Tuesday, 6 May 2008

Driving Turn at Peak Rail - Part One: Preparation

Visitors to preserved railways are often interested in what's involved in becoming a working volunteer, so here's a description of a recent turn.

As a driver, I normally 'book on' rather later than the fireman but, on this occasion, the fireman and I travelled to Peak Rail together, so that meant I left earlier than normal and arrived just after 5 a.m. when it was still dark. There's a Mess Hut where volunteers 'Sign on' on arrival and, having changed into overalls and safety boots, we made our way to the locomotive, an 0-6-0T 'Austerity', standing in the open, over an inspection pit. There are a couple of electric lights near the stabling point which help a lot, but a good torch is still a necessity. We were lucky that the morning was reasonably mild - it can be a bit miserable when it's cold and positively unpleasant when it rains.

The engine had been used the day before so, despite standing in the open overnight, the boiler was still fairly warm. This considerably reduces the time necessary to raise steam. From cold, you need to allow around 4 hours for this size locomotive, eight hours or more for bigger engines. There are all sorts of techniques for speeding steam raising, but they are generally frowned upon as they can adversely affect maintenance costs. Sometimes, engines are kept 'in steam' overnight but, apart from the cost of fuel, this normally requires staff to be on hand through the night so it's not too common.

Before a new fire can be lit, a series of checks are necessary to ensure the safety of the boiler. Two gauge glasses allow the level of water in the boiler to be deemed sufficient and the boiler is examined outside and inside both the firebox and smokebox to check for leaks. The integrity of the fusible plug in the roof of the inner firebox is also checked. This device melts and discharges steam into the firebox in the event of the boiler water level falling dangerously. 'Dropping the plug' is one of the worst sins a fireman can commit.

The firebox still had the ashy remains of the previous day's fire, so some time was spent removing this, using various shovels and implements manipulated through the firehole door from the cab A bad sign was that some of these remains had fused onto the cast iron firebars, requiring the upper half of the operator's body to be inserted through the firehole in order to wield various implements to dislodge the sheets of fused slag from the firebars so that it could then be shovelled out. The fireman and I shared this task, taking turns. The boiler was hot enough that after about a minute it was necessary to have a breather. You can imagine that you ingest a fair bit of dust and ash in the process, even if you decide to look for a facemask first. In the meantime, the inside of the smokebox could be examined and, where necessary, the 'char' removed.

On completion of these unpleasant and dirty tasks, a new fire could be set. Various techniques can be used. On this occasion, wood was placed on a thin layer of coal then more wood was ignited from rags soaked in used oil carefully added on top. Having established a decent wood fire, further coal was added until a raging fire resulted. It's essential to have a big enough fire to produce enough heat. An engine like the 'Austerity' will have around half a ton of water in the boiler - that's quite a big kettle to bring to the boil, even if the water is warm to start with!

Having helped the fireman get the fire started, I was able to carry out the tasks of examining the mechanics of the engine and 'oiling round'. The 'exam' is carried out at least daily and oiling daily or more frequently, depending upon the duty. Although the 'Austerity' has some grease points provided with nipples, the majority of lubrication on a steam locomotive uses mineral oil in a 'total loss' system - there's no collection, filtration and re-use. Most of the oiling is done with a fairly 'thin' oil with a viscosity of around SAE220. This is often called 'motion' oil or 'bearing' oil, but other names are in use. I find the term 'lubricating' oil, which some people use, particularly confusing, so I avoid that.

To make sure everywhere gets dealt with, it's desirable to be methodical, so I usually start with the six crankpins (remove screw cap, top up oil, replace cap, also adding a little oil to the oil holes on the gradient pins. Then, mounted on the foot-framing near the smokebox is an oil box either side to feed the piston glands and valve spindle glands. Lying on the foot framing, you can reach between the frames to get at four oil pots with hinged lids on each set of slidebars, then remove screw caps, oil and replace caps on two little ends (where each connecting rod is articulated to its crosshead) and two valve rods. From this position, I normally also deal with the four oil holes at the top of the lifting links and the two holes of the weighshaft trunnions.

I find the best way to get at the inside motion on this class is to lower yourself between the frames from the footframing on the left side of the engine (access on the right side is prevented by the reach rod), standing on the brake rigging or whatever foothold you can find to avoid dropping down into the pit below. How difficult this process is partly depends how the engine was left by yesterday's driver. If the right-hand crankpins have been left at 'seven o'clock' (for this class of locomotive), the job is rather easier. There's not usually steam to move at this stage so, if the engine is on a 'bad angle', you normally oil as much as you can and remember to come back later once you have steam to reposition the locomotive. It is possible to move the engine manually using a pinch bar but there's not usually much enthusiasm for this - it's easier to grumble about yesterday's crew.

Before you enter the motion, it's vital that you ensure that the engine is secured by following the mantra "Reverser in mid-gear, drain cocks open, regulator properly shut, handbrake hard on". Once you're in the motion, it's not easy to get out, so it's important that the fireman knows your whereabouts and that you both keep a good lookout for any other movements - many men have been killed or badly mauled when a locomotive being prepared in this way has been accidently struck by another engine. Setting a 'NOT TO BE MOVED' board (as shown in the photograph at the top) is a good precaution, but it doesn't actually prevent an accident.

Climbing into the motion so as to face towards the rear of the engine, it should be possible to remove the screw caps, top-up with oil and replace the caps on the left big end and the two eccentrics for the left cylinder, as shown in the picture. Reaching across, you have to do the same for the right big end and the two eccentrics for the right cylinder. If the weather is cold, it's all too easy to drop one of the screw caps, slowing down the process whilst the missing cap is located, cleaned (anything you drop gets covered in ash from the pit) and screwed back in.

If the big ends and eccentrics are worn, your oil feeder is sure to need replenishing at some stage, so it's a good idea to remember to put the oil 'bottle' (shown above - it's actually made of tinplate) within reach on the framing. Otherwise you have to try to attract the attention of your fireman or, failing that, extricate yourself from the motion, get some more oil and insert yourself back into the motion. Once the big ends and eccentrics are done, it's necessary to turn round to face the front of the engine - easier said than done in the restricted space between the frames.

From this new position, the various oil holes on both expansion links and both dieblocks can be dealt with. Once this is done, you can haul yourself up onto the footframing and climb down to ground level. I normally do my 'exam' underneath the locomotive next. Again, it's important that the fireman knows your location. There are some oiling points on the handbrake screw, steam brake piston and brake rigging I look to and sometimes I add a little oil to the damper linkage and the linkage to the cylinder drain cocks (usually referred to as 'taps').

Most important is to study everything you pass, looking for anything unexpected - something becoming detached, unusual wear, missing split pins or nuts, anything broken, loose or showing signs of cracking (particularly on the springing), anything out of alignment. Careful examination during preparation greatly reduces the chances of suffering a failure 'on the road'. Since, by this time, the engine is warming up, this process is usually accompanied by being engulfed in drifting steam and having hot water dripped down your neck.

Back at ground level, the six axleboxes have to be attended to. On an 'Austerity' the top of each axlebox is formed into an oil reservoir covered by a sheet metal plate. From each reservoir, three tail trimmings deliver oil to the crown of the axlebox and the two hornguides which allow the axlebox to move up and down under the control of the spring. There's not much space to reach through the spokes of each wheel and prise-up the metal cover plate so as to attend to the reservoir and it's necessary to remove any water which has collected in the reservoir with a syphon before 'topping up'. If the locomotive is on a 'bad angle', either the crankpin or balance weight will stop the job being done until you've 'set' the engine in a better position.

Returning to the footplate, there are a couple more oil pots with hinged lids and I usually apply a little oil to the reverser and its rack, the lower slides of the firedoors and the various moving parts of the arrangement of levers which opens the firedoors.

A much thicker oil is used for parts in contact with steam requiring lubrication - usually the two cylinders, the two valve chests and the steam brake cylinder. A compound oil with a viscosity of SAE 600 or above is used. This oil retains adequate lubrication qualities at the high temperatures expected where there's steam. Again, there are various names for this oil - 'thick' oil, 'cylinder' oil, 'steam' oil, 'black' oil and, because this oil is often dispensed by a lubricator, 'lubricating' oil (now you see why I don't call 'thin' oil 'lubricating' oil).

There's a small, brass globe oiler near the boiler backhead, positioned in the steam line to the steam brake cylinder. A little 'thick' oil will help to avoid the embarrassment of the brake piston siezing in the brake cylinder the first time you try to stop (I often tell people "Always brake as if you expect the brakes not to work, 'cos one day, you'll be right!"). However, caution must be used in filling this oiler. If the steam brake application valve is 'passing' at all (often the case), rather than the oil flowing obediently into the oiler, hot water and oil may spray out all over you.

Cynics may think that this is why the job of filling the globe oiler on the steam brake line is often given to the fireman, but the explanation is probably more prosaic. I mentioned that 'steam' oil is often dispensed by a lubricator. Where fitted, this is usually mounted on the fireman's side so that makes it more logical for the fireman to look after the 'steam' oil. The Great Western (of course) were the exception to this convention. Lubrication was (quite correctly) regarded as so vital to the running of the engine that the lubricator was always fitted in front of the driver and was the drivers responsibility.

So, why the need for a lubricator? The problem is to provide a supply of oil from a suitable reservoir to cylinders and steam chests pressurised at boiler pressure. Without digressing too far, two simple types are the Displacement Lubricator, where steam condenses to hot water in the oil reservoir and thereby displaces oil into the steam/oil line, and the Sight Feed Lubricator, as fitted on today's engine. The Sight Feed Lubricator is a more sophisticated form of the Displacement Lubricator offering better control of the oil supply. The condensing steam supply is independently controlled, the oil supply can be shut off when the locomotive is stationary and a needle valve in each outgoing oil line allows the feed rate to be accurately set by observing the formation and breakaway of oil globules through a glass window. Excellent when working, but they can be temperamental.

I should mention in passing that modern locomotives tend to use mechanical lubricators where a series of small pumps, one per oil line, are driven from some oscillating part of the motion. This type of lubricator can be used to dispense both motion oil and steam oil. We'll leave the question of 'atomising', to try to obtain a more regular oil film on the parts to be protected, for another time.

The locomotive should be about ready for traffic by now. The fireman should certainly check that both injectors are capable of delivering water to the boiler. This can be done by deliberately raising the boiler pressure until the safety valve 'lifts' and ensuring that this occurs within a few 'pounds per square inch' of the registered pressure. Putting on an injector will then 'cool' the boiler, lowering the pressure and allowing the safety valve to close.

The driver should also check that the vacuum ejector for the train brakes is capable of creating the correct partial vacuum (21 inches of mercury for this locomotive) and that there are no blockages in the brake pipes to the flexible hoses on the front and rear bufferbeams. If time is short, this last test is sometimes deferred until the locomotive is actually in traffic but this is not to be recommended.

Oh, and if you're very lucky, there may even be time for a "brew" before movements commence!

Click to see Part 2.