Cranes of ancient Rome

The heyday of the crane in ancient times came before the Roman Empire, when construction work increased on buildings that reached enormous dimensions. The Romans adopted the Greek crane and developed it.

The simplest Roman crane, the Trispastos, consisted of a single-beam gallows, a winch, a rope, and a block containing three pulleys. Thus having a mechanical advantage of 3:1, it has been calculated that a single man working with the winch could lift 150 kilograms (3 pulleys × 50 kg = 150 kg), assuming that 50 kilograms represent the maximum effort that a man can exert over a longer period. Heavier types of crane offered five sheaves (Pentaspastos) or, in the largest case, a three by five sheave system (Polyspastos) with two, three or four masts, depending on the maximum load. The Polyspastos, when operated by four men on both sides of the winch, could lift up to 3000 kg (3 ropes × 5 pulleys × 4 men × 50 kg = 3000 kg). In case the winch was replaced by a coupling, the maximum load even doubled to 6000 kg with only half the equipment, since the coupling possesses a much larger mechanical advantage due to its larger diameter. This meant that, with respect to the construction of the Egyptian pyramids, where about 50 men were needed to move a 2.5-ton block of stone up the ramp (50 kg per person), the lifting capacity of the Roman Polyspastos proved to be 60 times higher (3000 kg per person).

However, Roman buildings offer numerous stone blocks much heavier than those. Led by Polyspastos indicate that the total lifting capacity of the Romans was far beyond that of any single crane. In the temple of Jupiter in Baalbek, the blocks weigh up to 60 t each, and the corner cornices block even over 100 t, all raised to a height of 19 m above the ground. In Rome, the capital block of Trajan's column weighs 53.3 tons and had to be lifted to a height of 34 m.

It is assumed that the Roman engineers achieved the lifting of these extraordinary weights by two means: first, as suggested by Heron, a lifting tower was installed; four masts were arranged in the shape of a quadrilateral with parallel sides, not unlike a tower, but with the column in the middle of the structure. Secondly, a multiplicity of winches were placed on the ground around the tower, so, although it has a lower leverage ratio than the links, the winches could be installed in higher numbers and operated by more men (and animals). This use of multiple capstans was also described by Ammianus Marcellinus (17.4.15) with respect to the raising of the Lateran obelisk in the circus Maximus (AD ca. 357). The maximum lifting capacity of a single winch can be set by the number of iron holes in the monolith. In the case of the Baalbek architrave blocks, which weigh between 55 and 60 t, eight holes suggest a weight of 7.5 t due to the iron in the gaskets, which is in the capstan. Lifting such heavy weights in a concerted action required a great deal of coordination between the work groups applying power to the winches.

Medieval cranes

The coupling crane was reintroduced on a large scale after the technology had fallen into disuse in Western Europe following the fall of the Western Roman Empire. The closest reference to a coupling reappears in literature archived in France around 1225, followed by an illuminated painting in a manuscript probably also of French origin dated 1240. In navigation, the closest applications of harbor cranes are documented for Utrecht in 1244, Antwerp in 1263, Bruges in 1288 and Hamburg in 1291, while in England the coupling is not recorded before 1331.

Generally, vertical transportation was safer and cheaper done by cranes than by other methods common for the time. Areas of ports, mines, and, particularly, buildings where the docking crane played an important role in the construction of tall Gothic cathedrals. However, archived and illustrated sources of the time suggest that machines were reintroduced as couplings or wheelbarrows, so as not to completely replace more dependent methods of work such as ladders, troughs and stretchers. Something that is important to mention is that old and new machinery continued to coexist on medieval construction sites and in ports.

Cranes in Ancient Greece

The first vestiges of the use of cranes appear in Ancient Greece around the century BC. C. These are iron tong marks on the stone blocks of the temples. Their purpose for elevation is evident in these marks (distinctive cuts c. 515 BC)[7] since they are made in the center of gravity or in pairs equidistant from a point on the center of gravity of the blocks.[8]​.

The introduction of the winch and pulley soon led to an extensive replacement of ramps as the primary means of vertical movement. For the next two hundred years, Greek buildings contemplated handling lighter weights, as the new lifting technique allowed the loading of many smaller stones as it was more practical than a few larger stones. In contrast to the archaic period and its tendency toward ever-increasing block sizes, classical age Greek temples such as the Parthenon invariably offered blocks of stone that could be used to carry no less than 15-20 tons. Also, the practice of erecting large monolithic columns was practically abandoned and then using several wheels to make up the column.[9]​.

Although the exact circumstances of the change from ramp to crane technology remain unclear, it has been argued that the volatile social and political conditions of Greece made the use of small equipment more convenient for construction professionals than large implements for inexperienced work, making the crane preferable to the Greek polis than the labor-intensive ramp, which had been the norm in the autocratic societies of Egypt and Assyria.

The first unequivocal literary evidence for the existence of the composite pulley system appears in the mechanical exercises (Mech. 18, 853a32-853b13) attributed to Aristotle (384-322), but perhaps elaborated at a slightly later date. Around the same century, block sizes in Greek temples began to resemble their archaic precursors again, indicating that there must have been found the way to use more sophisticated compound pulley in the most advanced Greek works by then.

Cranes of ancient Rome

The heyday of the crane in ancient times came before the Roman Empire, when construction work increased on buildings that reached enormous dimensions. The Romans adopted the Greek crane and developed it.

The simplest Roman crane, the Trispastos, consisted of a single-beam gallows, a winch, a rope, and a block containing three pulleys. Thus having a mechanical advantage of 3:1, it has been calculated that a single man working with the winch could lift 150 kilograms (3 pulleys × 50 kg = 150 kg), assuming that 50 kilograms represent the maximum effort that a man can exert over a longer period. Heavier types of crane offered five sheaves (Pentaspastos) or, in the largest case, a three by five sheave system (Polyspastos) with two, three or four masts, depending on the maximum load. The Polyspastos, when operated by four men on both sides of the winch, could lift up to 3000 kg (3 ropes × 5 pulleys × 4 men × 50 kg = 3000 kg). In case the winch was replaced by a coupling, the maximum load even doubled to 6000 kg with only half the equipment, since the coupling possesses a much larger mechanical advantage due to its larger diameter. This meant that, with respect to the construction of the Egyptian pyramids, where about 50 men were needed to move a 2.5-ton block of stone up the ramp (50 kg per person), the lifting capacity of the Roman Polyspastos proved to be 60 times higher (3000 kg per person).

However, Roman buildings offer numerous stone blocks much heavier than those. Led by Polyspastos indicate that the total lifting capacity of the Romans was far beyond that of any single crane. In the temple of Jupiter in Baalbek, the blocks weigh up to 60 t each, and the corner cornices block even over 100 t, all raised to a height of 19 m above the ground. In Rome, the capital block of Trajan's column weighs 53.3 tons and had to be lifted to a height of 34 m.

It is assumed that the Roman engineers achieved the lifting of these extraordinary weights by two means: first, as suggested by Heron, a lifting tower was installed; four masts were arranged in the shape of a quadrilateral with parallel sides, not unlike a tower, but with the column in the middle of the structure. Secondly, a multiplicity of winches were placed on the ground around the tower, so, although it has a lower leverage ratio than the links, the winches could be installed in higher numbers and operated by more men (and animals). This use of multiple capstans was also described by Ammianus Marcellinus (17.4.15) with respect to the raising of the Lateran obelisk in the circus Maximus (AD ca. 357). The maximum lifting capacity of a single winch can be set by the number of iron holes in the monolith. In the case of the Baalbek architrave blocks, which weigh between 55 and 60 t, eight holes suggest a weight of 7.5 t due to the iron in the gaskets, which is in the capstan. Lifting such heavy weights in a concerted action required a great deal of coordination between the work groups applying power to the winches.

Medieval cranes

The coupling crane was reintroduced on a large scale after the technology had fallen into disuse in Western Europe following the fall of the Western Roman Empire. The closest reference to a coupling reappears in literature archived in France around 1225, followed by an illuminated painting in a manuscript probably also of French origin dated 1240. In navigation, the closest applications of harbor cranes are documented for Utrecht in 1244, Antwerp in 1263, Bruges in 1288 and Hamburg in 1291, while in England the coupling is not recorded before 1331.

Generally, vertical transportation was safer and cheaper done by cranes than by other methods common for the time. Areas of ports, mines, and, particularly, buildings where the docking crane played an important role in the construction of tall Gothic cathedrals. However, archived and illustrated sources of the time suggest that machines were reintroduced as couplings or wheelbarrows, so as not to completely replace more dependent methods of work such as ladders, troughs and stretchers. Something that is important to mention is that old and new machinery continued to coexist on medieval construction sites and in ports.