Safety apparatus and method for working platform

Abstract

Apparatus (1, la) for monitoring the correct use of a safety harness (41) connectable to a platform of a Mobile Elevated Work Platform (MEWP) or the like, the apparatus comprising aperture means (6) a

Description

[0001] SAFETY APPARATUS AND METHOD FOR WORKING PLATFORM

[0002] The present invention relates to apparatus to monitor the attachment of safety harness to an anchor point and the like. More particularly but not exclusively, the invention relates to such apparatus for use on mobile elevated work platforms to monitor anchoring of safety harness and to take action if the safety harness is not suitably anchored.

[0003] It is clearly highly desirable for those working at height on Mobile Elevated Work Platforms (MEWPs) to be protected from falls. The IPAF Global MEWP Safety Report has shown that during the operation of boom type MEWPs (also known as “cherry-pickers”) and other equipment involving working at height, falling from heights leads to the biggest number of fatalities.

[0004] All boom operators are now required to wear a fall restraint harness during the full range of operation. This is because the falling risks are present not only while working at height, but also during travelling conditions as the boom is elevated or lowered, given the cantilever / catapult effect resulting from the operator’s location relative to the chassis of the MEWP apparatus.

[0005] The compulsory wearing of fall restraint harness is not at present mandated for scissor lift MEWPs in the UK, although a rise in compulsory harness policies is being seen across UK construction sites. The number of falls from scissor lifts is significantly lower than for boom type MEWPs, but wearing harnesses would still be beneficial in many situations, even where the risk might be more of injury than death.

[0006] Another issue has been observed, which lessens the effectiveness of fall restraint harnesses. This is the tendency of a number of operators to use inappropriate or nondesignated anchor points for their harnesses, such as looping connectors around a hand rail or other fixture on the platform. These fastenings may not be sufficient to resist possible imposed stresses, for example if the harness is retaining an operator who has fallen from the platform.

[0007] Worse, there are still a few overconfident operators who do not believe that they need full safety equipment and that it interferes with their freedom of action. They may be tempted to operate the MEWP platform without wearing or anchoring their safety harnesses, or to disconnect their harnesses from the anchor point on the platform for greater convenience, once out of sight of the ground. Despite the potential consequences, this does still occur.

[0008] It is also possible that the harness might accidentally not be attached correctly or might not be attached at all due to the operator forgetting. It is also possible that an anchored harness might become disconnected from the anchor point accidentally,

[0009] It is both legally and morally the responsibility of those managing work at heights to take all actions necessary to ensure that the necessary safety equipment is worn and used correctly, for the sake of the safety of the operators. It is clear that it is not sufficient to rely solely on the operators’ own actions to ensure safety.

[0010] It is hence an object of the present invention to provide equipment to detect correct attachment of safety harnesses to dedicated anchor points on MEWP platforms and the like, and to notify operators and others if the safety harness is not correctly anchored.

[0011] It is a further object of the present application to provide such equipment that also interrupts functions of the MEWP if the safety harness is not correctly anchored.

[0012] According to a first aspect of the present invention, there is provided apparatus for monitoring the correct use of a safety harness connectable to a platform of a Mobile Elevated Work Platform (MEWP) or the like, the apparatus comprising: aperture means adapted to receive a connector means of the safety harness engagingly, detector means adapted to detect absence or presence of the connector means engagingly received within the aperture means, the detector means comprising an induction loop means mounted to the aperture means such that an inductance of the induction loop means is altered by the absence or presence of the connector means of the harness within the aperture means; said induction loop means providing an output having a first condition in the presence of the connector means and a second condition which the connector means is absent, said output being fed to an electrical circuit that forms a part of the MEWP such that the mobile elevated work platform is prevented from moving without said connector means being engaged with said aperture means, and in which the apparatus further includes an indicator means the provides a visual cue to an operator that the detection means has detected the connection of the connector means of a harness to the aperture means.

[0013] The output from the inductive loop means may prevent the platform being driven around a worksite, or may prevent the platform being elevated or lowered, or prevent both elevation and driving, without the presence of the connector means in the aperture means. By driving we mean forward / backward motion and steering of the platform during that motion where the platform has steerable wheels.

[0014] In a preferred embodiment, the apparatus comprises means to mount it to an existing harness anchor point of the platform, optionally being detachably mountable thereto.

[0015] In an alternative embodiment, the apparatus is an integral part of a harness anchor point of the platform.

[0016] The apparatus may include a housing that contains the induction loop, and a cable may be provided that is fixed at one position to the housing and at the other may be secured to the platform of the MEWP. This cable may comprise a multi-strand flexible steel cable. The cable should be capable of supporting the weight of a user when suspended from the cable, and may be sufficiently highly rated to restrain the user should they fall from a platform. For instance, the cable may be rated to maintain integrity under a load of up to 22.24kN or more.

[0017] The cable may be hollow and an electrical wire may pass through the hollow cable at least along a portion of its length starting from the housing and extending beyond the housing, the electrical wire being electrically connected to the induction loop either directly or indirectly. Passing the electrical wire along the inside of the cable provides protection against damage of the electrical wire. It also makes assembly simpler as there is no need to feed the electrical wire to the housing through a separate grommet in order to achieve an appropriate level of waterproofing.

[0018] One end of the cable may be fixed to the housing by a suitable clamp and extend into the housing, the electrical wire projecting from this end into the housing. The clamp therefore grips the cable around the wire to secure them to the housing. The electrical wire may exit the cable close to the clamp or at the clamp on the side opposite the housing or at a point close to the free end of the cable furthest from the housing. The later is preferred as it gives good protection to the wire until it is close to the point where the cable is secured to the MEWP. A protective shroud, such as a sleeve of heat shrink material, may be provided to cover the location where the wire exits the cable outside of the housing.

[0019] The free end of the cable furthest from the housing may be folded back on itself to form a loop and secured using a clamp, the electrical cable exiting the cable at a point close to this clamp on the side nearest the housing.

[0020] The output may be connected to the electrical circuit of the mobile elevated work platform in such a manner that emergency operation of the platform to lower the platform can be performed with or without the presence of a connector means, so that the apparatus does not interfere with this safety feature of the mobile platform. Emergency operation may enable the platform to be lowered.

[0021] Preferably, the output of the inductive loop means comprises a node at which a voltage is provided that varies between a first level when no connector means is detected to a second different voltage when it is detected. For instance, when not detected the output voltage may be zero and when connected may be a positive nonzero voltage. This may be fed into a electrical circuit of the platform that comprises an electronic control unit.

[0022] Alternatively, the output of the inductive loop means may comprise a node which is held open to present an infinite resistance when no connector is detected, and connected to a ground or earth point when a connector means is detected. When held open no current can flow through a circuit in which the output is connected in series and when closed a current can flow to ground. Again this may be connected to an electrical circuit of the platform that comprises an electronic control unit.

[0023] The output may be connected to a switch to open and close the switch as a function of the condition of the output. The switch may be wired in series in an electrical line of the platform along which signals are passed that determine whether or not the platform can be moved. It may, for example, be wired in series in an electrical circuit of the platform between a switch operated by a foot pedal and a control circuit of the platform.

[0024] In one arrangement the switch may be a relay, and the output may be connected to one side of the low voltage coil of a relay, the other side connected to a supply voltage, the output ports of the relay being normally isolated from each other but being connected to allow current to flow between the ports when the connector means is detected by the inductive loop means. The relay may form part of the controller means of the platform.

[0025] The mobile elevated work platform may include a user operable control by which the user commands movement of the platform and the switch may selectively disable or enable the function of the user operable control.

[0026] The user operable control may be a button, switch, lever or foot pedal of the mobile elevated work platform and by connecting the switch in line with the control the control may be prevented from causing the platform to move.

[0027] The user operable control may be a dead man’s switch operated by a foot of the user.

[0028] The apparatus may comprise a housing within which is located the inductive loop means. The housing may be a clam shell with an upper part and a lower part, each having an opening, the inductive loop means being located inside the shell such that the loop is aligned with the openings.

[0029] The openings in the housing may define at least a part of the aperture means.

[0030] The apparatus may include an electrical cable that comprises a first conductor that provides an electrical connection to the of the inductive loops means. It may also include a second conductor that provides electrical power to the inductive loop means, and a third conductor that provides an earth return for the detector means. The indicator means may comprise a light such as an incandescent lamp or light emitting diode which is illuminated when an operator is securely connected to the apparatus and is not illuminated at any other time.

[0031] Alternatively, the indicator means may comprise a second light that is illuminated when an operator is not securely connected to the apparatus.

[0032] The second light may always illuminate when the apparatus is connected to the MEWP.

[0033] The apparatus may draw power for the light from a battery of the MEWP or like. As such the apparatus may not include its own power source.

[0034] Of course, a power source could be provided such as a rechargeable battery.

[0035] The light may be switched on and off by connecting the light to the output of the inductive loop means.

[0036] The platform could then be employable in a zone potentially having a flammable or explosible atmosphere.

[0037] Preferably, the apparatus comprises cover means enclosing the aperture means when closed, said cover means being openable to provide access to the aperture means for the connector means of the harness.

[0038] The apparatus may comprise load gauge means, operatively connected to the control means, adapted to operate when a load on the apparatus has exceeded a pre-set load limit, so as to activate the alerting means and / or the control switch means.

[0039] The load gauge means is thus adapted to provide an alert and / or to cause the control switch means to act to prevent operation of the control means to move the platform. In a second aspect of the present invention, there is provided in combination an apparatus of the first aspect and an MEWP having a control panel which includes control means for controlling the movement of the MEWP and in which the output of the inductive loop means of the apparatus is connected to the control panel meansof theMEWP.

[0040] The MEWP may include a relay which is connected into a power line of the MEWP that supplies power to a drive motor or part of an internal combustion engine of the platform that is required to make the platform move.

[0041] The relay coil may be connected in series between a Deadman’s switch of the MEWP and the output of the inductive loop means such that the relay is closed only when the deadmans switch is depressed by an operator and the connection means is detected by the detector means.

[0042] In a third aspect of the present invention, there is provided a Mobile Elevated Work Platform comprising control means for a platform having a control panel which includes control means for controlling the movement of the MEWP and in which a switch is connected into a power line of the MEWP that supplies power required for movement of at least part of the MEWP, the switch including input terminals connectable to the output of an apparatus of the first aspect such that the power in the line is interrupted when the detector means does not detect that a harness has been connected to the apparatus.

[0043] In a fourth aspect of the present invention, there is provided a method of modifying a mobile elevating work platform MEWP to improve the safety of operators working at height on MEWPs and the like, comprising the steps of breaking a power line that carries power required to move the platform and reconnecting the two sides of the break to opposing sides of a relay, and subsequently connecting the relay to at least one monitoring apparatus as described in the first aspect above, mounting said apparatus to anchor points on an elevating platform of a MEWP.,

[0044] Embodiments of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings, in which: Figure 1 is a schematic elevation of a first monitoring apparatus embodying the present invention, in a closed configuration;

[0045] Figure 2 is a schematic elevation of the monitoring apparatus of Figure 1, in an open configuration;

[0046] Figure 3 is view of an alternative design of housing which does not have the covers for the aperture;

[0047] Figure 4 is a circuit diagram of a suitable inductive loop means of the apparatus and the connection of a light to the output to indicate the correct operation of the apparatus;

[0048] Figure 5 is a circuit diagram showing the connection of the inductive loop means to the control circuit of an MEWP;

[0049] Figure 6a and 6b are frontal and rear elevations respectively of a safety harness and lanyard for use in the present invention;

[0050] Figure 7 is a scrap perspective view of a snap-hook connectable to any of the monitoring apparatus of the present invention, mounted to a lanyard;

[0051] Figure 8 is a perspective view of a lanyard for use with the safety harness of Figures 6a and 6b, fitted with a proprietary connector;

[0052] Figure 9 is a perspective view of an adjustable lanyard for use in the present invention, fitted with two carabiners;

[0053] Figures 10 to 13 are elevations of four existing carabiners and snap-hooks usable with the monitoring apparatus of the present invention;

[0054] Figure 14 is a scrap perspective view of a first platform of a MEWP, fitted with two different forms of anchor point for receiving a monitoring apparatus of the present invention; Figure 15a is a scrap perspective view of a second platform of a MEWP, fitted with a third form of anchor point for receiving a monitoring apparatus of the present invention;

[0055] Figure 15b is a scrap perspective view of one of the anchor points of Figure 15a;

[0056] Figure 16 shows a first arrangement of the electrical circuit that illuminates the indicator, and

[0057] Figure 17 shows a second arrangement of the electrical circuit that illuminates the indicator.

[0058] Referring now to the Figures of the accompanying drawings, and to Figures 1 and 2 in particular, a first monitoring apparatus 1 comprises a fastening loop 2 by which it may be mounted to a secure anchor point provided on a platform of a Mobile Elevated Work Platform (MEWP) - details of which are shown in Figures 14 to 15a and described below. The monitoring apparatus may be attached to the anchor point by means of any conventional shackle, snap-hook, link or the like, having a suitable strength rating (the entire system should be capable of handling an imposed force of 22.24kN, so each link between the MEWP and a safety harness worn by an operator should be able to take at least a force of 22.24kN).

[0059] The monitoring apparatus 1 has two covers 3 that together enclose its operative components in a closed configuration, as shown in Figure 1. Each cover 3 is pivotable about a pivot pin 4 mounted to a main body 5 of the monitoring apparatus 1 into an open configuration, as shown in Figure 2. Preferably, these covers 3 are manually pivotable between configurations. Alternative embodiments can use sliding covers in place of the pivotable covers 3 shown herein. In each case, the covers may be biased closed with a spring arrangement if preferred.

[0060] In the open configuration of Figure 2, the opened covers 3 reveal an aperture means in the form of circular aperture 6 extending through the main body 5 of the monitoring apparatus 1, through which a connector means such as a carabiner, snap-hook or the like may be passed and fastened, thus connecting a lanyard of a safety harness (see below) securely to the monitoring apparatus 1 and thence to the anchor point and the MEWP platform.

[0061] In this monitoring apparatus 1, the monitoring function is provided by an inductive loop means that includes a conductive ring 7 extending around a circumference of the aperture 6. This ring 7 has a significant inductance when connected to an electrical circuit. However, when a metal object such as a carabiner or hook is located within the aperture 6 and the ring 7 it significantly alters the inductance of the ring 7 and so disrupts the electrical circuit, thus generating an electrical signal to indicate the presence of the carabiner / hook safely engaged with the monitoring apparatus 1. This signal provides an output of the inductive loop means.

[0062] The output of the indictive ring is fed along an electrical wire which is located inside a steel wire cable. The cable is clamped at one end to the housing using a crimp with sufficient pressure to prevent the cable and housing being separated within the 22.24kN load limit but not so great as to crush and damage the electrical wire. The cable is formed into a loop at the free end, and the wire exits the cable close to this loop.

[0063] Figure 3 is an electrical circuit diagram showing the connections to the ports of the inductive loop means 7, these ports being connected to respective conductors or a multi-core electrical cable 8. As shown one port, considered to be the output of the inductive loop means, is selectively held at floating voltage (isolated from ground and presenting an infinite resistance to any load connected to it) and connected to the ground allowing current flow through the output.

[0064] The output is used to activate an indicator lamp to confirm safe engagement, located on the monitoring apparatus 1 itself, or alternatively or additionally a light may be provided on a control panel on the MEWP platform, on a control panel located on a base element of the MEWP at ground level, or on another ground station.

[0065] Figure 4 shows the light being connected to the output port. In this arrangement it is normally not lit but will illuminate when the inductive loop detects that a user has clipped into the apparatus. The electrical cable extends from the monitoring apparatus 1 to the control panel, and there will be existing data transfer connections between the control panel on the platform and the control panel at ground level. Further transmission beyond this point is most easily by wireless telecommunication methods, in formats including Bluetooth, GSM, MMS, SMS and email. It would thus be possible to transmit data regarding connection or disconnection to a remote device in the control of a responsible person for recording and possible subsequent investigation. Telematics and Internet of Things systems could be employed in this respect.

[0066] The monitoring apparatus 1 indicates by the light whether there is a secure physical connection to the monitoring apparatus 1 and the anchor point. In addition, the output of the monitoring apparatus 1 is connectable to a switch element within the control panel on a platform, and this switch element acts to prevent operation of this control panel to move the platform, by an operator on the platform, unless the monitoring apparatus 1 is indicating that the carabiner or other hook is currently engaged. (Note: the control panel at ground level remains operable, so that the platform can be returned to ground level whether or not an operator on the platform is safely connected to the monitoring apparatus 1).

[0067] Figure 5 shows how the output can be connector to an electrical circuit of the MEWP to operate a relay which in turn can be used to prevent movement of the platform. The switch comprises a 12 Volt automotive relay in this example. Where appropriate a differently rated relay, such as a 24 volt relay, may be used. This will depend on the electrical architecture of the MEWP. The two sides of the coil of the relay are connected respectively to a 12 volt supply and to the output of the inductive loop means. With no connector means inserted in the aperture no current can flow through this coil. The switched ports of the relay are connected in series between a power supply required to power movement of the platform and to the components used to move the platform such as an electric drive motor or throttle actuator of an internal combustion engine.

[0068] When the inductive loop means detects that a harness has been connected, the output is connected to ground allowing current to flow through the coil. This causes the relay switched ports to be connected and power to flow through the relay to the components. The platform can then be moved by the operator in the usual manner. Note that the positive supply for the coil is provided through a foot switch or dead man’s switch labelled e-stop in Figure 5. This is a pedal that must be depressed for the coil to be energised even when the inductive loop output is connected to ground. The overall function of the apparatus is therefore to disable the Deadman’s switch when the operator is not correctly clipped into the apparatus.

[0069] Although direct electrical connections to transmit signals are described above, other communications connections can be used. As well as using wireless telecommunications arrangements in place of some or all of the hard-wired electrical connections set out above, pneumatic, or hydraulic connections can be used. These would be of particular use if the MEWP is intended for use in a flammable atmosphere where electrical arrangements might cause a spark. Mechanical connections to transmit signals are also possible - for example Bowden cables.

[0070] Figures 16 and 17 show two ways in which an indicator- additional to the one on the housing of the monitoring apparatus 21 can be wired so that the light is illuminated when a user is safely clipped in. In Figure 16 power for the indicator light comes from the output side of the relay when the relay is closed, and in Figure 17 is comes from the input coil side of the relay when it is energised. By suitable routing of the wires the indicator of the monitoring apparatus may tap into the electrical circuit this way.

[0071] Figure 4 also shows a typical carabiner 23 suitable for engagement with the aperture 26 of the monitoring apparatus 21, and other monitoring apparatus 1, 11, comprising a frame 29 with an inwardly deflectable spring-loaded gate 30.

[0072] Figures 6a and 6b show a typical safety harness 41 to be worn by an operator working on the platform of a MEWP. The harness 41 comprises a set of woven straps 42 and adjustable buckles to be worn fitting snugly around the torso and abdomen of the operator. A lanyard 43 (in this case comprising a rope or cable) extends from the harness 41 and has a snap-hook or carabiner 45 at its end remote from the harness 41. In conventional harnesses 41, this carabiner 45 would be attached directly to an anchoring point on the platform, but in the present invention, it is attachable to a monitoring apparatus 1, 11, 21, 31 which is in turn attached to an anchor point. In this embodiment, the lanyard 43 is attached to the harness 41 with a loop, snap-hook or carabiner 46 located in the middle of the operator’s back, so as to minimise the chance of the lanyard 43 getting in the operator’s way when working. Also, the lanyard 43 is provided with a doubled portion 44, looped around the carabiner 45 and back on itself, by which the lanyard 43 as a whole can be adjusted in length. Normally, the lanyard 43 is kept as short as possible, consistent with freedom of movement, to ensure that the operator physically cannot fall off the platform (it is always more desirable to prevent a fall than to arrest a fall in progress, as would be a possibility with a longer lanyard. It also helps to keep the lanyard out of the operator’s way. Some lanyards incorporate inertia reel systems to keep the lanyard as short and taut as possible, but it is found that such systems do not always operate satisfactorily when an operator is carrying out all the movements involved in working from a MEWP platform.

[0073] Figures 7, 8 and 9 show features and examples of existing lanyards for safety harnesses 41. Figure 7 shows a typical snap-hook 51 with a hooked frame 49 and a pivotable gate 50 extending across remote ends of the frame 49, deflectable inwardly of the frame 49 to allow passage into its interior, but spring-loaded to close the frame 49 afterwards. The lanyard 52, here a rope or cable, is looped though a separate aperture on the frame 49.

[0074] Figure 8 shows a proprietary lanyard 61 comprising a woven strap 62 instead of a rope or cable. The lanyard 61 is adjustable in length by means of a doubled section 64, looped round a terminal carabiner 46 and held at a desired length with a constricting sleeve 63. The terminal carabiner 46 is suitable for connection to a safety harness 41 as shown in Figure 6b. At a remote end of this particular lanyard 61, there is a proprietary connector 65 comprising a flat profiled tongue 66, which is releasably inserted into a co-operating proprietary socket, locking the connector 65 in place. (For this connector 65, apparatus as shown above could be incorporated into the proprietary socket or mounted around a slot of the socket where the tongue 66 is to be inserted, probably with a change of aperture geometry to conform to that of the socket, rather than the aperture forms shown). Figure 9 shows a versatile lanyard 71 which has a simple oval carabiner 68 at each end, comprising a frame 69 and a spring-loaded gate 70. This lanyard 71 comprises a rope, cable or cord 72, with a doubled section 74 at one end for length adjustment. The doubled section is formed by passing the cord 72 through a slide buckle 73, looping it through the adjacent carabiner 68, and securing the end of the cord 72 to the slide buckle 73.

[0075] Figures 10 to 13 show various forms of carabiner or snap-hook that can be used as connectors for safety harnesses and associated lanyards. Figure 10 shows what is known as a “termination connector” or Class T connector 81, which comprises a frame 79 forming most of a loop, and a spring-loaded gate 80 deflectable inwards of the frame 79 to allow the connector 81 to be engaged with something, but sprung to close the loop again once engagement is complete. There is a separate aperture 84 to receive a lanyard or the like. This form of connector 81 is useful to ensure that loading is in a particular direction.

[0076] Figure 11 shows a “basic” or Class B connector 91. This is a fairly standard carabinertype connector, with a hooked frame 89 forming most of a loop and a spring-loaded gate 90 completing the loop when closed. This particular version has a sleeve on the gate that can be moved to enclose a junction between the frame 89 and the gate 90, thus preventing accidental deflection of the gate 90. Such connectors can also be made with a screw fitting to fasten a moveable end of the gate 100 to a respective end of the frame 99, in place of a simple co-operating hooks arrangement.

[0077] Class B connectors can be used almost anywhere in these systems as long as they have the right load rating.

[0078] Figure 12 shows a “multi-use” or Class M connector 101, which also comprises a hooked frame 99 and a deflectable gate 100 to complete the loop of the connector 101, the gate 100 here being fitted with a fastening arrangement as described above. However, in this Class of connector 101, an interior of the frame 99 is subdivided by a divider element 103 to produce a secondary aperture 104, for example to receive a lanyard. This allows a load to be directed on to major and minor axes of the connector 101 Figure 13 shows an “anchor connector”, also known as a Class A connector or a Selbstschlieconnector 111. This also comprises a hooked frame 109 with a spring- loaded gate 110 to complete an enclosed loop, with a separate aperture 114 that can receive a lanyard. This form of connector 111 has its frame 109 shaped to engage more readily and securely with certain shapes of anchor point.

[0079] Turning now to Figure 14, this shows part of a MEWP platform 121 and examples of suitable anchor points 126, 127. The platform 121 is surrounded with a safety railing or cage 122, made up in conventional fashion from vertical 124 and horizontal 123 railing members. There is a control panel 128 for the platform 121 built into the cage 122, which is here shown with its cover closed for simplicity.

[0080] A first form of anchor point 126 comprises a diagonal strut, welded across a corner where vertical 124 and horizontal 123 railing members meet. This defines a triangular aperture with which a carabiner, snap-hook or other connector on an end of a lanyard can engage. As shown, these first anchor points 126 are best placed midway up the sides of the cage 122, maybe 50cm to 60cm above a floor of the platform. This keeps the lanyard from under the operator’s feet, doesn’t require the operator to bend far to fasten his lanyard to the anchor point 126, and provides a convenient geometry for the lanyard and harness to keep the operator safe within the cage 122.

[0081] A second form of anchor point 127 is also shown. This is a simple continuous metal loop or shackle 127 encircling a vertical railing member 124 and resting on top of a horizontal railing member 123. The carabiner, snap-hook or the like on the end of a lanyard can engage simply and securely with this loop / shackle 127. As with the first anchor points 126 described above, these second anchor points 127 are best located midway up a side of the cage 122.

[0082] Figures 15a and 15b show a second MEWP platform 131 fitted with a third form of anchor point 135. This MEWP platform 131 is also provided with a safety railing or cage 132 made up of vertical 134 and horizontal 133 railing members, with a control panel 138 for the platform 131 built into the cage 132. A foot-operated “dead man’s switch” 139 of conventional form is mounted to a floor 137 of the platform 131 adjacent the control panel 138. The third anchor points 135 comprise sheet steel welded to extend in a vertical plane between a vertical railing member 134 and a horizontal railing member 133, in a corner where they meet, preferably extending downwardly from the horizontal member 133. This anchor point 135 defines a rounded aperture 136, into which the carabiner, snap-hook or other connector from a lanyard can be inserted to engage with the anchor point 135. Again, the third anchor point 135 is best located midway up a side of the cage 132.

[0083] Thus, one of the monitoring apparatus 1, 11, 21, 31 described above can be attached securely to a respective anchoring point 126, 127, 135 on the cage 122, 132 of the respective MEWP platform 121, 131 and operatively connected to the control panel 128, 138 of the platform 121, 131. An operator wearing a safety harness and lanyard can then connect the lanyard to the monitoring apparatus, which will detect the carabiner, snap-hook, etc., of the lanyard and light up the indicator lamp to show that the operator’s harness is securely anchored, and in most variants also allow the operator to operate the control panel to move the platform as desired.

Claims

CLAIMS1. Apparatus for monitoring the correct use of a safety harness connectable to a platform of a Mobile Elevated Work Platform (MEWP) or the like, the apparatus comprising: aperture means adapted to receive connector means of the safety harness engagingly, detector means adapted to detect absence or presence of the connector means engagingly received within the aperture means, the detector means comprising an induction loop means mounted to the aperture means such that an inductance of the induction loop means is altered by the absence or presence of the connector means of the harness within the aperture means; said induction loop means providing an output having a first condition in the presence of the connector means and a second condition which the connector means is absent, said output being fedto an electrical circuit that forms a part of the MEWP such that the mobile elevated work platform is prevented from moving without said connector means being engaged with said aperture means, and in which the apparatus further includes an indicator means the provides a visual cue to an operator that the detection means has detected the connection of the connector means of a harness to the aperture means.

2. Apparatus according to claim 1 comprising a housing that contains the induction loop and a cable that is fixed at one position to the housing and at the other may be secured to the platform of the MEWP.

3. Apparatus according to claim 2 in which the cable comprises a multi-strand flexible steel cable.

4. Apparatus according to claim 2 or claim 3 in which the cable is hollow and an electrical wire passes through the hollow cable at least along a portion of its length starting from the housing, the electrical wire being electrically connected to the induction loop.

5. Apparatus according to claim 4 in which one end of the cable is fixed to the housing by a suitable clamp and extends into the housing, the electrical wireprojecting from this end into the housing such that the clamp grips the cable and the wire to secure them to the housing.

6. Apparatus according to claim 5 in which the electrical wire exits the cable having passed through the clamp on the side opposite the housing and a protective shroud, such as a sleeve of heat shrink material, is provided to cover the location where the wire exits the cable outside of the housing.

7. Apparatus according to any preceding claim in which the output from the inductive loop means is connectable to the mobile platform to prevent that from being driven around a worksite, or prevent the platform being elevated or lowered, or prevent both elevation and driving, without the presence of the connector means in the aperture means.

8. Apparatus according to claim any preceding claim in which the output of the inductive loop means comprises a node at which a voltage is provided that varies between a first level when no connector means is detected to a second different voltage when it is detected.

9. Apparatus according to any preceding claim in which the output of the inductive loop means comprises a node which is held open to present an infinite resistance when no connector is detected, and connected to a ground or earth point when a connector means is detected. When held open no current can flow through a circuit in which the output is connected in series and when closed a current can flow to ground.

10. Apparatus according to any preceding claim in which the output is connected to a switch to open and close the switch as a function of the condition of the output.1 1. Apparatus according to claim 10 in which the switch is a relay, and the output is connected to one side of the low voltage coil of a relay, the other side connected to a supply voltage, the output ports of the relay being normally isolated from each other but being connected to allow current to flow between the ports when the connector means is detected by the inductive loop means.

12. Apparatus according to claim 10 or claim 11 in which the mobile elevated work platform includes a user operable control by which the user commands movement of the platform and the switch selectively disables or enables the function of the user operable control.

13. Apparatus according to claim 12 in which the user operable control is a dead man’s switch operated by a foot of the user.

14. Apparatus according to any preceding claim comprising a housing within which is located the inductive loop means.

15. Apparatus according to claim 14 in which the housing is a clam shell with an upper part and a lower part, each having an opening, the inductive loop means being located inside the shell such that the loop is aligned with the openings, the openings in the housing defining at least a part of the aperture means.

16. Apparatus according to any preceding claim in which includes one or more electrical cables that comprise a first conductor that provides an electrical connection to the output of the inductive loops means, a second conductor that provides electrical power to the inductive loop means, and a third conductor that provides an earth return for the detector means.

17. Apparatus according to any preceding claim in which the indicator means comprises a light such as an incandescent lamp or light emitting diode which is illuminated when an operator is securely connected to the apparatus and is not illuminated at any other time.

18. Apparatus according to claim 17 in which the indicator means comprises a second light that is illuminated when an operator is not securely connected to the apparatus.

19. Apparatus according to any preceding claim which is an integral part of a harness anchor point of a mobile elevated work platform.

20. In combination an apparatus of any preceding claim and an MEWP having a control panel which includes control means for controlling the movement of the MEWP and in which the output of the inductive loop means of the apparatus is connected to the control panel means of the MEWP.

21. A Mobile Elevated Work Platform comprising control means for a platform having a control panel which includes control means for controlling the movement of the MEWP and in which a switch is connected into a power line of the MEWP that supplies power required for movement of at least part of the MEWP, the switch including input terminals connectable to the output of an apparatus of any of the preceding claims such that the power in the line is interrupted when the detector means does not detect that a harness has been connected to the apparatus.

22. A method of modifying a mobile elevating work platform MEWP to improve the safety of operators working at height on MEWPs and the like, comprising the steps of breaking a power line that carries power required to move the platform and reconnecting the two sides of the break to opposing sides of a relay, and subsequently connecting the relay to at least one monitoring apparatus according to any one of claims 1 to 20, mounting said apparatus to anchor points on an elevating platform of a MEWP.

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