Technical Integration
Metal and progress: certainly, throughout the latter part of
the Neolithic times, carriers of that era noticed that larger diameter
trunk-rollers passed more easily over obstacles encountered in the road. Otherwise, such rollers did not make it easy to change direction. So, there was
plenty of room for improvements on the transportation techniques that emerged
in the Neolithic.
Functional fact: wear was affecting the log rollers by
abrasion in their mid-section (where they were pressed against the fixed bearing/supports
under the "chassis" or even against the "chassis" itself),
causing them to thin. The phenomenon would have inspired the creation of solid
bridges with wheels at their extremities.
A first noticeable advantage of this difference in
diameters: the higher torque resulting from the movement of the larger diameter
ends of the log-roller helped to easier overcome the rolling resistance given
by the lower torque generated at the bearings/chassis in the middle area (where
the diameter had been reduced by wear). This would have given to the tech guys
of that era a first idea regarding what a reduction ratio in a rolling
mechanism might be good for. Agree, all this sounds dizzyingly complicated. Other
studies claim that, at some point during the early metal ages, the idea of an
axle with wheels – already present in pottery devices – ended up being
transposed to a higher scale, taking over the role of a solid axle with wheels
in the vehicles’ general concept.
Beginning with the time of copper and then bronze, new tools
were invented and perfected. These were used to produce increasingly
sophisticated and finely defined objects. The new metal tools, amenable to use
to obtain fairly rigorously defined shapes, allowed both the carving of wheels
from sections of large trunks and the carving of wheels from stone - those better
supported the idea of non-rigid mounting with the axle.
As the first part of the metal ages developed, solid wheels made from pieces of wood and stiffened with metal parts appeared, and new metal elements began to be used to attach wheels to axles and axles to the vehicle. The stiffening of a wheel made of wooden elements (thick planks) with metal parts was an important step in the wheel manufacturing technique. One such wheel, dated as coming from the year 5200 BC, was discovered in Slovenia (bottom right).
The most advanced invention related to the development of
vehicles during the Bronze Age was the directional front axle. This involved a
pivoting device to attach the axle to the chassis. The use of metal for small
parts highly resistant to mechanical stress was essential in that sense. The
toy figurine in the shape of a cow on wheels discovered at Cucuteni shows that
the idea of the wheels attached to an fixed axle was something familiar around
the year 3900 BC.
On a ceramic pot discovered in Bronocice (Poland) and dated
as coming approximately from the year 3600 BC, some four-wheeled chariots are
represented simplistically (top right image). It is only at this time,
approximately 4000 years BC, that the first carts can be considered as part of
the current life of the advanced human communities.
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