Provided is a weight capable of being easily attached to and detached from a load suspended-load rope. The weight is disposed to detect overwinding of a load suspended-load rope suspended from a derricking member of a construction machine. The weight includes a weight body, which has a cylindrical shape enclosing the load suspended-load rope, configured to be suspended from the derricking member through a string-like part. The weight body is formed with a rope insertion space that allows the load suspended-load rope to pass through the rope insertion space in the radius direction of the suspended-load rope. The rope insertion space includes an oblique slit part, which has a shape oblique to the center axis.

A wire rope hoist limiter device, includes a fastener arranged to be fastened around the wire rope of the wire rope hoist; a sliding weight arranged to slide along the wire rope of the wire rope hoist towards the fastener; and a detector arranged to be fastened to the wire rope of the wire rope hoist by means of the fastener. The detector is arranged to detect the sliding weight at a certain distance from the fastener and to give a stop signal for the wire rope hoist in response.

A wire rope hoist limiter device, includes a fastener arranged to be fastened around the wire rope of the wire rope hoist; a sliding weight arranged to slide along the wire rope of the wire rope hoist towards the fastener; and a detector arranged to be fastened to the wire rope of the wire rope hoist by means of the fastener. The detector is arranged to detect the sliding weight at a certain distance from the fastener and to give a stop signal for the wire rope hoist in response.

A switch assembly for a lift unit includes a switch, an emergency stop device, and a reset actuator. The switch is arranged to move between a closed position, wherein the switch electrically couples a lift motor of the lift unit to an energy source, and an open position, wherein the switch electrically decouples the lift motor from the energy source. The emergency stop device is coupled to the switch and arranged to move the switch from the closed position to the open position. The reset actuator is coupled to the switch and arranged to move the switch from the open position to the closed position, wherein the reset actuator is controllable to move the switch from the open position to the closed position.

A switch assembly for a lift unit includes a switch, an emergency stop device, and a reset actuator. The switch is arranged to move between a closed position, wherein the switch electrically couples a lift motor of the lift unit to an energy source, and an open position, wherein the switch electrically decouples the lift motor from the energy source. The emergency stop device is coupled to the switch and arranged to move the switch from the closed position to the open position. The reset actuator is coupled to the switch and arranged to move the switch from the open position to the closed position, wherein the reset actuator is controllable to move the switch from the open position to the closed position.

A crane includes an overload safety device and a identifying unit. The overload safety device includes a maximum-load calculating unit configured to calculate a maximum load that a winch drum is capable of winding up with driving torques output from the remaining electric motors other than a failed electric motor identified by the identifying unit, an updating unit configured to update a set hoisting ability value stored in a storing unit to a value equal to the maximum load, and a control unit configured to cause the remaining electric motors to operate when a value of a load derived by a load deriving unit is equal to or smaller than a latest set hoisting ability value stored in the storing unit and stop the operation of the plurality of electric motors when the value of the load derived by the load deriving unit exceeds the latest set hoisting ability value.

A crane includes an overload safety device and a identifying unit. The overload safety device includes a maximum-load calculating unit configured to calculate a maximum load that a winch drum is capable of winding up with driving torques output from the remaining electric motors other than a failed electric motor identified by the identifying unit, an updating unit configured to update a set hoisting ability value stored in a storing unit to a value equal to the maximum load, and a control unit configured to cause the remaining electric motors to operate when a value of a load derived by a load deriving unit is equal to or smaller than a latest set hoisting ability value stored in the storing unit and stop the operation of the plurality of electric motors when the value of the load derived by the load deriving unit exceeds the latest set hoisting ability value.

Various hoisting systems with anti-two-block sensing devices are provided. In one embodiment, an apparatus includes a crane having a hoisting line and an anti-two-block sensing device installed about the hoisting line. The anti-two-block sensing device includes an upper chandelier, a lower trigger assembly suspended from the upper chandelier, and a detector positioned to detect movement of the lower trigger assembly with respect to the upper chandelier. The lower trigger assembly can include two plates each having a hoisting line aperture and a slot that allows transverse installation of the plate about the hoisting line. Further, the two plates can be positioned such that their slots are offset from one another and the plates cooperate to fully surround the hoisting line. Additional systems, devices, and methods are also disclosed.

Various hoisting systems with anti-two-block sensing devices are provided. In one embodiment, an apparatus includes a crane having a hoisting line and an anti-two-block sensing device installed about the hoisting line. The anti-two-block sensing device includes an upper chandelier, a lower trigger assembly suspended from the upper chandelier, and a detector positioned to detect movement of the lower trigger assembly with respect to the upper chandelier. The lower trigger assembly can include two plates each having a hoisting line aperture and a slot that allows transverse installation of the plate about the hoisting line. Further, the two plates can be positioned such that their slots are offset from one another and the plates cooperate to fully surround the hoisting line. Additional systems, devices, and methods are also disclosed.

Various hoisting systems with anti-two-block sensing devices are provided. In one embodiment, an apparatus includes a hoisting system having a hoisting line, a sleeve positioned on the hoisting line, and an anti-two-block sensing device installed about the hoisting line so as to allow the hoisting line to move through the anti-two-block sensing device. The anti-two-block sensing device includes a detector positioned to detect a sleeve component when the sleeve is present within the anti-two-block sensing device. Additional systems, devices, and methods are also disclosed.