Tag Archives: contrade

A wooden roller bearing ? – A practical approach

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Every year in Artena, since 1992, takes place a big event which puts in competition all the contradas of the town. This event is called “Palio delle contrade di Artena” and is able to entertain several thousands of people challenging the contradas in rural games that recall the origin of Artena. One of the funniest games is called “La Carettella” in which every partecipant has to drive a kart entirely made of wood, down a hill, in less time possible. A guy, who is actually the captain of the contrada in which I live, came to me asking if it was possible to improve the performance by using some wood ball bearings. The idea seemed pretty challenging to me so I started googling around to find if anyone have ever had the same insane idea. Surprisingly I couldn’t find anything that wasn’t just a toy and unsuitable for such a stressful application . I spent several weeks thinking if it was possible to make a working bearing that was also reliable for a race plus several test session and ended up with the conclusion that the only way to know it was actually doing it. So I started looking for the wood with the best properties needed to be used for the volvent parts. My research lead me to Lignum Vitaean exotic wood with an extraordinary combination of strength, thoughness and density with the exceptional property of being self-lubricating. Actually it is also the hardest and heaviest wood on the earth, according to Wikipedia. Some really useful information such as elastic modulus, modulus of ropture, etc… can be found on wood-database.com. Of course these properties can change dramatically due to so many factors ( wood is not an isotropic material at all ) that they should be used very very carefully.  Continue reading