A method for assembling a crane that comprises erecting an upright ballast mast with a back mast top slide that is movable along the ballast mast and constructing a back mast using the upright ballast mast. This comprises the steps of providing a back mast upper section, multiple back mast intermediate sections, and a back mast lower section. The method also comprises connecting a part of the back mast including at least the back mast upper section, and possibly further including one or more pre-connected intermediate sections, to the back mast top slide. The part of the back mast that has been connected to the back mast top slide is stepwise extended by attaching further back mast intermediate sections and the back mast lower section. During the extension of the back mast the back mast top slide is stepwise raised along the upright ballast mast.

A davit (10) for arresting the fall of a person working at heights or for material handling where lifting of overloaded material is prevented, has a mast (12), a fuse holder (14) at the top of mast, a fuse head (16) connected to the fuse holder and having sacrificial fuses (18) arranged in series thereon, a jib arm (20) connected to the fuse head, and a primary fall arrestor system (22) having an arresting load limit and mounted to a side of the mast if the davit is to be used for arresting the fall of a person (25) working at heights, and/or a primary lifting-overload prevention system having a working load limit and safety factors if the davit is to be used for material handling where lifting of overloaded material (78) is to be prevented. When excessive forces are being absorbed either by the primary fall arrestor system or by the primary lifting-overload prevention system, the fuse head rotates downwardly relative to the fuse holder, and causes the breaking of one or progressively more of the sacrificial fuses until enough fuses have been broken to absorb the excessive forces.

A method and related device for reducing resonant vibrations and dynamic loads of cranes, where vertical motion of a pay load is controlled by a boom winch and a hoist winch. In an embodiment, the method includes determining resonance frequencies of the crane boom and pay load from inertia data of the boom and stiffness on at least the boom and hoist ropes, the resonance frequencies including a first frequency and a lower second frequency. In addition, the method includes automatically modifying the motion of the boom winch or the hoist winch to induce a damping inducing winch motion in the boom or hoist winch, by tuning a proportional integral (PI)-type boom winch speed controller or a PI-type hoist winch speed controller. The boom winch speed controller is tuned to absorb energy at the second frequency, the hoist winch speed controller is tuned to absorb energy at the first frequency.

A method and related device for reducing resonant vibrations and dynamic loads of cranes, where vertical motion of a pay load is controlled by a boom winch and a hoist winch. In an embodiment, the method includes determining resonance frequencies of the crane boom and pay load from inertia data of the boom and stiffness on at least the boom and hoist ropes, the resonance frequencies including a first frequency and a lower second frequency. In addition, the method includes automatically modifying the motion of the boom winch or the hoist winch to induce a damping inducing winch motion in the boom or hoist winch, by tuning a proportional integral (PI)-type boom winch speed controller or a PI-type hoist winch speed controller. The boom winch speed controller is tuned to absorb energy at the second frequency, the hoist winch speed controller is tuned to absorb energy at the first frequency.

A mobile crane comprising a main boom, which is supported on the mobile crane in such a way that the main boom can be rocked and which can be put upright by means of an elevating cylinder, and a main boom extension, which is releasably connected to a main boom head of the main boom by upper and lower pins. The main boom extension, proceeding from a home position, can be angled in relation to the main boom about a rocking axis by means of an angle drive after the upper pins have been released, which angle drive acts on a base of the main boom extension, where a drive of the mobile crane provided for a different task provides the kinetic energy for the angle drive. The angle drive is designed in such that a telescoping cylinder of the main boom provides the kinetic energy for the angle drive.

A mobile crane having a tiltably mounted main jibwhich can be erected by a tilting cylinder, and having a main jib extension releasably connected to a main jib head of the main jib by upper and lower bolts. Starting from a normal position, after release of the upper bolts, the main jib extension can be angled about a tilting axis relative to the main jib by an angling drive that engages on a foot of the main jib extension, and a drive that is provided for another purpose supplies the kinetic energy for the angling drive. The angling drive includes a lever element having two lever arms, pivotably mounted on the upper chord of the main jib extension, with the first lever arm being connected to a lifting cable of the lifting gear for operation of the angling drive and engaging the main jib head by the second lever arm.

A mobile crane having a tiltably mounted main jibwhich can be erected by a tilting cylinder, and having a main jib extension releasably connected to a main jib head of the main jib by upper and lower bolts. Starting from a normal position, after release of the upper bolts, the main jib extension can be angled about a tilting axis relative to the main jib by an angling drive that engages on a foot of the main jib extension, and a drive that is provided for another purpose supplies the kinetic energy for the angling drive. The angling drive includes a lever element having two lever arms, pivotably mounted on the upper chord of the main jib extension, with the first lever arm being connected to a lifting cable of the lifting gear for operation of the angling drive and engaging the main jib head by the second lever arm.

This invention relates generally to a method for making a deck for use in construction. In one embodiment, the method includes, but is not limited to, positioning a first box tube substantially parallel to a second box tube; attaching a plate to the first box tube and the second box tube, the plate extending between the first box tube and the second box tube; coupling a hydraulic cylinder to the plate; slidably inserting a first extension member at least partially into the first box tube; slidably inserting a second extension member at least partially into the second box tube, the first and second extension members having a beam extending therebetween; coupling the hydraulic cylinder to the beam; positioning a platform having one or more wheels on the plate and over the hydraulic cylinder such that the platform is rollable relative to the plate; and attaching the platform to the beam such that the platform is operable to retractably extend beyond an edge of a floor of a building in conjunction with the first and second extension members in response to actuation of the at least one hydraulic cylinder.

This invention relates generally to a method for making a deck for use in construction. In one embodiment, the method includes, but is not limited to, positioning a first box tube substantially parallel to a second box tube; attaching a plate to the first box tube and the second box tube, the plate extending between the first box tube and the second box tube; coupling a hydraulic cylinder to the plate; slidably inserting a first extension member at least partially into the first box tube; slidably inserting a second extension member at least partially into the second box tube, the first and second extension members having a beam extending therebetween; coupling the hydraulic cylinder to the beam; positioning a platform having one or more wheels on the plate and over the hydraulic cylinder such that the platform is rollable relative to the plate; and attaching the platform to the beam such that the platform is operable to retractably extend beyond an edge of a floor of a building in conjunction with the first and second extension members in response to actuation of the at least one hydraulic cylinder.

A portable hoist assembly for lifting, relocating and lowering loads includes a trailer that is both wheeled and configured to couple to a vehicle. A power module, a lift arm and an actuator are coupled to the trailer. The actuator is operationally coupled to the power module and the lift arm. A fastener is operationally coupled proximate to a second end of the lift arm. The fastener is configured to couple the lift arm to a load. The actuator is positioned to motivate the lift arm and the fastener upwardly and downwardly. The load that is coupled to the lift arm is elevated from a first resting position to a raised position, repositioned by movement of the trailer, and lowered from the raised position to a second resting position.