EP1596941B1

EP1596941B1 - Safety devices

Info

Publication number: EP1596941B1
Application number: EP04704271A
Authority: EP
Inventors: Keith Martin Turney
Original assignee: Central (High Rise) Ltd
Current assignee: Central (High Rise) Ltd
Priority date: 2003-02-26
Filing date: 2004-01-22
Publication date: 2008-08-20
Anticipated expiration: 2024-01-22
Also published as: GB0304359D0; ATE405329T1; WO2004075993A1; GB2398821B; GB2398822A; GB2398821A; ES2312952T3; EP1596941A1; GB0312216D0; GB2398822B; DE602004015938D1

Abstract

A safety brake for a fall arrest system, for use with a vertical track 46 such that downward pressure on lever 50 via a carabiner through hole 53 forces, by action of a cam on lever 50, brake shoe 56 against track 46. A gravity actuated switch 80 falls as shown so that tooth 81 engages notch 82 in member 59 so that upward force on lever 50 does not actuate the brake but downward force does, and because of switch 80, the safety brake may be installed either way up.

Description

The present invention relates to a clip for use in a fall-arrest system for protecting workmen operating at elevated positions.
It is often necessary for workman to gain access to elevated positions on, for example, a building, a bridge or on scaffolding to carry out a variety of tasks such as maintenance or cleaning. A slip or fall from such position can result in a serious or even fatal injury and so a harness must be worn by the workman which is attached via a lanyard to a fall-arrest device mounted on the building. It is essential that the system is flexible and easy to use so that workmen can move around and carry out their task without having to repeatedly detach themselves from, and reattach themself to, the fall-arrest device and compromising their safety in the process.
A known fall-arrest system comprises a safety track in the form of a cable or wire which is permanently or temporarily fixed to the building or other structure and to which the workman is attached via a safety clip which is linked to the free end of a lanyard attached to a harness worn by the workman. Movements of the workman generally parallel with the cable are unrestrained because the clip is free to slide along the cable in response to a pull on the lanyard. As the clip remains permanently coupled to the cable, a fall is quickly arrested preventing bodily injury. Fall arrest systems of this type are generally well known and workmen are usually obliged to use them when working at elevated positions in order to comply with various health and safety regulations.
The safety clip for attaching the lanyard to the cable generally comprises an elongate tubular hook portion to receive the cable and a jaw that may be opened to facilitate the attachment of the clip to the cable and closed to retain the clip on the cable so that the cable can slide freely through the hook portion. It is important to ensure that sliding movement of the clip along the cable is not impeded or interrupted by any support used to attach the cable to the building. To overcome this, a gap or slot is maintained between the tip of the jaw and the tip of the hook so that the supports, which have a thin neck part formed from flat plate in a region adjacent to where they attach to the cable may slide through the gap without it being necessary for the workman to detach and reattach the clip on either side of the support.
The clip has a loop portion through which a linking member such as a ring or karibina may pass to attach the end of a lanyard to the clip. The loop is sized and positioned so that, when the linking member is passed through the loop, it substantially prevents or blocks movement of the jaw from the closed to the open position so that the clip cannot inadvertently detach itself from the cable whilst the linking member is in place.
It will be appreciated that it is important to ensure that the gap or slot between the end of the hook and the end of the jaw is sufficient to enable the supports holding the cable to pass through it easily but is not allowed to become so large that it is greater than the diameter of the cable along which the clip is to slide, otherwise the cable may pass through the gap releasing the clip from the cable. If, for example, a linking member having a smaller cross sectional diameter is used to attach the lanyard to the clip, the jaw has a greater freedom of movement between the closed and open position as it is not blocked by the linking member to the same extent than a linking member having a larger cross section. Potentially, therefore, the jaw could still open to a sufficient extent to allow a smaller diameter cable to fit through the gap detaching the clip from the cable.
It will therefore be appreciated that a problem with known safety clips of the type described above is that they are only designed to work with cables and linking members within a relatively small size range. The use of the clip with cables and/or linking members outside this range can be dangerous because it may result in the inadvertent release of the clip from the cable for the reasons explained above.
An object of the present invention is to overcome or substantially alleviate the aforementioned problems and to provide a safety clip for use in a fall arrest system that is not only easier to operate but is safer to use than conventional safety clips.
It is known from GB 2370312 to provide a safety clip for use in a fall arrest system including a track, the safety clip comprising a body and a jaw pivotably mounted on the body and movable between an open position in which the body can be attached to, and detached from, the track and a closed position to retain the clip on the track.
A safety clip according to the present invention is characterised by a cam member rotatably mounted on the body, the jaw being biased toward the open position, the cam member and jaw cooperating in response to rotation of the cam member to pivot the jaw into the closed position.
Preferably, the body includes a hook portion to receive the track and the cam member and jaw are configured such that, when the jaw is in the closed position, a gap is present between the tip of the jaw and the tip of the hook portion.
In one embodiment, the body comprises a connecting part depending from the hook portion, the connecting part having an aperture therein to receive a linking member for attachment of the clip to a lanyard.
Preferably, the cam member is pivotally attached to the connecting part, the clip being configured such that rotation of the cam member is substantially prevented when the linking member is received through the aperture.
Advantageously, the cam member is annular and the aperture in the connecting part and in the cam member are aligned when the cam member is positioned such that the jaw is in a closed position, the linking member being receivable through both the aperture in the connecting part and in the cam member to substantially prevent rotation of the cam member relative to the connecting part.
In a preferred embodiment, the cam member is configured such that any limited rotation of the cam member that is still possible when the linking member is received through the apertures in the connecting part and the cam member is operable to cause the jaw to move beyond the closed position to one in which the size of the gap between the jaw and the hook portion is reduced or eliminated.
Preferably, cam surface is formed on the outside of the annular cam member and comprises a first cam surface and a second cam surface adjacent to the first cam surface.
Conveniently, the first and second cam surfaces are substantially flat and meet at an oblique angle.
Preferably, the first cam surface lies in engagement with the jaw when the jaw is in a closed position.
In one embodiment, a region between the first and second cam surfaces lies in engagement with the jaw when the cam member is initially rotated and the gap between the jaw and the hook portion is reduced or eliminated.
The jaw preferably cooperates with the second cam surface when the coupling member has been removed and the cam member is allowed to rotate beyond said initial rotation.
In another embodiment, the cam member includes biasing means to bias it into a position in which the jaw has been pivoted into the closed position.
The present invention also provides a fall arrest system incorporating a safety clip according to the invention.
Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:-

Figure 1 is a front perspective view of a safety clip according to an embodiment of the invention;
Figure 2 is a rear perspective view of the safety clip illustrated in Figure 1;
Figure 3 is an exploded perspective view of the safety clip shown in Figures 1 and 2;
Figure 4 is a front perspective view of the safety clip shown in Figure 1 but with the cam member rotated so that the jaw is in an open position;
Figure 5 is a front view of the safety clip shown in Figure 1 mounted on a cable and with a karibina attached;
Figure 5a is a front perspective view of an alternative version of the safety clip according to the present invention with the jaw in a closed position; and
Figure 5b is a front perspective view of an alternative version of the safety clip according to the present invention with the jaw in the open position;

Referring now to Figures 1 to 5 of the accompanying drawings, there is shown in Figure 1 a safety clip 1 for use in a fall-arrest system in which the clip 1 may be slidably and releasably attached to a track secured to a building, scaffold or other elevated structure. The clip 1 includes a body 2 comprising a hook portion 3 and a connecting portion 4. A jaw member 5 is pivotally mounted to the body 2 between the hook portion 3 and the connecting portion 4 and a cam member 6 is pivotally mounted to the connecting portion 4.
The hook portion 3 and jaw member 5 together define an elongate tubular opening in which is received the track, such as a cable 7 (see Figure 5) of the fall arrest device when the clip 1 is attached thereto. It will be appreciated that the opening has a significantly larger cross-sectional diameter than the cross-sectional diameter of the cable 7 so that the clip 1 is free to slide along it.
The connecting portion 4 depends from the hook portion 3 and has an aperture 8 therein to receive a linking member such as a karibina 9 (see Figure 5), which is attached to a lanyard extending from a harness worn by the workman using the system.
The cam member 6 is more clearly illustrated in Figure 3 and is pivotally mounted on the connecting portion 4 for rotation about an axis "A" indicated in Figure 3 and has a hole 10 therein of substantially the same diameter as the aperture 8 in the connecting portion 4. The cam member 6 is generally annular in shape with a smooth outer profile except in a head region 11 where the cam member has a flattened first cam surface 12 between two second cam surfaces 13 extending at an oblique angle from the first cam surface 12. The first cam surface 12 may have a protruding shoulder or ridge (not shown) for engagement with the jaw member 5 and for reasons that will become apparent.
The jaw member 5 is mounted to the body 2 generally between the hook portion 3 and connecting portion 4 for rotation about an axis "B" indicated in Figure 1 and comprises a pair of legs 14 depending from a central section 15. The inner face of the legs 14 and central section 15 have an arcuate or curved shape so as to form part of the tubular opening to receive the cable 7. The body 2 includes a cylindrical shaft 16 to receive an axle 17 the ends of which are received in corresponding openings 18 in the remote end of each leg 14 to attach the jaw member 5 to the body 2. A coil spring 19 is also mounted within a recess 20 formed in the body 2 at one end of the shaft 16. One end 21 of the spring is received in an extension 21a to the recess 20 in the body 2 and the other end in a corresponding recess (not shown) in the jaw member 5. The spring 19 biases the jaw member 5 into the open position, or the position illustrated in Figure 4.
The cam member 6 is pivotally mounted to the connecting portion 4 via a screw 22 that extends through an shaft 23 in the edge of the annular cam member 6 and through a corresponding shaft 24 in the connecting part 4. The screw 22 is threadingly engaged in a boss 25 on the other side of the connecting part 4.
The cam member 6 is free to rotate in either direction about the axis "A" in response to manipulation by a user's fingers. However, in an alternative embodiment, the cam member 6 may be sprung in a similar way to that of the jaw member 5, so that it is biased into the closed position which is the position shown in Figure 1.
The cam member 6 may be retained in the position shown in Figure 1 by a catch mechanism 26 received in a threaded opening 27 in the connecting portion 4. The catch mechanism includes a spring 28 and a stud 29 that protrudes from the connecting portion 4 and is received in a recess (non shown) in the rear surface of the cam member 6 when the cam member 6 is in the position shown in Figure 1. When sufficient torque is applied to the cam member 6 to overcome the biasing force provided by the spring 28, the stud 29 is deflected inwardly out of the recess allowing the cam member 6 to rotate about the axis "A". A grub screw 29a retains the spring 28 and the stud 29 in the opening 27. It will be appreciated that the biasing force is adjustable in response to tightening or loosening of the grub screw 29a in the threaded opening 27.
Operation of the safety clip 1 will now be described. To attach the hook portion 3 to the cable 7, the jaw member 5 must be pivoted into an open position so that a gap (indicated by X in Figures 1 and 4) between the tip of the hook portion 3 and the tip of the jaw member 8 is sufficient to enable the cable 7 to pass therebetween into the tubular opening. Movement of the jaw member 5 into the open position is achieved by rotating the cam member 6 about the axis "A" so that the jaw member 5 can pivot, due to the bias provided by the spring 19, into the open position shown in Figure 4. It will be appreciated that, prior to rotation of the cam member 6 from the position shown in Figure 1, the first cam surface 12 on the cam member 6 is in engagement with the outer surface of the jaw member 5 and so the jaw member 5 is prevented from rotating into the open position by the cam member 6.
Once the cable has been received in the tubular opening, the jaw member 5 may be moved into the closed position to retain the cable in place. This is achieved by rotating the cam member 6 in the opposite direction back into the position shown in Figure 1, or releasing it if the cam member 6 is biased by a spring. As the cam member 6 is rotated, the cam surfaces 12,13 engage the outer surface of the jaw member 5 and force it to close against the biasing force provided by the spring 19 so that the distance X is reduced and escape of the cable 7 is prevented. It will be appreciated that a small gap X is always maintained to allow the clip 1 to pass over supports (not shown) used to mount the cable 7 to the structure, as explained above.
Once the clip 1 is attached to the cable, a linking member 9 may now be attached to the clip 1 by inserting it through both the aligned apertures 8,10 in the connecting part 4 and the cam member 6.
It will be appreciated that rotation of the cam member 6 from the position shown in Figure 1, in which the jaw member 5 is held in a closed position, to the position shown in Figure 4, in which the jaw member 5 is allowed to pivot into an open position is prevented by the linking member 9 which locks the cam member 6 in place. However, rotation of the cam member 6 is only prevented to the extent that the diameter of the aperture 10 in the cam member 6 is the same as the diameter of the linking member 9 passing through it. In practice, the diameter of the linking member 9 is smaller than the diameter of the aperture 10 to allow the linking member 9 to hang loosely from the clip 1. Therefore, rotation of the cam member 6 is not entirely prevented.
A feature of the clip 1 is that an initial rotation of the cam member 6 actually serves to make the gap X between the tip of the jaw member 5 and the tip of the hook portion 3 smaller than when jaw member 5 is in the normal closed position with the cam member 6 in the position shown in Figure 1. As the cam member 6 rotates, the part of the cam surface between the first and a second cam surfaces 12,13 engages the jaw member 5 forcing it beyond the closed position so that gap X reduces. Further rotation of the cam member 6 then causes the jaw member 5 to engage the second cam surface 13 and the jaw member 5 to open. It is not until the aperture 10 in the cam member 6 and the aperture 8 in the connecting portion 4 are almost completely out of alignment that rotation of the cam member 6 allows the gap X to widen. Therefore, irrespective of the diameter of the linking member 9, the jaw member 5 cannot move toward the open position until the linking member 9 is removed from the apertures 8,10.
A second embodiment of safety clip 100 according to the invention is illustrated in Figures 5a and 5b. The safety clip 100 is similar to the safety clip 1 of the first embodiment except that in this modified version, the cam member 6 has been replaced with another annular cam member 101 and the connecting part 4 of the body has two arms 103 between which the annular cam member 101 is pivotally mounted for rotation about an axis "F" indicated in the Figures. The cam member 101 is therefore mounted for rotation to the body at an angle of 90 degrees relative to its position in the first embodiment.
The annular cam member 101 has an aperture 104 therein to receive a linking member such as a karibina 9. It will be appreciated that the annular cam member 102 cannot rotate into a position in which the jaw member 5 can move into an open position, as shown in Figure 5b, until the linking member 9 has been removed. As with the first embodiment, the cam member 101 is shaped so that any initial rotation of the cam member 101 due to the aperture 104 being larger than the diameter of the linking member 9 will cause the jaw 5 to move beyond the closed position so that the gap between the hooked portion 3 and the jaw 5 reduces, thereby preventing possible detachment of the safety clip 100 from the cable. The cam member 101 is provided with a flattened region 105 to facilitate rotation of the cam member 101 about the axis "F". The flattened portion 105 also engages in a seat (not shown) in the rear faces of the arms 103 when the jaw is moved into the closed position to prevent further rotation of the cam member 101 in the same direction.
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

A safety clip for use in a fall arrest system including a track, the safety clip comprising a body (2) and a jaw (5) pivotably mounted on the body (2) and movable between an open position in which the body (2) can be attached to, and detached from, the track and a closed position to retain the clip on the track, characterised by a cam member (6) rotatably mounted on the body (2) and the jaw (5) being biased toward the open position, the cam member (6) and jaw (5) cooperating in response to rotation of the cam member (6) to pivot the jaw (5) into the closed position.
A safety clip according to claim 1, wherein the body (2) includes a hook portion (3) and the cam member (6) and jaw (5) are configured such that, when the jaw (5) is in the closed position, a gap is present between the tip of the jaw (5) and the tip of the hook portion (3).
A safety clip according to claim 2, wherein the body (2) comprises a connecting part (4) depending from the hook portion (3), the connecting part (4) having an aperture (8) therein to receive a linking member for attachment of the clip to a lanyard.
A safety clip according to claim 3, wherein the cam member (6) is pivotally attached to the connecting part (4), the clip being configured such that rotation of the cam member (6) is substantially prevented when the linking member is received through the aperture (8).
A safety clip according to claim 4, wherein the cam member (6) is annular and the aperture (8) in the connecting part (4) and in the cam member (6) are aligned when the cam member (6) is positioned such that the jaw (5) is in a closed position, the linking member being receivable through both the aperture (8) in the connecting part (4) and in the cam member (6) to substantially prevent rotation of the cam member (6) relative to the connecting part (4).
A safety clip according to claim 5, wherein the cam member (6) is configured such that any limited rotation of the cam member (6) that is still possible when the linking member is received through the apertures (8) in the connecting part (4) and the cam member (6) is operable to cause the jaw (5) to move beyond the closed position to one in which the size of the gap between the jaw (5) and the hook portion (3) is reduced or eliminated.
A safety clip according to claim 6, wherein a cam surface is formed on the outside of the annular cam member (6) and comprises a first cam surface (12) and a second cam surface (13) adjacent to the first cam surface (12).
A safety clip according to claim 7, wherein the first and second cam surfaces (12,13) are substantially flat and meet at an oblique angle.
A safety clip according to claim 7 or 8, wherein the first cam surface (12) lies in engagement with the jaw (5) when the jaw (5) is in a closed position.
A safety clip according to claims 7, 8 or 9, wherein a region between the first and second cam surfaces (12,13) lies in engagement with the jaw (5) when the cam member (6) is initially rotated and the gap between the jaw (5) and the hook portion (3) is reduced or eliminated.
A safety clip according to any of claims 7 to 10, wherein the jaw (5) cooperates with the second cam surface (13) when the linking member has been removed and the cam member (6) is allowed to rotate beyond said initial rotation.
A safety clip according to any preceding claim, wherein the cam member (6) includes biasing means to bias it into a position in which the jaw (5) has been pivoted into the closed position.
A safety clip according to claims 1 or 2, wherein the body (2) includes a pair of arms depending from the hooked portion (3), the cam member (6) being located between said arms and pivotally mounted thereto.
A safety clip according to claim 13, wherein the cam member (6) has an aperture (10) therethrough to receive a linking member and the arms substantially prevent rotation of the cam member (6) when a linking member is received through the aperture.
A fall arrest system incorporating a safety clip according to any of claims 1 to 14.