Anchor point interlock

Abstract

A Mobile Elevated Work Platform (MEWP) comprises a platform (6) with at least one anchor point (20) integral to the platform, the anchor point including an aperture means (23) adapted to receive a connector means (101) of the safety harness (41) engagingly. An induction loop detect absence or presence of the connector. The induction loop provides 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. An indicator (11) such as a light is provided as 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. The integral induction loop may be located in a housing (21) that is integral to the platform and can bear the weight of an operator falling from the platform.

Description

[0001] ANCHOR POINT INTERLOCK

[0002] The present invention relates to mobile elevated work platforms and to platforms that include apparatus to monitor the attachment of safety harness to an anchor point and the like.

[0003] It is clearly highly desirable for those working at height on Mobile Elevated Work Platforms (MEWPs) to be protected from falls. Within this the document the term Mobile Elevated Work Platform encompasses boom type elevated platforms and scissor lift platforms. It also is intended to cover any other apparatus that includes a movable platform on which an operator can stand in order to perform a work function at an elevated height such as inspection, repair, installation, dismantling or other work roles. The MEWP may be able to drive over a surface under its own power or may be manually movable by an operator to allow the platform to be positioned close to where the work is to be performed. 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 MWEP 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 a Mobile Elevated Work Platform (MEWP) comprising: a platform which can be raised and lowered and supports an operator; at least one anchor point integral to the platform, the anchor point including an 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 mobile elevated work platform further includes an indicator means that 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] The anchor point may include a separate housing part that contains the induction loop and which is integral to the platform. The housing may be configured to withstand the full load of an operator falling from the platform that is secured to the anchor through a suitable fall arrest system, e.g. a harness and a lanyard.

[0015] A load bearing member may be provided within the housing which is secured to the platform and which is configured to withstand the forces in the event of an operator falling. This allows the housing to be a non structural part of the anchor point.

[0016] The load bearing member may comprise a ring or bar, such as a metal ring. This metal ring may be circular and concentric with the aperture means and the inductive loop means.

[0017] The housing may include a lid that can be removed to allow access to the inductive ring within the housing. The anchor point may be secured to a fixed part of the platform through one or more fastenings such as welds, bolts, rivets or adhesive patches. Alternatively the anchor point may be thread onto a fixed part of the platform so that it is held captive.

[0018] The platform may comprise a floor and set of railings that extend above the floor of the platform and the anchor point may be secured to the railing or may be a part of a rail or post of the railing.

[0019] For example where a railing is an elongate bar the anchor point may be formed by providing a through opening in the bar that forms the aperture means with a void provided within the bar to accommodate the inductive ring. Alternatively a housing for the inductive ring that includes the aperture means may be secured to the elongate bar.

[0020] The platform may include a panel that is secured to the railing and the housing may be secured to the panel or may form a part of the panel.

[0021] 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.

[0022] 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 non-zero voltage. This may be fed into a electrical circuit of the platform that comprises an electronic control unit.

[0023] 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. 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.

[0031] 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.

[0032] Alternatively, the indicator means may comprise a second light that is illuminated when an operator is not securely connected to the apparatus.

[0033] The second light may always illuminate when the apparatus is connected to the MEWP.

[0034] 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.

[0035] Of course, a power source could be provided such as a rechargeable battery.

[0036] The light may be switched on and off by connecting the light to the output of the inductive loop means.

[0037] The platform could then be employable in a zone potentially having a flammable or explosible atmosphere.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] The MEWP may include 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.

[0042] The indicator means may form a part of the control panel. The indicator means may comprise a light at each anchor point that has a monitoring means and additionally a respective light for each anchor point at the control panel. The lights may be overlaid on a graphical representation of the platform so that an operator can identify which anchor point has been properly used to tie off a worker to the platform.

[0043] 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.

[0044] 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.

[0045] The Mobile Elevated Work Platform may include 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.

[0046] The MEWP may include N anchor points, where N is an integer greater than one, each including an 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. The MEWP may include a selector that can be set to indicate a number M of operators where M is an integer less than or equal to N and the MEWP may include a checking means that monitors the outputs of the N anchor points to determine if M of the anchor points are providing outputs having the second condition. This provides a check that the expected number of operators are all tie onto the platform.

[0047] The checking means may comprise a solid-state logic circuit or a microprocessor.

[0048] The selector may be lockable in position from outside of the platform or inside of the platform. A key operated lock may be provided which must be unlocked by a complimentary key to enable the selector to be altered. This would allow a person responsible for Health and safety set a required number of operators for the platform according to a task to be performed or according to conditions such as weather or the firmness of the ground or where additional materials are to be carried by the platform that may limit the total weight of operators that can be safely raised.

[0049] The selector may be configured such that it may be set remotely, for instance over a wireless connection.

[0050] Instead of a physical key the selector may be locked using an electronic lock such as a keypad or on receipt of a digital lock or unlock code received over a wireless network from a remote device.

[0051] The MEWP may be configured such that the platform cannot be raised if the number of anchor points outputting a signal having a second condition does not match the number set by the selector.

[0052] Embodiments of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings, in which:

[0053] Figure 1 is a view of an embodiment of a mobile elevated platform which falls within the scope of the first aspect of the invention; Figure 2 is a view of the platform of the MEWP of Figure 1 showing the location of a pair of anchor points and a control panel;

[0054] Figure 3 is an enlarged view of an anchor point which forms a part of a monitoring apparatus of the MEWP;

[0055] Figure 4 is an exploded view of the anchor point of Figure 3 showing the inductive loop that is located with the outer housing of the anchor point;

[0056] Figure 5 is a circuit diagram of a suitable inductive loop means of the anchor point and the connections of the inductive loop to and from an external circuit including an indicator light;

[0057] Figure 6 is a circuit diagram showing the connection of the inductive loop means to the control circuit of the MEWP;

[0058] Figure 7a and 7b are frontal and rear elevations respectively of a safety harness and lanyard for use in the present invention;

[0059] Figure 8 is a scrap perspective view of a snap-hook connectable to any of the monitoring apparatus of the present invention, mounted to a lanyard;

[0060] Figure 9 is a perspective view of a lanyard for use with the safety harness of Figures 7a and 7b, fitted with a proprietary connector;

[0061] Figure 10 is a perspective view of an adjustable lanyard for use in the present invention, fitted with two carabiners;

[0062] Figures 11 to 14 are elevations of four existing carabiners and snap-hooks usable with the monitoring apparatus of the present invention;

[0063] Figure 15 is a perspective view of an alternative anchor point that can be used in the MEWP of Figure 1, Figure 16 is a perspective view of another alternative anchor point that can be used in the MEWP of Figure 1;

[0064] Figure 17 shows an alternative arrangement of the electrical circuit that illuminates the indicator,

[0065] Figure 18 shows an alternative embodiment of a Mobile Elevated Work platform in accordance with the invention; and

[0066] Figure 19 shows an alternative arrangement of the electrical circuit that includes a selector for selecting the number of occupants on the platform.

[0067] Referring now to the Figures of the accompanying drawings, Figure 1 shows a mobile elevated work platform (MEWP) 1 in accordance with the invention. The MEWP in this example is a boom type platform having a wheeled base unit 2 mounted on a chassis 3 and a set of four wheels 4. A traction unit such as a diesel engine or electric motor and battery is located in the base unit 2 and drives at least one of the wheels. One pair of wheels can be steered through an actuator acting on a steering rack (not shown). The main body 2 supports a boom 5 that can be extended and retracted, and whose angle relative to the horizontal can be adjusted. Attached to the end of the boom distal from the base unit 2 is a platform 6 which is sized to support one or more operators.

[0068] The platform 6 is shown in more detail in Figure 2. It comprises a base or floor 7 surrounded by a protective railing 8 having vertical posts and horizontal rails. A control panel 9 is fixed to the railings and provides controls that enable an operator to start and stop the traction unit, move the MWEP around relative to the ground and to raise and lower the platform by altering the length and angle of the boom. As shown the controls include a joystick 10 and a stop / start button 11. A light 12 is also included which forms part of a monitoring apparatus as explained hereinafter.

[0069] Fixed to the platform railing are a pair of anchor points 20, a so called tie down loop. In practice the platform 6 may have more than two anchor points each having the same characteristics. The anchor point 20 is specifically designed to be able to resist the loads that may be applied in the event of an operator falling from the platform when the operator is attached to the anchor point through 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). The anchor points are best placed midway up the sides of the railings, 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 20, and provides a convenient geometry for the lanyard and harness to keep the operator safe within the railings of the platform

[0070] One anchor point 20 of the embodiment of Figure 1 is shown in more detail in the scrap view of Figure 3 and comprises a ring shaped housing 21 which in this example is in the form of a clam shell that has two half clams that fix around an indicative sensor ring 22. The ring 22 is shown outside of the housing 21 in the exploded view of Figure 4. One part of the clam shell housing is fixed to the railing through welds or using bolts so that the anchor point forms an integral part of the platform 6. The other part is releasably fixed to the other shell to form a secure a watertight enclosure for the sensor ring. The two parts of the clamshell 21 when connected form a donut shape that together enclose its operative components in a closed configuration The shell and the hole at the centre define an aperture means in the form of circular aperture 23 extending through the shell, 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 anchor point and thence to the MEWP platform. Because the inductive ring in this example is concentric with the aperture means the connector means when fitted will also pass through the inductive ring and will be detected as a change in inductance of the inductive ring.

[0071] 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.

[0072] Figures 6, 7 and 8 show features and examples of existing lanyards for safety harnesses 41. Figure 6 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.

[0073] Figure 7 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 5b. 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).

[0074] Figure 8 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 9 to 12 show various forms of carabiner or snap-hook that can be used as connectors for safety harnesses and associated lanyards. Figure 9 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 10 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 11 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

[0079] Figure 12 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. The anchor point of the MEWP, unlike a convention passive anchor point, provides a monitoring function 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.

[0080] The output of the indictive ring is fed along an electrical wire. Figure 5 is an electrical circuit diagram showing the connections to the ports of the inductive loop means 22, these ports being connected to respective conductors or a multi-core electrical cable. 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. The output is used to activate the indicator lamp 11 of the control panel to confirm safe engagement.

[0081] Figure 5 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.

[0082] 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.

[0083] 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).

[0084] Figure 6 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.

[0085] When the inductive loop means detects that a harness has been connected to the anchor point, 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.

[0086] Note that the positive supply for the coil is provided through a foot switch or dead man’s switch labelled e-stop in Figure 6. 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.

[0087] In Figure 6 the power for the indicator light comes from the input coil side of the relay when it is energised power for the indicator light comes from the output side of the relay when the relay is closed. In an alternative arrangement shown in Figure 17 the power for the indicator light 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. 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.

[0088] Figures 15and 16 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.

[0089] The anchor points 29 shown in the embodiment of Figure 2 has the form of donut but other shapes of anchor point can be provided in accordance with the invention, One alternative form of anchor point 120 is shown in Figure 15 and comprises a diagonal strut, welded across a corner where vertical and horizontal railing members of the railing meet. The diagonal strut and vertical and horizontal portions of the railing define a triangular aperture means withing which a carabiner, snap-hook or other connector on an end of a lanyard can engage. An inductive sensor of a complimentary shape or a ring as shown in Figure 15 may be housed within the triangle formed by the strut and vertical can be horizontal members. The strut provides the required strength. The whole strut and inductive ring may be covered by a protective housing which does not need itself to be structural.

[0090] In a further arrangement shown in Figure 16 an anchor point 220 may comprise a continuous metal loop or shackle encircling a vertical railing member of the railing and resting on top of a horizontal railing member. This loop or shackle forms and aperture means with which a carabiner, snap-hook or the like on the end of a lanyard can engage simply and securely. As with the first anchor points described above, these anchor points are best located midway up a side of the railings. The loop may be hollow to define a void which can contain an inductive sensor ring, and a wired connection or wireless connection will be made from the inductive sensor out to the controls of the MWEP. In the case of a mobile elevated work platform that has more than one anchor point, such as a platform having two as shown in Figure 1, a selector may be provided that can be set to indicate a number M of operators where M is an integer less than or equal the number of anchor points and also include a checking means that monitors the outputs of the anchor points to determine if M of the anchor points are providing outputs having the second condition. This provides a check that the expected number of operators as set using the selector are all tied onto the platform.

[0091] Figure 19 shows an electronic circuit 100 that includes a selector and checking means. In this example the selector comprises a two position switch 101. When in the first position the interrupt signal must flow through only one relay 103 so that the circuit operates in the manner of Figure 6, but in the second position it must pass through two relays 103, 104 which both need to be closed to operate the MEWP. The two relays 103, 104 in series provide a logical AND function, so that they work together as the checking means. Of course, other arrangements can be provided within the scope of this invention.

[0092] The selector 101 in Figure 19 includes an optional lock 105 that enables the selector to be locked in a selection position from outside of the platform or inside of the platform. This must be unlocked by a complimentary key, or entering a code into a code pad, to enable the selector 101 to be altered. This allows a person responsible for Health and safety set a required number of operators for the platform according to a task to be performed or according to conditions such as weather or the firmness of the ground or where additional materials are to be carried by the platform that may limit the total weight of operators that can be safely raised.

[0093] Whilst the example of Figure 1 shows a boom type lifting platform the invention may be embodied in a variety of different types of mobile elevated work platform. Figure 18 shows a scissor lift platform 1001 that a platform 1006 that is raised and lowered by a scissors linkage 1005 instead of a telescopic boom.

Claims

CLAIMS1. A Mobile Elevated Work Platform (MEWP) comprising: a platform which can be raised and lowered and supports an operator; at least one anchor point integral to the platform, the anchor point including an 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 mobile elevated work platform further includes an indicator means that 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. A mobile elevated work platform according to claim lin which the anchor point includes a separate housing part that contains the induction loop and which is integral to the platform configured to withstand the full load of an operator falling from the platform that is secured to the anchor through a suitable fall arrest system.

3. A mobile elevated work platform according to claim 1 in which the anchor point includes a separate housing part that contains the induction loop and a load bearing member is provided within the housing which is secured to the platform and which is configured to withstand the forces in the event of an operator falling.

4. A mobile elevated work platform according to claim 1, 2 or 3 in which the anchor point is secured to a fixed part of the platform through one or more fastenings.

5. A mobile elevated work platform according to any preceding claim in which the indicator means comprises a light which is illuminated when an operator is securely connected to the apparatus and is not illuminated at any other time.

6. A mobile elevated work platform according to any preceding claim including 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 anchor point is connected to the control panel means of the MEWP.

7. A mobile elevated work platform according to claim 6 in which the indicator means comprises a light at each anchor point that has a monitoring means and additionally a respective light for each anchor point at the control panel.

8. A mobile elevated work platform according to any preceding claim that comprises N anchor points, where N is an integer greater than one, each including an 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.

9. A mobile elevated work platform according to claim 8 including a selector that can be set to indicate a number M of operators where M is an integer less than or equal to N and the MEWP and a checking means that monitors the outputs of the N anchor points to determine if M of the anchor points are providing outputs having the second condition.

10. A mobile elevated work platform according to claim 9 in which the checking means comprises a solid-state logic circuit or a microprocessor.1 1. A mobile elevated work platform according to claim 8, 9 or 10 in which the selector is lockable in position from outside of the platform or inside of the platform.

12. A mobile elevated work platform according to claim 1 1 in which a key operated lock is provided which must be unlocked by a complimentary key to enable the selector to be altered.

13. A mobile elevated work platform according to any one of claims 8 to 12 in which the selector is configured such that it may be set remotely.

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