GB2398822A

GB2398822A - Safety brake for fall arrest

Info

Publication number: GB2398822A
Application number: GB0312216A
Authority: GB
Inventors: Keith Martin Turney
Original assignee: Central Technology Inc
Current assignee: Central Technology Inc
Priority date: 2003-02-26
Filing date: 2003-05-28
Publication date: 2004-09-01
Anticipated expiration: 2023-02-26
Also published as: EP1596941B1; EP1596941A1; ATE405329T1; GB2398821A; DE602004015938D1; WO2004075993A1; GB0304359D0; GB0312216D0; GB2398822B; GB2398821B; ES2312952T3

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

1 2398822 Safety Device

Description

The present invention relates to a safety clamp for use in a fall-arrest system for proteetmg 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 mamtenanee or eleanmg. A slip or fall from such position can result m a serious or 0 even fatal Mary 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 hoked 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 chp remains permanently coupled to the cable, a fall is quickly arrested preventing bodily Injury. I7all 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 chp for attaching the lanyard to the cable generally composes 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. 'l'o overcome this, a gap or slot is mantamed between the tip of the jaw and the tip of the hook so that the 2 suppotts, 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.

s lthe 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.

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 arrested.

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 devotee 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. 'whys 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 - 3 hand to carry out the task he is attempting to perform whilst he is changing position or climbing and this Is restuctve 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. 'lthe 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 venerable to a serious accident.

It is an object of the invention, to provide a safety clamp that substantially overcomes or alleviates all the problems referred to above.

According to the invention, there is provided a safety clamp for use in a fall-arrest system having a track configured to follow a substantially vert1eal or tnelmed path, the clamp comprising a first and a second end and a gripping mechanism ineludlug 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 befog 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 - 4 mechansm Includes gravity actuated switching means operable to change the direction in which the actuating IcvOt is rotatable to cause the gripping mechanism to engage the track, so that the gripping mechanism always engages the track in response to the application of a downwardly directed load to the aCtuatlog lever s Irrespective of whether the clamp IS mounted on the track with said htst 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 2s 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. - s -

Prcferably, the slide member includes a tooth at each end for cooperation with a corrcspondng notch on the actuating lever when the slide member drops mto engagement with the actuating lever.

s In one embodiment, each tooth and each notch engage to prevent rotation of the actuating member In the upward direction when other 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 metnber.

The body conveniently mcludcs 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.

lathe adjustable biasing means may conveniently cormprse a spring biased bearing member in cogagement 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 beanog member against the brake shoe.

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

Embodmcuts of the invention will now be described, by way of example only, with reference to the accompanying drawings, in whch:- Fl(-rURE I is a rear perspective view of a safety clamp according to the Invention;

- G

FIGURE 2 Is an exploded perspectvc view from the front of the safety clamp shown in Figure 1; FIGURE 3 Is an exploded perspective view from the rear of the safety clamp shown in Figure 1; FIGURE 4 is an end view of the safety clamp shown in Figure 1; FIGURE 5 is a cross-sectonal view of the safety clamp shown in Figure 1, along line X-X in Fgurc 4; FIGURE 6 shows a front view of the gripping mechanism and switching means with the body removed; I:'IGURE 7 shows a rear view of the gripping mechanism and the switching means with the body removed; FIGURE, 8 shows another embodiment of the safety clamp according to the present invention; FIGURE 9 shows a first sectional view along the lme Z-Z m Figure 8 with the hook part in a closed position; FIGURE 10 shows a second sectional view along the lme Z-Z In Figure 8 with the hook part m an open position; and FIGURE 11 shows an exploded perspective view of the safety clamp illustrated In Figure 8.

Refctring now to Figures I to 7 of the accompanying drawings, there is shown a safety clamp 40 for use m a fall arrest system comprising a body 41 having a hooked portion 42 dcfmng a tubular openmg 43 extending through the body 41 between end faces 44,45 to sldeably receive a track 46 (see Figure 5) 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 7. 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 usmg the device. The opposite end 54 of the actuating lever 49 Is - 7 received in a recess 55 m a brake shoe 5G 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 5, 6 and 7 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 G6 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. 'lithe 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 bearings 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. 'lthe brake shoe 56 is prevented from being pushed out of the body 41 into the tubular opening 43 by engagement of the pins 6G 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 6X to compress or decompress the springs 73. The pins G6 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. 'lthe 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. - 8

Each tooth 81 has a shoulder 82 and an inclined face 83 for cooperation with a corresponding shoulder G3 and inchned face 62 forming each notch 60 m 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" m Figures 6 and 7 so that the tooth 81 at s one end of the bar 80 can engage with a corresponding notch 60 in one of the wmgs 59 of the actuating lever 49, as shown m Figure 6 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 8G extending through the _.

body 41 and an aperture 87 in the actuating member 49 and is threadngly engaged in a hole 88 in the cover. 'lathe 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 reccivcd 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 mcchansm, the slide bar 80 and the track 46 are shown m Figure 6 and 7, 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 asccading 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 l;gures 6 and 7 because the shoulder G3 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 6 and 7 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, net so that the end face 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 - 10 embodment will now be described with reference to Figures 8 to I t which fulfills tints requirement.

In the clamp 110, according to the second embodiment, the hook portion 111 Is pivotable about an axis "Y", Indicated in Figures 8 to 10, relative to the body 112 between a closed position, in which the clamp is connected to the cable 46, as shown m l-'gure 9, and a released position, in which the cable can be disconnected from the cable 46, as shown in Figure 10. 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 Flock plate 114 slideably mounted in a recess In the rear face of the body 112 for movement In the direction indicated by arrow Q m Figures 9 and 10. 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 portc>n 111 has a tail llG that extends beyond the pivot axis "Y" that narrows towards its tip. This creates a space 117 between the tall 116 and the body 112 to receive the tip 118 of the lock plate 114 when the hook portion 111 is m the closed position as shown in Figure 9. 'lihe tip 118 of the lock plate 114 is chamfered so that the Inner surface of the tail 11G 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 prcveoted 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 11) ant<> the locked pOSltOi1 In which the tip 118 of the lock plate 114 Is received in the space 117. 'lathe 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 mto the <>pen position shown In Figure 10. 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. - 11

Figure 9 shows a cross sectional view of the clamp 110 when the lock plate 114 has been retracted against the spring 119 to allow rotation of the hook portion 111 as shown In I;tgure 10. 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 tnember rotates to lock the clamp 40 on the track 4G changes automatically in response to change In the orientation of the clamp 40, rather than m 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 IS require setting by the user.

The inventions have been described with reference to preferred embodiments only.

Modifications and alterations to the embodiments fallmg within the scope of the appended claims are Included within the scope of protection. - 12

Claims

Claims 1. A safety clamp for use In a fall-arrest system having a stack

configured to follow a substantially vertical or nclmcd 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 prevcut 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 shde 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 m response to the 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.
2. A safety clamp according to claim 1, comprising 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 gnppmg mechanism being mounted within the body.
3. A safety clamp according to claim 2, wherein which the actuating lever is mounted to the body for rotation about an axis substantially at right angles to the tubular path and the direction m which the clamp slides along the track.
4. A safety clamp according to claim 2 or 3, wherein cane end of the actuating lever extends from the body, said end having an aperture therein for attachment of a workman thereto via a lanyard.
5. A safety clamp according to claim 4, wherem 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.

s
6. A safety clamp according to claim 5, wherein a cam surface Is 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.
7. A safety clamp according to any of claims 1 to (I, wherein 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 m which the actuating member can be rotated.
8. A safety clamp according to claim 7, wherein 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.
9. A safety clamp according to claim 8, wherein 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.
10. A safety clamp according to any of claims 7 to 9, wherein the actuating lever is 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.
11. A safety clamp according to any of claims 7 to 10, wherein the body includes a guide channel to loosely receive each end, and guide movement of, the slide member. - 14
12. A safety clamp according to any of claims 4 to 11, wherein at least two retaining pins extend from the brake shoe mto an elongate slot in the body to retam the shoe m the body, the pin being biased against a wall of the slot by adjustable biasing means received in the body. s
13. A safety clamp according to claim 12, wherein the adjustable biasing means compose 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 bearmg member against the brake shoe.
14. A safety clamp according to any of claims 2 to 13, wherein the hook portion is pivotally attached to the remainder of the body and locking means are provided to enable the hook portion to be rotated relative to the remainder of the body when IS the locking means are released.
15. A safety clamp according to claim 14, wherem the lockmg means comprises a spring biased plate, the plate and the hooked portion having cooperating surfaces that engage to prevent rotation of the hooked portion.
16. A fall arrest system incorporating the safety clamp according to any of claims 1 to 15.
17. A safety clamp substantially as herelnbefore described with reference to Figures 1 to 11 of the accompanying drawings.

lo. rim rail arrest SysLclII subsLalLially as herelllbefore diescrlL)eu Incorporarillg a safety clamp m accordance with claim 1.

17. A safety clamp substantially as herenbefore described with reference to figures I to 11 of the accompanying drawings.

18. A fall arrest system substantially as hereinbefore described.

Amended claims have been filed as followed Claims 1. A safety clamp for use in a fall-arrest system having a track configured to follow a substantially vertical or nclrled path, the clamp comprising a first and a second end and a gripping mechanism tucludrlg a rr>tatatly mounted actuating lever operable, when the clamp is mounted on the track and the actuahrlg lever is rotated in response to the application of a down\vardly detected 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 m the opposite dlrecuon being 0 substantially prevented to allow the clamp to slide freely in an upward direction along the track ill response to the application of an upwardly directed load to the actuating member, wherein the grtpprtlg mechanism includes gravity actuated, swtchmg means operable to change the director In WtlICh the actuating lever Is rotatable to cause the gripping mecllaorsm to engage the track, so that the gripping mechanism always engages the track m response to the application of a downwardly directed load to the actllatmg lever Irrespective of whether the clamp is motlrlted on the track with said first or second end uppermost.

2. A safety clamp acccrdtag to claim 1, comprising a body having a hook portion to define a substantially tubular Patti through the body between the frost and second ends to receive the track, the grrpptng mechanrsn1 being mounted withers the body.

3 A safety clamp according to claim 2, wherein which the actuating lever Is 2s Counted to the body for rotation Alcott an axis substantially at right angles to the t,l,l?r r?1-1! An t1' 1tt.r r,r' try rhr t, roof f 1,rrr cltrif C ?Irr, 1. r.f!r 4. A safety clamp according to claim 2 or 3, wherein one end of the actuating lever cxtencls fi(jLn the bocly, said and havilly,- an pertLll- e therem for att:achmcllt of a workman thereto via a lanyard.

5. A safety clamp according to claim 4, wllerem the grrpprrlg mechanism includes a brake shoe sldeably mounted wrthr1 the IJody for engagement with the lb 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.

s 6. A safety clamp according to claim 5, wherein a cam surface Is 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.

7. A safety clamp according to any of claims I to G. wherein the switching _. . . _ TO 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.

8. A safety clamp according to claim 7, wherein the slide member includes a tooth at each end for cooperation with a corresporldrlg notch on tile actuating lever when the slcle member drops into engagement with the actuating lever.

9. A safety clamp according to claim 8, wherein 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 dlrectiorl.

10. 1\ safety clamp according to any of claims 7 to 9, wherein the actuating lever Tic r ''TrNt?l!,T mounts] run on pole ertrnri't', Err, top 1!'-''lt', to{' -lo! .':! ktt'(llT]=T L11IIItIL)TI1 LLI1 C1IJI1?'Tj-C 191111118 11L L1lU 511 111(:111191 LL> 111(JUI1L L11 51iLIC 111Cll1L)Cr WiLlll11 the body adjacent to the actuating member.

1 l. A safety clamp according to any of claims 7 to 10, wherein the body includes a guide channel to loosely receive each end, and guide movement cuff, the slide member. -1 '

12 A safety clamp according to any of claims 4 to 11, \vherein at least two retaining pitas extend from the brake shoe mto an elongate slot m the body to retain the shoe In the body, the pin bemg biased against a wall of the slot lay adjustable biasing means received In the body.

13. A safety clamp according to claim 12, wherein the adjustable biasing means 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 acllust the biasmg force applied by the bearing member against the brake shoe.

14. A safety clamp according to any of claims 2 to t3, wherein the hook portion is pivotally attached to the remainder of the body and locking means are provided to enable the hook portion to be rotated rclatve to the remainder of the body when the locking means are released.

15. A safety clamp according to claim 14, wherein the locking means comprises a spring biased plate, the plate and the hooked portion having cooperating surfaces that engage to prevent rotation of the hooked portion.

16. A fall arrest system incorporating the safety clamp according to any of claims 1 to 1 5.