A fall arrest device comprises a casing with an entry hole for the wire rope, and an exit hole for the wire rope, and a clamping mechanism and an overspeed detector arranged inside the casing. The speed detection mechanism comprises a driven roller arranged to be driven by the wire rope. The driven roller has one or more selected areas to be detected by a sensor, and the device further comprises a motion indicator configured to receive a signal from the sensor when the sensor detects one of the selected areas. The motion indicator is configured to give different indications depending on whether or not the signal is received from the sensor, and such indications are detectable from outside the casing. Methods for operating such a fall arrest device and method for retrofitting fall arrest devices are also disclosed.

An elevator includes a car, a counterweight, and a hoisting member connecting the car with the counterweight over a traction sheave. A free fall protection system includes a free fall protection controller, a free fall protection member connecting the car with the counterweight over the traction sheave or over a separate free fall sheave. The car and the counterweight are supported by the hoisting member in normal operation and by the free fall protection member only in a situation in which the hoisting member support fails. At least one free fall protection brake is arranged to stop the movement of the free fall protection member and thereby also the movement of the car and/or the counterweight, when being activated by the free fall protection controller.

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 fall arrest device comprises a casing with an entry hole for the wire rope, and an exit hole for the wire rope, and a clamping mechanism and an overspeed detector arranged inside the casing. The speed detection mechanism comprises a driven roller arranged to be driven by the wire rope. The driven roller has one or more selected areas to be detected by a sensor, and the device further comprises a motion indicator configured to receive a signal from the sensor when the sensor detects one of the selected areas. The motion indicator is configured to give different indications depending on whether or not the signal is received from the sensor, and such indications are detectable from outside the casing. Methods for operating such a fall arrest device and method for retrofitting fall arrest devices are also disclosed.

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 cable-braking apparatus includes a main body unit at which a main cable is positioned, a drive unit provided at the main body unit so as to generate a drive force, an elastic compression unit configured to compress or release the main elastic element using the drive force generated by the drive unit, a press unit actuated by the elastic compression unit so as to move a press plate thereof to thus press the main cable, and a movement control unit configured to lock or release an anchor pin to thus control movement of the press unit. The main elastic elements are compressed and released by the action of the gear train and the clutch, thereby offering an effect of preventing malfunctions.

The invention discloses a power-loss triggering device, including: a frame, an electromagnet and an impact bar; the impact bar vertically and movably penetrates through the frame; an energy storage piece is arranged and the energy storage piece may exert a downward action force on the impact bar; when the electromagnet is energized, the impact bar is positioned through electromagnetic force; when the electromagnet loses power, the impact bar loses a holding power from the electromagnet and conducts a downward impact movement under the action force of the energy storage piece. The power-loss triggering device is implemented through the electromagnet and an intermediate mechanism. In this invention, the electric current, the energy consumption and the cost of the electromagnet are reduced, the service life of the long-time energized electromagnet is prolonged.

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.