Tower crane with a detection of a rotating part autorotation or oscillation state in an out of service configuration

A tower crane comprising:

• a tower on which a rotating portion is pivotally mounted along an orientation axis by a pivot mechanism, the pivot mechanism including at least a motorized orientation system, a mechanical orientation brake and an angular detector configured to detect an orientation angle of the rotating portion, wherein the tower crane is configurable between a service configuration in which the rotating portion is rotatably driven on the tower along the orientation axis by the motorized orientation system, and an out of service configuration in which the rotating portion is rotatably released on the tower according to the orientation axis for orientation in a direction corresponding to a wind direction, the mechanical orientation brake being deactivated in the out of service configuration;
• a control/command unit connected to the motorized orientation system, the mechanical orientation brake and the angular detector, wherein, in the out of service configuration, the control/command unit activates a monitoring mode in which the control/command unit detects, as a function of variations in the angle of orientation of the rotating portion or as a function of variations of an angular speed of the rotating portion established from the variations of the orientation angle, if the rotating portion is in one of the following movement states:
• an autorotation state corresponding to a rotary movement of the rotating portion in a given direction over at least one complete turn, wherein a variation of the orientation angle according to an angular amplitude is at least greater than one angular autorotation threshold of at least 360 degrees in a first given time interval or at an angular speed greater than a given autorotation speed threshold, and
• an oscillation state corresponding to a back and forth movement of the rotating portion about the orientation axis, wherein at least one cycle of variations of the angle of orientation includes movement of the rotating portion in a first direction then in a second direction, opposite to the first direction, and wherein an angular displacement of the orientation angle is at least equal to an angular oscillation threshold comprised between 20 and 180 degrees in a given second time interval or at an angular speed greater than a given oscillation speed threshold.

A method for monitoring a tower crane comprising a tower on which a rotating portion is pivotally mounted along an orientation axis by of a pivot mechanism, the pivot mechanism including at least a motorized orientation system, a mechanical orientation brake and an angular detector configured to detect an orientation angle of the rotating portion, wherein the tower crane is configurable between a service configuration in which the rotating portion is rotatably driven on the tower along the orientation axis by the motorized orientation system, and an out of service configuration in which the rotating portion is rotatably released on the tower along the orientation axis for orientation in a direction corresponding to a wind direction, the mechanical orientation brake being deactivated in the out of service configuration, wherein the tower crane further comprises a control/command unit connected to the motorized orientation system and to the angular detector, the monitoring method comprising:

• in the out of service configuration, activating a monitoring mode in which the control/command unit detects, as a function of variations in the angle of orientation of the rotating portion or as a function of variations of an angular speed of the rotating portion established from the variations in the orientation angle, if the rotating portion is in one of the following movement states:
• in an autorotation state, corresponding to a rotary movement of the rotating portion in a given direction over at least one complete turn, wherein a variation of the orientation angle according to an angular amplitude is at least greater than an angular autorotation threshold of at least 360 degrees in a first given time interval or at an angular speed greater than a given autorotation speed threshold, and
• in an oscillation state, corresponding to a back and forth movement of the rotating portion about the orientation axis, wherein at least one cycle of variations of the angle of orientation includes movement of the rotating portion in a first direction then in a second direction, opposite to the first direction, and wherein an angular displacement of the orientation angle is at least equal to an angular oscillation threshold comprised between 20 and 180 degrees in a second interval of given time or at an angular speed greater than a given oscillation speed threshold.