Components of a retractable type fall arrester 1 General

A retractable type fall arrester comprises a retractable lanyard made of wire rope, webbing or synthetic fibre rope which is stored on a reel within a protective housing. The reel is spring-biased so as to wind the retractable lanyard in, which ensures that it is always under a light restraining tension and there is the shortest possible length between the housing and the user. The reel incorporates an inertial clutch mechanism. This allows the lanyard to be slowly extracted and automatically retracted to accommodate the user’s body movements while carrying out the work. In the event of a fall, the lanyard is rapidly extracted until it reaches a critical velocity (termed the “lock-on speed”) at which point the clutch locks, simultaneously activating a braking mechanism that decelerates the user over a short distance, prevents further extraction of the lanyard and brings the user to a complete stop. The user then remains suspended by the retractable type fall arrester to await rescue (see Figure 18).

NOTE This mechanism is similar to that used in inertia reel seat belts fitted for occupant restraint in motor vehicles.

The end of the lanyard external to the housing is terminated with a connector which has a swivel joint. Such connectors are known as swivel hooks.

Key

1 Anchor 3 Retractable lanyard 2 Retractable type fall arrester 4 Walkway

Figure 18 — Example of a retractable type fall arrester operating to arrest a fall

4

3

2

1

BS 8437:2005

© BSI 29 April 2005 39

The swivel hook is used to connect the retractable lanyard to the user’s harness, and has a stop to prevent the lanyard from being fully retracted into the housing. The swivel joint prevents twisting and untwisting of the lanyard as a result of the user turning repeatedly during the work.

The maximum working length of a retractable type fall arrester is the distance from the bearing point of the housing connector to the bearing point of the swivel hook measured with the retractable lanyard fully extracted (see Figure 19).

The maximum working length determines the size and mass of the retractable type fall arrester and the distance the user is able to move away from point at which the housing is connected. The maximum working length is usually in the range 2.0 m to 50.0 m.

The retractable type fall arrester selected should be such that when it is connected to an overhead anchor point, the maximum working length is sufficient to allow the user to reach the whole of the intended work area without continually having to relocate the device.

Retractable type fall arresters conforming to BS EN 360 should be used.

Key

1 Connector 2 Swivel hook

L Maximum working length of retractable type fall arrester (with retractable lanyard fully extracted)

Figure 19 — Maximum working length of a retractable type fall arrester

2

1

9.3.2.2 Retention or reserve stop

A retractable type fall arrester with a retention or reserve stop should be used. This is especially important in conditions in which the user might need to be near to, or at, the position at which the retractable lanyard is fully extended. A retention or reserve stop is a safety device which keeps a reserve length of lanyard on the reel which is not released when the lanyard is fully extracted during normal use. In the event of a fall, the stop releases the reserve length of lanyard and so prevents any “bottoming out” effects in which the user could be subjected to an excessive arrest force due to there not being enough lanyard around the reel to enable the device to operate correctly.

9.3.2.3 Fall arrest indicator

The fall arrester used should be one that has a fall arrest indicator mechanism. Operation of the indicator tells the user that the retractable type fall arrester has previously sustained a shock loading and that it needs to be taken out of service.

The fall arrest indicator may be mounted on the housing or on the lanyard connector. Housing mounted indicators are appropriate when the housing can be seen by the user. However, in some situations retractable type fall arresters are pre-installed at some height above the user, so it is virtually impossible for the user to see if an indicator has operated or not. In such situations, an indicator mounted on the lanyard connector is more appropriate since it can be checked prior to attachment of the lanyard to the user’s harness.

9.3.2.4 Tag leads

In some situations, retractable type fall arresters are semi-permanently installed at a considerable height above the workplace. The user then cannot reach the swivel hook to pull out the lanyard in order to connect the swivel hook to his harness. In such circumstances a length of cord, known as a “tag lead”, can be attached to the swivel hook and allowed to hang down to where the user can reach it. The user can pull out the lanyard by pulling on the tag lead. The tag lead can then be removed and the swivel hook connected to the user’s harness in the usual way. Upon completion of the work, the tag lead can be reattached, and the lanyard can be allowed to retract back slowly.

9.3.2.5 Webbing attachment strap

When using a retractable type fall arrester with a wire rope lanyard, consideration should be given to using a short webbing attachment strap between the user’s harness and the lanyard connector, as this would be easier to cut should this be necessary during a rescue.

9.3.3 Additional components for larger retractable type fall arresters