Illustrated Architecture Dictionary
Relevant VocabularySledges: Sleds
Levers: A bar used for prying or dislodging something. A lever is a beam connected to ground by a hinge, or pivot, called a fulcrum.
Winch: A hauling or lifting device consisting of a rope, cable, or chain winding around a horizontal rotating drum, turned by a crank or by motor or other power source; a windlass.
Pulley: A wheel with a grooved rim around which a cord passes. It acts to change the direction of a force applied to the cord and is chiefly used (typically in combination) to raise heavy weights.
There are three main types of pulleys: fixed, movable, and compound. A fixed pulley's wheel and axle stay in one place. A good example of a fixed pulley is a flag pole: When you pull down on the rope, the direction of force is redirected by the pulley, and you raise the flag.
Crank: Bent up bar. A part of an axle or shaft bent out at right angles, for converting reciprocal to circular motion and vice versa.
Spindle: A rod or pin serving as an axis that revolves, or on which something revolves.
Pre-Greek Construction Techniques
The largest of the Sarsen stones transported to Stonehenge weighs 50 tons — which means that transportation by boat would have been impossible. The prevailing theory is that the stones were literally dragged using an intricate series of sledges, ropes, ramps, and levers.
The birth of the crane is inextricably tied with the birth of the pulley — first devised by ancient Mesopotamians as early as 1500 BC for hoisting water. The first compound pulleys were created by Archimedes of Syracuse around 287 – 212 BC, which he used to lift an entire warship, along with its crew.
Water would have been the key element. According to the study, the ancient Egyptians moistened the sand where the wooden sleds on which the stone blocks were transported moved. The key would have been to spill the precise amount of water.
The stones of the Pyramids of Giza were likely hoisted into place in a similar fashion. The “regular” slabs that tourists see on the outside surface of the pyramids are 3 tons each, but the biggest supporting slabs weigh up to 70 tons.
The Colossi of Memnon each weighed 700 tons each. By comparison, most common tower cranes today have a lifting capacity of only 12 to 20 tons, and most construction cranes go up to 300 tons.
Greeks Invented the First Crane
GreekBoston.com (online Dec. 2019)
A crane is a mechanical object that is designed to lift heavy objects.
Prior to the invention of the crane, builders relied on ramps to construct their buildings. Although this worked to a point, it wasn’t as efficient as the crane.
Cranes Are an Ancient Greek Invention
Archeologists have uncovered evidence that the Ancient Greeks were the first to use cranes to lift heavy objects. They predict that they were first in use in the 6th Century B.C. When observing various archaeological sites, they noticed that there were distinct markings that created grooves and holes in some of the stone structures. They surmised that these grooves and holes were created by some kind of lifting device. At this time, they were mostly used to lift heavy stone blocks when they were making temples.
Early cranes were made with simple ropes, which were used to hoist the stones more easily and efficiently. Over time, the Greeks introduced the winch and pulley.
Invention of Greek Cranes
The first vestiges of the use of cranes appear in Ancient Greece in the 6th century BC. These are iron tongs marks on the stone blocks of the temples.
It is evidenced in these marks (distinctive cuts c. 515 BC) its purpose for the elevation since they are made in the center of gravity or in equidistant pairs of a point on the center of gravity of the blocks. The introduction of the winch and the pulley soon leads to an extensive replacement of ramps as the main means of vertical movement.
The first unambiguous literary evidence to support the existence of the system composed of pulleys appears in the mechanical exercises attributed to Aristotle (384-322), but perhaps drawn up at a slightly later date.
Wikipedia (online Dec. 2019)
A 13th century drawing of a treadwheel crane
During the High Middle Ages, the treadwheel crane was reintroduced on a large scale after the technology had fallen into disuse in western Europe with the demise of the Western Roman Empire.
... cranes were placed in the initial stages of construction on the ground, often within the building. When a new floor was completed, and massive tie beams of the roof connected the walls, the crane was dismantled and reassembled on the roof beams from where it was moved from bay to bay during construction of the vaults.
Thus, the crane ‘grew’ and ‘wandered’ with the building with the result that today all extant construction cranes in England are found in church towers above the vaulting and below the roof, where they remained after building construction for bringing material for repairs aloft.
Roman and Medieval Treadwheels
Note the treadwheel at left
The coupling crane was reintroduced on a large scale after the technology had fallen into disuse in Western Europe after the fall of the Western Roman Empire.
The Romans adopted the Greek crane and developed it.
A wheel crane (Latin: Magna rota) is a wooden, human-powered crane. It was used mainly during the time of the Romans and the Middle Ages in the construction of castles and cathedrals.
The often heavy loads were elevated while an individual walked inside a cage-like wooden wheel. The rope connected to a pulley is wound on a spindle by the rotation of the wheel, thus allowing the device to lower or lower the platform with the load to be moved.
Styled like colossal human hamster wheels, these cranes allowed huge loads to be hoisted with ease.
The treadwheel crane was a wooden, human-powered lifting and lowering device invented in Ancient Rome. It was used in construction and industry for lifting all manner of materials and produce.
Its creation was a revelation at the time, granting a single person the ability to lift roughly 3,000 kilograms (6,600 pounds) of weight, rather than a completely manual 50 kilograms (110 pounds). As such, while it could take 50 workers to haul a 2.5-ton block of stone during the construction of Egypt’s pyramids, by using a treadwheel crane, the equivalent load could be lifted in Roman construction projects by just three.
Key to this was the huge mechanical advantage granted by the large-diameter treadwheel; it acted as a force amplifier, with the low force input of the treadwheel workers increased dramatically at the output end.
A typical system placed two peddlers side by side in a large, tracked wooden wheel, itself turning around a central shaft. As the wheel was set in motion by the pacing of the workers, it would rotate the central shaft, which in turn would draw in or let out a connected pulley.
The pulley extended out along the crane’s lifting bar and then down to the floor, where objects could be either loaded or unloaded.
In the temple of Jupiter in Baalbek, the blocks weigh up to 60 tons each, and the cornices of the corner block even over 100 tons, all raised to a height of 62' above the ground. In Rome, the capital block of the Trajana column weighs 53.3 tons and rises to a height of 112'.
Despite its fairly crude design, the treadwheel crane remained in widespread use right up to the end of the 18th century.
Unfinished Cologne Cathedral, 1856, with 15th-century crane on south tower in upper left