A hoist security arrangement for avoiding dropping of the load when the chain or cable breaks includes a longer redundant auxiliary chain or cable disposed alongside the main chain or cable and which is raised and lowered synchronously with the slightly shorter main chain or cable so that the main chain or cable normally supports the entire weight of the load. If the main chain or cable breaks, the load drops slightly until the slack in the redundant auxiliary chain or cable is eliminated to hold the load solely by tensioning the auxiliary chain or cable. The extent of slack is set to insure that slight lengthening of the main chain as caused by wear does not result in loading of the auxiliary chain or cable.

A brake is operationally coupled by gear engagement to an axle of a device, whereby turning on the brake prevents the axle from rotating. Monitoring condition of the brake includes driving the axle of the device in a first rotation direction when the brake has been turned on. The axle of the device is driven in a second rotation direction when the brake has been turned on. A first position angle of the axle of the device, which follows from driving the axle of the device in the first rotation direction, is measured. A second position angle of the axle of the device, which follows from driving the axle of the device in the second rotation direction, is measured. A clearance of the gear engagement of the brake is determined on the basis of a difference of the first and the second position angles.

A brake is operationally coupled by gear engagement to an axle of a device, whereby turning on the brake prevents the axle from rotating. Monitoring condition of the brake includes driving the axle of the device in a first rotation direction when the brake has been turned on. The axle of the device is driven in a second rotation direction when the brake has been turned on. A first position angle of the axle of the device, which follows from driving the axle of the device in the first rotation direction, is measured. A second position angle of the axle of the device, which follows from driving the axle of the device in the second rotation direction, is measured. A clearance of the gear engagement of the brake is determined on the basis of a difference of the first and the second position angles.

A hoist security arrangement for avoiding dropping of the load when the chain or cable breaks includes a longer redundant auxiliary chain or cable disposed alongside the main chain or cable and which is raised and lowered synchronously with the slightly shorter main chain or cable so that the main chain or cable normally supports the entire weight of the load. If the main chain or cable breaks, the load drops slightly until the slack in the redundant auxiliary chain or cable is eliminated to hold the load solely by tensioning the auxiliary chain or cable. The extent of slack is set to insure that slight lengthening of the main chain as caused by wear does not result in loading of the auxiliary chain or cable.

A hoist security arrangement for avoiding dropping of the load when the chain or cable breaks includes a longer redundant auxiliary chain or cable disposed alongside the main chain or cable and which is raised and lowered synchronously with the slightly shorter main chain or cable so that the main chain or cable normally supports the entire weight of the load. If the main chain or cable breaks, the load drops slightly until the slack in the redundant auxiliary chain or cable is eliminated to hold the load solely by tensioning the auxiliary chain or cable. The extent of slack is set to insure that slight lengthening of the main chain as caused by wear does not result in loading of the auxiliary chain or cable.

A magnetizer configured to form a main magnetic flux path so as to include a set interval in an axial direction of a wire rope includes a first pole piece and a second pole piece, which are arranged so as to sandwich the set interval therebetween, each have a U-shaped cross section which is formed so as to surround the wire rope in a circumferential direction of the wire rope for about a turn without coming into contact with the wire rope. When the wire rope is magnetized by the magnetizer, a leakage magnetic flux generated from the wire rope damaged portion is detected by a magnetic sensor.

A lifting device includes a primary attachment point for engagement with a hoist of a crane, a plurality of redundant attachments for engagement with a structure adjacent the hoist, a first hoist having a first hoist wire for holding or moving a load, a second hoist having a second hoist wire for holding or moving the load; and, a reeving system for engagement with the first hoist wire and the second hoist wire such that at least one hoist wire will hold the load if another hoist wire fails.

A lifting device includes a primary attachment point for engagement with a hoist of a crane, a plurality of redundant attachments for engagement with a structure adjacent the hoist, a first hoist having a first hoist wire for holding or moving a load, a second hoist having a second hoist wire for holding or moving the load; and, a reeving system for engagement with the first hoist wire and the second hoist wire such that at least one hoist wire will hold the load if another hoist wire fails.

A back-up load retention system includes a retention line which is connected to a load, a counterweight unit which is connected to the retention line, and a double-acting hydraulic cylinder which is connected to the counterweight unit. The counterweight unit maintains a tension force in the retention line. The double-acting hydraulic cylinder brakes and/or stops the load in a case of a failure in a main lifting system.

A back-up load retention system includes a retention line which is connected to a load, a counterweight unit which is connected to the retention line, and a double-acting hydraulic cylinder which is connected to the counterweight unit. The counterweight unit maintains a tension force in the retention line. The double-acting hydraulic cylinder brakes and/or stops the load in a case of a failure in a main lifting system.