Method for assembling a crane and method for operating a crane

A method for assembling a crane, which crane comprises a main boom, a back mast and a ballast mast, said back mast having in an assembled state a foot end and a ballast mast end, said main boom having in an assembled state a foot end and a load end, wherein both the main boom foot end and the back mast foot end are pivotably connected to a mast foot assembly, and wherein the ballast mast end of the back mast is pivotably connected to the ballast mast, which method comprises the following steps:

• erecting the ballast mast with a back mast top slide that is movable along the ballast mast and which back mast top slide is fixable in a plurality of positions relative to the ballast mast,
• constructing the back mast using the ballast mast, which comprises the following steps:
• providing a back mast upper section, which has a length that is shorter than the final length of the back mast, and which back mast upper section has a ballast mast side end and a back mast side end,
• providing multiple back mast intermediate sections, which each have a length that is shorter than the final length of the back mast, and each have a first end and a second end,
• providing a back mast lower section, which has a length that is shorter than the final length of the back mast, and which back mast lower section has a foot side end and a back mast side end,
• connecting a part of the back mast including at least the back mast upper section, and further including one or more pre-connected intermediate sections, to the back mast top slide,
• stepwise extending the part of the back mast that has been connected to the back mast top slide by attaching further back mast intermediate sections and the back mast lower section, and
• stepwise raising the back mast top slide along the ballast mast during the extending of the back mast.