A connecting device connects a first attachment and a second attachment constituting a working machine with each other. The connecting device includes a first connected member, a second connected member, and a connecting member (connecting pin 15). The first connected member extends outward from a first side surface of the first attachment, the first side surface extending in a longitudinal direction of the first attachment. The second connected member extends outward from a second side surface of the second attachment, the second side surface extending in a longitudinal direction of the second attachment, the second connected member facing the first connected member when the first attachment and the second attachment come into a connection state. The connecting member connects the first connected member and the second connected member with each other.

A lifting unit includes a jib foot forming a proximal part of a jib in a service configuration, a counter jib supporting a balancing ballast, a securing part between the jib foot and the counter jib to secure the lifting unit to a mast, and a cylinder connected to the jib foot such that the jib foot is movable between a lowered position and a lifted position. A second cylinder is connected to the securing part.

This automatic unfolding and folding tower crane comprises a mast and a jib which are movable between an operation configuration and a transport configuration.

The mast has a first mast section (2.1) and a second mast section (2.2). The jib has a first jib section (4.1) and a second (4.2) jib section. The first jib section (4.1) has an upper limit (4.11) and a lower limit (4.12) defining a height (H4.1) of the first jib section (4.1). The first mast section (2.1) is rotatably connected to the first jib section (4.1) about a hinge axis (Y24).

The jib direction (X4) is shifted with respect to the mast direction (Z2) parallel to the hinge axis (Y24). A distance between the hinge axis (Y24) and the lower limit (4.12) is greater than 75% of the height (H4.1) of the first jib section (4.1).

A self-climbing tower crane includes a crane base configured to be placed on a support at a hoisting site, tower segments to erect a crane tower, a crane tower lifting unit mounted on the crane base, and a slewable jib unit. The tower crane is configured to, with the slewable jib unit connected to an upper tower segment, erect the crane tower by stacking tower segments onto one another from below to lengthen the crane tower under the slewable jib unit. The crane tower includes an upper section to be composed of a series of multiple upper tower segments and a lower section to be composed of a series of multiple lower tower segments. Each upper tower segment is embodied as a tubular girder type tower segment. Each lower tower segment is embodied as a latticed structure type tower segment. The tower crane further includes an upper stabilizer device and a lower stabilizer device, each configured to horizontally connect the upper section of the crane tower to an external tall structure, e.g. a wind turbine mast.