Brave New Railway

After the criticism heaped upon Network Rail following engineering overruns in the past, in December 2008 Network Rail were quick to applaud their own "massive achievement" in finally completing the 9,000,000,000 pound sterling upgrade of the West Coast Main Line.

It was a genuine tragedy that the crash of a light aircraft near Little Haywood in Staffordshire closed the line on 2nd January 2009, immediately following re-opening after the Christmas engineering closures. Almost as soon as the line was re-opened, a train brought down the overhead at Watford, causing widespread cancellation and delay on 5th January 2009. On Tuesday, another train brought down the overhead at Bletchley and, for good measure, workmen shorted an overhead cable at Nuneaton. Again, there were delays and cancellations. The passengers had to be evacuated from one train at Wembley after enduring freezing conditions for over a hour. And then, on Wednesday, a train brought down the overhead at Kenton, resulting in cancellation of all services for the day.

On Thurday 8th January 2009 I had to travel to London for a meeting and I approached the station at Wolverhampton with some trepidation (and notes about possible alternative journeys via Chiltern Line to Marylebone and Arriva Cross Country to Paddington). Of course, the beginning of the year has brought the usual above-inflation fare increases (up to 11% for some fares) which the Train Operating Companies justify as the price for improving the railway. At Wolverhampton I was assured that trains were currently running normally and, indeed, the 09:45 departure was only 8 minutes late away at 09:53. This was caused by the late arrival of the down train forming my departure. We were Birmingham New Street in at 10:15, out at 10:19, Birmingham International in at 10:30, out at 10:31, Coventry in at 10:40, out at 10:41. We managed to make up a little time on the journey to London, arriving Euston at 11:38, only 4 minutes late on schedule.

I wasn't quite so lucky on my return. A preceding departure from Euston had failed on the down fast, requiring us to be swopped to the down slow to get past the recalcitrant. This resulted in a 20 minute late arrival. I suppose the prospect of making up time was dashed by Network Rail's decision to impose a 110 m.p.h. temporary speed restriction south of Rugby.

I believe there were further problems on Friday and it's estimated that over 250,000 passenger journeys have been affected in just 5 days. A Network Rail spokesman gushed that the chaos was due to an "extraordinary list of unfortunate incidents". The grown-ups amongst us probably think that phrase is a fair description of what we expect in normal life. I'm ashamed, humiliated and disgusted that, in railways as in apparently most activities, my country appears an impotent laughing-stock.

MIC - Brakes

The Mutual Improvement Classes of the old steam railways still continue for today's preservation volunteers. This is one of a series of posts from notes of talks given by Jan. To find them all, select label 'MIC'.

1. History and theory

Before the coming of railways, horse drawn wagons didn't need much braking. Such brakes as were provided tended to be a piece of wood which rubbed against the tread of a wheel. The increased weight and speed of trains meant that braking became important. It's hard work to start any wheeled vehicle because Sir Isaac Newton's laws of mechanics say that you need to supply energy to change the state of rest. The required energy is proportional to the product of the mass and the square of the speed change. But you may have noticed that, with a railway vehicle, it takes much less effort to keep it moving. In theory, Newton's laws say a body should keep going at uniform speed without any further work being done. But in any practical vehicle, there's friction between the turning and stationary parts of the vehicle. This rubbing generates heat which uses up the energy of motion until the vehicle stops (the energy of motion or kinetic energy is converted into heat energy), unless you keep supplying energy to make up these frictional losses.

Steam locomotives were so powerful and the frictional losses relatively so small, that it's possible for an engine to haul lots of wagons. Thus, energy of motion is large because the mass is large. The unexpectedly high speed of early trains means that the energy of motion is large, by the square of the speed. In other words, a train travelling at 20 mph has four times the energy of motion of the same train travelling at 10 mph. That train will not stop until all the energy of motion has been converted into heat. This is why driving a locomotive is different from, say, driving a car. The energy of motion of 7029 'Clun Castle' is proportional to mass times square of speed. At 15 mph, the 135 ton locomotive has the same energy of motion as a 1-ton car travelling at 175 mph.

So braking technology suddenly became important, particularly on trains conveying passengers. A guard or brakeman would travel on the last vehicle, provided with some form of handbrake which could be applied as required. Great Western locos still have a distinctive-toned separate brake whistle to allow the driver to let the guard know that braking assistance is required. To increase the braking effort available, every fourth or fifth coach would be provided with a brakeman and handbrake. This simple arrangement gave rise to some terrible accidents either when the driver lost control of the train or when a coupling broke on a rising gradient and the rear part of the train rolled backwards towards the following train. Armagh 1889 was one of the most famous accidents of this class. Even today, catch points are provided on rising gradients so that breakaway wagons rolling backwards will be deliberately derailed, rather than letting them accelerate towards a following train.

Towards the end of the nineteenth century, the Railway Inspectorate gave up its long-standing campaign seeking voluntary co-operation by the railway companies in improving braking systems and changes made it a legal requirement for passenger trains to have an 'automatic' brake. The three requirements were that this brake be effective on all vehicles on the train, be capable of application by driver, guard and (through the communication cord) passengers and be automatically applied to both halves of a divided train. Back in 1875, brake trials of competing designs, carried out at Newark, had shown that designs based on the use of vacuum or compressed air were capable of meeting the requirements. Both systems came into widespread use, principally the vacuum system in Britain and the Empire and the air system elswewhere. British railways now use the air brake, but in the steam era the vacuum brake was the most common and that's the pattern we will look at in more detail in section 4 below.

2. Scotches

If vehicles have no operative brake, they must be properly secured when left on a siding, by the use of wooden scotches. One scotch is placed on either side of a wheel so as to prevent movement in either direction. Alternately, an unbraked vehicle may be coupled to an adjacent vehicle which has effective handbrakes.

3. Handbrakes

The simplest braking system is the handbrake found on most wagons. A cast iron brake shoe can be forced against the tyre of one or more wheels by pressing a long brake lever downwards. When the handbrake is applied on a moving vehicle, the friction between brake block and tyre as the wheel revolves generates heat, slowing the movement. The cast iron is softer than the steel tyre, so the brake block is worn away with use. Once stopped, an applied brake will make it harder for the vehicle to move again. Adjustments are provided in the brake linkage to allow wear in the brake block to be compensated, but eventually the complete block needs to be replaced. The block is usually fixed to the rigging with a wedge shaped cotter secured by a split pin, to facilitate exchange.

To apply the brake, the lever is dropped, pressed down hard and secured in that position by pushing a pin (attached to the wagon by a chain) through one of a series of holes. The harder the brake lever is pushed down, the greater the retarding force. A wooden 'brake stick' is used to apply the desired downward pressure. The square end of the brake stick is placed over the brake handle and the end of the brake stick is located securely under a convenient part of the wagon (such as the spring), allowing you to push down the rounded end of the brake stick with one hand and insert the pin with the other. Do not use a shunting pole as a lever, or be tempted to climb on the brake lever and use your weight to depress the brake lever.

To release the brake, press down the brake handle as described above and remove the pin, carefully remove the pressure and lift the handle fully upwards so that it can be located on the ledge provided.

On old wagons, the brake handle only works the brake blocks on one side of the wagon. On more modern wagons, pressing down the brake handle on either side applies the brake blocks to all four wheels. Either way, the brake handles on both sides of a wagon must be 'picked up' before you attempt to move it. Remember, when leaving a wagon on a siding you must apply the handbrake before you uncouple it from the engine and, when collecting a wagon, it must be coupled to the engine before the handbrake is removed.

Handbrakes may be applied by other means such as a short lever or a wheel. Usually, the wheel is turned clockwise to apply the brake ('screw down') and anti-clockwise to release the brake, but check each vehicle. On goods brake vans and the guard's compartment of passenger stock, a horizontal wheel mounted at waist height on a column rising from the floor within the vehicle is usual. This type of brake generally has a pawl and ratchet arrangement so that, once the brake is applied, it cannot be released accidentally. To release the pawl, turn the brake wheel slightly clockwise so that the pawl can be lifted up to its released position. Before applying the brake, make sure the pawl is flipped down so that it can work against the ratchet and hold the brake applied. Locomotive handbrakes are often on a column similar to a guard's brake, but with an L-shaped handle in place of a wheel. Where a chain is provided, this should be slipped over the handle after applying the brake, to prevent accidental brake release.

4. The Vacuum Brake

The automatic or continuous brake provides a brake on each vehicle which can be applied by the driver, the guard or passengers. When passengers operate the communication cord (now called the PCD, Passenger Communication Device), a partial brake application is made to alert the driver. The term 'automatic' refers to the fact that, if a train becomes divided, the brakes will automatically be applied to both halves.

Let's look at the vacuum brake in more detail. The brake blocks and brake rigging are similar to a handbraked vehicle (and may be worked by a co-acting handbrake lever or wheel) but are connected by a vertical piston rod to a piston which can move up and down in a sealed brake cylinder. This piston is made airtight in the cylinder by a rolling ring or slipping band gasket around the edge of the piston. Where the piston rod passes out through the bottom of the brake cylinder, there is also an air-tight gland. The lower section of the cylinder is connected by pipes to the flexible vacuum hoses on either end of the vehicle. If these hoses are open to the air, then there is atmospheric pressure underneath the brake piston. If the brake has been previously manually released (described below), then there's also atmospheric pressure above the piston. The weight of the brake piston and its piston rod causes the piston to fall to the bottom of the brake cylinder and this RELEASES the brake blocks, allowing the vehicle to be moved. The upper and lower parts of the brake cylinder are interconnected through a one-way ball valve which lets air flow from the upper to lower part, but prevents airflow from lower to upper half.

Before moving off, the driver will create a partial vacuum in the train pipe which runs the length of the train, with adjacent vehicles connected using the flexible vacuum hoses ('bags'). The locomotive sucks air out of the train pipe so as to reduce the pressure in the brake pipe considerably below atmospheric pressure. The partial vacuum created is registered on brake gauges on the locomotive and in the guard's van or compartment. A reading of '0' represents atmospheric pressure, '21' is the degree of vacuum used by most locomotives and '25' is the higher vacuum used by ex-Great Western locomotives.

These numbers are in units called 'inches of mercury' since Torricelli discovered a simple way of creating an almost perfect vacuum and measuring it in terms of the height of a column of mercury in a closed-end glass tube. The units are often shown as 'ins/Hg' where Hg is the chemical symbol for mercury (it's an abbreviation of the latin name for mercury). Bigger numbers represent a more-perfect vacuum.

Air is sucked out of the lower part of the brake cylinder and the ball valve allows air to be extracted from the upper part of the cylinder as well, so that the train pipe and both sides of the brake pistons are at the same partial vacuum. Assuming that the vehicle brake was originally released, as described above, the brake pistons remain in the bottom position and the brakes remain off. Leaks anywhere on the system allow air to bleed in, reducing or destroying the vacuum. The locomotive will normally carry on sucking whilst the train is in motion to compensate for minor leaks, but more serious leaks must be investigated and corrected before departure. If the engine is creating 21 in/Hg, there must be at least 18 in/Hg at the rear of the train.

The driver applies the brake by partially destroying the vacuum in the train pipe. Operating the brake application valve deliberately allows air into the brake pipe. The further the brake valve is moved, the more air is admitted to the brake pipe. Since the engine is still sucking, altering the position of the valve alters the vacuum in the train pipe.

15 in/Hg is the normal value for initial brake application, 10 in/Hg. is the value for full service braking. Lower values are only applied in an emergency.

Allowing air into the train pipe lowers the vacuum underneath the brake piston, but the vacuum above the brake piston remains at the initial value because of the one-way valve. There is now, say, 21 in/Hg above the brake piston and 15 in/Hg below. The pressure underneath the piston is greater than the pressure above, causing the piston to rise upwards in the cylinder, pulling on the brakes.

As the driver admits more air to the brake pipe, so the differential pressure across the brake piston increases, pulling the brakes on harder. To release the brakes, the driver puts the brake valve back to 'release', stopping the inrush of air and allowing the locomotive to re-create the vacuum in the train pipe and the underside of brake pistons, which rises back to 21 in/Hg. Once again, the same partial vacuum is present on both sides of the brake piston, allowing gravity to make the piston fall and the brakes are released.

In a system as described above, the front brakes are applied before those at the rear, because of the time it takes for air admitted by the driver's brake valve to travel down the train pipe and reduce the vacuum at the rear.

This problem was overcome by the introduction of the Direct Admission Valve ('DA Valve') which is fitted adjacent to each brake cylinder. The DA Valve is a diaphragm valve actuated by the difference in vacuum between the train pipe and the lower part of the brake cylinder. When the driver admits air to the brake pipe to make a brake application, the DA Valve opens on the difference in vacuum between the train pipe and lower part of the brake cylinder. The open DA Valve allows air directly into the lower part of the cylinder until the vacuum in the lower part of the brake cylinder is the same as the vacuum in the train pipe, when the DA Valve closes. Thus, the driver's valve only supplies air to the train pipe: each brake cylinder is directly fed with air under the control of the DA valve on that cylinder and the brakes are applied more quickly. The procedure for releasing the brakes is unchanged.

When a vacuum-fitted vehicle is uncoupled from a train on which the vacuum brake has been previously operative, the train pipe will be open to atmosphere, but there will still be vacuum above the piston, causing the vehicle brake to be applied. You may not rely on this brake, as any leaks will destroy the vacuum above the brake piston and allow the brake piston to fall, releasing the brakes. The brake is said to 'leak off' so you must apply handbrakes or scotches to secure the vehicle. If the braking system is in good condition and air cannot leak past the brake piston, it may be some hours (or even days) before the brake leaks off.

Before the brake has leaked off, it may occur that the vehicle needs to be moved as part of a shunting operation, preferably without having to re-create the vacuum in the train pipe. This is achieved by manually allowing air into the upper part of the brake cylinder so as to equalise the pressures on either side of the piston, allowing the piston to fall and release the brakes. Air is admitted by operating a short lever on each brake cylinder which pushes the ball valve off its seat, letting air past. The lever is attached to a stout cord extending to either side of the vehicle, always called the 'string'. To help you find the string, a star or similar symbol is painted on the underframe adjacent to the string. To release the brake, locate the symbol, reach in and pull the cord hard enough to unseat the ball valve. Keep pulling until you can see that the brake piston is fully down. Remember that bogie vehicles have two brake cylinders and you will need to pull both strings. Vacuum-fitted locomotives are not provided with strings, but some form of release valve will be provided. You must find out the arrangements before you try to shunt a dead engine.

Vehicle brakes work with whatever degree of vacuum the engine can create, but the higher level used by ex-GW locomotives gives a higher available maximum brake effort and better tolerance to leaks before brake force is compromised. A problem arises if a GW locomotive works a train and is then replaced by a locomotive creating only 21 in/Hg. Even when the driver of the GW locomtive destroys the vacuum, 25 in/Hg remains in the upper part of the brake cylinders. When the other locomotive is connected and creates 21 in/Hg, the brakes are not properly released - the difference in vacuum between the upper and lower sides of the piston means that the brakes will be partially applied. The solution is to walk along the train, pulling each string, so that every brake is released. Then, the new engine can create 21 in/Hg which will become the new level of working vacuum in the upper part of each vacuum cylinder.

Tipton Curve Junction Signal Box

In 'Visiting Signalboxes' I described how, in the late '50s and early '60s, I managed to visit (and unofficially operate) a number of mechanical signal boxes in the West Midlands. Most of the notes I made at the time are mislaid, so I'm a bit hazy on chronology.

Geography

Back in the '50s,the Stour Valley Line from Birmingham to Wolverhampton ran through Tipton, where there was a triangular junction with the double-track Princes End Line. The boxes controlling the triangle were Tipton and Bloomfield Junction (both on the Stour Valley Line) and Tipton Curve Junction (on the Princes End Line). Beyond Princes End, the line continued to Wednesbury, where it joined the South Stafford Line. The London and North Western Railway originally provided a passenger service but it can't have been very popular because the passenger service was withdrawn in the 1930s. Although the Princes End - Wednesbury section was built as double-track, it had been singled by the time I knew it but a healthy freight traffic remained.

Traffic

A lot of trains originated at the marshalling yard at Bescot, routed via the South Stafford Line to Wednesbury, then via Princes End to Tipton Curve Junction. Here, the left-hand branch led to Tipton and the South Stour, serving goods depots at Tipton, Albion and Oldbury. The right-hand branch led to Bloomfield Junction and the North Stour, serving the goods depot at Bloomfield Junction, the steelworks at Spring Vale and the steel terminal at Monmore Green. There was occasional traffic to private sidings, like the scrap yard at Deepfields or Mond Gas Sidings near Dudleyport. Princes End signal box still controlled private sidings, like Austin's, but I saw very little traffic to and from there. Tipton Curve had one siding - the 'Tip Siding'. This made a trailing connection with the Down Branch from Tipton to Tipton Curve just short of Tipton Curve box.

The majority of the traffic was probably to and from the steelworks at Spring Vale. The blast furnace required supplying continuously with iron ore, coke and limestone in substantial tonnages. Various minerals were used by the electric arc furnaces to produce special grades of steel. Steel, in various forms, was taken away for use elsewhere. Most of this freight was rail-bourne.

Opening hours

Tipton Curve Junction Signal Box was only open as required. When the box closed, the road was set to and from Tipton and the signals cleared so that trains could run on and off the branch at Tipton. But every train to or from Bloomfield Junction direction required the Porter-Signalman to walk from Tipton to Tipton Curve to open the box. As the name implies, most of the Porter-Signalman's shift was taken up with porter's duties at Tipton Owen Street station, where there was still a substantial parcels sundries traffic. There was often a lady on this duty. Political Correctness had not yet overtaken us and the lady Porter-Signalman was just referred to as the 'Porter-Signalman' or, more often, by the railway slang term 'Porter-Bobby'.

Construction

Tipton Curve Signal Box had been a typical, neat London and North Western all-wooden construction, with a 'Webb' Tumbler Interlocking frame. There was no mains electricity or gas laid-on, so lighting was provided by 'Tilley' paraffin lamps. Some years earlier, there had been a serious fire, which I believe was caused by a 'Tilley' lamp. The operating floor of the box had been completely destroyed. To get the box back in operation, minimum repairs were made to the signalling equipment and an unpainted wooden shed with a sloping roof and a few small windows was stuck over the lever frame. It was the ugliest box I ever worked, and it remained like that until it was abolished when Wolverhampton Power Signal Box was commissioned!

Block Signalling

Absolute Block Signalling was in operation between the signal boxes at Tipton Curve Junction and Tipton Station Box, Bloomfield Junction and Princes End. L&NWR block signalling instruments were used at all these boxes. Tipton Curve also had a Block Switch, to inter-connect the block circuits from Tipton Station and Princes End when Tipton Curve was 'Switched-Out'.

Signals

Signals were upper-quadrant tubular post types. The home signal protecting the facing junction had two dolls - the left stop signal read towards Tipton with a fixed distant for Tipton underneath, the right stop signal read towards Bloomfield Junction with a fixed distant for Bloomfield Junction underneath. This signal was always called the 'four-armer'. There were two home signals reading 'from Bloomfield Junction' and 'from Tipton'. There was also a ground signal controlling movements out of the Tip Siding. Movements into the Tip Siding were controlled by handsignal. There was also a starting signal on the down, towards Princes End. A fixed distant for Princes End was carried underneath the starting signal.

Recollections

Tipton Curve wasn't very busy - there were lots of pauses waiting for anticipated freight trains from Spring Vale which had become delayed awaiting a 'margin' - so I spent lots of time clambering over the frame in the locking room and trying to teach myself about the 'Webb' Tumbler Interlocking frame. For all its perceived defects, it's still my favourite frame.

The Tip Siding was used by the Engineers to dispose of the tons of white sludge produced by the water softening plant at various locations in the area. Water treatment of locomotive boiler water supplies had been introduced extensively by the L.M.S. to reduce maintenance costs. A series of elderly L&NWR locomotive tenders had been converted as sludge tankers. Periodically, the Tipton shunt would arrive dragging a nondescript selection of these vehicles to propel into the siding. All these tenders were loose-coupled, so a rough stop would result in a flood of white liquid sludge being thrown from the filler lids on the tanks - it was advisable to stand well clear! Volunteers on overtime from Tipton would empty the tanks by opening the bottom valves and allowing the sludge to discharge. The siding stood on embankment so, slowly, the 'no-man's land' within the triangle was being filled up. The sludge was a mixture of solid and liquid, so there was a lot of unpleasant, physical work using shovels to clear blockages and remove dried-out sludge.

The 'four-armer' was on an embankment in a fairly bleak spot, close by an abandoned quarry called locally 'The Cracker'. It was not uncommon to open the box for the first time on a winter morning, place the levers back in the frame and discover that the Tipton direction home was frozen 'off'. This meant walking to the 'four-armer', climbing the signal and breaking the ice which had formed overnight.

Near the 'four-armer' there was an underground fire which burned for years. I can remember in winter, with snow on the ground, a clear patch of track near the signal with steam rising!

I had another mishap with the 'four-armer'. The 'Stop' position of an upper-quadrant signal arm is, of course, 'nine o'clock' and the 'Off' position 'ten-thirty'. One day, I pulled off for an approaching freight and was surprised to see the arm go 'over the top' to the 'one o'clock' position because the arm stop had broken!

Oh, and there was the 'Animals on the Line' incident. Princes End Box had received a report of horses wandering about on the line between him and Tipton Curve, which he passed on by telephone. I was working the box unofficially and the signalman had disappeared on an errand somewhere. Bloomfield put a train of empties on the block so I got the road from Princes End but decided I'd have to stop the train and get the driver to examine the line. The curve from Bloomfield to Tipton Curve was vicious, so we always tried to give trains a 'run at it'. I kept my home signal 'On' as the train slowly wound towards me. When he stopped, it was clear that the driver was not best pleased, but there was no help for that. Grudgingly agreeing to proceed with caution, the driver painfully got the train away again. By the time the driver got to the field with the broken fence, the horses had decided that the permanent way offered poor foraging and they'd gone back to their paddock. When the signalman returned, he was amused by my embarrassment at the driver's displeasure. Once we'd confirmed that a temporary repair had been made to the fence, trains could run normally again.

When I first took an interest, most of the freights were steam-hauled by Stanier 'Eight Freights' or 'Fives'. I remember a night-time trip on the footplate of a Stanier Class 8 down the bank to Wednesbury with a raft of empties from Spring Vale. This must have been over twenty years before I started working on the footplate myself in preservation and I found the noise, the heat and the contrast between the blackness outside and the blinding whiteness of the fire fairly terrifying. On another night, I had a similar freight trip, this time on a Brush type 4 (now class 47). I remember the deafening noise from the Sulzer engine behind the cab and being impressed by the four or five thousand amps that the main generator was supplying to the traction motors. The 'Tipton Shunt' engine would occasionally go to Wednesbury with a 'trip' working. This was usually an '03' or an '08' diesel shunter. I had one brake van trip behind an '08' to Wednesbury to pick up a train. But as dieselisation increased and manual signal boxes decreased, I lost interest.

When the electrification of the Stour Valley was in progress, the Princes End Line was often used as a diversionary route for passenger trains at weekends but I can't remember details. I think I only once travelled on a passenger train over the route, on a DMU (this is described in 'A Sunday Stroll to Stafford'). I worked Tipton Curve Box a few times when passenger trains used the line. Because of the fairly sharp curvature between Tipton Curve Junction and Tipton, there was a Local Instruction prohibiting passenger trains from passing on this section and a second passenger train could not be put 'on the block' until the first train was clear.

One 'claim to fame' I remember was when the "largest single load ever carried by British Railways" passed over the Princes End Line en route from John Thompson. This is described here.

I was very lucky to have these experiences which link me to a time so different from the present.

MIC - Disposal

The Mutual Improvement Classes of the old steam railways still continue for today's preservation volunteers. This is one of a series of posts from notes of talks given by Jan. To find them all, select label 'MIC'.

1. Introduction

When steam locomotives come out of traffic, a number of activities are carried out as part of Disposal. If the loco is not required the next day, the fire will often be withdrawn, leaving a clear firebox and ashpan ready for the next turn of duty, although many railways prefer to leave some clean fire in the firebox to allow it to cool more slowly. If a large locomotive is to be steamed the next day, the fire will be cleaned and a maintaining fire built up to last overnight. When small locomotives are required next day, the fire may be withdrawn or a small warming fire may be left in the firebox. The smokebox char should be removed and, if possible, the locomotive coaled and watered before stabling.

2. Safety

Disposal can be a heavy and dirty process and it is usually carried out by staff who have been on duty for a number of hours and may be suffering from fatigue. Cumbersome and hot fire-irons have to be dragged around and hot clinker may need to be thrown off the footplate in areas where there may be other people. It is also often carried out at dusk or in darkness, increasing the hazards. For these reasons, incidents are most likely during disposal and you must thus redouble your efforts not to put yourself or others at risk. Failure to maintain adequate boiler pressure during disposal may result in shunting movements being carried out with only partially effective brakes.

3. Coming 'On shed'

The fireman will normally be able to reduce his firing rate prior to coming 'on shed', so as to minimise the amount of fire to be disposed and avoid disposing unburnt coal. However, nice judgement is called for so as to preserve adequate boiler pressure for any shunting which is required and to allow the boiler to be filled before leaving the engine. As the boiler pressure drops, not only will the tractive effort of the locomotive be reduced but it may be impossible to create the correct level of vacuum and the braking effort of the steam brake (if fitted) will be reduced.

4. Drawing the fire

If the fire has been well-managed and correctly 'run-down' this job is not too bad, even on a large engine. On a 'traditional' steam locomotive, an assortment of fire-irons is used to push the remaining fire and ash through the firebars into the ashpan, leaving the whole of the grate clear. The aim is to slide the fire-iron up and down the firebars, dislodging any matter adhering and helping the ash to drop through the air spaces. Avoid digging the end of the firebar into the air spaces as it is all too easy to unintentionally dislodge firebars and drop them into the ashpan. A Pricker (with an L-shaped end) is best used on its side. A fire-iron with an intentional kink (the Bent Dart) is good for reaching the back corners of the firebox. Particularly on a long firebox, a Rake is useful to move the used fire forward and backwards until it drops through the firebars. Small amounts of soft clinker may be broken up and pushed through the air spaces: anything substantial needs to be shovelled out ('paddled out') through the firehole door with the Clinker Shovel and dropped over the side of the footplate. Clinker shovels invariably get badly distorted with the heat, making the clinker removal operation difficult and time-consuming - one of the best incentives for careful firing which will largely avoid creation of clinker and ease disposal. If necessary, the firebox Deflector Plate (also called the Smokeplate or Baffleplate) may be removed to give more space for operating the fireirons. The Deflector Plate can be lifted out carefully on the back of the firing shovel, but remember that it will remain hot for some time and certainly shouldn't be placed on a wooden cab floor!

Locomotives with a Drop Grate (like 'Flying Scotsman') provide a means of dumping clinker into the ashpan without resorting to a Clinker Shovel, but care is necessary to avoid blocking the hinge with ash, preventing the drop section from being raised again.

Modern locomotives may be fitted with a Rocking Grate which allows clinker to be broken up 'on the road' by rocking the left side or right side of the grate. During disposal, operating the rocking action to its fullest extent will quickly discharge the whole fire into the ashpan. If a Hopper Ashpan is also fitted, ashpan doors can be opened to directly discharge the ash. Ensure that there is no build-up of ash to prevent the doors from properly reclosing, and, once closed, ensure that all catches are properly set to prevent the doors unexpectedly opening.

Although modern practice is to discharge ash into some form of wheeled skip which can be afterwards lifted out of the pit, traditional practice carried out at most preserved railways deposits ash directly into the pit. Where the luxury of a Hopper Ashpan is absent, the contents of the ashpan are scraped into the pit by opening all the Damper Doors and wielding an Ashpan Rake from the pit underneath the engine. This can be an unpleasant task and, where possible, a water hose should be used to cool the ash and minimise the dust. Ash will normally collect on the brake rigging and the various pipes running underneath the locomotive. Make sure that it is brushed off or sluiced off with water before finishing.

5. Filling the boiler

Once the fire is removed, all dampers and the firehole door should be shut to minimise the cold air entering the firebox, which can chill the firebox tubeplate and encourage leaks through too rapid cooling. For this reason, any subsequent movements of the locomotive under its own power should be confined to short, light engine movements.

As the boiler pressure starts to drop, the temperature of the steam will fall and the hot water will contract. One or both injectors should be put on to ensure that, even when cold, the water will be well up the gauge glass. As the pressure falls, injectors may need adjusting: the water flow will need to be reduced as the pressure drops, otherwise the injector may 'knock off'. Once the boiler is full, make sure that the injector steam and water cocks are fully closed.

Make sure the blower valve is off and shut any auxiliary valves applicable to the particular locomotive, for instance, the steam cock supplying the brake or atomiser. Where a main shut-off cock on a manifold is to be closed, do not over-tighten or it may be difficult to open again. Where backhead injectors are provided with square-headed shut-off cocks, close these with a suitable spanner (if so instructed) but avoid overtightening.

Finally, the gauge glass (or gauge glasses) should be isolated and the pressure within relieved by opening and then closing the blow-down cock. Before the engine is left, the handbrake should be hard on, reverser placed in mid-gear, regulator closed and cylinder drain cocks opened.

MIC - Firing Steam Locomotives (1)

The Mutual Improvement Classes of the old steam railways still continue for today's preservation volunteers. This is one of a series of posts from notes of talks given by Jan. To find them all, select label 'MIC'.

Steam locomotives are a type of 'heat engine' where energy is generated as heat and then some of this heat is converted into mechanical work. The steam engine is an 'external combustion' engine - the heat is generated in a different place (the firebox) from where it is converted into mechanical work (the cylinders). In contrast, in an 'internal combustion' heat engine (petrol or diesel engines) heat is both generated and converted into mechanical work in the cylinders.

In a steam locomotive, the heat is usually produced by burning coal (wood, coke or oil are also used) and this involves fire. A fireman (in the sense of firefighter) has to understand fire with a view to stopping it. A fireman (in the sense of steam-raiser) has to understand fire with a view to promoting it.

Three things have to be present to start (or maintain) a fire:-

Fuel
Oxygen
Heat

These three things are often represented as the 'Triangle of Fire' - Take away any one and the fire goes out.

A fuel is anything which gives out more heat when it burns than it takes to make it burn. 'Burning' means the chemical reaction between the fuel and oxygen and the reactions we are interested in are 'exothermic' - they give out heat.

Coal doesn't burn.
Wood doesn't burn.
Even paper doesn't burn.
Vapours burn.

If paper burned, your newspaper might spontaneously combust! Fuels have to be warmed to a temperature at which they emit a burnable vapour. This temperature is called the Flashpoint. For coal it is typically 800 degrees Farenheit, for wood 400 degrees Farenheit, for mineral oil even lower. Petrol emits vapour at temperatures way below freezing point. At room temperature, petrol emits flammable vapours which spread rapidly (and these vapours can be detected by smell). This is why you must never, NEVER be tempted to use petrol to assist a fire.

A disposable lighter contains liquified gas under pressure. Pressing the control lever opens a valve, releasing gas (fuel) which can be ignited by a spark from a flint (heat), provided there is air (Which contains oxygen). The gas chemically combines with oxygen in the air, giving off heat. When starting a fire, the temperature of the lighter flame is sufficient to produce burnable vapours from paper or rag which, in turn, can heat wood until it gives off vapours which burn. The temperature of burning wood is high enough to warm coal until it, too, emits flammable vapour and at last the coal fire is started.

What controls the rate of combustion in a coal fire? Vapours are only given off at the surface of a solid fuel like coal, so the rate at which gases are released and combustion takes place depends upon the surface area. Imagine a lump of coal, cubical with an 8 inch side length. It has 6 faces, each with a surface area of 64 square inches, giving a total surface area of 512 square inches. Now imagine splitting the coal down the middle, giving 2 slabs of coal, each 8 x 8 x 4 inches in size. The total surface area of the 2 slabs is now 640 square inches, 25% bigger than originally. All other things being equal, the 2 slabs of coal will burn 25% faster than the original cube of coal. This is why large lumps of coal should be broken to about the size of a fist before firing.

Oxygen is supplied to the fire in the form of atmospheric air. Only about 1/5 of air (by volume) is oxygen. Most of the rest of air is nitrogen, which takes no part in the reactions in the firebox, but the nitrogen does absorb heat from the fire which is wasted when discharged to the atmosphere through the chimney. The steam blast on a locomotive is used to suck a large volume of air through the firebox, increasing the rate of combustion and thus the rate of steam generation.

Next time, we'll look a little closer at the chemical reactions which occur when our fuel vapours burn.

MIC - The Working of Trains

The Mutual Improvement Classes of the old steam railways continue for today's preservation volunteers. This is one of a series of articles taken from talks originally given by Jan at Birmingham Railway Museum. To find them all, select label 'MIC'.

Birmingham Railway Museum is a yard site: you are always within walking distance of anywhere else. That does not give the true flavour of most railways where, for most of the time, trains are in the back of beyond and the train crews must be self-reliant. The guard is in charge of the train and its passengers; the driver and fireman provide the motive power. When things go wrong, each must try to sort the problem out using their own resources. Firemen should be able to persevere with producing steam even under adverse conditions; drivers are expected to make minor repairs, where possible, to keep a train going to a station where help can be provided. This is why adequate training and experience is so important.

The driver is responsible for examining the locomotive before he takes it off shed. A keen eye at this stage can save a lot of trouble later when on the road. It's important that loco crew book on in sufficient time to allow thorough preparation and examination - time pressure is only likely to lead to defects remaining unnoticed or the loco going into traffic with a poorly-prepared fire which may give problems later.

The guard is responsible for satisfying himself as to the safety of the train and its fitness to run. Usually the guard will need to personally carry out an examination which means walking all round the train. Many things are apparent if the guard takes the time to check. Doors on passenger stock should be unlocked and checked. Defective doors, if not capable of being repaired before going into service, must be locked and labelled. There should be no more than two defective doors on a vestibule coach: the guard may need to evacuate passengers in an emergency and not all the remaining doors may remain usable following an incident.

On passenger trains, the Guard should check for no apparent damage to brake rigging, dynamos properly fixed and drive belts intact, couplings and brake hoses correctly connected between vehicles, steam heating connections properly made and latched (where provided and when required), carriage lighting electrical connectors plugged together, battery box covers secured and nothing obviously broken, damaged or hanging down under the vehicle. The 'communication cord' is now called the 'Passenger Communication Device' or 'PCD' (it's rarely a 'cord' on modern vehicles). PCD tell-tales ('butterfly valves) must be in the 'reset' position. On goods vehicles, some of the above checks are applicable and, in addition, handbrake levers should be picked up to the released position on both sides of the vehicle and handwheels unscrewed (except for any brakes deliberately applied to secure the train prior to connection of a locomotive or except for the guard's brake which will be released immediately prior to departure).

Passengers will turn to a guard for help when there are problems, so the guard should be able to radiate quiet confidence when in public.

If locomotive and train are carefully prepared as described, the train crew will have confidence in the train and can afterwards concentrate their attention on running the train efficiently.

Once the locomotive is attached to a train, the driver will work to the requirements of the guard and so the guard should plan any shunting movements required prior to entering service and make any necessary arrangements with the signalman. Once the train is in the platform of a staffed station, the guard temporarily relinquishes control to the station staff who arrange for the loading of passengers and the closing of doors prior to departure. Assuming a brake test has already been carried out, immediately prior to departure the guard will request the driver to create vacuum and release the guard's handbrake. The driver is then responsible for ensuring that the train does not move. When station duties are complete, the station staff give the 'all right' signal to the guard (one arm raised above head by day, white light displayed above the head at night). If the departure running signal (where provided) is clear, the guard will then give the 'rightaway' to the driver (green flag waved above the head by day, steady green light at night, accompanied by a whistle). Where necessary, for instance on a curving platform, the station staff will relay the guard's 'rightaway' to the driver by giving the 'alright' signal to the driver. When the driver has checked for himself that the departure signal is off, he will then sound the whistle as a warning and start the train. The period whilst the train is drawing out of the platform is potentially dangerous - people may try to leave or board the train: persons standing on the platform may get entangled with door handles so station staff and the guard must keep a good lookout. In addition, the fireman should look back checking the platform until the whole train is clear of the platform in case the station staff or guard exhibit a danger signal. For this purpose, the fireman may cross to the driver's side of the footplate, where necessary, as the driver will be concentrating on the line ahead. When the rear of the train is clear of the platform without incident, the fireman should report the fact to the driver.

On the road, the driver's first duty is to keep a good lookout. When not otherwise engaged, the fireman should also keep a lookout, particularly in locations where the fireman may get an earlier view than the driver. Periodically, the loco crew should look back at the train to make sure that everything is normal. The driver, in particular, should develop a keen ear, listening for any sound indicating that all is not well. Once under way, many drivers will allow only minimal, essential conversation on the footplate, so as not to disturb their concentration.

The guard must pay careful attention to the progress of the train - he is normally responsible for entering the actual timings in the Guard's Journal which forms the official log of the trip. He will add notes covering any unusual event which has a bearing on the running of the train. The guard should be particularly alert to any potentially dangerous situations, such as children leaning out of windows or playing with door handles. Where required, the guard may operate his brake setter to indicate to the driver that the train should be stopped. The guard will not normally make an emergency brake application except in extreme situations, as a rapid stop may injure passengers, particularly on a train which is crowded or with standing passengers. If possible, the guard will attract the attention of the driver with a partial brake application and leave the driver bring the train safety to a stand.

During the journey, the driver will observe the vacuum gauge. If the registered vacuum falls, the driver must assume that a failure has occurred, a passenger has operated the PCD (communication cord) or the guard has operated the brake valve. The driver will then promptly bring the train to a standstill in a suitable position from which help may be provided.

From time to time, the guard will check that the vacuum gauge indicates the requisite vacuum and if the registered vacuum falls (except during normal service braking) he must assume that a failure has occured or the communication cord has been pulled. Each coach is provided with a tell-tale ('butterfly valve') to indicate when the cord has been pulled.

If a train stops out of course (except when stopped at a signal) the driver and guard must confer and agree on the action to be taken and the need for protection. Unless the train can be re-started quickly, protection must be provided at the rear of the train on the line on which it is travelling and, in the case of accident, any other affected line on which trains may approach.

If a train is stopped by a signal, the regulations must be carried out. Unless the line on which the train is standing is track circuited (indicated by a white diamond fixed to the signal post) the fireman will usually be required to go to the signal box to advise the signalman of the position of the train, unless a Signal Post Telephone is provided for this purpose.

When an unfitted freight train is being worked, the fireman may be required to partially apply the locomotive handbrake to supplement the braking effort. As necessary, the guard will work the handbrake in the brake van to help to control the train. On a downhill stretch, the guard will frequently partially apply the brake to keep the couplings tight, to prevent the shock as the couplings are pulled tight again at the bottom of the descent. On approaching a stopping point (and periodically during a long journey), the driver will make a trial application of the brakes to satisfy himself that the proper braking effort is available. The initial braking will reduce the vacuum to 15 in/Hg. Full service braking is carried out at 10 in/Hg. Prior to stopping, the driver will release the brakes so that the train comes to a stop without a jerk ('stop on a rising vacuum'). The driver should have previously noted a suitable marker for the class of locomotive and length of train so that the train is brought to a stand in the correct position.

Steam around Morecambe

Although I didn't realise it at the time, the holiday my mother and I had in Morecambe in 1952 gave a unique opportunity to see steam working in the area. Well, it was a holiday for me but my mother was responsible for a party of about 200 pensioners from the West Midlands who had come for a week's holiday organised by a voluntary organisation. In those far-off days, it was safe for me to entertain myself and, although I loved the sea and the beach, it wasn't long before I found my way to the station at Morecambe Promenade. First, a little background.

Both the London and North Western Railway and the Midland Railway operated branches to Morecambe to support the significant local and tourist traffic. Morecambe Euston Road was the L&NWR terminus in the town, less than two miles from a triangular junction with the West Coast Main Line a little over two miles north of Lancaster Castle station. The later Midland Railway branch terminated at Morecambe Promenade, an airy, spacious station right on the front and ideally suited for holiday traffic. The Midland branch went through Lancaster at Lancaster Green Ayre station, continuing across country to the Midland main line at Skipton, giving access to Leeds and the South. A single-line steeply-graded branch less than half a mile long linked the two stations at Lancaster. The Midland Railway promoted its own route to Ireland, with a branch about four and a half miles in length from a triangular junction just outside Morecambe to the port of Heysham.

As early as 1908, the Midland Railway electrified the 20 track miles embracing Lancaster Green Ayre and Morecambe Promenade, together with the branches to Lancaster Castle and Heysham. They chose an experimental system of electrification with the overhead contact wire fed at 6.6 kilovolts, 25 Hertz.

The 'Gloucester Transport History' site, rather improbably, has an interesting feature on the electrified lines around Morecambe here.

The original electric trains were finally withdrawn in 1951 and British Railways decided to modernise the system as a testbed for 50 Hertz electrification, prior to making decisions about main line electrification.

Whilst the modernisation was taking place, push-pull fitted Stanier 0-4-4T from the 41900 series were drafted in to maintain the service with 'Push-Pull' trains (sometimes called 'auto' or 'motor' trains) where the locomotive is permanently coupled at one end of the rake of coaches. When the engine is leading, driver and fireman are on the footplate in the normal way. But, when travelling in the opposite direction, the driver moves to a small compartment at the opposite end of the train, from where he has a good view ahead and can drive 'remotely'. Normally, the driver is provided with a brake application valve, a control for the regulator, an audible warning and an electric bell for communication with the fireman. In addition to his normal duties, the fireman has to set the reverser in the correct direction and 'link-up' as necessary.

On Great Western 'Push-Pull' trains, a mechanical linkage connected the remote regulator handle in the end coach to the actual regulator handle on the locomotive footplate but on L.M.S. lines, the use of a 'Vacuum Controlled Regulator' was widespread, where the remote regulator valve in the end coach operated a mechanism on the locomotive which actually adjusted the regulator over pipes and flexible hoses between vehicles. The system used vacuum created by the locomotive ejector to move the regulator proportionally, just as the brake valve proportionally moves the brake rigging.

Since trains typically started at Lancaster Castle, reversed at Lancaster Green Ayre, reversed again at Morecambe Promenade and terminated at Heysham before repeating the process in reverse, 'Push-Pull' working was essential in taking over from the old electric trains.

So, what of my adventures when I discovered the 'Push-Pull' trains at Morecambe Promenade? I'll tell you another time but before finishing this time, I will conclude the potted history of the modernisation.

Most of the original overhead catenary system was retained, but a section was 're-wired' to test various proposed designs of lightweight masts, to assist the design of main-line overhead electrification systems. To keep the cost of the 50 Hertz trains down, three surplus 3-car sets built in 1914 by Metropolitan Carriage for fourth-rail, low-voltage d.c. systems in the London area were converted at Wolverton. By the end of 1952, trial running had commenced and all local trains reverted to electric traction on 17-Aug-1953.

There's a article on the modernisation in the 'Railway Magazine' December 1953 issue.

You can find more detailed track and signalling diagrams of the route in the excellent series of publications from the Signalling Record Society 'British Railways Layout Plans of the 1950's'. The ex-Midland Lines around Morecambe are included in 'Volume 12: ex-MR Main Line Carlisle to Leeds, associated branches and point lines' (ISBN: 1 873228 15 5).

Years later, in 1967, I did a sketch of the layout of Lancaster Green Ayre which is here.

For details of what remained of this route in 2005, refer to 'Railway Track Diagrams Book 4: Midlands & North West', Second Edition, published by Trackmaps (ISBN: 0-9549866-0-1). The First Edition of this book was published by Quail in 1988.

Wikipedia has a useful Article on the history of the Morecambe Branch and the railway today.

[Revised August 2011]