Crane
Mobile Crane
History of Crane
Ancient Greek
Ancient Greek invented the crane for lifting heavy materials in the late 6th century BC. The archaeological found evidences that shows the existence of crane no later than 515 BC. Those evidences were some holes which were on the stone blocks of Greek temple. Those holes are found either above the center of gravity of the block, or in pairs equidistant from a point over the center of gravity. According to archaelogists, those holes were the places for both lifting tongs and Lewis irons.
The introduction of the winch and pulley hoist soon lead to a widespread replacement of ramps as the main means of vertical motion. But when Greeks reduced the weight of stones and loads due to the several reasons such as political condition of Greece-which preferred employment of small and professional construction teams rather than large bodies of unskilled labors-leads them to use crane instead of ramps.
Evidence shows the existence of the compound pulley system appears in one of the ancient books named Mechanical Problems attributed to Aristotle. But later, more complex compound pulley must have found by Greeks construction sites by then. That is why we call Greeks as inventor of the crane.
Ancient Rome
It is obvious that the golden age of crane in ancient time was during the Roman Empire. On that time, building construction especially tall buildings increased. Roman started to develop the Greek crane in order to build tall buildings.
Trispastos was the simplest Roman crane which consisted of a single-beam jib, a winch, a rope, and a block containing three pulleys. By using Trispastos, a single man could raise 150 kg. Then the Romans by adding two more pulleys Pentaspastos and in case of largets one, a set of three by five pulleys Polyspastos and eith two, three or four masts depending on the maximum load. And if they replaced the winch with a treadwheel, the maximum load could be doubled. Later, they developed the crane which was able to lift 60 tons load.
Middle Ages
During the high Middle ages, the treadwheel crane was begun to use frequently after the technology had fallen into disuse in western Europe with the demise of the Western Roman Empire.. First evidence of using treadwheel crane was in France about 1225. The earliest uses of harbor cranes are documented for Utrecht in 1244. Generally, vertical transport could be done more safely and inexpensively by cranes than by customary methods. These types of cranes were used in harbors, mines and in building sites.
Although different types of crane was introduced on that time, cranes did not replaced labor intensive methods such as ladders, hods and handbarrows completely. Cranes are operated manually by windlasses with radiating spokes, cranks and by the 15th century also by windlasses shaped like a ship’s wheel.
The reappearance of the treadwheel crane may have resulted from a technological development of the windlass from which the treadwheel structurally and mechanically evolved.
Industrial Reveloution
The first modern cranes were used at harbours for loading cargo in 1838. A hydraulic water powered crane was invented in 1838 by Armstrong. His crane used a ram in a closed cylinder that was forced down by a pressurized fluid entering the cylinder a valve regulated the amount of fluid intake relative to the load on the crane.
Using hydraulic crane was widespread on that time and several companies were built to design and build the hydraulic crane. Armstrong who invented hydraulic crane improved his crane design, the most important innovation of him was the hydraulic accumulator. Where water pressure was not available on site for the use of hydraulic cranes, Armstrong often built high water towers to provide a supply of water at pressure.