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A level-luffing crane is a crane mechanism where the hook remains at the same level while luffing: moving the jib up and down, so as to move the hook inwards and outwards relative to the base. [ 1 ] Usually the description is only applied to those with a luffing jib that have some additional mechanism applied to keep the hook level when luffing.
A jib or jib arm is the horizontal or near-horizontal beam used in many types of crane to support the load clear of the main support. [1] [2] An archaic spelling is gib. [3] Usually jib arms are attached to a vertical mast or tower or sometimes to an inclined boom.
The "hammerhead", or giant cantilever, crane is a fixed-jib crane consisting of a steel-braced tower on which revolves a large, horizontal, double cantilever; the forward part of this cantilever or jib carries the lifting trolley, the jib is extended backwards in order to form a support for the machinery and counterbalancing weight. In addition ...
Jib crane. Cranes are used to transport loads over variable (horizontal and vertical) paths within a restricted area and when there is insufficient (or intermittent) flow volume such that the use of a conveyor cannot be justified. Cranes provide more flexibility in movement than conveyors because the loads handled can be more varied with ...
The crane was powered by a semi-portable steam engine in a small cabin at the rear of the jib, also helping as a counterweight. 1871 timber queen post truss jib, for the North Sea Canal Construction of the Dutch Noordzeekanaal from 1865 to 1876 used a variety of cranes, including two significant examples of the Hercules type.
An overhead crane, commonly called a bridge crane, is a type of crane found in industrial environments. An overhead crane consists of two parallel rails seated on longitudinal I-beams attached to opposite steel columns by means of brackets. The traveling bridge spans the gap. A hoist, the lifting component of a crane, travels along the bridge.
Early French crane loading coal for a gasworks. A bulk-handling crane is one that, instead of a simple hook that can handle a range of slung loads, has an integral grab for lifting bulk cargoes such as coal, mineral ore etc. Where the grab is a two-piece hinged bucket, it is known as a shell grab or shell bucket. Working the grab requires extra ...
To lift a load, a separate line runs up and over the mast with a hook on its free end, as with a crane. [ 1 ] [ 2 ] Derricks are especially useful for high-rise rigging, jobs that cover a long period of time, or jobs when the impact to street or pedestrian traffic is a concern. [ 3 ]