APPARATUS

The present invention relates to a work platform for use at elevated work areas and safety restraint apparatus therefor. More particularly it related to a mobile elevated work platform of the kind that is usually fitted to a vehicle and can be raised to access an elevated work area and lowered to allow workers to alight from or mount the platform.

Mobile elevated work platforms (MEWPs) are used to gain access to aerial work areas such, for example, tall buildings, street lighting, trees etc. The platform, often referred to in the field as a "basket", has a floor and perimeter guard rails intended to prevent a worker from moving outside the floor area. The platform is typically mounted on to or towed behind a vehicle on the end of a telescopic arm that can be extended to provide access to a work area and retracted when not in use.

In circumstances where a worker cannot access the work area fully from the basket there is a temptation to step or lean outside the confines of the rails and thus risk falling from a height. In order to prevent such accidents safety standards have been introduced which demand that the worker is fitted with personal safety equipment to prevent falls. Conventionally, workers use a restraint lanyard which is fixed at one end to a harness worn by the worker and at the other end to the guard rails of the basket. Such a lanyard typically comprises a synthetic fibre rope or webbing, wire rope or chain that is of a fixed length. Such an arrangement (often referred to in the trade as a "Work Restraint" system) does not prevent the worker from falling outside of the basket; whilst it should prevent the worker from going beyond the confines of perimeter guard rails, in practice the location of the anchorage points and the length of the lanyards used means that there are areas where the user will be able to go beyond the rails and a fall is possible.

Lanyards of the kind referred to above can often be too long and tend to trail on the floor of basket where they are a tripping hazard. Shorter lengths are available as are adjustable lengths but they still tend to be a tripping hazard or hinder the user's working efficiency. Moreover, such lanyards do not incorporate fall arrest devices that

serve to arrest the descent of a worker in the event of a fall. The lack of energy absorbing capacity in such lanyards means that if a fall does occur the potential load applied to the MEWP, and in particular the arm, will exceed its load specification. This can result in the arm swaying or bending dangerously such that the faller bounces up and down and risks collision with surrounding structures. It can even carry the risk of the MEWP vehicle toppling over, particularly if the arm is extended to its full vertical height.

Fall arrest lanyards incorporate energy absorbers that are commonly in the form of overlapping layers of webbing that, in the event of a predetermined tensile force being applied to them, serve to absorb the energy of the fall through overcoming friction or stitching between them. Whilst this can reduce the impact of the fall it does not counter all of the disadvantages referred to above. In particular, the impact force can be up to 6kN and deployment of shock absorbing material will increase the clearance height required and therefore the device has to be located in an overhead position. The use of inertia reel type fall arrest devices is known but they are not suitable for use in MEWP baskets as they require anchorages above the user in order to limit the force and the fall distance. Generally there is no suitable structure in the basket to allow the device to be located above head height. The nature of these devices is such that they do not restrict the movement of a user in order to prevent falls but are rather intended to arrest those falls.

It is an object of the present invention to obviate or mitigate the aforesaid disadvantages.

According to a first aspect of the present invention there is provided a work platform for use at elevated locations comprising a floor surrounded by perimeter guard rails and safety restraint apparatus, the apparatus comprising at least one retractable elongate flexible element having a first end secured to a mounting on the platform and a second end with a connector for connection to a harness of a user, the safety restraint apparatus being configured to prevent a user moving outside the guard rails.

The use of a retractable elongate flexible element ensures that the it does not trail on the floor or otherwise hinder the user but still serves as a work restraint.

The mounting is preferably disposed at or below the height of the rails above the floor.

The safety restraint apparatus is preferably configured such that the elongate flexible element has a maximum length that does not exceed the distance between the mounting and the perimeter rail in any direction. Alternatively, the restraint apparatus may comprise two elongate flexible elements for connection to the same user, the elongate flexible elements being connected to mountings at opposed locations at or adjacent to the rails.

The mounting may be disposed in the centre of the platform. The mounting may comprise a bracket fixed to floor and may comprise a member that extends above or below the floor with the first end of the elongate flexible element being connected to said member. The member may be an upright.

The mounting may have a swivel connection to ensure that the elongate flexible element is correctly oriented with respect to a user.

The elongate flexible element is ideally retractable into a housing that is connected to said mounting in which case the housing may be connected such that it can swivel relative to the mounting.

The first end of the elongate flexible element is preferably wound around a rotary reel which may be rotatably mounted in a cassette. The cassette is ideally disposed in the housing which has an aperture through which the elongate flexible element egresses.

The reel is ideally biased to rotate in one direction so as to retract the elongate flexible element.

There may be provided a roller at or adjacent to the housing aperture, the roller serving to prevent twisting of the elongate flexible element and to ensure that it is paid out in the correct direction. The platform may be connected to an extensible arm. The platform and arm are preferably mobile and may be connected to a vehicle for this purpose.

The elongate flexible element is preferably webbing or cable.

It is to be understood that the safety restraint apparatus may comprise more than one elongate flexible element, one being provided for each potential occupant. The capacity of the work platform will determine the number of elements required.

Specific embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure l is a perspective view of safety restraint apparatus forming part of the present invention;

Figure 2 is a schematic side view of a work platform according to the present invention showing three different mounting positions for the safety restraint apparatus of figure 1 ;

Figure 3 is a plan view of a work platform of the present invention fitted with safety restraint apparatus of the present invention and illustrating the operating range; and

Figure 4 is a plan view of a work platform of the present invention fitted with two safety restraint apparatuses of the present invention and illustrating the respective operating ranges.

Referring now to figure 1, there is shown safety restraint apparatus 10 for use in the present invention. It comprises an elongate length of retractable synthetic webbing 11 of conventional design that is stowed on a rotary reel 12 of a cassette 13 within a housing 14. A first end 15 of the webbing 11 extends from the periphery of the reel 12 out of an aperture 16 in the housing 14 and has a karabiner 17 at one end that is connectable, in use, to a harness of a user (not shown).

A second end of the webbing 11 is fixed to and wound around the reel 12. In use the webbing 11 is extended out of the housing 14 by pulling on the second end so as to rotate the reel 12 and to unwind the webbing from the reel 12. The reel 12 is biased to rotate in the opposite direction by a torsion spring or the like so as to retract the webbing 11 into the housing 14 when no opposing force is applied so as to assume the stowed configuration. It also has a centrifugal based locking system, of the kind found in the seatbelt cassette in a vehicle, that prevents sudden rotational acceleration of the reel and therefore rapid pay out of the webbing 11. A cassette of this kind is

available from Spanset Limited and is used exclusively in fall arrest devices. Turning now to figure 2, the safety apparatus 10 is shown in three alternative positions A, B and C on a work platform 20. In use, the platform 20 is mounted on the end of a telescopic arm on a vehicle (neither the arm nor the vehicle are shown in the figures) such that it can be selectively raised towards an elevated work area or lowered towards the vehicle. The platform 20 is in the form of a basket comprising a floor 21 and perimeter rails 22 that are designed to prevent a worker moving out of the basket when in an elevated position. Access to the basket is provided by a gate G in the rails that is lockable in a closed position when the platform 20 is in use. hi each case the safety restraint cassette 13 is fitted with a roller 23 adjacent to the housing aperture 16. The roller 23 serves to ensure that the webbing 11 pays out in the correct direction and does not become twisted during retraction.

In position A the retractable safety restraint apparatus 10 is mounted to the underside of the floor 21 by a mounting bracket 24 that comprises a base 25 bolted to the floor 21 and an upright member 26. A rear wall 27 of the cassette housing 14 is fixed to upright member 26 of the bracket 24 and the webbing 11 passes upwards through a gap in the floor 21 to be connected by the karabiner 17 to a harness worn by the user. As the user walks away from the cassette 13 the webbing 11 pays out and as he/she moves towards the cassette 13 the webbing 11 retracts back into the housing 14 so that it does not present a tripping hazard or other hindrance to the user. The webbing 11 is of a predetermined length such that it does not allow the user to move outside of the rails 22 or outside of a predefined safe working zone.

In an alternative position B the base 25' of the bracket 24' is bolted to the topside of the floor 21 and the upright member 26', which is longer than that of the bracket of position A, supports the cassette housing 14' of the safety restraint apparatus 10' with the aperture in the housing 14' facing the floor.

The arrangement of position C shows a high-level mounting bracket 24" that is fixed to the floor 21 in the same way as the arrangement of position B. In this embodiment the upright member 26" is significantly longer than that of the previous embodiments and the cassette housing 14" is fixed at the top of the upright member 26".

The mounting bracket is the attachment point on the structure of the platform to which the user can connect in that it provides the mounting point for the cassette housing 14.

In each case the lateral position of the safety restraint apparatus 10 within the basket is for illustrative purposes only and it will be appreciated that it may be positioned at any convenient location, but typically in the centre of the basket. In general, where the basket is to be occupied by a single worker the bracket is mounted centrally so as to provide an operating range as illustrated in figure 3. The maximum pay out length of the webbing 11 is designed so as to restrain the worker from moving outside the perimeter of the floor 21. In an alternative configuration illustrated in figure 4, the basket is occupied by two workers each with a separate retractable restraint apparatus 10a and 10b. Here the brackets 24a and 24b are spaced from the centre of the basket such that the operating range of each worker is confined to only one side of the basket with just a small area of overlap between the respective ranges as shown by the circles.

The upright member 26 of the bracket 24 may have a swivel design so that the cassette 13 is always suitably oriented as the worker moves around the basket.

It will be appreciated that any suitable arrangement of safety restraint apparatus may be used. For example two separate restraints may be disposed at opposed spaced locations at the perimeter of the basket and each connected to the same harness of the user. Moreover, the webbing may be replaced by any form of suitable elongate flexible element such as a cable or chain etc.

The safety restraint apparatus design of the present invention can be "retrofitted" to existing MEWPs or may be incorporated as standard as part of the original design and construction by the MEWP manufacturer. The cassette 13 is removable from the mounting bracket 24 so that it is interchangeable with other cassettes offering different webbing lengths. The cassettes and/or the housings may be colour-coded and/or labelled to indicate the webbing length.

It is to be understood that the centrifugal locking system is not essential to the restriction of movement of the user as the ultimate length of the webbing, when fully extended, is the determining factor in preventing the user go beyond the limit of the

perimeter guard rail. The locking system is an optional feature that has the benefit of restricting the travel of the user in the event of unintentional or unexpected movement of the MEWP.