The Egyptian Pulley is a two component, true pulley fabricated from high compressive strength materials (well known in the Old Kingdom) and is a simple mechanism that the Old Kingdom Egyptians could have employed to lift the 2.3 million Great Pyramid stones. The Pulley has been successfully demonstrated full scale. Evidence of use of the Egyptian Pulley design exists in the Great Pyramid itself.
Novel Features of the Egyptian Pulley
- Compressive Loading: The design involves only compressive loading of its two components.
- Pulley Efficiency: The (roughened) rope groove prevents the rope from slipping, thereby efficiently changing the rope's direction (as a true pulley does).
- High Strength Materials: The materials of construction are high compressive strength materials -- limestone, granite, or copper.
- Matching Diameters: The design involves close matching of the cylinder diameter and cradle inner diameter, thereby spreading the load and reducing wear.
- Polished and Lubricated: The mating surfaces of the cylinder and cradle are polished smooth (sealed with natural resin, as needed) and lubricated to assure low rotational friction.
- Rope Protection: The rope groove protects the rope, like a conventional pulley sheave, in two ways: from surface abrasion; and, critically, by maintaining the cross-sectional integrity of the rope, i.e., its twist structure.
- Axial Translation: The design allows some axial translation of the cylinder (within the limits of the axial length of the cradle) thus eliminating rope deflection and related rope and Pulley stresses -- meaning that the pullers do not have to maintain a perfect in-line pull position.
- Cylinder Capture: The cradle design allows for effective “capture” of the cylinder so that is stays in correct position during high loads and does not slip out of the cradle.
The Great Pyramid -- Application Benefits of the Egyptian Pulley
- Large Diameter Rope Use: The high compressive strength of the Egyptian Pulley allows the use of a large diameter, high strength pull rope.
- Small "Footprint": The relatively small size of the Egyptian Pulley as employed to lift a pyramid stone means multiple Egyptian Pulleys could have been utilized -- to meet the stone lifting rate required.
- Pullers on Horizontal Surface: The Egyptian Pulley allows the pullers to be positioned on the top, horizontal surface of the pyramid during construction.
- Easily Repositioned: The Egyptian Pulley (weighing less than 200 pounds total) can be readily disassembled and easily repositioned.
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