 
CRANES (MACHINE HISTORY)
ORIGINS OF THE MODERN DAY CRANE
A crane is a lifting machine
equipped with a winder, wire ropes or chains and sheaves that can be
used both to lift and lower materials and to move them horizontally.
Put in basic terms, it uses one or more simple machines to create
mechanical advantage to enable the movement of loads beyond the
normal capability of a human.
The principles of operation of today's CRANE EQUIPMENT is taken for
granted, however, we thought you might be interested in learning a
bit about the history of the Crane and its development into the
modern age of technology.
The Greeks and Romans were very
creative and innovative in the area we now call mechanics. The Greeks
invented some simple machines, and put them together in novel ways to
make complex machines, from the compound pulley to the Antikythera
mechanism. Early CRANE EQUIPMENT made from wood beams, ropes and
pulleys helped hoist obelisks and stone temple columns in the Ancient
Greek and Roman civilisations.
CRANE EQUIPMENT ANCIENT
GREEK TECHNOLOGY
The first CRANES appeared in Ancient Greece and were used to build an
entire nation in the fifth century B.C. The word crane is taken from the
fact that these machines have a shape similar to that of the tall,
long-necked bird of the same name. How did the Ancient Greeks manage to
lift large columns of stone to construct their buildings?
The Ancient Greeks mastered the concepts of leverage and
counter-balancing. CRANE EQUIPMENT for lifting heavy loads was invented
by the ancient Greeks in the late 6th century BC. They were a very
advanced civilisation and developed some particularly complex devices to
accomplish their construction requirements.
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An artist's
drawing of ancient CRANE EQUIPMENT used in the construction
of the Parthenon |
The Parthenon
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CONSTRUCTION OF THE PARTHENON
In
439BC the Parthenon was dedicated to the goddess Athena and it took
15 years to complete. This is a remarkably short time when one
considers the principles of architecture employed, some of which are
still unknown to us.
The temple’s main function was to shelter the monumental statue of
Athena that was made by Pheidias out of gold and ivory. The temple
and the chryselephantine statue were dedicated in 438, although work
on the sculptures of its pediment continued until completion in 432
BCE.
Prior to the fifth century B.C., Doric temple construction was
mainly of wood. But the builders of the Parthenon wanted a temple
that would be far more impressive and far more durable than other
Greek temples of their time. Two factors, the city's great wealth
and its large population of skilled workers and slaves, enabled the
Athenians to build the Parthenon entirely of stone.
The 20,000 tons of marble used in the construction of the Parthenon
came from quarries on Mount Pentelicon, about ten miles from Athens.
The Athenians were skilled in the use of the simple machines
(earliest form of crane equipment) required to move massive amounts
of marble: pulleys, levers, and inclined planes. Quarrymen and
stonemasons used iron and wooden tools to hammer and wedge out
blocks of marble. Each piece was cut according to the architect's
specifications.
Blocks used for columns were cut into round drums. On the sides of
the drums, the stone cutters left protruding chunks of stone intact
to be used as handles so that the drums could be lifted into place.
The drums were divided into four sections, each with a different
finishing polish. The center of each drum was hollowed out to allow
the insertion of a wooden peg. Laborers used pulleys to lift the
drums into place. No mortar was used in the construction of the
columns or elsewhere in the temple. With the drums in place, twenty
deep, fluted channels were cut on each column to enhance its
vertical lines.
The Parthenon construction cost the Athenian treasury 469 silver
talents. While it is almost impossible to create a modern equivalent
for this amount of money, it might be useful to look at some facts.
One talent was the cost to build one trireme, the most advanced
warship of the era.
All temples in Greece were designed to be seen only from the
outside. The viewers never entered a temple and could only glimpse
the interior statues through the open doors. The Parthenon was
conceived in a way that the aesthetic elements allowed for a smooth
transition between the exterior and the interior that housed the
huge statue of Athena.
Archaeological records indicate that by C.515 BC, distinctive cuttings
for both lifting tongs and lewis irons began to appear on stone blocks
of Greek temples. These holes point at the use of a lifting device, and
since they are to be found either above the center of gravity of the
block, or in pairs equidistant from a point over the centre of gravity,
they are regarded by archaeologists as positive evidence for the
existence of CRANE EQUIPMENT.
The introduction of the winch and pulley hoist in Ancient Greek CRANE
EQUIPMENT soon lead to a widespread replacement of ramps as the main
means of vertical motion. For the next two hundred years, Greek building
sites witnessed a sharp drop in the weights handled, as the new lifting
technique made the use of several smaller stones more practical than
that of fewer larger ones.
Although the exact circumstances of the shift from the ramp to CRANE
EQUIPMENT technology remains unclear, it is believed that the social and
political conditions of Greece were more suited to the employment of
small, professional construction teams, making the crane more preferable
to the Greeks than the more labour-intensive ramp which had been the
norm in the societies of Egypt and Assyria.
The first literary evidence for the existence of the compound pulley
system appears around (384-322 BC). At this time, block sizes of Greek
temples began to increase in weight and size again, indicating that the
more sophisticated compound pulley must have found its way into Greek
construction sites by then.
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Picture depicting ancient
Greek Crane construction site - Parthenon |
Greco-Roman Trispastos ("Three-pulley-crane"), the simplest
crane type (150 kg load) |
Greco-Roman Pentaspastos ("Five-pulley-crane"), a
medium-sized variant (ca. 450 kg load) |
Ancient
Greek Crane Model
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