page_title: Treadwheel crane
section_title: Harbour usage
hierarchical_section_title: Treadwheel crane / History / Middle Ages / Harbour usage
caption_attribution_description: Alter Krahnen, Trier, Germany
context_page_description: A treadwheel crane is a wooden, human powered, hoisting and lowering device. It was primarily used during the Roman period and the Middle Ages in the building of castles and cathedrals. The often heavy charge is lifted as the individual inside the treadwheel crane walks. The rope attached to a pulley is turned onto a spindle by the rotation of the wheel thus allowing the device to hoist or lower the affixed pallet.
context_section_description: According to the "present state of knowledge" unknown in antiquity, stationary harbour cranes are considered a new development of the Middle Ages. The typical harbour crane was a pivoting structure equipped with double treadwheels. These cranes were placed docksides for the loading and unloading of cargo where they replaced or complemented older lifting methods like see-saws, winches and yards.
  Two different types of harbour cranes can be identified with a varying geographical distribution: While gantry cranes which pivoted on a central vertical axle were commonly found at the Flemish and Dutch coastside, German sea and inland harbours typically featured tower cranes where the windlass and treadwheels were situated in a solid tower with only jib arm and roof rotating. Dockside cranes were not adopted in the Mediterranean region and the highly developed Italian ports where authorities continued to rely on the more labor-intensive method of unloading goods by ramps beyond the Middle Ages.
  Unlike construction cranes where the work speed was determined by the relatively slow progress of the masons, harbour cranes usually featured double treadwheels to speed up loading. The two treadwheels whose diameter is estimated to be 4 m or larger were attached to each side of the axle and rotated together. Their capacity was 2–3 tons which apparently corresponded to the customary size of marine cargo. Today, according to one survey, fifteen treadwheel harbour cranes from pre-industrial times are still extant throughout Europe. Some harbour cranes were specialised at mounting masts to newly built sailing ships, such as in Danzig, Cologne and Bremen. Beside these stationary cranes, floating cranes which could be flexibly deployed in the whole port basin came into use by the 14th century.
caption: Tower crane at the inland harbour of Trier from 1413
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