Construction Cranes

The ancient Egyptians used ramps to get heavy stones to the top of the pyramids. This method was inefficient and there was a lot of man power needed to complete the task. The Greeks were inventive and came up with a simple machine that created a mechanical advantage. The crane. The crane uses a wire drum, wire ropes (or chains), and sheaves. The crane can lift or move horizontally a load many times heavier than what a human can lift alone.

This way of using pulleys was described by Aristotle in Mechanical problems. The stones used for the Greek temples have scaring in them that is said to be proof of crane use. These were the ancient equivalent to modern Industrial Hoists. The next people to use the crane were the Romans. This occurred when they were having a building hayday. The Romans constructed buildings that were larger than what was built before.

The amount that the crane can bare depends on the number of pulleys that are used. The crane that was used by the Greeks had between three and five pulleys, and can bear between 3000kg and 6000kg. Beast of burden and human power were used to operate the cranes. The crane with three pulleys was called the Tripastos, the five pulley crane carried the name Pentapastos. This was all during the building hayday. With bigger buildings cranes needed to be able to lift heavier loads.

The Romans were able to achieve this by replacing the winch with a treadmill. This doubles the load that the crane could handle. Then humans went through the dark ages and cranes were forgotten. It was not until the middle ages was the crane used again. The first time they were seen again was in Utrecht in 1244. The crane was used for making the gothic cathedrals. The treadmill came back in 1331, and instead of man or animal power these cranes used a winlass.