GB2471285A

GB2471285A - Reversible fall arrest device

Info

Publication number: GB2471285A
Application number: GB0910804A
Authority: GB
Inventors: Keith Turney
Original assignee: Central Technology Inc
Current assignee: Central Technology Inc
Priority date: 2009-06-23
Filing date: 2009-06-23
Publication date: 2010-12-29
Also published as: WO2010149691A1; GB0910804D0; EP2445590A1

Abstract

A safety clamp 1 for use in a fall arrest system having a track 2 configured to follow a substantially vertical or inclined path is disclosed. The safety clamp 1 being mountable on a track 2 with either end uppermost, and comprises a body 3and first and second actuating members 4,5 rotatably mounted to the body 3. One of said actuating members 5 rotates in response to the application of an upwardly directed load to enable the clamp 1 to freely slide along the track 2 in the direction of said load. Said actuating member 5 also rotates in an opposite direction in response to the application of a load in a downward direction such that it engages a track2 to prevent downward movement of said safety clamp 1 along the track 2. The first and second actuating members 4,5 are configured such that the actuating member 5 that rotates to allow the clamp to slide freely along the track 2 in said one direction but engage the track 2 when moved in the downward direction, depends on which end of the safety clamp 1 is uppermost on the track 2.

Description

Safety Device

Description

The present invention relates to a slide brake device for use in fall-arrest system for protecting workmen operating at elevated positions.

Workmen who need to gain access to elevated areas local to potential fall hazards are generally required by health and safety regulations to be equipped with an appropriate safety system such as a fall restraint or fall arrest system so that in the event of a slip or fall potential injury or fatality can be prevented. These systems typically involve the workman wearing a harness attached via a lanyard and a safety clip to a fall arrest system mounted on a building. Fall arrest systems generally comprise a track of a rigid cable or rod secured to the roof or other structure by end anchors and it may also be further supported by intermediate anchors. Fall arrest systems enable the workman to move relatively unrestrained because as the workman moves the lanyard pulls on the clip such that the clip freely slides along the track or line over any intermediate anchors. The track is typically horizontally orientated so that if a workman would slip their fall would be arrested by the lanyard pulling on the horizontal track.

The use of a safety clip is limited when work is undertaken on inclined or steep sections or when using ladders or stairs, because if the workman were to fall, the clip is free to slide downwardly along the cable and so the fall is not quickly arrested.

To overcome the foregoing, it is known to provide a device which is free to slide along the track which locks or clamps the device against the track when a load is applied to a trigger forming part of the device, so that, should the workman fall, the lanyard attached to the harness worn by the workman pulls on the trigger under the weight of the workman, immediately preventing the device from sliding along the track and arresting the fall.

This type of clamp only locks against the track when load is applied to it in one direction of movement i.e. the downward direction. The workman is then free to move in the opposite direction dragging the clamp via the lanyard in an upward direction and so is able to keep both hands free. However, it is imperative that the workman attaches the clamp to the track in the correct orientation otherwise the clamp or brake will not activate should the workman fall. Although current safety clamps bear indications of how to correctly mount the clamp on the track it has been known for workmen to inadvertently mount the clamp in the wrong orientation, i.e. upside down.

The present invention seeks to overcome or substantially alleviate the aforementioned problems to provide a safety clamp for use in fall arrest system.

According to the present invention there is provided a safety clamp for use in a fall atrestsystem having a track configured to follow a substatia1ly vertical or inclined path, the safety clamp being mountable on a track with either end uppermost and comprising a body and first and second actuating members rotatably mounted to the body, one of said actuating members rotating in response to the application of an upwardly directed load to enable the clamp to freely slide along the track in the direction of said load, said actuating member also rotating in an opposite direction in response to the application of a load in a downward direction such that it engages a track to prevent downward movement of said safety clamp along the track, wherein the first and second actuating members are configured such that the actuating member that rotates to allow the clamp to slide freely along the track in said one direction but engage the track when moved in the downward direction depends on which end of the safety clamp is uppermost on the track, Preferably, the body comprises a hook portion providing a tubular path which extends through said body for receiving the track.

Conveniently, the first and second actuating members are mounted on the body for rotation about two spaced parallel axes perpendicular to the tubular path.

The actuating members may extend out of the body and have an aperture therein for attachment of a workman's lanyard thereto extending through the apertures in both actuating members.

Preferably, the actuating members overlap in the region of the apertures to enable a lanyard to be passed through the apertures in both actuating members.

Conveniently, an opposite end of each of the first and second actuating members comprises a surface for engagement with the track during application of a load in a downward direction thereby preventing downward movement of the safety clamp.

In one embodiment, a portion of said surface is arcuately shaped to enable the actuati1g members to rotate in response to the application of an upward or downward directed load.

Preferably, the actuating members are mounted on the body having their arcuately shaped portions facing each other enabling the safety clamp to function with either: of the actuating members uppermost.

In one embodiment, the arcuately shaped portions of the actuating member are configured to engage the track to prevent the safety clamp from sliding downwards along the track.

Conveniently, biasing means is secured on the body between the actuating members to restrict rotation of the actuating members during the application of an upward directed load.

Preferably, the biasing means comprises a torsion spring having an arm extending from each end, one arm lying in engagement with a respective actuating member.

In one embodiment, the actuating members comprise a second longitudinal side having a lip which prevents rotation beyond a certain point as a load is applied to the actuating members.

Two studs may be mounted on the body preventing rotation of the actuating members beyond a certain point as a load is applied to the actuating member.

A fall arrest system incorporating the safety clamp as described above.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which; Figure 1 shows a perspective view of a portion of a safety clamp according to the present invention mounted on a track; Figure 2 shows a perspective view of part of a body of the safety clamp of Figure 1; Figure 3 shows a side view of the part of the body of Figure 2; Figure 4 shows a perspective view of an actuating member of the safety clamp of Figure 1; Figure 5 shows a side view of the actuating member of Figure 4; Figure 6 shows a frontal view of the safety clamp of Figure 1 in an unused position; Figure 7 shows a frontal view of the safety clamp of Figure 1 mounted on a track positioned to be attached to a lanyard or the like; Figure 8 shows a frontal view of the safety clamp of Figure 1 mounted on a track, in a normal position; and Figure 9 shows a frontal view of the safety clamp of Figure 1 mounted on a track and in position of arresting a fall.

Referring now to Figure 1 of the accompanying drawings, there is shown a safety clamp I for use in a fall arrest system having a vertical or substantially inclined track or cable 2. A portion or cover of the body of the clamp 1 is omitted to enable the components of the device to be seen clearly. A workman wearing a harness is attached to the safety clamp 1 via a lanyard such that the clamp 1 can slide upward in response to the application of upwardly directed load and also be controlled by the workman enabling it to slide in a downward direction, however in the event of a fall, the safety clamp I prevents any downward movement so as to attest the fall of the workman The configuration of the safety clamp 1 allows it to be attached to the -5.-track 2 in eithet orientation, i.e. with edge A' facing upward or downward, as will

become apparent from the following description.

The safety clamp 1, as illustrated in Figure 1 and 6 to 9, comprises a body 3, two actuating members or levers 4, 5 pivotally mounted to said body 3, biasing means in the form of a spring 6 engaging with the actuating levers 4, 5 and two studs 7, 8.

The body 3, as seen in Figures 2 and 3, comprises a plate 10 having a hook portion 11 defining a tubular path 13 to slidably receive a track or cable mounted on a building or other structure to which access is being sought. Five holes are formed on the plate; a central hole 12 for mounting the spring 6, two adjacent holes 13, 14 for pivotally attaching the actuating levers 4, 5 and two holes 15, 16 located at the upper corners of the plate for securing the two studs 7, 8.

The actuating levers 4, 5 are formed with an aperture 19, as illustrated in Figures 4 and 6 to 9, for attachment of a lanyard or a carabiner thereto that extends from a harness worn by a workman using the device. At the opposite end to the aperture 19, the levers comprise a flat surface 20 which engages the track 2 during the application of a downward directed load. On either actuating lever, a corner 21 of a first longitudinal side 22 and the flat surface 19 is arcuately shaped and extends into a first protrusion 23 of the first longitudinal side 22. The first protrusion 23 is formed with a hole 24 such that a fastening mechanism can extend through said hole 24 and the corresponding hole 13, 14 on the plate 10 of the body 3, enabling the levers to rotate about parallel axes perpendicular to the tubular path of the plate 10. Between the first protrusion 23 and the aperture 19 of the actuating levers 4, 5 is a second protrusion 25 which is generally cylindrically shaped having a longitudinal axis 26 parallel to the axis of rotation of the respective actuating lever 4, 5.

The actuating levers 4, 5 are configured to have an inconsistent thickness as can be appreciated from Figure 5. The thickness of the aperture 19 extends in an opposite direction compared to the thickness of a lower portion 26 of the actuating levers 4, such that one design can be used for both actuating levers 4, 5. Furthermore, the thickness of the lower portion 26 displaces one of the apertures 19 in relation to the other and so enables the apertures 19 to overlap as they pivot relative to the body 3.

The actuating levers 4, 5 are positioned with their first longitudinal sides 22 facing each other enabling two arms 27 of the spring 6 to engage with the second cylindrical protrusions 25. The spring 6 provides resilient force on the two actuating levers 4, 5 causing the apertures 19, in an unused state, to be departed such that their second longitudinal side 28 is pushed towards the studs 7, 8 which are secured to the plate 10 resulting in the actuating levers 4, 5 assuming an upright position as seen in Figure 6.

Operation of the safety clamp 1 engaging with a track will now be described in reference to Figures 1 and 7 to 9. To attach a harness worn by a workman to the safety clamp, the workman rotates the actuating levers 4, 5 towards one another against the force of the spring 6, so that the apertures 19 overlap as can be appreciated from Figure 7. This allows for a lanyard, a carabiner or the like attached to the harness to be feed through the two apertures 19 of the actuating levers 4, 5 as seen in Figure 1. The workman is now safely connected to the safety clamp and the overall fall arrest system. As the workman is stationary, the safety clamp 1 assumes a resting position, which in an inclined section of the track 2 involves the lower actuating lever 5 rotating under its own weight, and also due to the weight of an attached carabiner or the like, in a direction in which its aperture moves away from the spring 6 such that the arcuately shaped corner 21 of the lower actuating lever 5 engages with the track 2, as illustrated in Figure 8 This causes friction between the safety clamp and the track such that the clamp 1 remains on the track 2 as the workman is stationary. If the workman was to move in an upward direction the actuating levers 4, 5 rotate in response to the pulling of the lanyard causing the lower lever 5 to disengage with the track 2, as illustrated in Figure 7, so that the safety clamp 1 can freely slide along the track 2. The spring 6 prevents the lower actuating lever 5 to rotate beyond a certain point in response to the upward load, and because the lanyard or the like is feed through the apertures of both actuating levers rotation of the upper actuating lever 3 is restricted so as to prevent its flat surface 20 from engaging with the track 2 which would impede on the upward movement of the safety clamp 1.

In the event of a fall, a load in a downward direction is applied to the safety clamp I causing the upper and lower actuating levers 4, 5 to rotate such that the flat surface of the lower actuating lever 5 completely engages the track 2 and is maintained in such a position owing i6 longitudinal side 28 of the lower portion 26 preventing any further rotation of said actuating lever 5. The engagement of the flat surface 20 of the lower actuating lever 5 and the track 2 causes friction to such an extent that the movement of the safety clamp I relative to the track 2 is halted and so arrests the fall of the workman. The upper actuating lever 4 does not contribute in arresting the downward movement of the safety clamp I in response to the application of a downward directed load, however it does enable the safety clamp to be oriented either way on the track 2 and thereby avoiding the possibility of positioning the safety clamp 1 in the wrong direction which for conventional safety clamps would result in an actuating lever not engaging the safety track to stop the fall of a workman.

It will be appreciated that the safety clamp according to the present invention provides the significant advantage that the workman attached thereto will be protected in the event of a fall irrespective of the orientation of the clamp mounted on the track. As two actuating levers are reflectively configured, the safety clamp can be orientated with either actuating lever uppermost and so the safety clamp will always function correctly and lock against the track in the event of a fall and does not require setting by the user. Furthermore, it should be undetstood that the configuration of the safety clamp according to the present invention also obviates the need for the workman to re-orientate the safety clamp when used on tracks and lines comprising different orientated sections in which the edge A' of the safety clamp continuously change between being uppermost and bottommost.

The invention has been described with reference to preferred embodiments only.

Modifications and alterations to the embodiments falling within the scope of the appended claims are included within the scope of protection.

Claims

Claims 1. A safety clamp for use in a fall arrest system having a track configured to follow a substantially vertical or inclined path, the safety clamp being mountable on a track with either end uppermost and comprising a body and first and second actuating members rotatably mounted to the body, one of said actuating members enablthé clamp to freely slide along the track in the direction of said load, said actuating member also rotating in an opposite direction in response to the application of a load in a downward direction such that it engages a track to prevent downward movement of said safety clamp along the track, wherein the first and second actuating members are configured such that the actuating member that rotates to allow the clamp to slide freely along the track in said one direction but engage the track when moved in the downward direction depends on which end of the safety clamp is uppermost on the track.
2. A safety clamp according to claim 1; wherein the body comprises a hook portion providing a tubular path which extends through said body for receiving the track.
3. A safety clamp according to claim 1 or claim 2, wherein the first and second actuating members are mounted on the body for rotation about two spaced parallel axes perpendicular to the tubular path.
4. A safety clamp according to any preceding claim, wherein the actuating members extend out of the body and have an aperture therein for attachment of a workman's lanyard thereto extending through the apertures in both actuating members.
5. A safety clamp according to claim 4, wherein the actuating members overlap in the region of the apertures to enable a lanyard to be passed through the apertures in both actuating members.
6. A safety clamp according to claim 4 or claim 5, wherein an opposite end of each of the first and second actuating members comprises a surface for engagement with the track during application of a load in a downward direction thereby preventing downward movement of the safety clamp.
7. A safety clamp according to claim 6, wherein a portion of said surface is to th application of an upward or downward directed load.
8. A safety clamp according to claim 7, wherein the actuating members are mounted on the body having their arcuately shaped portions facing each other enabling the safety clamp to function with either of the actuating members uppermost.
9. A safety clamp according to claims 7 or 8, wherein the arcuately shaped portions of the actuating member is configured to engage the track to prevent the safety clamp from sliding downwards along the track.
10. A safety clamp according to any preceding claim, wherein biasing means is secured on the body between the actuating members to restrict rotation of the actuating members during the application of an upward directed load.
11. A safety clamp according to claim 10, wherein the biasing means comprises a torsion spring having an arm extending from each end, one arm lying in engagement with a respective actuating member.
12. A safety clamp according to any preceding claim, wherein the actuating members comprise a second longitudinal side having a lip which prevents rotation beyond a certain point as a load is applied to the actuating members.
13. A safety clamp according to any preceding claim, wherein two studs are mounted on the body preventing rotation of the actuating members beyond a certain point as a load is applied to the actuating member.
14. A fall axtest system incoxpoxating the safety clamp accoxding to any of t1.img 1 to 13.