GB2522721A

GB2522721A - Fall arrest device

Info

Publication number: GB2522721A
Application number: GB1401959.0A
Authority: GB
Inventors: Ian Lawton
Original assignee: Heightec Group Ltd
Current assignee: Heightec Group Ltd
Priority date: 2014-02-04
Filing date: 2014-02-04
Publication date: 2015-08-05
Also published as: GB201401959D0

Abstract

A fall arrest device comprises a body 4 having (i) a rope guide path for receiving a rope 1, (ii) an attachment point 14 provided for attaching a load thereto, wherein the action of a load applied to the attachment point results in jamming of the rope in the rope guide path to arrest movement of the device on the rope, and (iii) a linkage member 26 (e.g. a flexible member such as a rope or chain or a rigid member) attached thereto which may be held by or otherwise attached to the user. Should the user fall or otherwise descend too quickly the said linkage member allows a load to be applied to the device so causing it to restrain the rope in the rope guide path. The rope guide path may be defined by the space between a pair of opposing cam surfaces, for example one fixed cam 8 and one moveable cam 6.

Description

I

( Fall Arrest Device This invention relates to a fall arrest device arresting the descent of a person or other load down a rope, lifeline, cable, web or other similar elongate load supporting member or line (collectively referred to hereinafter as "rope"), and in particular to a fall arrest device for use for arresting the descent of a person down a rope in the event of a fall.

When working at height it is typical for a person to use fall arrest device being coupled to a rope, whereby the device is adapted to automatically lock onto the rope in the event of a fall. C.

Such fall arrest devices connect to the safety harness of the user, typically via a lanyard, and freely travel up and down the rope, engaging the rope when the force applied to them via the harness exceeds a predetermined threshold (i.e. when the user slips or falls). Such devices commonly contain a cam pivotally mounted on the body of the device and a cooperating abutment with the rope passing therebetween.

In one known design, when a load is applied to the body of said device via an attachment point on the body, the rope comes into operative contact with the distal end of the cam, urging the proximal end of the cam toward the abutment, thereby :.:. engaging the rope therebetween. In an alternative design, the attachment point for the harness is provided on the distal end of the cam such that a load applied to the attachment point urges the proximal end of the cam toward the abutment, thereby engaging the rope therebetween.

A problem with such known fall arrest devices is that the device tends to rest below the user when in its free running position, the device freely moving down the rope to which it is attached under the actiOn of gravity until it is arrested by a lanyard attached to a harness worn by the user. In the event of a fall, the user can fall through a distance equivalent to twice the length of the lanyard before a load is applied to! the device causing the device to lock onto the lifeline. This can lead to an increased risk of injury to the user due to the distance of such fall and the sudden deceleration of the user when the device locks onto the lifeline. If the lanyard is shortened to reduce this risk, the device tends to get in the way of the user and can C' be damaged by work being carried out by the user, such as painting, grip blasting etc. According to the present invention there is provided a fall arrest device comprising a body having a rope guide path for receiving a rope therein and an attachment point for attaching a load thereto, wherein the action of a load applied to the attachment point results in restraining of the rope in the rope guide path to arrest movement of the device on the rope, said device having a linkage member attached thereto, said linkage member may be held by or otherwise attached to the user suspending the device substantially therebelow, characterised in that should the user fall or otherwise descend too quickly said linkage member allows a load to be applied to the device so causing it to restrain the rope in the rope guide path.

Preferably said linkage member is directly or indirectly coupled to said device.

Preferably said linkage member is attached to said device such that if a load is applied to it said device will restrain the rope in the same manner as if a load were applied to the attachment point.

Preferably said linkage member comprises a flexible member, such as a rope or chain. Alternatively the linkage member may comprise a rigid link, said linkage member being pivotally coupled to said first body. * *

* Preferably said linkage member comprises a flexible member with a toggle to facilitate its being held. * S. * . * * *

At least a portion of said linkage member may be formed from an elastic material.

In one embodiment the linkage member may be adapted such that it becomes detached from the device when the load applied to it exceeds a predetermined level.

( At least a portion of one of said guide surfaces of the first rope guide path may be defin&d by a face of a moveable cam, adapted to be moveable into a rope jamming position, wherein the rope is pressed between the moveable cam and the opposing rope guide surface to arrest movement of the rope through the rope guide path.

In. one embodiment said moveable cam may comprise an elongate member having a side surface defining one of said opposing rope guide surfaces of the first rope guide path, one end of said elongate member defining a cam surface moveable into said jamming position when the rope acts against a second opposite end of the elongate member when the device is rotated by virtue of a load applied to the attachment point. (

In an alternative embodiment said attachment point may be provided on a distal end of said elongate member, whereby a second end of said elongate member defines a cam surface moveable into said jamming position when by virtue of a load applied to the attachment point.

An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which :.* Figure 1 is a schematic view of a fall arrest device in accordance with a first embodiment of the present invention; and (.. . * * * Figure 2 is a schematic view of a fall arrest device in accordance with a second embodiment of the present invention. * ** * * * * .

As shown in Figure 1, a fall arrest device 2 in accordance with an embodiment of the present invention comprises a first part comprising a base plate 4 and a cover plate (omitted for clarity) mounted parallel to the base plate 4, the cover plate being pivotally movable between a rope loading/removing position and a closed position to allow a rope, such as a lifeline I or secondary line, to be inserted and then retained in the device 2 in a rope guide path defined between opposed guide surfaces of a moveable cam 6 and a fixed cam 8.

The moveable cam 6 is mounted on a first side of the rope guide path and the fixed cam 8 is mounted on a second side of the rope guide path. The moveable cam 6 is pivotally mounted on the body of the device for pivotal movement about a pivot axis extending perpendicular to the base plate 4 and perpendicular tp the rope guide path. A lower end 10 of the moveable cam 6 is moveable to a jamming position, wherein the lifeline is jammed between the lower end 10 of the moveable cam 6 and the fixed cam 8, when the lifeline acts against the upper end 11 of the moveable cam 6, as will be described in more detail below.

An attachment eye 14 is defined by aligned apertures in the base plate 4 and cover plate connecting the device 2 to a lanyard attached to a harness of a user of the ( device 2, for example via a karabiner or similar connector inserted through the attachment eye 14.

A flexible tether 26 is operatively coupled to the user at a first end and is coupled to the base plate, directly or indirectly, at a second end.

The fall arrest device 2 may be used as a back up device on a lifeline to arrest the fall of a person should the working equipment, such as an ascender or descender, attached to a working line fail.

In use, the cover plate is moved to its open position and the lifeline 1 is inserted into the rope guide path between said rope guide surfaces of the moveable cam 6 and fixed cam 8. The cover plate is then moved to its closed position to retain the device on the lifeline 1. A lanyard attached to a harness of the user is attached to the lanyard attachment 14.

The tether 26 is held by, or otherwise attached to the user at a position substantially above the device.

During normal use of the working equipment on the working line, the weight of the user is supported by the working equipment.

( During movement of the working equipment on the working line, the device is either lifted via the tether if the user ascends or allows the device to move down the lifeline under gravity if the user descends.

Where a sudden downward acceleration occurs, in the event of a failure of the working equipment or working line, the tension in the tether i reduced allowing a force to be applied to the lanyard attachment 14 to change the angle of the first body of the device 2 with respect to the lifeline I and causing the moveable cam 6 to rotate to lock on the lifeline 1. Thus the body of the fall arrest device 2 is rotated, under the action of the force applied by the lanyard via the lanyard attachment 14, causing the lifeline to push against the upper end 11 of the moveable cam 6 to push the lower end 10 of the moveable cam 6 into its jamming position against the lifeline 1, arresting movement of the lifeline 1 through the rope guide path without damage to device or lifeline 1, thus retaining the user suspended from the lifeline 1 by the device 2.

In a second embodiment, shown in Figure 2, the attachment eye for attachment of a harness to the device is provided on a distal end of the moveable cam so that a load applied to the attachment eye urges the lower end of the moveable cam into its jamming position against the lifeline, as is known in the art. In such embodiment, the tether may be coupled to the body of the device or to the distal end of the * moveable cam, either via the attachment eye or an adjacent connection. (.. * -* *

* The invention is not limited to the embodiment(s) described herein but can be amended or modified without departing from the scope of the present invention. In an alternative embodiment the tether may be formed from or incorporate an elastic material, such as an elastic cord or spring, to ensure that the lanyard may apply a load to the attachment eye. Alternatively the tether may be arranged to detach from the body of the device if a sudden force is applied.

Claims

C Claims - 1. According to the present invention there is provided a fall arrest device comprising a body having a rope guide path for receiving a rope therein and an attachment point for attaching a load thereto, wherein the action of a.load applied to the attachment point results in restraining of the rope in the rope guide path to arrest movement of the device on the rope, said device having a linkage member attached thereto, said linkage member may be held by or otherwise attached to the user suspending the device substantially therebelow, characterised in that should the user fall or otherwise descend too quickly said linkage member allows a load to be applied to the device so causing it to restrain the rope in the rope guide path.
2. A device as claimed in claim 1, wherein said linkage member is directly or indirectly coupled to said device.
3. A device as claimed in claim 1 or claim 2 wherein said linkage member is attached to said device such that if a toad is applied to it said device will restrain the rope in the same manner as if a load were applied to the attachment point.

* 20
4. A device as claimed in claims 1 to 3, wherein said linkage member substantially :.: comprises a flexible member, such as a rope or chain. 0***.
5..: 5. A device as claimed in claims I to 3 wherein said linkage member substantially comprises a rigid member.
6. A devi as claimed in claim 5 wherein said linkage member is pivotally coupled tosaidbody.
7. A device as claimed in any of claims 1 to 4, said linkage member comprises a flexible member with a toggle to facilitate its being held. -
8. A device as claimed in any of claims 1 to 7, wherein at least a portion of said linkage member is formed from an elastic material.
9. A device as claimed in any of claims 1 to 8, wherein the linkag&member is adapted such that the second body becomes detached from the first body when the bad applied lathe attachment point exceeds a predetermined level.
10. A fall arrest device as claimed in any preceding claim, wherein at least a portion of one of said guide surfaces of the first rope guide path may be defined by a face of a moveable cam, adapted to be moveable into a rope jamming position, wherein * the rope is pressed between the moveable cam and the opposing rope guide surface to arrest movement of the rope through the rope guide path. -.
11. A device as claimed in any preceding claim, wherein said moveable cam may comprise an elongate member having a side surface defining one of said opposing rope guide surfaces of the first rope guide path, one end of said elongate member defining a cam surface moveable into said jamming position, when the rope acts against a second opposite end of the elongate member when the device is rotated by virtue of a load applied to the attachment point. -
12. A device as claimed in claim 11, wherein said attachment point may be provided on a distal end of said elongate member, whereby a second end of said * *. 20 elongate member defines a cam surface moveable into said jamming position when :.; by virtue of a load applied to the attachment point. * .(_*} * ..*.
13. A fall, arrest device substantially as herein described with reference to the accompanying drawings. *. *. * . . * * * .