But with the mechanical fun, comes a bit of theory and background. A gear can be described as a rotating machine part that boasts cut ‘teeth’, teeth which mesh with another toothed component to transmit ‘torque’.
Above is a simple gear train in which three meshing gears side by side transmit rotational motion. You can see that the smallest gear is rotating more quickly than the other two. Even though the largest gear is rotating more slowly, its torque is proportionally greater. And you can see that the largest one is moving in the opposite direction to the smaller gears on either side.
In 4th century BC, Aristotle wrote: “The direction of rotation is reversed when one gear wheel drives another gear wheel.” A century later, other Greek polymaths and inventors were using gears in water wheels for modifying the provided rotational speed for application to pumps and other machines. Such early gears were often wooden with pegs for teeth, and lubricated with animal fat.
Midway through the last millennium the development of gears really kicked on, with clock-making flourishing in the metalworking towns of Germany and France in the 15th and 16th centuries, and then the industrial revolution in Britain in the 18th century that saw a proliferation in metal gearing.
Gear design and manufacture bloomed even more in the 19th century with the advent of the personal automobile which, of course, made huge strides in the 20th century.
Today, the most significant gear developments have been in terms of materials, with new metallurgical techniques increasing the life of automotive and industrial gears, while consumer electronics have seen the development of quiet, reliable, lubricant-free plastic gears.
The videos we are showcasing here are slightly wackier versions than your usual gear trains. These unusual cubic (above) and heart-shaped (below) gears have you scratching your head wondering if this is engineering as conducted through the Looking Glass in Alice in Wonderland.
The heart one is definitely striking – the sort of organ, possibly, that the Tin Man from the Wizard of Oz was hankering after.
Then there is the paradoxical gear system (above). In traditional gears, as Aristotle noted, the tooth from one gear must mesh with two teeth in the second gear and, to work, these gears will spin in opposite directions.
The video of the paradoxical gears sees the tooth of one gear pass in front of the second gear without meeting any of the second gear's teeth. It has to, otherwise the gear train will lock.
Then there is the gear system that changes speed – three different speeds. Within each rotation, the speed changes from slowest, to the medium speed to the fastest speed.
What the practical application of this gear would be is anyone’s guess, though as one commentator says, this looks like something Lady Gaga would wear as underwear.
Along similar lines is the gear system that changes direction.
Finally, there is this video (above) of a epicyclic or planetary gear system, i.e. a system comprising one or more outer gears, or planet gears, revolving about a central, or sun, gear.
Apparently the guy made it to prove to his work colleagues that a planetary gear system in which the planet gears are of different sizes can work. Bravo!
To find out more about the industrial application of gears, please visit: science.howstuffworks.com/transport/engines-equipment/gear.htm