There are two of these, one on either side. Injectors supply water to the boiler. To operate them, the water is turned on first, then the steam from the valves at top of the picture. The injectors combine the water with steam through a series of cones. The first or "steam" cone accelerates the steam into a fast powerful jet. This then mixes with the water from the water valve and is condensed in the combining cone producing a very fast jet of hot water. This jet of water then jumps a gap (the overflow gap) before entering the delivery cone. The delivery cone is the reverse of the previous two and gets wider down its length. This has the effect of slowing down the water jet and converting its momentum into pressure. This pressure is high enough to overcome the boiler pressure and force the water through the 'clack' valves (non-return valves) thus replenishing the water level. You can sometimes see the fireman looking over the side of the cab at the injector overflow beneath the cab step as he or she adjusts the controls to ensure the injectors run 'dry', and thus at their greatest efficiency.

Steam locomotives have two injectors. Both may be ‘live steam’ injectors, using steam direct from the boiler to operate them. Some locomotives have one live steam injector and one ‘exhaust’ injector which, as its name implies, uses exhaust steam taken direct from the blast pipe, which carries used steam from the cylinders to the chimney. However, the basic principle remains the same. Hover your mouse over the water valve (the valve closest to the camera at the lower right of the picture) for a basic explanation of how injectors work.

Both this and the Supplementary steam valve (the centre of the three valves at the top of the picture) are operated together to start the exhaust steam injector, once the left-hand water valve (partially hidden by the toolbox at the lower left of the picture) has been turned fully on. When the locomotive is running, exhaust steam is automatically supplied to the exhaust injector and this is used to force water into the boiler. The auxiliary steam supply replaces exhaust steam when the regulator is shut, ensuring that the injector continues to work.

Both this and the Auxiliary steam valve (the left of the three valves at the top of the picture) are operated together to start the exhaust steam injector once the left-hand water valve (partially hidden by the toolbox at the lower left of the picture) has been turned fully on. This supplementary steam valve starts the injector working and helps to keep it running.

The red line indicates the pressure at which the safety valves on the top of the boiler will lift – a vital safety device.

This valve turns on the steam supply which is used to heat the carriages on cold days. The steam is supplied to the Mason’s or reducing valve which finely controls the steam supply to radiators in the carriages.

Finely controls the supply of steam for the radiators in the carriages, maintaining the pressure at a constant level.

This indicates the train heating pipe pressure. Note that different pressures are recommended for different lengths of train. The pressure is measured in pounds per square inch.

The water gauge is a glass tube, protected by a reinforced glazed frame. It indicates the water level in the boiler. To help read the water level, the back of the frame is painted white with diagonal black stripes which refract when viewed through water. The injectors are used to increase the water level. The frame includes shut-off valves operated by the long lever and, underneath, a drain valve. In the event of a broken gauge glass the frame can be isolated by closing the shut-off valves. To the right of the frame are two small cocks, one above the other. These can be used to check the water level in an emergency.

An oil lamp which illuminates the water level when dark or in tunnels.

These operate flaps on the ash pan beneath the firebox to control the supply of air to the fire bed (known as 'primary air').

Fine adjustment controls for the exhaust injector.

On occasions when the locomotive is handling a heavy train and the driving wheels have a tendency to lose adhesion or 'slip', particularly when starting, on a severe gradient or the rails are greasy, a jet of sand can be directed at the wheel tread to aid adhesion. One lever is for the forward direction, the other reverse.

On some locomotives, the reverser is turned on a worm screw (screw reverse) rather than this 'lever reverse' which can require considerable effort to move. The lever is moved either forward or reverse of centre (where it is located in the photograph) to adjust the piston valves so that when the regulator is opened, steam supply drives the locomotive either forwards or backwards. You’ll notice a series of notches in the frame – these allow the valve travel (or 'cut-off') to be finely adjusted for maximum efficiency.

This is the "throttle" and it opens the main steam valve which supplies steam from the boiler, through the piston valves to the cylinders. The wider the regulator is opened, the more steam is supplied.

Attached to the regulator arm, this opens and closes the ‘W’ valve.

This device supplies steam through a series of jets up the chimney, thus causing a partial vacuum in the smokebox and drawing air through the fire. This increases the rate of combustion of the coal. The blower is also used when there is a danger of the fire ‘blowing back’ into the cab, such as when the locomotive is running through a tunnel or when the regulator is closed.

Mounted in the roof, steam is supplied to the condenser where is turns into hot water. This is then supplied to the hydrostatic displacement lubricator.

This is almost unique to Great Western-design locomotives. It works by taking hot water at boiler pressure from the condenser in the roof and displacing the heavy lubricating oil contained in a reservoir in the lubricator. The oil is released into the water stream at a controlled rate and globules of oil can be seen through the sight glasses. The rate of delivery can be controlled by the inverted 'T' shaped valves you can see beneath the sight glasses. This locomotive has five delivery streams - two for the left hand piston and cylinder, two for the right hand piston and cylinder and one for the regulator valve (just out of sight). The oil is carried through the 'W' valve where the oil is atomised and piped to where it's needed.

Drain valve for the hydrostatic displacement lubricator.

This valve creates a vacuum to take the brakes off the locomotive and train. The amount of vacuum is indicated by the vacuum gauge. When the locomotive is running, a vacuum pump driven by the valve gear maintains vacuum and the ejector need not be used. Great Britain is one of the very few countries which used vacuum brakes. Trains in almost every other country have always used air brakes and today, trains on the UK national network are also now air braked.

This is used to destroy the vacuum generated by the ejector in a controlled way, thus moving a piston in the brake cylinder on the locomotive and on each vehicle in the train and applying the brakes. The valve is shown in the 'on' position.

This couldn’t be simpler. The valve supplies a mixture of water and steam from the injector to a flexible hose which can be used to damp down the coal (to keep down dust) and wash the footplate floor. On some locomotives, there may in addition, be valves here for an ashpan sprinkler and on some tank engines, a coal bunker sprinkler.

Hinged at the bottom, this flap can be raised using the chain you can see attached to it, to a position partially blocking the firehole when the firehole doors are wide open. The flap is designed to allow a measured amount of air over the top of the flap - the lower cut outs match the shape of the fire hole. The air admitted by the flap is known as 'secondary air' – 'primary air' is supplied via the dampers through the grate. The air combines with the volatile gasses and unburned hydrocarbons emitted by the fire to improve combustion and thus reduce the amount of smoke made when the engine is working. The flap is also useful when firing – by closing the flap between shovelfulls of coal the amount of cold air admitted to the firebox is kept to a minimum.

Made of heavy cast steel, the doors slide in runners to open and close the firehole.

Beneath the tender of most long distance mainline locomotives (except on the Southern) is a water scoop which could be lowered by means of this handle to collect water from troughs built between the rails on level stretches of line. It was an effective means of topping up the tender tank, thus increasing the range of the locomotive without having to stop for water. For safety reasons, the water scoop is locked in place so that it can’t be accidentally lowered on to the track. There are no examples of water troughs remaining.

The picture ShowContents a locomotive over a section of water trough. The buildings towards which the locomotive is approaching contain tanks and chemicals (water softeners, to prevent scaling), and automatically kept the water in the troughs topped up.
Photo courtesy of "Mike's Railway History".

Hidden behind the tool locker on this photograph. As the name implies, this lever is wound to mechanically apply the brakes to the locomotive tender (or driving wheels on tank locomotives). The brakes on locomotives and rolling stock comprise cast steel blocks which are forced on to the wheel treads when the brakes are applied.

Tool/storage boxes.

This control operates two cocks on each of the two cylinders and one on each piston valve. These allow steam and water to escape. When the locomotive is left standing the valves are left open so that condensing steam can drain out. When the engine starts moving after a period standing still, you can see the steam escaping noisily from the cylinders at the front of the engine. These are a vital safety device because water doesn’t compress so if any water is allowed to gather in the cylinders it could cause severe damage if the engine is moved.

Excess water or condensation is blown out of the cylinders through valves operated from the footplate. The drains can easily be seen on locomotives with outside cylinders such as these on 9F 2-10-0 no. 92203 'Black Prince'.

A vital part of the footplate equipment. Standing on a shelf immediately above the firehole door, the tea keeps piping hot.

So called because it is roughly a ‘W’ shape. Operated by the regulator, this valve supplies water carrying oil from the hydrostatic displacement lubricator and water carrying lubricating oil to the cylinders, pistons and regulator valves.

The Great Western Railway pioneered train safety by introduction of the Automatic Warning System in the early part of the 20th century. An electrical shoe under the locomotive made contact with a ramp in the centre of the track. The ramp was energised depending on the state of the signals ahead of the train. The bell rang if the line was clear, a horn sounded if it was at danger. The system greatly improved safety and allowed trains to travel at speed in poor visibility. The current Train Protection & Warning System (TPWS) now being fitted to all UK trains is an advanced version of this system, which continued in use until the 1960’s.

The picture on the right shows a GWR publicity photograph c.1930 of a Castle class locomtoive, ShowContenting the shoe making contact with the ramp between the rails.

An interesting notice to enginemen dated 1909 – it remained in place on Great Western engines until the end of steam.

Great Western engines were fitted with two whistles of different notes. The higher pitched whistle was used as a normal warning; the lower pitched one was used as a signal to the Guard, for example to put on the guards van handbrake when working freight trains that were loose-coupled or non-fitted (ie, no vacuum brakes).

Used to relieve any remaining vacuum in the braking system.

The gauge has two indicators – one for the vacuum reservoir and one for the train pipe. The measure is in 'inches of mercury'. The train brakes are fully off when around 25 inches of mercury are shown by both indicators (other railways used only 21 inches of mercury). Applying the brakes will cause the train pipe indicator to fall rapidly as air is admitted to the system via the brake lever. The reservoir indicator will fall much more slowly. Any break in the train pipe, or an emergency brake application by the guard or by the 'communication chord' will admit air to the system, partially applying the brakes and warning the driver of a problem.