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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.
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.
By August 10, 2012, concrete flooring had been completed to the 93rd story of the tower, One World Trade Center had risen to the 105th floor and glass installation was at the 82nd floor. [58] The building was structurally topped out on August 30, 2012 when the last of the spandrel beams were installed between the parapet columns. [59]
Jib lengths of up to 160 metres (520 ft) give a lifting radius of up to 100 m (330 ft). They also have a small footprint compared to gantry or Goliath cranes. The performance of super-heavy jib cranes is measured in tonne-metres, the product of weight and lifting radius, typically as much as 100,000 tonne-metres for large cranes. [8]
A jib crane is a type of crane - not to be confused with a crane rigged with a jib to extend its main boom - where a horizontal member (jib or boom), supporting a moveable hoist, is fixed to a wall or to a floor-mounted pillar. Jib cranes are used in industrial premises and on military vehicles.
The crane had three smaller hoists for lifting 10, 20 and 50 tons. The main hoist has two 125 tonne lifting units which could be coupled for a combined lift of 250 tonnes. The crane had a maximum jib tower height of 81.4 m. The crane is self-propelled with two propellers and floats on pontoons.
Multiple fires raging across the Los Angeles area will cost insurers as much as $30 billion, Wells Fargo and Goldman Sachs estimated in a report released this week. The ongoing fires, according to ...
The jib was slewed by a mechanism on the ground, and bearings at the top of the tower and where the extension met the ground allowed it to turn. [ 1 ] [ 2 ] The winch on each arm was powered by two 52 horsepower (39 kW) electric motors for hoisting and two 14 horsepower (10 kW) motors for slewing, and a 18 horsepower (13 kW) motor for slewing ...