Richard Trevithick who had been playing with pumping engines and boilers in Cornwall for some years, built the first steam locomotive – a not very useful machine. But it was his second locomotive in 1804 that was the first really useful locomotive as it could haul loads of 25 tons at 8kph up grades of 1 in 36. This loco was the Pen-y-Darren. Trevithick pushed boiler technology along.
While James Watt was content to use steam at barely above atmospheric pressure, Trevithick could see the advantage in using “strong steam” at around 50psi. This provided a catalyst for further great leaps in engine development.
Steel technology was moving along now, enabling the Engineers to construct stronger vessels to safely produce steam at progressively higher pressures. Higher steam pressure provides more power from smaller cylinders so there were spinoffs in weight, cost and fuel efficiency.
The first commercial steam boat was built in the U.S. in 1807, but it was powered by an engine built by Watt in the UK. It was more of a self propelled barge than a ship. The Clermont had a single cylinder engine driving side paddle wheels of 4.5met diameter through a system of cranks and gears. The boiler was made locally from copper. The first steam powered crossing of the Atlantic Ocean came (relatively) soon after in 1819 by the S.S. Savannah which was assisted by sails.
By 1829, railway engines had taken a variety of shapes and forms as builders tried to gain an edge over other engineers. Along the way many failed as the evolution process forced out the weak and helped the strong until in 1829 the locomotive was in the format that we consider “conventional” i.e. side mounted cylinders with connecting rods to the wheels, firebox at the rear of the boiler and the chimney front mounted with exhaust being used to induce air through the fire on the grate.
All of these aspects were not new and had been tried many times by various engineers, but it was George Stephenson who first brought them together in a small locomotive called “The Rocket”. From here, railway engines evolved in smaller steps as the need for speed, power and fuel efficiency called.
Since Cugnot had operated his 3-wheeled carriage, several engineers had also attempted construction of useful road vehicles. It was the boiler invented by Walter Hancock and patented in 1827 that set things moving on the road. Within a few years he had a vehicle for hire in London that travelled at 19kph, and then soon after that the first steam powered “mass” transporter (bus) was carrying 20 people at 34kph.
Meanwhile around the world portable engines had been in use since Trevithick combined his high pressure boiler and engine into a single unit when he built his first loco.
Portable engines took a variety of forms throughout these years and the logical progression by 1842 was to Traction Engines – self moving steam engines that could power many types of machinery. Road condition was poor and this hindered the development such that Traction Engines had to be engineered very heavy to withstand the shaking and vibrations they encountered on the road. About 1870, these engines standardised into the format we know that included gear drive to the wheels, cylinder over the boiler and crankshaft over the firebox and exhaust up the chimney – the format very reminiscent of railway locos.
Around the 1850 era, articulation was experimented with to enable locos of reasonable size to negotiate tight bends whilst having sufficient power to haul up steep gradients. This was particularly important in some of the more mountainous European countries.
Anatole Mallet was an engineer in France who introduced compounding to railway locomotives in 1876 with a single High Pressure cylinder exhausting to a single Low Pressure cylinder. Compounding was designed into many locomotives of different wheel configurations in England and South America. The two cylinder compound was a little unusual in that it only emitted TWO exhaust beats per turn of the driving wheels instead of the normal FOUR.
Back on the road in England, John Fowler introduced double cranks to his Traction Engines and about this time they were being referred to as “Road Locomotives”. Some of these engines were quite large, weighing in at around 17 tonnes with cylinders of 170mm diameter for the HP and 290mm Diameter for the LP cylinders with a stroke of 305mm providing for power outputs of some 70-100 horse power from boiler pressures of 1400 kPa (200 psi). These engines could haul useful loads of 40T at low speed.
Boiler and steel technology was moving along.
Perhaps the ultimate development of the Traction Engine was the modification to the Fair Ground Engine where a dynamo was mounted in front of the smokebox and a canopy was added with appropriate flourishes – twisted brass fluting, bright colours, and other polished brass adornments.
Michael Faraday had discovered that electricity could be produced by mechanical means back in 1831, but it was not until 1870 that a Frenchman produced a self excited dynamo with ring wound armature that electricity generation became a real proposition. Paris had some electric lighting in 1875 and a French engineer took it to London in 1878.
Lights flickered greatly due to the poor governing and lack of suitable engines. Many engineers tried to adapt the large, slow rotating engines of the time by way of using pulleys and ropes to increase the speed but the need was there for rapidly revolving engines to be direct coupled to a dynamo.
Finally, 1890 saw the first high speed engine by George Bellis which, after commissioning, ran for 29 years. Bellis (and Morcom) produced compound engines with enclosed crankcases which had become necessary to retain oil from fast moving cranks. They also introduced pressure lubrication to their engines. This form of lubrication and enclosing of crankcases was an important part of the development later on of the Internal Combustion engine.
With the introduction of electricity, by 1894 Charles Parsons could see the need for high speed rotation to drive dynamos. In Parsons turbines, the steam flows axially, expanding slowly through each of multiple stages. Because he lost patents on this genre of turbine, he created a radial flow turbine which he used to produce power the first turbine powered vessel the “Turbinia” in 1897.
As turbines produce their power at high rpm’s, the need for gearing becomes necessary for ship propulsion. But turbines are extremely well suited to electricity generation where dynamos (generators) need to run at constant speed regardless of load – so very different from wheeled machinery which previously had lead much of the development of steam.
Due to commercial considerations all steam power evolution had been driven by the need to make money. Vehicular design was no exception and had revolved around passenger carrying – trains and buses – yet although traction engines were quite mobile, carrying goods by road had been given little consideration. Laws governing road vehicle use (as well as road condition) had been very restrictive. Thornycroft in England had begun development of a steam van and around 1896 built his first prototype. This comprised a vertical boiler behind the drivers position and a horizontal engine slung underneath the van. Soon, other manufacturers followed. Steam lorries enjoyed a life of some 30 years in Britain until a reformed tax system started to drive them off the roads – just as petrol and diesel engined trucks started to take over anyway.
Next Page – History of Steam – Post 1900