An installation jib for a girder beam installation and removal system includes a main body having a first end and a second, opposite end, the main body extending along a longitudinal axis between the first end and the second end. The installation jib further includes a first sub-frame element coupled to the main body, a first roller coupled to the first sub-frame element, a second sub-frame element coupled to the main body, and a second roller coupled to the second sub-frame element. The first sub-frame element and the second sub-frame element are spaced longitudinally apart from one another, and the first roller and the second roller each are configured to rotate about an axis that is parallel to the longitudinal axis.

An installation jib for a girder beam installation and removal system includes a main body having a first end and a second, opposite end, the main body extending along a longitudinal axis between the first end and the second end. The installation jib further includes a first sub-frame element coupled to the main body, a first roller coupled to the first sub-frame element, a second sub-frame element coupled to the main body, and a second roller coupled to the second sub-frame element. The first sub-frame element and the second sub-frame element are spaced longitudinally apart from one another, and the first roller and the second roller each are configured to rotate about an axis that is parallel to the longitudinal axis.

An under the hook lifting device configured to lift an object is provided. The lifting device includes a boom having a first end and a second end, and a strap having a length extending downwardly from the first end of the boom, where the strap is configured to be secured to an object. A winch is positioned on the boom, where the winch is configured to adjust the length of the strap extending downwardly from the first end of the boom. The lifting device also includes a counterweight extending downwardly from the second end of the boom, and a trolley positioned at the second end of the boom, where the trolley is slidable along the boom. The counterweight is supported by and movable with the trolley, where the position of the trolley along the boom is movable to maintain a substantially horizontal position of the boom. Methods of lifting an object with a lifting device are also provided.

A mobile crane is configured so that a boom is raised by a derrick cylinder in response to a raise signal output from a derrick lever and the derrick cylinder is stopped in response to the derrick angle of the boom reaching the maximum angle corresponding to the hoisted-down length of a rope.

A mobile crane is configured so that a boom is raised by a derrick cylinder in response to a raise signal output from a derrick lever and the derrick cylinder is stopped in response to the derrick angle of the boom reaching the maximum angle corresponding to the hoisted-down length of a rope.

The invention relates to a crane, in particular a rotary tower crane, comprising a crane boom, from which a load hook can be raised and lowered via a hoist cable, and an electric power supply on the load hook and/or an optionally provided trolley which can be moved on the crane boom. According to the invention, the electric power is directly generated at the location where it is required, and in the process kinetic energy present at said location is converted into power. According to the invention, the electric power supply comprises a generator which is arranged on the load hook and/or on the trolley and which can be driven by a deflecting and/or running pulley and/or a cable running around the deflecting pulley.

The invention relates to a crane, in particular a rotary tower crane, comprising a crane boom, from which a load hook can be raised and lowered via a hoist cable, and an electric power supply on the load hook and/or an optionally provided trolley which can be moved on the crane boom. According to the invention, the electric power is directly generated at the location where it is required, and in the process kinetic energy present at said location is converted into power. According to the invention, the electric power supply comprises a generator which is arranged on the load hook and/or on the trolley and which can be driven by a deflecting and/or running pulley and/or a cable running around the deflecting pulley.

The present invention relates to a crane, in particular in the form of a revolving tower crane, having a jib (3) and a counter-jib (4), which are articulated on a jib articulation piece (8), wherein the jib (3) comprises an outer jib part (3a), which is articulated on an inner jib part (3i) in a hinged manner and is held by a guy (10). According to the invention, the inner jib part (3i) is in the form of a cantilever, which is fastened to the jib articulation piece (8) in a flexurally rigid manner and held, wherein the outer jib part (3a) is articulated on the cantilever in a hinged manner and is held by the guy (10).

A Building Element Lift Enhancer is described. The Building Element Lift Enhancer provides for the movement and precise placement of building elements such as blocks or sheet products by one worker. The Building Element Lift Enhancer senses the force applied by a user to the building element and converts that user applied force to mechanically assisted force from the Building Element Lift Enhancer, allowing the user to precisely move and handle large, heavy or bulky building elements by direct interaction with the building element.

A Building Element Lift Enhancer is described. The Building Element Lift Enhancer provides for the movement and precise placement of building elements such as blocks or sheet products by one worker. The Building Element Lift Enhancer senses the force applied by a user to the building element and converts that user applied force to mechanically assisted force from the Building Element Lift Enhancer, allowing the user to precisely move and handle large, heavy or bulky building elements by direct interaction with the building element.