History - Steam Engine
|Watt linkage with rigid rear axle . . .|
Even among experts there is the opinion that up to the twenties of the last century, all the essential features of the combustion engine had already been invented, at least mechanically. There is
no doubt there's something to it if you leave out the electronics. Conversely, however, one can also claim that this type of engine has only received its final polish through the exhaust gas restrictions.
The steam engine has experienced a similar fate. It also had some problems that seemed to be solved when the combustion engine was about to lose its place. We want to continue the development up to this... time once
from their point of view. You can't necessarily say that it triggered the Industrial Revolution, but both have inspired each other very much.
It is the arduous path to a machine that delivers continuous turning power, which in the end also achieves a reasonably acceptable level of efficiency. We already had the more or less serviceable vehicles with steam drive.
But what about the need to develop steam engines at all? But you probably already know that, that they were created out of problems in mining.
Denis Papin's inventions already reached as far as Hessen (Germany) and he was invited to save a coal mine there. It failed because of the technology for the production of his machine. But why actually to feed a
machine with mined coal that pumps the groundwater? It is said that the mining of coal was particularly intensified in England because, in view of the Anglo-Saxon climate, a large part of the forests had been burned there.
It was at least the case that the distribution channels for wood, e.g. through channels, had to be expanded because it was no longer sufficiently available with the previous transport methods. In addition to this, wood and by
no means metal was the material par excellence before the Industrial Revolution, just think of shipbuilding in Great Britain, where it gained international recognition at the time.
No, the first attempts to cast iron in a moulds often ended in cannonballs with the really lowest demands. Incidentally, at that time, the forerunners of today's blast furnaces were also
loaded with wood. Looking at the development in sequence, then even with the next stage of development only pots, pans etc. were possible. No prospect of the enormous demands on
the fits for a steam engine.
The canals therefore initially also enabled the transport of hard coal. At the end of the 17th century the mining of hard coal is becoming more and more difficult. At least horses are doing the work on the pumps. Maybe that's
where the 'horsepower' comes from. But you can imagine that such horsepower takes up space, even and especially when it is constantly running in circles. Besides they had to feed their horses with oats. With a steam
engine one would have had the chance to use some of the abundantly mined coal.
At least Thomas Newcomen (1663-1829) succeeded in delaying the threatened end of coal production by means of a machine. Since hardly anyone ever achieved major inventions on his own, Newcomen also used
Thomas Savery's invention in addition to Papin's preliminary work. The first usable steam engine already had the balance beam (balancer), which was then often found in steam engines, but not yet a piston driving a crank
|Atmospheric steam/fire engine|
Newcomen was a master blacksmith and that certainly helped the accuracy of his work. He was able to introduce more tightness into such a system and increase the fits of the steam-powered piston on one side and the
water-pumping piston on the other. Unfortunately, he did not know how to help himself in any other way than to lower the pressure generated outside in a steam boiler in the working cylinder at the appropriate time by
means of injected water.
It is a small catastrophe in terms of efficiency to simply entrust heat to the environment that has been produced with great effort and at great cost. But at least there was a certain continuity, which was later expressed in up
to 16 strokes and more per minute and not yet in revolutions per minute. At least nobody had to take care of horses anymore and afterwards the machine ran automatically except for the coal supply.
By mentioning efficiency, we have already the sticking point that brought coal production back to its limits. Because if you take the cool from the now extracted, double possible mining depth
to feed almost all the coal to the machine that makes this possible, then the whole thing is pointless. James Watt (1736 - 1819) worked as a mechanic at the University of Glasgow shortly after the middle of the 18th
So Watt did not invent the steam engine at all, but added such essential components that the unit for power was later named after him. This includes a condenser, which ensures that the heat remains in the system. He is
said to have achieved savings of over 60 percent with this alone (Wikipedia). At first, it remained with the back and forth movement and also with the fact that the steam pressure already, like the gunpowder at Huygens,
lifted the additionally weighted piston and which only did work when going down.
It was the fear of the high pressure, not entirely unjustified. After all, our present TÜV was not founded for testing motor vehicles but for the urgently needed monitoring of steam boilers. It was only much later that Watt
succeeded in significantly increasing the efficiency of the engine again by driving the piston in both directions at high pressure.
The invention of the Watt linkage also falls into this period. In the motor vehicle sector it is known for controlling lateral forces on a rigid (rear) axle. The principle is important. While a Panhard rod (picture below), for
example, pulls the axle to the same side when deflecting or rebounding, here it remains largely no offset laterally. Watt used the linkage to guide the piston and piston rod as straight as possible.
Later on, instead of a linkage, this construction was used, in which the stroke movement of the piston was transmitted to a shaft. Due to the rotating gear wheel rigidly connected to the rod, it is a kind of planetary drive that
transmits the torque to the lower shaft in the same way as a crank drive would.
Of course, at that time the crank mechanism was already known and Watt would have liked to use it. But unfortunately it was still protected by patent at that time, so Watt had to take the detour via this planetary drive.
Basically, this way of transmitting steam power to a shaft naturally inspired the idea of a steam engine to drive vehicles. James Watt probably used it
at first to prevent his engine from turning too fast by means of a connected centrifugal governor.