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© 2002 Roundhouse Eng. Co. Ltd.
A "live steam" engine is one which is actually driven by steam which has been produced by heating water until it boils, just like the real thing. This is quite different to an engine that has the outward appearance of a steam loco but has an electric or clockwork motor driving the wheels.
Water is heated inside a sealed container (the boiler) until it boils and produces steam. It is kept boiling while ever steam is required. Because this process is contained within the boiler, the pressure of the steam increases to a pre-determined limit and it is this pressurised steam that is drawn off as required to power the cylinders.
Yes, provided it is used correctly. A safety valve is fitted to the boiler to prevent the steam pressure rising above its normal operating level. On ROUNDHOUSE models, this is 40 psi (pounds per square inch) which is about 2.7 bar. When the steam pressure reaches this level. the safety valve opens and allows excess steam to 'blow off' to atmosphere. Both the operator and any spectators must be aware the engine is very hot when being operated and emits very hot steam both through the chimney and the safety valve.
In the larger scales and full size locomotives, coal is the most common fuel used, and some full sized loco's also use oil.
In models, you have the choice of Butane gas, coal or spirit (meths or alcohol). ROUNDHOUSE standard locomotives are all fired by butane gas which is the simplest method of heating the water. The gas is stored in a special tank mounted on the locomotive and fed, via a gas regulator valve, to a burner mounted either below and outside the boiler (externally fired) or inside a tube (flue) which passes right through the boiler from one end to the other (internally fired). Whichever the method, when ever the burner is lit it is heating the water to produce the steam. The rate at which steam is produced is controlled by the gas regulator. Turning it up increases the heat at the burner and thus the amount of steam produced whilst turning it down has the opposite effect.
ROUNDHOUSE do not produce any coal or spirit fired locomotives however, we do work closely with two other manufacturers who do. Visit our Special Locomotives. page for details of these.
It is passed from the boiler through a regulator valve and down to the cylinders. In the cylinder, it pushes a piston from one end to the other, first one way then the other. The piston is mounted on a rod (piston rod) which is attached by a special swivelling joint (the crosshead) to a second rod, (the connecting rod) which in turn is connected to the wheel or crank. As the piston is pushed backwards and forwards, it causes the wheel to rotate.
The steam has to be sent to each end of the cylinder in turn and the used steam must exhaust up the chimney. This is taken care of by a valve in the valve chest mounted either on top or at the side of the cylinder. It must also do it at the right time on every stroke of the piston and this is accomplished by means of the valve gear.
The amount of steam passing to the cylinders is controlled by the steam regulator.
There are numerous valve gears, most of which are named after their designer, Walschaerts, Baker, Hackworth and Stephenson are some common types.Some are outside valve gears and have all their working linkages clearly visible, as with Walschaerts and some are inside and are hidden from view between the frames of the engine. Whatever the type of valve gear or size of loco, they essentially do the same job of controlling the flow of steam to and from the cylinders at the correct time. This is known as the 'valve events'. They also allow the engine to run in either direction by shifting the valve events by 180 degrees.
Most current ROUNDHOUSE 'Classic Series' loco's are fitted with a simplified Walschaerts valve gear and changing from forward to reverse can be accomplished manually by moving a reversing lever in the cab or by radio control from a distance. Hackworth valve gear is found on the 'Charles Pooter' model which is also reversed by means of a lever in the cab.
Locomotives in the 'Basic Series' are fitted with slip eccentric valve gear. This is a much simpler mechanism comprising an eccentric driven by a pin on the locomotive wheel which in turn drives a rod connected to the valve spindle (one for each cylinder). The drive pin locates in a curved slot in the eccentric and allows the valve events to move 180 degrees to give forward and reverse running. Changing direction is achieved by manually moving the locomotive for one wheel revolution in the desired direction. This sets the gear for that direction of running untill moved again manually in the oposite direction.
There is a simple routine to preparing a loco for operation on all but one of the ROUNDHOUSE models.
The loco will run for around 30 minutes on one boiler filling and during that time, you have full control over starting, stopping, speed, direction and steam production. At the end of a run, after the gas tank is empty, the process can be repeated.
Certain ROUNDHOUSE locomotives can be fitted with a water top up system and hand pump so that you can keep topping up the water level in the boiler as it is used. In this way it is possible to keep the engine in steam for long periods.
Radio control is a standard option on all ROUNDHOUSE 'classis series' locomotives. This gives full control of stop, start, speed and direction from a distance. Standard two channel radio control equipment is used on either the 40 MHz FM or 27 MHz AM wavebands depending on the country being supplied. One channel operates the reversing valve gear and the other operates the steam regulator. A radio controlled locomotive is supplied complete with transmitter and batteries are fitted.
The 'basic series' locomotives can be fitted with radio control by the owner using a fitting kit that is available as an accessory. On these models, because they are fitted with slip-eccentric valve gear, the r/c is only operative on the steam regulator to control stop, start and speed. Reversing, in this case, still has to be done manually.
Like any machine, regular lubrication is very important and is relay the only ongoing maintenance needed. Periodically, a general check round for loose screws or nuts and simple adjustment to cylinder glands (adjustable seals round the moving piston and valve rods) is required due to the constant heating up and cooling down of the engine.
Insulated wheels are fitted as standard on certain models and are an optional extra on others, but not 'basic series' models, so you can operate ROUNDHOUSE steam locomotives on the same track as your electric trains without shorting out the system.
Because a working steam engine exhausts a certain amount of water and oil from the chimney, track cleaning may be required a little more frequently but this does not normally cause a problem.
Although more involved than gas or spirit firing, it is well within the capabilities of most people to learn the art of coal firing provided you use common sense. The boiler is more like a full size one in that it will have a firebox at the rear (to contain the fire) and multiple flue tubes passing through the water to carry heat from the fire to the smokebox. The heat passing down the flue tubes is what boils the water, just as in the gas fired boiler described earlier.
Because the fire is contained within a closed firebox, air flow has to be induced in these small models, to keep the fire going. For initial fire lighting, an electric blower is placed on the chimney top until there is enough pressure in the boiler for the steam itself to be used to create the draught. Note, although called a blower, the electric version actually 'sucks' air. When the engine is stationary, and steam pressure has been raised, a valve in the cab can be opened to send a small jet of steam up the chimney and create an air draught through the fire. When the engine is running, the exhaust from the cylinders passes up the chimney and does the same. Coal burns away and drops out into a tray fixed beneath the fire (ash pan) as ash, so more coal has to added at regular intervals to keep the fire going, just as with any coal fire. The time between adding coal depends on the boiler design and firebox size but is commonly between five and fifteen minutes.
Because of the way the boiler is constructed, the level of the water inside has to be maintained within certain limits and a water gauge is fitted to the boiler to monitor it. Topping up is done by water pumps that can be either hand operated or driven by one of the loco's axle's though most models will have both types fitted. The hand pump is used when the engine is stationary and the axle pump operates while the engine is moving.
A typical operating procedure is as follows:-
The running of a coal fired loco requires far more inter-action between driver and machine and can be extremely rewarding. This is a very brief description of the firing procedure, but should give you an idea of what is involved.
32mm gauge pro's and conns.
Have a good look at what rolling stock, track and accessories are available for both gauges and see which appeals to you most.
Roundhouse have supplied different oils over the years as the requirements of the models changed.
The current oil is, to use it's correct title, 'Compounded Bearing Oil 220' (220 being the weight or viscosity) and was chosen after consultation with the oil's manufacturer and discussion as to its precise application and working environment. The last change of oil was brought about a few years after Roundhouse adopted internal gas firing and some engines were experiencing blocked super heater pipes after prolonged use. The blockages were caused by carbonised oil, though this had never been a problem with the earlier externally fired models. The key points that dictated what oil to use were as follows.
I offer the above case both to illustrate the fact that no one steam oil is 100% suitable for all needs, and to explain why the current Roundhouse oil is so different from it's predecessor.
Please note that using the current 220 oil in an older Roundhouse loco that was originally supplied with the thicker oil will not cause any problems other than an oily engine. Using thicker oil in the current models should not be a problem as far as lubrication is concerned (slightly less getting to the cylinders), but may lead to long term carbonisation in the superheater.
When choosing an oil, you should look at the particular requirements of the model in question. A low pressure oscilating cylindered loco with displacement lubricator will need quite a different type to say a coal fired engine running at 90 psi with oil fed by pump directly to the cylinders. Also, if you are playing about with or changing between different weights of oil, a lubricator with adjustable feed rate is desirable as the this can vary considerably.
Ordinary Butane or Iso-butane gas (as used in gas cigarette lighters) is the preferred fuel, though for economy, the larger canisters as used for blowlamps or camping stoves etc. are better. The larger canisters have an EN417 threaded self sealing valve on top and require a special adapter to couple up to the filler valve on the locomotive.
Mixed gasses, i.e. Butane with a proportion of Propane mixed in, are available, and may be used on current models if straight Butane is unavailable. These come in a variety of mixes ranging from 90/10 to 60/40 with one of the most common being 70/30. The figures refer to the proportions of the mix i.e. 70/30 contains 70% butane and 30% propane. If using mixed gasses, always choose the one with the largest proportion of butane. The addition of propane slightly alters the gasses properties. This can make the burner a little more difficult to light when cold or after filling the gas tank. Always open the regulator very slowly when lighting, and only just sufficient for ignition to take place. Opening too much too soon may extinguish the flame until the burner reaches normal operating temperature.
If you have an older Roundhouse locomotive, check out our Technical section for further information.
If manual control is desired for your steam loco, then you should aim for as level a railway as you can manage as this will give far easier control around the railway. Like most powered vehicles, you can not use one power setting to achieve a constant speed both uphill and downhill and the regulator will require opening more to climb up a gradient and closing at the top to prevent running away down the other side. The steeper the gradient, the worse this effect becomes.
Radio control does however give you the ability to control the steam regulator from a distance and is therefore necessarry if your railway has to include steep gradients.
Steam oil has already been covered in an earlier question and takes care of all the internal components of the cylinders. For all other moving parts, a medium grade general lubricating oil (20w50 motor oil or similar) is required and should be applied as follows.
Before each operating session.
Axles, axle bushes, crank pins on each outside crank, all valve gear pins, expansion links and pivot bush's, crosshead/slide bar, piston rod, valve rod, valve rod fork end, lifting links, weigh shaft,
Once each month when loco is used regularly.
pony truck axles (if fitted), pony truck pivots, radio control linkages to both reversing gear and regulator, reversing lever on manual models, tender axles and bogie pivots, roof hinge screws, gas regulator spindle, steam regulator spindle.
Do you have any questions not answered here?
support@roundhouse-eng.com
© 2002 Roundhouse Eng. Co. Ltd.