Archiv der Kategorie: mechanical tinkering

Contributions to projects with and around the topic of mechanics.
Projects such as the construction of the Stirling engine or hot-air engine are presented here

The steam engine

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Wilesco steamengine

The following piece is about 40 years old model steam engine from the manufacturer Wilesco. (Thanks to Manfred for the loan for the media preparation). The model consists of a highly polished and nickel-plated brass kettle, which is built into an old copper-colored boiler house with brick pattern. Heating is done with a dry spirit burner located under the boiler. The pressure vessel has a spring safety valve and a „Domdampfpfeife“. The pressure line is led to a single-acting pendulum cylinder, which in turn drives the crank and the flywheel on it via a connecting rod.Trockenspiritusbrenner.

IMAG0064The entire model is mounted on an iron plate. In order to be able to drive mechanical models with the machine, a pulley is mounted on the shaft of the flywheel. Since the model has been stored in a carton for the past forty years, a few small jobs have been done. Piston and crank were stiff and had to be cleaned and re-oiled. The crank was a bit out of alignment with the flywheel shaft.

IMAG0057The seals of the „Domdampfpfeife“ and the pressure relief valve were also brittle and hardened and were replaced. Here I was able to use a suitable punching tool made of „new“ old gasket material to knock out and insert two new gaskets. Now the model was a little bit freed from the dust of the last years and cleaned and a start attempt was nothing in the way.

Now the spirit burner could be filled with a small piece of dry spirit, which was probably even older than the machine itself. At least the original box looks like this:

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The flame licker

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A small mechanics project occupied me this time. It is again about a hot air engine. This time not about the Stirling engine, but the so-called „flame eater“.

During the search in the World Wide Web, I found, among other things, the website of Mr. James Maiwald. Mr. Maiwald is an ambitious modeler and specialist in the field of Stirling and vacuum engines. He develops and manufactures his own models in all variants and also offers them as a kit.

More precisely, it is a vacuum motor, which is popularly also called a flame eater. He is one of the hot air engines, but unlike the Stirling engine is an open system.

Technically speaking, it is an atmospheric engine, since here the external air pressure does the work (comparable to the first gasoline engine). As a result, the maximum piston force is limited to the product of piston area and air pressure. (Wikipedia)

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Detail view slide valve

And exactly one such model (lying the flame eater) is here. As I assemble the engine and the first time commissioning is seen in the following short video …

More information and interesting models and kits can be found on the website of Mr. Maiwald: www.kellergeist71.de

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The Stirling engine

 
 
 
the finished machine

As a gift I received in the winter of 2014 a kit for a model of a Stirling hot air machine. The design plans, as well as the largely prefabricated parts, come from Mr. Klaus Künneth, the operator of the website www.kk-stirlingmotor.de

To build and install only a little manual skill and a few gauges and tools are needed. (Stand drill, drill and tap, a grinding block with polishing wheels, at least a sliding calliper, a little clear coat and machine oil). On some parts holes of various diameters are to be made. For example, on the flywheel, the connecting rods. In the cylinder and head cover, the mounting holes are to drill and thread to cut.

drill the flywheel

After preparing all the items, everything is polished to a high gloss on the polishing machine. Then you can start with the assembly. All in all, one should take a few hours to have the model beautiful, meticulous and functional. From a few parts is then also quickly made a small spirit burner, which provides the necessary heat for operation under the working piston. Everything together is then mounted on the clear lacquer-sealed wooden base plate.

finished polished unit
The functioning of the Stirling engine is described by Mr. Künneth on his website as follows:
 
„The Stirling engine is also called a hot air engine and is a heat engine in which a closed working gas such as air (in this case) or helium is alternately heated and cooled from outside at two different areas (hot side and cold side) to generate mechanical energy. The Stirling engine works on the principle of a closed cycle and is an example of the energy conversion of a poorly usable form of energy (thermal energy) in the better usable form of energy of mechanical energy. The Stirling engine can be operated with any external source of heat (or cold) (solar, wood, gas, liquid fuels, in this model with spirit).“
 
short video link:
 
 
 
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