke exhausts up the funnel. I suspect that this is caused by the exhaust steam being able to easily pull more draught through the hole in the fire and up the funnel, but whatever the reason it is a useful warning that you need to do something quickly to sort out the fire.

The result of over coaling a Station Road Steam Stafford model steam loco

Over coaling was mentioned previously, and this photo taken when the grate assembly was removed for cleaning shows the result of doing so. In their determination to make a good deep fire, or simply in an effort not to let a hole develop in the fire, the driver on this occasion has added too much coal and managed to push it over the grate backplate. This is waste of coal as it will not burn in the bottom of the firebox; but worse, if too much coal is pushed over the backplate it could start to block the fire tubes in the boiler. The backplate reaches up to about the level of the middle of the two larger diameter fire tubes, and its purpose is to create a space between the fire and the boiler end so that the hot fire gasses can easily flow into all of the fire tubes (on its way to the funnel) to heat as much water as possible in the boiler. As Robert Stevenson found back in the days of the historic Rocket locomotive, the more fire tubes you have in your boiler the more steam you can produce. So if you over coal and start to cover, or block up, the fire tubes you will seriously limit the ability of the boiler to create steam. In extreme cases over coaling is as bad as under coaling, so the art of firing is probably the most difficult to acquire skill to acquire.

Improving your Driving Skills.

The first, and most important skill to acquire, is to be able to operate the injector to add water to the boiler while driving the loco. There is no difference in the way you operate the injector but you have to get used to operating it without constantly looking for the water overflow or watching the water rise in the sight glass as you really need to keep watching the track in front of the loco. To start with try operating the injector on a section of track were you can see some distance ahead, for example on a nice long straight, because you can then afford to take your eyes off the track for a short while. I know that I keep stressing the need to look ahead, but it is from personal experience. In the past I've been rammed by other drivers who were looking down at their engine instead of looking ahead to see me stopped at a signal, and if you look at the "Problems" page of this website you can see what happened when I first tried operating an injector while driving. On that occasion I failed to see a piece of building debris that was knocked beside the track and ended up well of the rails.
As you become comfortable with using the injector while moving start to think about when is the best time to use it. These times are when the loco has been working hard but then eases up, for example at the top of a climb or when slowed by signals or track features such as points or tight curves. The fire will be burning very bright producing more steam than the loco now needs, so adding water to the boiler will cool things down a bit at the precise time that you no longer require the excess steam (or power). By the time that you next need power the new water will have been warmed by the hot fire and the loco will be ready for more hard work. The only time you may encounter a problem with this injector technique is if the loco is stationary (as at a red signal) and then you attempt to start off again with the injector operating. If you try this you will almost certainly find that the injector stops working when you open the regulator, so you would have to turn off the injector steam and restart the injector.

Clinker from the firebox of a model steam engine

Now, if you have been running your Stafford for an hour or more you may find that to keep the boiler pressure up to even 80 psi you are having to use a really strong blast of the steam blower. A cursory look in the firebox door will probably show a bright fire and you may be puzzled as to why you just can't seem to raise enough steam to run the loco. The answer is almost certain to be a build up of clinker on the grate.
If you have read the article on coal available from the "firing up" page of this website you will know about the formation of clinker and why it occcurs, but now you need to deal with it. This photo shows pieces of clinker that have been removed from a firebox. You may notice that it consists of all sorts of non flammable impurities from the coal that have melted, and then having found their way downwards to the cooler layer of the fire sitting on the grate they have fused together into solid lumps. Left alone this clinker will form a solid layer (like a carpet) over the grate and stop air getting to the coal on the grate to let it burn properly.
There is no way to stop clinker from forming, so all you can do is try to limit its affects by regular raking of the fire. Your rake will need a pointed end that can reach between the bars of the grate, and the aim is to break up the clinker layer so that as much of it as possible falls through the bars of the grate into the "ash pan" underneath. Unfortunately as you rake the clinker to break it up you will also break up the much softer coal, so you need to be careful not to go to far and end up without a fire !
With Gentoo and coal from Signal Fuels this raking needs to be done about once an hour when hauling passenger trains at Pinewood, but you will need to see the problem for yourself to determine when it is affecting your Stafford as the coal and driving style will all affect the clinkers formation.
Once you have raked out the clinker you will probably have to add a lot of coal to restore the fire to its correct level and use a lot of steam blower to "light up" all the new coal. There will also be a lot of ash in the bottom of the firebox that you should shovel out (via the air inlet) and dispose of so that the fire can breathe properly.

If you have mastered all of the above you are probably ready to start pulling passenger trains for public running, where you will find that keeping the train ready for "instant departure" without any real breaks is a really pleasant challenge. Public passenger running is the reason why I now drive a locomotive rather than my traction engine, as to put it simply I get bored just driving about for no purpose but relish the challenges of the Pinewood tracks very busy public running days.
The key to keeping your Stafford ready for action at all times is to think ahead and anticipate what the engine will need. If you think back to when you were firing up you will remember that it took quite a while to get a good hot fire burning, and even when you started to use the steam blower it took several minutes to raise the boiler pressure from 40 to 100 psi. Steam engines are slow to react when you want more of anything, but conversely they can appear to run out of steam pressure very quickly. Consider the worst case where you have just pulled a loaded train around the track and then you stop in the station for ten minutes due to a holdup of some sort. When you first stop the fire should be burning brightly and there should be a good head of steam in the boiler. If you have been looking after the engine during the run you may have plenty of water in the boiler and plenty of coal on the very hot fire so when the train stops, if left alone, the boiler pressure will probably rise and the safety valve may open. You don't really want this to happen, so once stopped you can open the fire door a little (about a 1/4" or 6mm at the latch end) to allow some cooler air to pass through the fire tubes and help reduce the amount of steam being raised. If possible you can also add water to the boiler and coal to the fire, both of which will reduce the amount of steam the boiler creates. However, you need to think ahead to when you want to move off again. If you just sit there and wait until you need to depart the fire will have died down, and even though the boiler pressure may still be showing 100 psi the boiler will not be producing steam, so as soon as the regulator is opened the boiler pressure will start to drop. As previously mentioned it will now take quite a while to get the fire hot to produce the steam you require, and all the while the train is moving you will be using even more steam. In the worst case you will simply run out of steam and the train will stop moving. To prevent this you need to think ahead. While the train is stopped, and the boiler pressure seems to be high, you will still need to use the steam blower to keep the fire burning nicely and thus everything hot and ready to create more steam. Only practice will really improve your skills, but in time you will learn how to anticipate what you need to be doing. It really is a bit of a balancing act with some things being hard to see. An apparently bright fire may just be a thin layer of bright coal on top of a layer of ash (or clinker), so you need to decide when to rake the fire (but don't do that too often or you will simply drop the good fire into the ash pan). Likewise an apparently good head of steam may just be the residual steam after the last run, while in reality a cool fire is not actually producing any more steam. As they say "practice makes perfect" and anticipation is the key; don't react to a situation but plan ahead to keep the locomotive in a stable condition.

Braking heavy loads.

If you are driving "light engine" on most tracks you will find that simply fully closing the regulator will give you enough braking to descend any gradient. However occasionally, and especially if you are pulling a loaded passenger train, you will probably require more braking. The only standard option on the Stafford class locomotive is to use the handbrake but this is slow to operate as it takes a lot of turns to wind it on or off. The optional vacuum brakes will be mentioned later, but there is one other "trick" you can use to slow the train which I learnt from fellow traction engine drivers. Note: This will only work if your Stafford has the early style of cylinder draincocks fitted (rotary operation). If your Stafford has the later type of cylinder drain cocks (linear bar operation) then the internal ball valve will lift to relieve the "vacuum" being generated in the cylinders and little braking effect will be produced.
If the regulator is fully closed and the train is still picking up speed you can move the reversing lever much closer to the centre position than where it is positioned for normal running. As you approach the centre position you will feel the braking effect working, and you can control the amount of additional braking you get by altering the position of the reversing lever. The closer to the centre position the greater the braking effect will be. There are no notches to lock the reversing lever in place, but you can hold the lever with your hand and control the trains descent of quite severe gradients (or slow a train entering a station) in this fashion. Of course it is no substitute for vacuum brakes operating on every axle of a passenger train, but it does work and I find it more controllable and faster using than the Stafford's handbrake.

The operation of the vacuum braking system is covered in detail in the "controls" section of this website, but the basics are repeated below. Don't forget that the Stafford's vacuum braking does not operate on the locomotive, but only on any trucks or carriages that it is towing that are fitted with vacuum braked axles. You can also read about the modifications I have made to my Stafford's vacuum braking system in the Modifications / Functional section of this website.
The operation of the vacuum braking system is much easier if your driving truck (or carriages of the train) have a vacuum limiting valve fitted. A vacuum limiting valve sets the maximum vacuum level that can be created in the train brake pipe (normally 15 inches of Mercury) in the same way that a safety valve sets the maximum boiler pressure. If you don't have a vacuum limiting valve fitted then you will have to be very careful when operating the vacuum ejector steam valve to not create more than 15 inches of vacuum because if you aren't careful you can end up in a situation where the train brakes become stuck partially on, as explained below:

If you simply open the vacuum ejector steam valve and create a vacuum it is probable that you will end up with more than 20 (or even 25) inches showing on the vacuum gauge. When the vacuum brakes are next operated the vacuum in the train pipe is released and the vacuum in the train reservoirs will apply the brakes. To release the brakes you need to create a vacuum in the train pipe equal to the vacuum in the reservoirs, but if you boiler pressure is now lower you may find that you cannot recreate that original level of vacuum again and the train brakes will now remain partially applied. If a vacuum limiting valve is fitted (set at 15 inches of Mercury) then the ejector will always be able to create sufficient vacuum to fully release the train brakes regardless of the boiler pressure or how you operate the controls.

Assuming that the train is properly connected up and that there are no leaks you will need to set up the controls before you are ready to start driving. Initially make sure that the vacuum brake operating lever is in the up (Off) position and then open the ejector steam valve about a turn and watch the vacuum gauge. It will take a time to create the vacuum as initially all the train reservoirs will be empty, but after a while the gauge should reach the required 15 inches. If it doesn't do so you may need to look for leaks in the system, brake valves that are not actually closed (on the Stafford or possibly the guard's van) or reservoir vacuum relief valves that have been left open. Once you have an indication of about 15 inches the vacuum limiting valve will prevent the level increasing any further and you can partially close the ejector steam valve to a position just sufficient to maintain the vacuum. If you don't have a vacuum limiting valve then you will need to control the steam flow to the ejector to manually control the vacuum level (or you could end up with stuck brakes as explained above). Once you have a stable vacuum level, apply the vacuum brakes by fully opening the vacuum brake control on the Stafford and the vacuum gauge should drop to zero very quickly. It may even be worth checking each truck or carriage at this point to confirm that the brakes are actually engaged.
Now comes the tricky bit. Move the Stafford's vacuum brake lever back into the closed (Off) position and ensure that the ejector steam valve is only open a tiny bit. The aim is to find the least possible ejector steam control valve opening that will pull the vacuum back to the required 15 inches in a couple of seconds. You may need to apply the brakes and then release them several times to get the valve opening correct. Once you have the ejector steam valve set, and provided that you don't let the boiler steam pressure vary too much, you are ready to drive the train without needing to operate the ejector steam control valve.
If you want to stop the train using the vacuum brakes you simply close the Stafford's regulator, and then operate the vacuum brake control to apply the brakes. However, if you only want to slow the train then you only partially open the vacuum brake control valve. As you feel the brakes start to act, move the vacuum brake control lever back towards the closed (Off) position a little bit. There is a position between On and Off where no more air will be let into the trains vacuum brake pipe to apply the brakes any harder, but the steam ejector will not be able to create any more vacuum. If you then need more braking force move the control lever towards the On position and then back to the mid position when the brakes are working hard enough. To release them, move the lever all the way back to the Off position and within a couple of seconds the steam ejector will recreate the vacuum to release the brakes. It reads like a juggling act, but in practice it isn't as hard as this text makes it seem.

The final challenge.

The final skill to develop is to be able to fire the loco while on the move. So far you will have been able to operate the Stafford's controls and use the injector with only quick glances away from the track, but adding coal to the fire while on the move may be harder than you think. To start with the Stafford does not carry any coal onboard so the coal supply will have to be on your driving truck. The result is that you have to scoop up coal from somewhere below your knees, then get it through the firebox door and spread evenly onto the fire while the loco and you are swaying along the track, and all the while your hands are not on the locos controls and you are also trying to look ahead to ensure that you don't run into something (or pass a stop signal). Thankfully this is a skill that generally isn't necessary as the Stafford can normally run far enough to get you back to a stopping place to add more coal, but it is a very useful skill to master for those rare occasions when you can take the loco out for a long nonstop run.
There isn't much advice to be offered on this topic, other than the obvious one that you will need to work out how to open and close the firebox door with your coal laden shovel. It just takes practice to be able to do the firing quickly so that you can get your hands back on the controls, and eyes on the track, as soon as possible. I also wouldn't advise trying to fire the loco while travelling at high speed, but it ultimately depends on the nature of the track. My personal best nonstop run to date with Gentoo has been about 45 minutes, but by then the loco probably deserves some oiling and your body may well need a chance to stretch out.

Summary.

To summarise the most important points of this page:

1) Always add coal and water in a "little and often" fashion.
2) If possible add water to the boiler as soon as possible after the loco has been worked hard, i.e. when you have just climbed a hill.
3) Use all the controls smoothly and gently. Vicious use of the regulator will probably just spin the wheels (which gets you nowhere), and over tightening the steam control valves may damage their valve seats leading to steam leaks.
4) Spend as much time as possible looking where you are going and not at the controls. You don't want to run into anything !
5) Try to anticipate what the engine will require so that you don't to have to react to a situation, but have planned ahead to be ready for what is about to happen.