The moving of heavy loads (stones) appears as early as the 5th millennium B.C. with the impressive megalithic structures in Western Europe, and later takes on epic dimensions with colossal construction projects of the first great civilisations (Egyptian etc.). However, concerning horizontal shifting, the traction on a specially shaped ramp using levers, ropes and sleds required synchronised manpower. The impressive structures of the Mycenaeans belong to this category, with the giant wall-gate lintels and vaulted tombs.
The greatest revolution, also in this sector, was brought about by the Greeks (6th c. B.C.) with the invention of the pulley and its use in various block and tackles (such as the two-wheeled pulleys, three-wheeled pulleys etc. for the doubling, tripling etc. exertion of force) in conjunction with the invention and application of various types of winches for the increased exertion of force according to the ratio of the length of the driving lever arms to the radius of the traction rope reel. The invention and development of multiple hoisting machines, such as the one-mast crane, the two-mast crane (today’s gantry), four-mast crane (today’s scaffolds), etc. in combination with the use of clever stone fastening methods, impressive methods of braking and suspension, lubrication and special sliders, rollers and suitably wheeled vehicles led to the Greek architectural marvel.
Modern lifting technology is the direct evolution of the impressive lifting technology of the ancient Greeks, by which great Greek engineers such as Archimedes, Heron, Pappus etc. theoretically occupied themselves.
Block and tackles (Polyspasta)
They consisted of the combination of a fixed and a movable “pulley” in an interdependent system by the lifting rope. In the wooden or metal sheath of each “pulley” one or more axles were fitted and around each one rotated one or more pulley-wheels. “Trispasto” was the system with three wheels (two in the top “pulley” and one in the bottom). “Tetraspasto” was the system with four wheels (two in each “pulley”), etc.
SOURCES: Vitrouvios, On architecture, X, 1-2, Heron of Alexandria, Mechanics, “Pappos of Alexandria, Mechanics.
Links, dowels and “empolia”
For the secure horizontal fitting of adjacent stone blocks, bronze or iron “links” in the form of I were usually used which were placed in corresponding curved sockets in the blocks and were stabilised and protected with cast lead. For their stable vertical mounting, “dowels” were used, i.e. bronze or iron laminas which were placed in a similar manner. For the secure connection of the vertebras of the pillars the “empolia” (i.e. wooden elements of square cross-section that were placed in corresponding square sockets in the centre of the vertebras) were used. The “empolia” had holes in their centre and were linked together by the “pole”, a vertical pin, allowing the free rotation of the vertebras.
SOURCES: A. Orlandos, The materials of structure of ancient Greeks (I & II), Manolis Korres, From Penteli to the Parthenon.
They basically consisted of a long axle which wrapped the rope pulling the load and were either firmly fixed in the radial axle or moveable levers in special sockets for the application of the required drawing force by the operators. Sometimes they had pulleys, sprockets or even worm gears to further increase productivity.
The ground winches for the lifting rope and the tautening of the balancing ropes were attached to a stably fastened vertical pole while the winches of the scaffolds were placed on horizontal beams with rollers for their easy horizontal shifting.
SOURCES: Vitrouvios, On architecture X, 1-2, Heron of Alexandria, Mechanics, Pappos of Alexandria, Mechanics.
Methods of stone suspension
For their elevation, the stones (with the use of wood for the protection of their acmes) were usually fastened by strong ropes that were attached to the grab of the crane. Due to the difficult removal of ropes on several occasions (the ropes would be crushed by the stone above after its placement), various brilliant systems of stone mooring were devised, such as:
A) Via apertures in the form of U that were carved on the top surface and internally of the stone (Olympia, Delphi, Temple of Aphaia, etc.).
B) Via carved ledges (elbows) on the longitudinal side surfaces of the stones that were usually later removed (Parthenon, Propylaia, etc.).
C) Via carved traverse grooves at the bottom part and sometimes on the sides of the stone as well (Selinous, etc.).
D) Via carved grooves in the form U in the traverse side surfaces of the stone (Akragas, Temple of Aphaia, etc.).
E) With the help of a pair of tongs (anchors and grabs) hung in notches (tenons and mortises) and suitably carved apertures of the stone (Parthenon, Olympia, Delphi, Epidaurus, etc.).
F) With the help of the cancer, scissors-like hinged pincers whose lower ends were hooked into suitable sockets on the top part or the sides of the stone and which automatically clasped with its elevation (Sounio, etc.).
G) With the help of the wolf, a system constructed by two metal or, more seldom, wooden pieces (one rectangular and the other of trapezoidal cross-section with only one side inclined), that were applied to respectively carved trapezoidal sockets of the stone (sidelong on one side) so as to wedge automatically during the elevation (e.g. Temple of Hephaestus, Ancient Agora of Athens etc.). The suspension was made either by aperture or by the shaped hook of the trapezoidal piece. During the post-Hellenistic period the wolf was used with three pieces, two of which were of trapezoidal cross-section with opposite inclinations (bell).
SOURCES: A. Orlandos, The materials of structure of ancient Greeks (I &II), Manolis Korres, From Penteli to the Parthenon.