The term Self-erecting crane is commonly used to describe two different types of tower crane.
Generally a type of tower crane, these cranes, also called self-assembling, jack-up crane or "Kangaroo" cranes, which lift themselves from the ground or lift an upper, telescoping section up using jacks, allowing the next section of the tower to be inserted at ground level or lifted into place by the partially erected crane itself. They can thus be assembled without outside help, and can grow together with the building or structure they are erecting.
The other form is a mobile or semi-mobile small tower crane that folds for transport. The lorry mounted versions are based on a crane carrier type chassis and have a folding boom with a telescopic tower. On some models the drivers cab operates like lift on the side and the operator gets in and it then his him up to the top of the tower were he then has good visibility of the work zone like on a normal tower crane. These cranes do not have a great lifting capacity in terms of load but have a 30m or more radius and a under hook height of 40m on the larger models.
The semi mobile version are on abase that has removable wheel for road transport as a trailer. These set up on a concrete base & ballast block are added to hold it in place then lifts it mast and folds out the jib and picks up addition ballast that rotates with the crane but is situated a the base of the tower withback stays from the top of the mast and jib to transfer the load. These are generally used on large houses or small flats developments or hotels often using panelised building systems with loads of less than 2 ton (they can lift uo to 5 ton close in) They are popular in Europe but are gaining in popularity in the UK and Ireland on tight city centr sites or prestigious house refurbisments were these is no access all round to use a Telescopic handler without destroying the gardens
For an animation of such a crane in use see this video  (here, the crane is used to erect a scaffold which in turn contains a gantry to lift sections of a bridge spire).
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