The Diesel Engine
The English electric 16CSVT is the heart of the class 50 and fundamental to its operation.
The class 50 is powered by a single English Electric 16CSVT engine. This 16 cylinder power plant is a development of the long line of traction diesel sets manufactured by the English Electric Company. The ancestors saw use in classes 08, 20, 40, 37 and the development still went on for the Valenta power plant used in the HST and others used in classes 56 and 58.
How does it work?
How does it work?
The heart of any diesel locomotive is its power plant, this is in principle no different to the engine found in many road vehicles, only more powerful. A diesel engine is made up of a number of cylinders, each is a tube bored in to a common piece of metal called the cylinder block. In each tube is a piston that can slide up and down. To prevent excessive wear on the block each cylinder has a liner made of a material better able to withstand the sliding action of the piston and cheaper to replace than the whole block when worn out. The piston is surrounded by a number of rings of metal which seal the gap between the piston and the liner preventing the atmosphere above the piston reaching the area below it.
The movement of the piston up and down inside the cylinder is called its stroke, one slide from top to bottom and then back up again (two strokes) will turn the crank shaft through 360 degrees (see diagrams on the next page). The crank shaft is connected to the piston by the connecting rod (or con rod) which has a bearing at each end, (big end below, little end above). By this means the linear motion of the piston is converted into rotational movement.
The crank shaft connects all the pistons via their con rods and it is used to transfer the power produced out of the engine. At the top of the cylinder in the head are valves and the fuel injector, these are also driven off the crank shaft to keep them in time with the piston.
The four stroke cycle
The four stroke cycle
Most diesel locomotives use what is known as a four stroke engine (that is the piston has to travel up and down twice to complete a full power cycle). This is best described by the diagrams below
To increase the power available from a given size of engine more fuel needs to be burnt. Increasing the amount of fuel used also requires more oxygen to ensure complete combustion. A turbo-charger is used to pump air under pressure into the cylinder and hence increase the amount of oxygen in the cylinder. In addition cool air has more oxygen in a given volume than warm air, so it is common to use an inter-cooler to increase the oxygen density too.
The power developed by the 16CSVT engine fitted to the class 50, comes from 16 cylinders of 10 inch diameter and 12 inch stroke, these are arranged in a V formation which allows two banks of cylinders to drive a common crank shaft. Each set of four cylinders is feed by a separate turbo charger and inter-cooler.