Steam locomotives in the Ceylon Government Railways deployed mainly 2 types of valve gears, namely Stephenson Valve Gear, in the earlier locomotives and Walschaert’s Valve Gear in the later classes of locomotives.
Walschaert’s gear employs a set of rods to attain the valve timing. This was fixed externally most of the time. Different cut-off positions and reversing was attained by lowering or raising the “Die Block”, which is connected to the “Radius Rod” which drives the valves. Die block moves inside a slotted and curved rod known as the “Expansion Link”. When the die block is at the bottom of the expansion link, the locomotive will move forward. And when the die block is at the top position of the expansion link, the locomotive will move backward. Die block at the centre will only inject steam into the cylinders, and this is done with Cylinder cogs open to clear any clogged water from the cylinders.
Water is admitted to the boiler with steam. Special equipment called the “Injector” is used here. Inside the injector are a set of cones, and they are named Water cone, Steam cone and the Combination cone in order. Water pipe from the tender (or the tank) is connected to the water cone, and steam is given into the injector into the steam cone. Steam pushes the water up the delivery tube into the boiler, partially heated. In the case of Tender – Tank locomotives (Ex- B2, B3) tender and side tanks were completely independent of each other. They had to be filled separately. Water in the side tanks was for the sole purpose of balancing the locomotive and to provide adhesion. It will not be used unless all the water in tender is used up. There had been a valve to select either tender or tanks supplies the water to the boiler.
Lubricator is another vital piece of equipment that should be well maintained. There are four outlets, which feeds lubricating oil into the 2 cylinders and the valves on the either sides of the locomotive. After servicing the locomotive, the lubricator is completely drained and cleaned. Afterwards, it is completely filled with oil. There are four watch-glasses on the face of the lubricator. When oil level is full, steam is opened up. Steam will condense to water and oil starts floating on it. Then the Fireman, with his watch in hand, adjusts the lubricator valves so that a drop of oil will be released every 30 seconds. This is a very fine adjustment, and any failures in lubrication will result creeks in the cylinders when in motion.
Next comes the firing. Initially, all the locomotives were coal fired. But on some occasions, coal was not available to the requirement, and then the easiest alternative was firewood. During the late 1940’s, locomotives were fired on firewood, and in those locomotives, the brick arch inside the firebox had to be removed. If not, logs thrown in will hit the arch and it will collapse in pieces. This brick arch was constructed using fire bricks, and a special kind of cement. The cement used had to be mixed to the right ratios with water and sand, or else the arch will be weak. It is supported by the fastenings and slabs constructed in the firebox. When dried and first lit, the arch will go dry completely and become rock-solid. The purpose of the arch was to retain heat and burn the fuel correctly and completely.
Initial fire was lit by using firewood dipped in oil, and they were lit and deposited inside the firebox. After that coal was shovelled in, but not dumped in. Coal was systematically deposited using the shovel at the far left end, far right end, middle right and left, and then near right and left. Pickers were used to adjust the coal bed. Fire grates were rocked in the middle of the journey so that burnt ash will be dropped.
Maintaining water into the boiler after lighting up the firebox is critical. There are 2 injectors per locomotive, and there are 2 watch-glasses mounted on the boiler faceplate. This is a tube of glass, covered in 3 sides with thick glass sheets. Open side had to be turned towards the boiler. Idea was to protect the crew, should the tubes explode. Water had to show up to the top nut of the indicator. If it overflows, that means there is too much water. If it gets lower, the crown plate will heat up, and collapse, which would result a boiler explosion. Fusible plugs made of lead were installed on the plate, so that if the plate heats too much, they’ll melt and let the pressure out, protecting the boiler.
Inside the boiler, there are 2 types of tubes. They are known as “Smoke Tubes” and “Flue Tubes”. Smoke tubes are smaller in diameter, through which smoke from the boiler pass. They are surrounded by water, and they produce the initial steam. This steam gathers in the Steam Dome. Flue Tubes houses the super heater elements. They are originating from the steam dome. They contain steam, and conduct steam to the Boiler Header. Header is divided into 2 chambers, the Saturated Chamber and Super Heated chamber. Steam after super heating will be given into the Super Heated chamber, then via the Blast Tubes to the Cylinders through valves. B1, B2, B8 and J1 classes were all super heated.
There were two types of Valves used in Sri Lankan locomotives. They were known as “Slide Valves” and “Piston Valves”. Slide valve had a “D” shaped piece of steel operating to and fro, acting as a valve. This was gradually replaced with more advanced piston valve. All super heated locomotives deploy piston valves.
Wheel slipping was a common problem experienced by the railways since the days immemorial. Deposition of sand on the rails before the Driving wheels was a time honoured tradition to overcome this issue. Initially, dry sand was used. Later on, a steam pipe was connected to the neck of the sand pipe, and wet sand was used.
When the Night Mail train from Badulla arrives at Peradeniya, first it travels along the loop line towards Colombo. Then the train sets back to the Colombo Platform of Peradeniya station. While reversing, Drivers used to deposit sand along the track, so that when starting towards Kadugannawa, there will be a fine bed of sand to provide good traction.
Special thanks to Mr. H. U. Thibbotumunuwe, retired District Inspector- Mechanical (Navalapitiya) for his generous nature in providing me all the above information. Prepared based on a discussion done with him…
Author : Subash Bandara Dhanasekara