These sections cover:
Water wheels are a class of old machines which were developed since 2000 years. The first account of a water wheel combined with a bucket chain was given by Philon of Byzanz.
Philon's self-containing machine to pump water to
a higer level. Although the idea of closing the loop
an thus inventing a perpetual motion machine seems
to be obvious, Philon gives no hint to this notion.
In classical machine construction, water wheels are characterized by a horizontal axis. We basically can distinguish 3 types of water wheels.
|The undershot water wheel
This type is the oldest. Vitruv described that type of water wheel in the 1st century B.C. It can be used wherever a swiftly running river is available. Its efficiency is around 25% In the 19th century, this type of wheel was further develeped. Especially the design by Poncelet reached an efficiency of 70%.
|The overshot water wheel
Overshot water wheels are in use since the 14th century. If they are well-made and the height of the upper water reservoir allows a large diameter of the wheel, an efficiency up to 75% or sometimes even 80% is possible.
|The center water wheel
This is the most recent type, being developed in the 16th century. It is a compromise between the two basic constructions. Older versions had up to 45% efficiency, modern types can reach up to 75% efficiency.
The typical construction element of water turbines is a vertical axis. The first wheels of this kind were invented and depicted in the late sixteenth century. Due to the shape of the shovels, they sometimes are called spoon wheels. The development of the modern water turbines began around 1820. 1824, the expression turbine was coined by the french engineer Claude Bourdin.
|This type of water wheel with vertical axis dates back to the end of the sixteenth century. The earliest design I could figure out is this one by Giovanni Branca. The construction element was used by Jacopo Strada for a recirculation mill which thus became the first PMM with a water turbine. Later, Andreas Boeckler recycled the idea in the mid-seventeenth century.|
|In places were swiftly running water is abundant, even primitive turbines survived until the twentieth century like these in the austrian Alps. Their efficiency is bad, but sufficient enough for the purpose, which in this case is grinding of marbles.|
|Modern turbines, like this disassembled Francis turbine (around 1880) have high efficiency of 80%, sometimes up to 90%.|
In the second half of the 18th century, first systematic research was made
to learn how water wheels worked and how to improve their efficiency by a
suitable design. The epoch is characteristic for the beginning of the industrial
revolution. We have to keep in mind, that James Watt also made his reasearch
work on steam engines at that time.
The task to improve water wheels was not only caused by scientific interest; but rather a commercial issue which made good energy sources crucial for a flourishing manufacturing industry.
|Piston pumps are a roman invention. They date back to 250BC. Authors like Vitruv and Heron of Alexandria give descriptions of pumps and other mechanisms whose function is based on cylinders and pistons.|
|Classic sucktion pumps only work, if water is to be pumped up less than approx. 10m (=33ft). In ancient times, this effect was explained by Aristotle's horror vacui i.e. nature abhors vacuum. It took until the mid-seventeenth century until Evangelista Torricelli, a pupil of Galileo Galilei found the correct explanation.|
The Archimedian screw is a very old type of pump. Researchers today think that the name is appropriate, as it can be tracked back until around 250BC. It was known in ancient greece and rome and even today has great practical value although most people are not aware of it, as the principle often is concealed in machine housings. Archimedian screws are used to lift water for irrigation purposes. As the device works continously, it can be operated in an easier manner than an piston pump with its intermittent working cycle. In ancient times, turning pumps used to be slaves' labour. Until recent, archimedian screws were in use in the middle east.
|A cross-section through an Archimedian screw||Irrigation in Egypt around 1950|
|The principle of the Archimedian screw can also be utilized to win mechanical energy. Often, the idea is attributed to Giovanni Branca, who described 1629 a predecessor of today's water turbines. In fact, Leonardo da Vinci made the same suggestion already around 1490. He used the principle for a perpetual motion machine!|
The hydraulic ram
The hydraulic ram was invented by Etienne Mongolfier, who was one of the famous Montgolfier Brothers who made the first successful tests with a hot air balloon. The hydraulic ram is a remarkable machine, as it can lift water higher than the running water flow which is used to power the machine. This sounds paradox at the first glance and seems to open a loophole for recirculation mill construction, but the first law of thermodynamics demands its tribute. However, one patent is known to me that suggested the hydraulic ram as central element of a recirculation mill.
xxx: French patent no. xxxxxx.
A ball-pump by Georg Agricola
This chapter is based on two books which both were published around 1920 in Germany. I were not sure where to put this chapter: here or into the Illustrated Historical Magazine of not so useful inventions.
|Das Buch der neuesten Erfindungen
(The Book of Most Recent Inventions)
|Der neuzeitliche Maschinenbau
(Modern Machine Construction)
The hydrovolve engine is a german invention which is no PMM at all, but an interesting technical concept with interesting flaws. The principle is based on an overshot waterwheel which powers a locomotive. The wheel is fed by an overhead canal which runs parallel to the railway tracks.
|Side view of a traction locomitive|
|Front view of two traction locomotives running in opposite directions|
|An experimental locomotive driven by a hydrovolve engine|
|The shape of the inner and outer turbine blades. The construction idea is a combination of an overshot whater wheel and a radial turbine. The shape of the blades shall provide the best possible usage of the streaming water power.|
|A disassembled hydrovolve engine|
By looking at these machines, some questions arise:
The last question gives an insight into the mindset of the inventor. He writes:
The combined use of siphon effect and turbine/waterwheel shall give the expected power. If we consider the potential energy of the water, and assume that this is converted by 100% into kinetic energy which is transferred by 100% to the locomotive's wheels, we can calculate this example:
which are around 55hp. Compared with the several thousand hp, a standard locomotive provides, this seems to be a rather poor result. But stop! What about the dynamics? If the locomotive runs along the upper canal, the water is forced into the guiding tube to the turbine. Moreover, the siphon effect should add power.
My first guess is: that seems to be misleading.
|Last update: 29 October 2003 /||