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 theit 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.

According to the present invention, there is provided 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, wherein a cam member is rotatably mounted on the body and the jaw is 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 in to one 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 main cam surface and a secondary cam surface adjacent to the main cam surface.

Conveniently, the main and secondary cam surfaces are substantially flat and meet at an oblique angle.

Preferably, the main cam surface lies in engagement with the jaw when the jaw is in a closed position.

In one embodiment, a region between the main and secondary 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 secondary 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.

In addition to the safety clip referred to above, the present invention also relates to a slide. brake device for use in a fall-arrest installation for protecting workmen operating at elevated positions.

The use of a safety clip, such as that already described, is generally used by workmen is moving around on a raised but generally flat platform or walkway on which the cable forming part of the fall-arrest system is generally installed in a horizontal orientation. However, 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 attested.

To overcome the foregoing, it is also known to provide a device which is free to slide along a track such as a cable or rigid rod attached to the building or other structure being worked on but which locks or clamps the device against the track when a load is applied to a trigger forming part of the device and to which a lanyard connected to a harness worn by the workman is attached so that, should the workman fall, a load is applied to the trigger to immediately prevent the device from sliding along the track and immediately arresting the fall.

Although safety clamps of the aforementioned type are known, they are often difficult or annoying for the workman to use. This is because the workman, must physically hold the body of the device by hand and slide it along the track as he moves. It is not possible to drag the device along the track by pulling on the lanyard because this applies a load to the device which will causes it to lock or clamp against the track. As the workman must slide the device along the track, he only has one hand to carry out the task he is attempting to perform whilst he is changing position or climbing and this is restrictive and could lead to the workman detaching himself from the device resulting in possible serious or even fatal injury should he then fall.

Attempts have been made to overcome the aforementioned problem by providing a modified clamp that 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 as he does so and keeping both hands free. However, it is imperative with this type of clamp that the workman attaches it to the track in the correct orientation otherwise the clamp or brake will not activate should the workman fall. Not only has it been found that a workman may inadvertently attach the clamp to the track in the incorrect orientation but there may also be circumstances along the same length of track that require the workman to move downwardly as well as upwardly. Therefore, even when the workman has correctly oriented the clamp on the track for the upwardly oriented sections, he will have to remove the clamp from the track and reorientate it

for sections of the track which are downwardly oriented. This may involve complete detachment from the fall arrest system making the workman vunerable to a serious accident.

It is another object of the invention, which is completely independent of the first object of the invention, to provide a safety clamp that substantially overcomes or alleviates all the problems referred to above.

According to another invention, there is provided a safety clamp for use in a fall- arrest system having a track configured to follow a substantially vertical or inclined path, the clamp comprising a first and a second end and a gripping mechanism including a rotatably mounted actuating lever operable, when the clamp is mounted on the track and the actuating lever is rotated in response to the application of a downwardly directed load thereto, to cause the gripping mechanism to engage the track and prevent downward movement of the clamp along the track, rotation of the actuating lever in the opposite direction being substantially prevented to allow the clamp to slide freely in an upward direction along the track in response to the application of an upwardly directed load to the actuating member, wherein the gripping mechanism includes gravity actuated switching means operable to change the direction in which the actuating lever is rotatable to cause the gripping mechanism to engage the track, so that the gripping mechanism always engages the track in response to tfie application of a downwardly directed load to the actuating lever irrespective of whether the clamp is mounted on the track with said first or second end uppermost.

The safety clamp preferably comprises a body having a hook portion to define a substantially tubular path through the body between the first and second ends to receive the track, the gripping mechanism being mounted within the body.

The actuating lever is conveniently mounted to the body for rotation about an axis substantially at right angles to the tubular path and the direction in which the clamp slides along the track.

Preferably, one end of the actuating lever extends from the body, said end having an aperture therein for attachment of a workman thereto via a lanyard.

In a preferred embodiment, the gripping mechanism includes a brake shoe slideably mounted within the body for engagement with the track, the opposite end of the actuating lever cooperating with the brake shoe so that rotation of the actuating member causes the brake shoe to slide relative to the body and engage the track.

A cam surface is advantageously formed on said opposite end of the actuating lever and the brake shoe has a recess therein to receive said opposite end and cooperate with the cam surface.

In a preferred embodiment, the switching means comprises a slide member configured to fall under its own weight into engagement with the actuating member in response to the first or second end being positioned uppermost so as to automatically change the direction in which the actuating member can be rotated.

Preferably, the slide member includes a tooth at each end for cooperation with a corresponding notch on the actuating lever when the slide member drops into engagement with the actuating lever.

In one embodiment, each tooth and each notch engage to prevent rotation of the actuating member in the upward direction when either the first or second end is uppermost, each notch and each tooth having an angled face that cooperate to permit rotation of the actuating member in opposite, downward direction.

The actuating lever is preferably pivotally mounted on an axle extending through the body, the axle also extending through an elongate opening in the slide member to mount the slide member within the body adjacent to the actuating member.

The body conveniently includes a guide channel to loosely receive each end, and guide movement of, the slide member.

In one embodiment, at least two retaining pins extend from the brake shoe into an elongate slot in the body to retain the shoe in the body, the pin being biased against a wall of the slot by adjustable biasing means received in the body.

The adjustable biasing means may conveniently comprise a spring biased bearing member in engagement with the brake shoe, the bearing member being received in an aperture in the body and retained therein by a screw rotatable to adjust the biasing force applied by the bearing member against the brake shoe.

The invention also comprises a fall arrest system incorporating the safety clamp according to the invention.

Embodiments of-each 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; 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; FIGURE 6 is a rear perspective view of a safety clamp according to another invention; FIGURE 7 is an exploded perspective view from the front of the safety clamp shown in Figure 6; FIGURE 8 is an exploded perspective view from the rear of the safety clamp shown in Figure 6;

FIGURE 9 is an end view of the safety clamp shown in Figure 6; FIGURE 10 is a cross-sectional view of the safety clamp shown in Figure 6, along line X-X in Figure 9; FIGURE 11 shows a front view of the gripping mechanism and switching means with the body removed; FIGURE 12 shows a rear view of the gripping mechanism and the switiching means with the body removed; FIGURE 13 shows another embodiment of the safety clamp according to the present invention; FIGURE 14 shows a first sectional view along the line Z-Z in Figure 13 with the hook part in a closed position; FIGURE 15 shows a second sectional view along the line Z-Z in Figure 13 with the hook part in an open position; and FIGURE 16 shows an exploded perspective view of the safety clamp illustrated in Figure 13.

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 main cam surface 12 between two secondary cam surfaces 13 extending at an oblique angle from the main cam surface 12. The main 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 1 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 1 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 1. A coil spring 19 is also mounted within a recess 20 formed in the body 1 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 1 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 main 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 main and a secondary 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 secondary 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 102 is pivotally mounted for rotation about an axis"F"indicated in the Figures. The cam member 102 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 102 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 102 is shaped so that any initial rotation of the cam member 102 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 103 is provided with a flattened region 105 to facilitate rotation of the cam member 103 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 103 in the same direction.

Referring now to Figures 6 to 12 of the accompanying drawings, there is shown a safety clamp 40 for use in a fall arrest system comprising a body 41 having a hooked portion 42 defining a tubular opening 43 extending through the body 41 between end faces 44,45 to slideably receive a track 46 (see Figures 5,6 or 7) mounted on the building or other structure to which access is being sought. A cover plate 47 is

mounted over an opening in the body 41 in which is received a gripping mechanism 48.

The gripping mechanism 48 comprises an actuating lever 49 pivotally mounted to the body 1 for rotation about an axis"A"indicated in Figure 2. A first end 50 protrudes from the body 41 through an opening 51 therein and has an aperture 53 therethrough for attachment of a lanyard thereto that extends from a harness worn by a workman using the device. The opposite end 54 of the actuating lever 49 is received in a recess 55 in a brake shoe 56 and has a cam surface 57 thereon for cooperation with the walls 58 of the recess 55 to cause the brake shoe 56 to slide into engagement with the track 46 when the actuating lever 49 is rotated. The actuating lever 49 also includes integrally formed and arcuately shaped wings 59 extending laterally from each side thereof. A notch 60 is formed in the edge wall 61 of each wing 59 and has an angled or inclined face 62 and a shoulder 63.

The brake shoe 56 is mounted in the body 41 so that it can slide in the direction indicated by arrow"B"in Figures 10,11 and 12 and it extends from one end 44 of the body 41 to the other end 45. The brake shoe 56 has an outer arcuately shaped face 64 facing into and forming part of the tubular opening 43. The face 64 serves to engage the track 46 to prevent movement of the clamp 40, as will be explained in more detail hereinafter.

The brake shoe 56 is retained in an elongate channel 65 in the body 41 by a pair of pins 66 threadingly engaged in holes 67 in the side wall 68 of the brake, shoe 56 which locate in elongate openings or recesses 69 in the body 41 to retain the brake shoe 56 in the body 41. The pins 66 are biased against the wall 70 of the openings 69 by a pair of adjustable bearing members 71 each comprising a ball bearing 72, a coil spring 73 and a grub screw 74 received in a threaded hole 75 in the body 41.

The beatings 72 bear against the upper surface 76 of the brake shoe 56 and urge it forward out of the channel 65 in which it sits. The brake shoe 56 is prevented from being pushed out of the body 41 into the tubular opening 43 by engagement of the pins 66 against the wall 70 of the openings 69. It will be appreciated that the force applied to the brake shoe 56 by the bearing members 71 is adjustable by rotating the

grub screws 68 to compress or decompress the springs 73. The pins 66 may slide within their openings 69 as the brake shoe 56 is slid by the actuating lever 49.

A slide member in the form of a bar 80 is mounted transversely across the actuating lever 49 against the wings 59. The slide bar 80 is longer than the width of the actuating lever 49 and so overlaps the wings 59 at each end. A tooth 81 upstands from each end of the slide bar 80 in the direction of the actuating lever 49 and faces a corresponding notch 60 in the edge 61 of the wings 59 of the actuating lever 49.

Each tooth 81 has a shoulder 82 and an inclined face 83 for cooperation with a corresponding shoulder 63 and inclined face 62 forming each notch 60 in the wings 59 of the actuating lever 49. The bar 80 is mounted so that it can slide longitudinally in the direction indicated by arrow"C"in Figures 11 and 12 so that the tooth 81 at one end of the bar 80 can engage with a corresponding notch 60 in one of the wings 59 of the actuating lever 49, as shown in Figure 11 and for the reasons explained in more detail below. The bar 80 has a central elongate aperture 85 therein.

The actuating member 49 is rotatably mounted on an axle 86 extending through the body 41 and an aperture 87 in the actuating member 49 and is threadingly engaged in a hole 88 in the cover. The axle 86 also passes through the elongate central aperture 85 in the slide bar 80 to mount the slide bar 80 and to constrain its sliding movement. Each ends of the slide member 80 is received in a guide recess 89 in the body 41.

Three threaded holes 90 are provided in the hooked portion 42 of the body 41 to receive threaded members 91 having bearing surfaces 92 thereon that protrude into the tubular opening 43. Adjustment of the threaded members 91 controls the position of the bearing surfaces 92 so that they contact the track and allow it to slide smoothly through the tubular opening 43 in the body 41.

Operation of the safety clamp 40 will now be described when it is used with a vertical track forming part of a fall-arrest system. The clamp 40 is first slid onto the track 46 so that the track 46 extends through the tubular opening 43. It will be appreciated that as the track 46 is vertical or inclined, one of the end faces 44,45

will be uppermost depending on which way up the clamp 40 is mounted on the track 46.

Although only the gripping mechanism, the slide bar 80 and the track 46 are shown in Figure 11 and 12, it will be appreciated that in this case, the clamp 40 has been mounted to the track 46 with the end 44 uppermost. In this orientation, the slide bar 80 slides or drops downwardly under its own weight due to gravity so that a tooth 81 on one end of the slide bar 80 engages a corresponding notch 60 formed in one wing 59 of the actuating lever 49. Now, when a load is applied to the actuating lever 49 in the upward direction caused by a workman ascending the building and pulling on the lanyard connecting him to the actuating lever 49, the actuating lever 49 cannot rotate in the direction of arrow"D"in Figures 11 and 12 because the shoulder 63 on the wing 59 of the actuating member is in engagement with the shoulder 82 on the tooth 81. As rotation of the actuating lever 49 is prevented, the brake shoe 56 is not moved and the clamp 40 remains free to slide upwardly along the track 46.

If the workman should fall, a load will now be applied to the actuating lever 49 in the opposite downward direction. The actuating lever 49 is not prevented from rotating in the opposite direction indicated by arrow"E"in Figures 11 and 12 because the angled face 63 of the notch 60 on the wing 59 is able to slide relative to the angled face 83 on the tooth 81. Rotation of the actuating lever 49 causes the cam surface 57 to engage the brake shoe 56 and slide it so that the clamp 40 engages the track and prevents movement of the clamp down the track 46.

If the clamp is now mounted to the track the other way up, i. e. so that the end face 45 is now uppermost, the slide bar 80 drops under its own weight due to gravity so that the other tooth 81 engages with the other notch 60 on the wing 59 of the actuating member 49 so that rotation of the actuating member 49 in the upward direction is still prevented and rotation in the downward direction is still possible.

Therefore, it will be appreciated that irrespective of which way up the clamp 40 is mounted to the track, i. e. with the end 44 or end 45 uppermost, it will never allow the clamp to slide down the track should the workman fall and a load is applied to

the actuating member but always allow him to slide up the track 46 when an upwardly directed load is applied to the actuating lever 49.

It will be appreciated that a disadvantage with the safety clamp 40 described above is that it can only be attached to the track or cable 46 by sliding it on from a free end of the cable. However, it is desirable that the workman be able to connect and disconnect the clamp from the cable at any point along its length. A modified embodiment will now be described with reference to Figures 13 to 16 which fulfils this requirement.

In the clamp 110, according to the second embodiment, the hook portion 111 is pivotable about an axis"Y", indicated in Figures 13 to 15, relative to the body 112 between a closed position, in which the clamp is connected to the cable 46, as shown in Figure 14, and a released position, in which the cable can be disconnected from the cable 46, as shown in Figure 15. A locking mechanism 113 is provided to enable the hook portion 111 to be locked in the closed position and released for removal of the clamp from the cable at any point along its length.

The locking mechanism 113 comprises a lock plate 114 slideably mounted in a recess in the rear face of the body 112 for movement in the direction indicated by arrow Q in Figures 14 and 15. The lock plate 114 has an actuating knob 115 upstanding from its surface to enable a workman to slide the lock plate 114 to release the hook portion 111.

The hook portion 111 has a tail 116 that extends beyond the pivot axis"Y"that narrows towards its tip. This creates a space 117 between the tail 116 and the body 112 to receive the tip 118 of the lock plate 114 when the hook portion 111 is in the closed position as shown in Figure 14. The tip 118 of the lock plate 114 is chamfered so that the inner surface of the tail 116 and the outer surface of the tip 118 engage each other when the lock plate 114 is in the locked position. Rotation of the hook portion 111 is prevented by the lock plate 114 when the tip 118 is located in the space 117.

The lock plate 114 is biased by a pair of springs 119 (see Figure 16) into the locked position in which the tip 118 of the lock plate 114 is received in the space 117. The user can slide the lock plate 114 against the bias provided by the springs 119 so that the tip 118 is withdrawn from the space 116 and the hook portion 111 is free to rotate into the open position shown in Figure 15. A cover 120 having an aperture 121 is mounted on the body 112 over the lock plate 114. The actuating knob 115 protrudes through the aperture 121.

Figure 14 shows a cross sectional view of the clamp 110 when the lock plate 114 has been tettacted against the spring 119 to allow rotation of the hook portion 111 as shown in Figure 15. As the hook portion 111 and lock plate 114 engage at an angle, any loading on the jaw is transmitted as a compressive force into the body.

Secondly, engagement at an angled face allows for wear take up and tolerances.

It will be appreciated that the safety clamp of the present invention provides the significant advantage that the workman does not need to worry about ensuring that the clamp 40 is mounted to the track in the correct orientation. As the direction in which the actuating member rotates to lock the clamp 40 on the track 46 changes automatically in response to change in the orientation of the clamp 40, rather than in response to activation of a manually operated switch, the clamp 40 will always function correctly and lock against the track 46 in the event of a fall and does not require setting by the user.

The invention ; have 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.