The invention provides a bearing. In particular, the invention provides a bearing for allowing a column of a davit to be rotatably mounted on a substantially upright shaft. The bearing has a body shaped to correspond to an internal profile of the column. The body has a first bore for receiving a component on which the bearing bears and a first pair of parallel, spaced second bores, narrower than the first bore, which extend across the first bore in a direction perpendicular to an axis of the first bore and are configured to receive retaining pins which engage with a groove in the component received in the first bore. A single bearing can be used to rotatably couple the davit to the shaft, or king post, with a plurality of different-spaced bores to account for different diameters of shaft. This improvement allows the davit to be manufactured easily and erected easily by users.

A lattice mast element for a crane comprises at least two longitudinal elements and at least one transverse element interconnecting the longitudinal elements and at least one bracing element for bracing the lattice mast element by interconnecting the longitudinal elements and/or the transverse element, wherein the longitudinal elements and the transverse element define a load bearing surface of the lattice mast element and the longitudinal elements are each configured as a two-dimensional load bearing structure.

A lattice mast element for a crane comprises at least two longitudinal elements and at least one transverse element interconnecting the longitudinal elements and at least one bracing element for bracing the lattice mast element by interconnecting the longitudinal elements and/or the transverse element, wherein the longitudinal elements and the transverse element define a load bearing surface of the lattice mast element and the longitudinal elements are each configured as a two-dimensional load bearing structure.

A piloting system for piloting a crane in work, including at least: a piloting interface, a control-command system connected to the piloting interface, work actuators ensuring the displacements of the load, and variable-speed drives connected to the control-command system and to the work actuators to receive piloting commands originating from the control-command system and to transmit to the work actuators speed setpoints. At least one amongst the variable-speed drives, referred to as the common variable-speed drive, is connected to at least two work actuators, referred to as the shared actuators, by a distribution relay, so that the common variable-speed drive alternately pilots each of the shared actuators.

The present invention relates to a lattice piece for a crane boom consisting of a first and a second lattice section element, each comprising a first chord member which extends substantially parallel to the longitudinal direction of the lattice section element, a second chord member which extends substantially parallel to the longitudinal direction of the lattice section element, a first web member which is firmly connected with the first chord member and the second chord member, and preferably extends in the plane defined by the first chord member and the second chord member, wherein a first web member is firmly connected with the first chord member and rises from a plane defined by the first chord member and the second chord member, wherein at its end facing away from the first chord member the second web member includes a fastening means for a releasable connection.

The present invention relates to a lattice piece for a crane boom consisting of a first and a second lattice section element, each comprising a first chord member which extends substantially parallel to the longitudinal direction of the lattice section element, a second chord member which extends substantially parallel to the longitudinal direction of the lattice section element, a first web member which is firmly connected with the first chord member and the second chord member, and preferably extends in the plane defined by the first chord member and the second chord member, wherein a first web member is firmly connected with the first chord member and rises from a plane defined by the first chord member and the second chord member, wherein at its end facing away from the first chord member the second web member includes a fastening means for a releasable connection.

The invention provides a davit with a number of useful features. A jib of the davit can be made with an overload indicator, which provides a straightforward, visible mechanism to ascertain whether the davit is fit for use following an overload condition. The jib can be made collapsible with telescoping sections, at least one of the sections having a plurality of flats to allow easy connection with other components of the davit, such as the lifting head. A single bearing can be used to rotatably couple the davit to the shaft, or king post, with a plurality of different-spaced bores to account for different diameters of shaft. Either or both of these improvements allow the davit to be manufactured easily and erected easily by users.

The invention provides a davit with a number of useful features. A jib of the davit can be made with an overload indicator, which provides a straightforward, visible mechanism to ascertain whether the davit is fit for use following an overload condition. The jib can be made collapsible with telescoping sections, at least one of the sections having a plurality of flats to allow easy connection with other components of the davit, such as the lifting head. A single bearing can be used to rotatably couple the davit to the shaft, or king post, with a plurality of different-spaced bores to account for different diameters of shaft. Either or both of these improvements allow the davit to be manufactured easily and erected easily by users.

A transportable unit has a skid with a pivot connector to pivotally attach to a first mast leg of a drill rig mast. The skid also has a support connector to attach to a second mast leg support of the drill rig mast and a substructure connector to attach to a substructure of a drill rig.

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.