WO2010128340A2

WO2010128340A2 - Fall prevention system and access ladder

Info

Publication number: WO2010128340A2
Application number: PCT/GB2010/050758
Authority: WO
Inventors: Stuart Arnold
Original assignee: Stuart Arnold
Priority date: 2009-05-08
Filing date: 2010-05-10
Publication date: 2010-11-11
Also published as: GB2471541A; GB201007763D0; GB2508116B; GB2508116A; GB0907949D0; GB201403529D0; GB2471541B; WO2010128340A3

Abstract

A fall prevention system for guarding at least one side of a platform (1) has a stowed state and a deployed state and comprises a first member (5) and a second member, an elongate flexible element (12) and a tensioner (22) for tensioning the said elongate flexible element (12). A ladder unit (11) comprises a ladder having a pair of spaced apart side members (52) and a plurality of rungs (61B) extending therebetween, and a ladder mount (41) which includes a bracket (43) attachable to an object, a pair of spaced apart ladder supports each pivotally mounted on the ladder mount and configured to receive a side member of the ladder (11) such that said side members may slide in the ladder support, and a securing means (50) to secure the ladder in a fixed position with respect to the ladder mount.

Description

FALL PREVENTION SYSTEM AND ACCESS LADDER

Field of the Invention

The present invention relates to a fall prevention system and an access ladder, in particular to a fall prevention system and access ladder for vehicles such as commercial vehicles.

Background of the Invention

Vehicles are used to transport goods from place to place. The load carrying platforms of commercial vehicles in particular are positioned at such a height that if an operator working on the platform were to fall off, he may well be injured, perhaps seriously. It has therefore been identified that vehicles should either be able to be loaded and unloaded without an operator being required to climb onto the load carrying platforms of such vehicles, or walk on and off the platform from/to a surface lying at substantially the same level as the load carrying platform. Where it is economic to do so, this is what happens. For example, curtain sided vehicles are generally loaded in palletised form, from the ground, using forklift trucks. Flatbed trucks are often load at factories in loading bays, the surfaces of which lie substantially at the same level as that of the flat bed of the truck.

However, there are circumstances where it is not practical to load and unload goods in a palletised form or to provide a loading bay. Elongate objects, such as pipes are a good example. As a rule they are often too large in both dimension and weight to palletise, and hence are typically loaded onto a vehicle where they are held in place by upstanding posts by means of a crane which may lift the pipes over the top of the posts (or alternatively the posts may be removed during loading).

In such a scenario, an operator would usually climb onto the working platform of the vehicle to position the pipes as they are lowered by the crane. Working in such conditions presents a danger to the operator. He may lose his footing, or be pushed by a swinging pipe that he is attempting to control, or simply mis-judge his position with respect to the edge of the trailer, any of which could result in a fall.

It is often the case that goods are delivered to locations where the construction of docking bays for loading/ unloading is simply not economically feasible.

It is evident that operators will continue to need to work at height, i.e. on the working platform. Hence, there is a need for a fall prevention system.

Attempts have been made to provide vehicles with fall prevention systems. Once such system comprises a set of inflatable mattresses deployed around the vehicle, their purpose being to cushion the fall of an operator from the vehicle. These systems are time consuming to deploy and put away and do not actually prevent a fall. The operator may still be injured in the event of a fall.

Another system comprises portable staging which is brought to a site to provide a temporary docking facility so that the operator may walk on and off the vehicle at a substantially similar level. However, such portable staging must be brought to a site, occupies space at the site, and adds to the logistical demands presented by the transportation of goods, and in many cases cannot be justified economically unless a significant number of deliveries are to be made.

Another system comprises a lanyard attached at one end to the vehicle and the other to the operator. Typically, the lanyard is attached to an inertia reel so that the operator may move about, drawing the lanyard off the reel, but if he were to begin to fall the increase in acceleration would cause the inertia reel to prevent the further release of the lanyard. Whilst such a system offers an operator a level of protection from falling, it would not prevent falls in all circumstances. This will depend on the operator's position on the vehicle relative to the attachment point of the inertia reel to the vehicle. On curtain sided vehicles a mono-rail is provided along each edge of the vehicle to overcome the afore-mentioned problem, but this would not work with a flatbed trailer. Another system for preventing falls involves attaching balustrade to the sides of the vehicle, so that if an operator on the vehicle were to fall, he would be caught by the balustrade and prevented from falling.

One system which claims to overcome the problems associated with the aforementioned systems is described in the patent application published under number WO 2008/117065. This patent application describes a combination of a load bed and a platform for a trailer. The platform is moveable between stowed and deployed positions. In the stowed position the platform is situated beneath the trailer bed, and in the deployed position the platform extends alongside the trailer bed, thereby providing a walk way. A balustrade is provided along the outside edge of the platform.

Whilst the system described in WO2008/117065 may be regarded as an advance on the prior art, it does present its own problems. First, it is heavy. Commercial vehicles have a maximum laden weight. Every additional unit of weight taken up by the vehicle is a unit of weight that cannot be added as payload. Since haulage operators tend to charge for their services according to the weight of goods that they carry, reducing the carrying capacity of a vehicle would make using such a vehicle undesirable. Also, commercial vehicles work in harsh environments where they are often hit either by the payload that is being loaded or unloaded or by the vehicle that is doing loading or unloading, or simply by the driver of the vehicle misjudging the position of an object and crashing into it, or forgetting that the platform is in the deployed condition and therefore hitting an object that had been missed when the platform was stowed. In the event that the platform is damaged when deployed it may not be possible to return the platform to its stowed position. The likely result of this is that the vehicle would not be able to travel on the public highway because it would be over the width permitted by law. A fitter would have to be sent to repair the system.

Whilst commercial vehicles present a risk of falling from a height, there are other situations also presenting a risk of falling from height. For example some large machine tools have a bed that is raised above the ground, and which workers must gain access to. Also, certain categories of plant include a platform which workers must gain access to and which is raised a significant height above ground level.

It would therefore be desirable to provide an improved fall prevention system. The present invention seeks to provide such an improved fall prevention system that removes or at least alleviates some of the problems identified above. Such a system would have application in the field of vehicles and other areas where a raised platforms are used and access to the platform is needed.

Another problem associated with access to vehicles, in particular commercial vehicles is the provision of a means of access to the working platform from ground level. Sometimes an operator will haul himself up on to the platform without aid, or he may climb up one of the wheels, or a ladder may be provided. The present invention concerns the provision of ladders.

Where ladders are provided with vehicles it is often the case that they are not physically attached to the vehicle. This gives rise to a number of results: First, the operator must retrieve the ladder from its stowed position, usually a locker of some description, and position it with respect to the vehicle, which may either be a position that the operator perceives as being suitable or a position designated by the designer of the vehicle. This takes time. The time taken to load, unload and haul loads is one determining factor in the economic viability of haulage operations. Hence, anything which increases loading and unloading times is detrimental to business of a haulage operator. Second, the ladder may easily be forgotten by the operator or removed by a passer by. When a driver arrives at another job, he may find the ladder missing, preventing or delaying him in loading/ unloading.

Another problem associated with the ladders described above is that health and safety guidance calls for such ladders to be "footed", meaning that whilst one person climbs up or down the ladder, another is holding the foot of the ladder in place. Such guidance is not necessarily limited to commercial vehicles and may apply to other situations where ladders are used. This additional personnel requirement adds costs to haulage operations or other activity where the platform is not part of a vehicle, or if the second person is not present potentially puts the person climbing the ladder at risk.

Some vehicles are provided with a fixed ladder extending substantially vertically. When a vehicle is loaded the height of the platform above the wheels and hence the ground supporting the wheels is reduced. For every day commercial vehicle operations this is not such a concern since the relative distance moved is not great. However, in special operations, such as the transport of crane ballast weights, the vehicle payloads are so great that the platform may fall through 300 mm during loading. A fixed ladder may engage the ground and buckle, or be positioned such that it is in danger of hitting objects that it would otherwise have missed.

It would therefore be desirable to provide an improved ladder, in particular for accessing platforms and in particular platforms of commercial vehicles.

Summary of the Invention

According to a first aspect of the invention there is provided a fall restraint system comprising a first member and a second member, an elongate flexible element and a tensioner for tensioning the said elongate flexible element, wherein the said element extends between the first and second members, and wherein at least one of the first and second members provides an elongate flexible element support, said element engaging the support.

The first and second members may comprise posts which may be located in brackets, and are preferably removably mounted in said brackets.

Preferably, the support is a pulley wheel.

It is preferred that the elongate flexible element extends back and forth between the first and second members. In order to facilitate this, supports are attached to the first and second members at a number of selected positions. Advantageously, the pulley wheels are mounted in brackets which may be removably attachable to the first and/or second members. Preferably, the brackets include an open end and extend beyond the edge of the pulley wheel.

In one embodiment of the invention, the bracket includes a return which passes over the surface of the pulley wheel that is configured to support the elongate flexible element.

Depending on the distance between the first and second members, it may be desirable to provide additional members therebetween, those members mounting at least one support with which the elongate flexible elements may engage. Such members may be in the form of posts and may be removably mounted in brackets.

Advantageously, the elongate flexible element is attached to a reel. This facilitates winding in and out of the elongate flexible element. The reel may form part of a winch. The winch or a part thereof may form the tensioner.

The reel may be mounted on one of the first and second members. Preferably, the member mounting the reel includes a plurality of supports oriented such that when the elongate flexible element passes over the supports it is caused to change direction. In one embodiment, the elongate flexible element passes over two supports each causing the said element to change direction through approximately 90 degrees.

The elongate flexible element may be rope, for example wire rope, or a wire.

The free end of the elongate flexible element is advantageously provided with an attachment means, such as a hook or a clip. Preferably, one of the first and second members is provided with a corresponding attachment means, such as a bracket or an eyelet to which the attachment means of the elongate flexible element may attach.

The fall restraint system may also include a pole which may be used by an operator to deploy or stow the fall restraint system from the ground. The pole is advantageously provided with a hook which in use engages with the elongate flexible element and allows the operator to position the said element where he desires.

Where the fall restraint system is provided on a vehicle, head and tail boards may also be provided. The head and tail boards may be formed of solid elements, such as steel bars.

Advantageously, the fall restraint system may have a deployed state and a stowed state and be moveable between the two said states. The system may include additional supports and/or attachment means to secure the elongate flexible element in a desired position, i.e. the stowed condition. In one embodiment a support is provided to towards the base one of the first and second members and an attachment means, such as a bracket or a hook or an eyelet is attached to the other. In the stowed condition the free end of the elongate element is attached to the attachment means and passes around the said support and is then tensioned by the tensioner.

In one particular embodiment where the fall restraint system forms part of a vehicle and it is desirable that the elongate flexible element should not be above the load carrying surface when stowed, notches may be provided to receive the elongate flexible element in parts of the vehicle that would otherwise be fouled by the said elongate flexible element.

The fall restraint system of the invention is particularly advantageous because it may be switched between its stowed and deployed states very easily and quickly, and furthermore this may be done by the operator from the ground using the above-mentioned pole. Further, the parts of the system are comparatively light in weight. Still further, much of the system can either withstand minor knocks or easily be replaced in the event of such a knock. For example, if the load carried by a crane were to engage with the elongate flexible element, there would be one of three outcomes: the element may stretch and return to its original size; stretch but not return to its original size, in which case the element may be wound in further on the reel or further tensioned; or the element may break. In the worst case scenario of a break in the element, the operator may repair the element, with a repair kit, or by fashioning a temporary repair, or just return to base with the element broken. With the other parts of the system, a knock resulting in something becoming bent would not as a rule prevent the vehicle from being moved on the road.

Still further, any posts arranged to support the elongate flexible element between the first and second members may be removed quickly and easily from the ground to facilitate loading and unloading.

The fall restraint system may be used to protect an edge of any length or any width, with the elongate flexible member passing back and forth at almost any desired spacing. All that is required is for supports (typically pulley wheels) to be suitably positioned and the elongate flexible element to be of sufficient length.

According to a second aspect of the invention there is provided a ladder unit comprising a ladder having a pair of spaced apart side members and a plurality of rungs extending therebetween, and a ladder mount, the ladder mount including a bracket attachable to an object, a pair of spaced apart ladder supports each pivotally mounted on the ladder mount and configured to receive a side member of the ladder such that said side member may slide in the ladder support, and a securing means to secure the ladder in a fixed position with respect to the ladder mount.

The spaced apart ladder supports are preferably mounted on to the ladder mount by two pairs of spaced apart levers, one pair of levers pivotally attached to each ladder support and the ladder mount. Together the levers, the ladder support and the part of the ladder mount form a parallelogram linkage.

Preferably, the ladder mount includes upright members, and the pairs of levers may each be attached to an upright member. The upright members may mount a locking member and a securing means. In one embodiment a locking means is mounted on one upright member and a securing means is mounted on another upright member. Securing the ladder in a stowed configuration on both sides of the ladder assists in ensuring stability in the stowed configuration. The ladder may include stops to limit the extent to which it may slide in the ladder supports.

The securing means preferably includes a locking member, which may be a bolt. Advantageously, the bolt has a locked state and an unlocked state and in the locked state the bolt engages with a part of the ladder and a part of the ladder mount. The bolt is preferably biased into the locked state, for example by a spring. The bolt may be slidably mounted in a bolt mount between the locked and unlocked states. For example, the bolt may be slidably mounted in a barrel. The bolt mount may include a cam surface adapted to withdraw the bolt from the locked state upon rotation of said bolt.

The securing means may include a part associated with the ladder configured to engage with the bracket to secure the ladder in a fixed position with respect to the ladder mount, and that part may comprise a plate so shaped and dimensional as to engage with the bracket. The bracket may include a channel configured to receive the said part, which may comprise an element attached to the ladder, such as a plate which may be attached to one or more of the side members or a rung, or one of the rungs itself.

The ladder may be an access ladder for a vehicle.

According to a third aspect of the invention there is provided a vehicle comprising a fall restraint system according to the invention.

According to a fourth aspect of the invention there is provided a vehicle comprising at least one ladder according to the invention.

According to another aspect of the invention there is provided a vehicle comprising a fall restraint system according to the first aspect of the invention and at least one ladder according to the second aspect of the invention.

Brief Description of the Drawings In the drawings, which illustrate preferred embodiments of the invention, and are by way of example:

Figure 1 is a schematic representation of one end of a vehicle according to the invention;

Figure 2 is a schematic representation of the other end of the vehicle illustrated in Figure

1;

Figure 3 is a schematic representation of a mid-section of the vehicle illustrated in Figures 1 and 2;

Figure 4 is a schematic representation of a post assembly of the vehicle illustrated in Figures 1 to 3 viewed from inside the vehicle;

Figure 5 is a schematic representation of the post assembly illustrated in Figure 4 viewed from outside the vehicle;

Figure 6 is a schematic representation of the pulley arrangement mounted on the post illustrated in Figures 4 and 5;

Figure 7 is a schematic representation of a ladder according to an aspect of the invention;

Figure 8 is a schematic representation of a ladder according to another aspect of the invention;

Figure 9 is a schematic representation of the foot part of the ladder illustrated in Figure 8; and

Figure 10 is a schematic representation of the top part of the ladder illustrated in Figures 8 and 9.

Detailed Description of the Preferred Embodiments Referring now to Figure 1 , there is shown part of a vehicle in the form of a flat bed 1 of a truck. The flat bed 1 could form part of a trailer, which in use would be towed by a tractor unit, or the flat bed of a rigid truck. The flat bed 1 comprises a surface 2 upon which goods are loaded, the surface 2 having edge members 3, 3'. The edge members may be formed from steel channel section. Brackets 4 are attached to edge members 3, 3' by bolts, welding or other suitable fasteners. The brackets 4 mount posts 5 which are preferably removably mounted in the brackets.

A head board 7 is attached to the front end of the flat bed 1 and comprises a pair of spaced apart posts 5, each post locating in a bracket 4. Cross members 8 are attached to teh posts 5 and to end members 9. The head board 7 serves to prevent an operator falling from the flat bed 1 over the front edge 3'. In the example illustrated the whole headboard 7 may be lifted out of the brackets 4. The head board 7 also mounts a hand rail 10, which is used by an operator to steady himself while climbing the ladder.

Winch mount assemblies 6 comprise a pair of spaced apart posts 5, each of which locates in one of a pair of brackets 4 attached to the edge members 3. The winch mount assembly mouths a plurality of pulley wheels which facilitate the arrangement of a rope 12 extending along each side of the flat bed 1. It is these ropes, together with posts 5 that restrain an operator from falling off the flat bed 1. One of the posts 5 of the winch mount assembly 6 mounts a hand rail 10'. A ladder 11 is attached to the edge 3 in the space between the hand rails 10 and 10'. The posts 5 may be lifted out of brackets 4 if required.

Figure 2 illustrates the rear of the flat bed 1. A tail board 13 comprising a pair of spaced apart posts 5 joined together by cross-members 8'. Each post 5 locates in a bracket 4, and whilst the tail board 13 would typically not be removed to facilitate loading for example, the tail board may of course be removed by lifting the posts 5 out of the brackets 4.

A ladder 11 is attached to the rear edge 3' of the flat bed 1. A hand rail 10' is mounted on an end post assembly 14. A hand rail may also be attached to the post 5 of the tail board 13. A return post assembly 15 is mounted proximate the rear end of the flat bed 1. The return post assembly 15 comprises a pair of spaced apart posts 5, which locate in brackets 4. Two pulley wheels 16 are mounted on one of the posts 5, each pulley wheel 16 being attached to a bracket 17 which is itself attached to the post 5. The brackets 17 are shaped so as to provide an opening through which a rope may be brought up to the pulley wheel 16. However, the bracket 17 extends beyond the outer edge of pulley wheel 16 so that if the rope should for some reason move away from the pulley wheel, the rope will nevertheless be constrained by the bracket.

Figure 3 shows a mid section of the flat bed 1. As can seen from Figure 3 posts 5 are mounted on the side 3 of the flat bed 1. Each post mounts three pulley wheels 16, each pulley wheel being attached to a bracket 17 such that the pulley wheel 16 may rotate about its own axis. The bracket 17 is attached to the post 5 by a suitable fastener, which in the illustrated example is a nut and bolt. The use of such a fastener rather than a weld allows brackets 17 to be replace dif they are damaged, rather than requiring the replacement of the whole post. As can be discerned from the drawings, above the pulley wheels 16, the brackets 17 are open. This allows the rope 12 to be lifted on or off the pulleys with relative ease.

The bracket 17' which mounts the uppermost pulley wheel 16 includes a return 17" which extends over the top of the pulley wheel 16 and serves to prevent the inadvertent removal of the rope to an unsafe position. Whilst there is sufficient space between the upper edge 5" of the post 5 to introduce the rope 12, in the event that the rope 12 is lifted upward, the return 17" of the bracket 17' prevents introduction of the rope.

The winch post 6 assembly will now be described in greater detail with reference to Figures 4 to 6, the winch post illustrated in those figures corresponding to the winch post 6 to the right hand side in Figure 1. The winch post 6 assembly comprises a pair of spaced apart posts 5, which locate in brackets 4 attached to an edge 3' of the flat bed 1. The posts 5 are joined together by cross-members 20, the upper cross-member 20 mounting a pulley wheel unit 25, which comprises two pulley wheels 28, 30 mounted on brackets 27 and 29 respectively, the bracket 27 being mounted on a member 26 which projects from and is attached to a post 5 and the upper-cross member 20. The bracket 29 is mounted directly to the underside of the upper- cross member 20. A further pulley wheel 16 is mounted on a bracket 17 which is attached to one of the posts 5 and is positioned such that a rope coming off pulley wheel 30 is aligned horizontally such that the rope would sit on the pulley wheel 16.

Referring to Figure in particular, two further pulley wheels 16 are attached to one of the posts 5 of the assembly 6 by means of brackets 17. The brackets 17 provide open ends so that a rope may be presented up to the pulley wheel 16 carried by the respective bracket. The open ends provided by brackets 17 face in opposite directions. This facilitates attachment of a rope

12.

A further pulley when 16 is attached to one of the posts 5 and provides for stowing of a rope 12 when the fall restraint system is not required, or better access to the vehicle is required. In the illustrated example this pulley wheel and bracket are situated at about the level of the winch 22.

The winch 22 forms part of the winch post assembly is mounted on a bracket 21 which is itself attached to one of the posts 5.

A rope 12 is attached to the winch 22, and is provided at its free end with a hook, so that the rope may be attached to an object and then pulled tight by operation the winch. In the example the winch is powered by a handle, but could equally be electrically, hydraulically, pneumatically powered for example.

The rope 12 passes from the winch 22 in a substantially vertical direction to pulley 28 over which it passes and changes direction through approximately 90 degrees, such that it lies substantially horizontal. The rope 12 then passes around the pulley wheel 30 where the rope again changes direction through approximately 90 degrees. Coming off the pulley wheel 30 the rope 12 remains in a substantially horizontal plane but extends in a direction substantially parallel with the edge 3. The rope 12 supported in this horizontal plane by the pulley wheel 16 attached to the top of the post 5 of the winch post assembly 6 as described above with reference to Figure 5 in particular.

From this point, the rope 12 may then either be deployed to provide a fall restraint or stowed to allow better access to the flat bed 1.

A description of how the fall restraint system is deployed and stowed will now follow:

In the stowed condition, the rope 12 extends around the pulley wheel 16 at the top of post 5 of winch post assembly, turns through approximately 90 degrees and travels vertically downwards to pulley wheel 16 proximate the winch 22 where it again turns through approximately 90 degrees. As can be seen from Figure 1, this pulley wheel 16 is positioned such that the rope 12 lies just below the level of the surface 2. The rope extends along the side of the flat bed 1 substantially parallel with edge 3 and is attached to the bracket 4 supporting the return post assembly 15. The bracket 4 is provided with a hole through which a clip of hook attached to the rope may be passed. In order that the rope 12 may lie below the level of surface 2, the brackets 4 are provided with notches 4a in which the rope 12 may lie. The winch 22 is wound by handle 23 to tighten the rope 12 and the winch is then locked so that the rope remains tights and out of the way.

Deploying the Fall Restraint System

If the posts 5 along the edges 3 of the flat bed 1 have been removed they are reattached, which is simply a matter of slotting their lower ends into brackets 4 and passing a pin through the post and bracket to secure one to the other.

To bring the rope 12 from the stowed condition to the deployed condition, the winch 22 is unlocked so that rope 12 may be drawn off. The rope 12 is then unhooked from the return post assembly 15 and lifted off the pulley wheel 16 proximate the winch 22. The rope 12 is then placed over the upper pulley wheel 16 of the return post assembly 15 (see Figure 2), and turned through approximately 90 degrees to travel vertically downward to the lower pulley wheel 16 of the return post assembly. The rope 12 is passed through the opening of bracket 17 onto the pulley wheel 16 where the rope is turned through approximately 90 degrees such that it lies in a substantially horizontal plane. The rope 12 is brought to the upper pulley wheel 16a of the winch post assembly 6. The rope 12 is passed through the opening in bracket 17 and presented up to the pulley wheel 16a, around which it passes and turns through approximately 90 degrees to travel vertically downwards to the lower pulley wheel 16b of the winch post assembly 6. The rope 12 is passed through the downward facing open end of bracket 17 and presented up to pulley wheel 16b, around which it passes and turns through approximately 90 degrees to travel in a substantially horizontal plane back to the return post assembly 15 where the hook or clip attached to the free end of the rope 12 is attached to an eyelet 31 fixed to a post 5 of the return post assembly 15.

The rope 12 then extends horizontally along the side of the flat bed 1 and three vertically spaced apart locations. Deployment is completed by lifting the rope 12 over the brackets 17 and allowing the rope to lower between the inside of the bracket 17 and the outside of the post 5 towards the pulley wheels 16. In the case of the upper bracket 17', the rope 12 must be lifted upward, and move side ways, then downward so that it is aligned with the opening presented between the return 17" and the top of the post 5. With the rope so positioned it is pulled sideways through the said opening until the rope is aligned with the space between the inside vertical surface of the bracket 17' and the outside of post 5, whereupon the rope may fall vertically to lie on the pulley wheel 16.

The winch is then wound so as to tighten the rope 12 and locked off when sufficient tension in the rope 12 has been attained.

To go back to the stowed configuration, the procedure is reversed.

It is advantageous that the stowed condition involves the rope 12 being partially extended for two reasons. First, it means that a smaller winch barrel is required, and second, the time taken to deploy the system is reduced because the rope 12 is partially drawn off the winch

22.

In the illustrated example the vehicle is provided with two ladder unites 11 to allow an operator to gain access to the surface 2 of the flat bed 1.

The ladder unit 11 will now be described with reference to Figures 1, 2 and 7. The ladder unit 11 comprises a ladder 40 and a mount 41. The mount 41 includes a bracket 42 which provides for attachment of the ladder unit 11 to the edge 3 of the flat bed 1. The bracket 42 includes holes 44 through which bolts are passed to facilitate the said attachment. A pair of brackets 46 are attached to side plates 43 of the bracket 42, the brackets 46 being attached to the side plates 43 by pins of bolts extending through holes 45 in the side plates 443. Each bracket 46 is shaped such that eh side member of the ladder 40 may slide therein.

The ladder 40 includes a plate 47 attached to the side members of the ladder 40. A bracket 50 mounting a bolt 50 is attached to the plate 47. The plate 47 includes returns 49 at each end thereof to facilitate attachment of the plate to the side members of the ladder 40. In Figure 7 the ladder is shown in the stowed position, with the bolt 50 extending through the side member of the ladder 40 and into a hole 51 in the side plate 43.

The bottom edge of the plate 47 sits in a channel in the bracket 42 formed by a lip 47'. The kip is covered with a resilient material 48, such as a piece of rubber or foam for example, which assists in maintaining the ladder 40 in the substantially vertical orientation illustrated in Figure 7.

To deploy the ladder 40, the operator releases the bolt 50, then lifts the ladder upward so that the underside of the plate 47 may clear the lip 47'. He then pulls the base of the ladder away from the bracket 42 so that the ladder may slide downwardly until the feet 53 of the ladder engage with the ground. Mounting the ladder so that it may slide in brackets 46 allows any change in distance between the surface 2 and the ground (due to the load placed on the surface 2) to be taken up.

Referring now to Figures 8 to 10, there is shown an alternative ladder arrangement for mounting on a platform. The arrangement comprises a ladder 60 comprising side members 60a with rungs 60b extending therebetween, and a ladder mount 61 which includes a plurality of bores 61a through which fasteners may be inserted to fasten the mount 61 to an object, such as the platform of a vehicle. The mount 61 also includes a top plate from which extend upright rails 62, 63. The top plate also provides a support for the ladder 60 in its stowed position.

The side members 60a of ladder 60 are arranged to slide in brackets 64, which are themselves attached to the upright rails 62, 63 by arms 65, which are pivotally attached to the side members 60a of the ladder 60 at pivot points 65a and to the rails 62, 63 at pivot points 65b. Upward and downward sliding of the side members 60a in the brackets 64 is limited by stops 6Od and 6Oe. The side members 60a of the ladder 60, the upright brackets 64, and the arms 65 together form a parallelogram linkage. The parallelogram linkage allows for the ladder 60 to move away from the ladder mount 61 so that the ladder may clear that mount and be lowered to the ground.

Referring now to Figures 8 to 10, the ladder 60 is secured in the stowed configuration shown in Figure 8 by a locking arrangement which comprises an upper locking means element 70 disposed to the top of the ladder and another disposed to the bottom of the ladder, and a lower locking means 75 disposed to the bottom of the ladder. The upper locking means 70 comprises a bracket 71 attached to the side member 60a of the ladder, by welding for example. The bracket 71 includes a curved portion 71a. In the locked configuration the curved portion 71a of the bracket 71 engages with a recess 63b of a bracket 63b which is itself attached to the upright rail 63.

The lower locking means 75 at the foot of the side member 60a of the ladder 60 comprises a bracket 76 attached to the side member 60a and a bracket 77 attached to the upright rail 62. A spring loaded pin assembly is attached to the bracket 77 and comprises a barrel 78 having a cam surface 79. A pin 80 is arranged to both slide within the barrel 78 and rotate about its own axis. A handle 81 projects from the pin 80 and engages with the cam surface 79. The pin 80 is of sufficient length to extend through a bore in the end face 76a of the bracket 76 when the pin 80 and bore are aligned, as they are in the locked configuration illustrated in Figure 9.

To deploy the ladder 60, an operator rotates the pin 80 about its own axis by gripping the handle 81 and turning the handle and hence the pin through approximately 180 degrees. As will be appreciated from Figure 9, as the pin 80 rotates, the action of the cam surface 79 on the handle 81 causes the pin 80 to slide axially within the barrel 78 and to disengage from the bore in the end face 76a of the bracket 76. With the lower locking means 75 unlocked, the operator may then slide the ladder 60 in the brackets 64 upwards to disengage the upper locking means 70. With both upper and lower locking means disengaged, the operator may then swing the brackets 64 and hence the ladder 60 outward and downward. The arms 65 rotate about the pivot points 65a, 65b until they lie below the horizontal. The operator then slides the ladder 60 within brackets 64 until the feet 60c of the ladder 60 rest upon a surface.

To return the ladder 60 to the stowed position illustrated in Figure 8, the procedure described above is reversed.

Both the parallelogram action of the arms 65 and the sliding nature of the ladder 60 in brackets 64 allow for the differences in height of a load platform above ground level to be taken up. For example, it may be necessary for the operator to climb on board the platform of a vehicle before it is loaded. The ladder would therefore be deployed and the operator would mount the platform via the ladder. However, as load is placed on the platform, the suspension of the vehicle would become compressed bringing the platform closer to the ground. Hence, to avoid the ladder buckling, it must be capable of moving with respect to the platform. The parallelogram arrangement also allows the ladder to be stowed within the perimeter of the platform when stowed, but be brought beyond the perimeter of the platform when deployed. The ladder 60 is relatively long. By providing locking means to both the top and bottom of the ladder, the ladder is made stable in its stowed configuration. Also, by providing a locking arrangement where each part of the arrangement is operable from the ground, the ladder may be moved easily between the deployed and stowed configurations.

The ladder of the invention provides a number of advantages. First, the change in distance between the surface 2 and the ground due to loading and unloading can be taken up. Second, the ladder is attached to the vehicle. This means that it is not necessary to have a second person footing the ladder, thereby saving labour and increase timeliness. Third, the ladder is much less likely to become separated from the vehicle than is the case where the ladder is stored loose. Fourth, the position of the ladder with respect to the truck is determined by manufacturer not the operator. Therefore the ladder may be provided with hand rails for example. In the case of the embodiment illustrated in Figures 8 to 10, the uprights 62, 63 may serve as grab rails.

Claims

1. A fall prevention system for guarding at least one side of a platform having a plurality of sides, the system having a stowed state and a deployed state and comprising a first member and a second member, an elongate flexible element and a tensioner for tensioning the said elongate flexible element, wherein in the deployed state the said element extends between the first and second members, and wherein at least one of the first and second members provides an elongate flexible element support, said element engaging the support, and the elongate flexible element extending along and guarding a side of the platform, and wherein in the stowed state the elongate member is positioned to allow access to the side of the platform.

2. A fall prevention system according to Claim 1, wherein the first and second members comprise posts.

3. A fall prevention system according to Claim 2, further comprising brackets configured to receive said posts.

4. A fall prevention system according to any preceding claim, wherein the support is a pulley wheel.

5. A fall prevention system according to any preceding claim, wherein the elongate flexible element extends back and forth between the first and second members, and wherein the first and second members mount a number supports each configured to support the elongate flexible element.

6. A fall prevention system according to any preceding claim, wherein each support is mounted in a bracket.

7. A fall prevention system according to Claim 6, wherein the bracket is removably attachable to the first and/or second members.

8. A fall prevention system according to Claim 6 or 7, wherein the bracket includes an open end and extends beyond the edge of the pulley wheel.

9. A fall prevention system according to any of Claims 6 to 8, wherein the bracket includes a return which passes over the surface of the elongate flexible element support.

10. A fall prevention system according to any preceding claim, further comprising additional members situated between the first and second members, the additional members mounting at least one support for supporting the elongate flexible element.

11. A fall prevention system according to any preceding claim, wherein the elongate flexible element is attached to a reel.

12. A fall prevention system according to Claim 11, wherein the reel forms part of a winch.

13. A fall prevention system according to Claim 12, wherein the winch or a part thereof forms the tensioner.

14. A fall prevention system according to any of Claims 11 to 13, wherein the reel is mounted on one of the first and second members.

15. A fall prevention system according to any of Claims 11 to 14, wherein the member mounting the reel includes a plurality of supports oriented such that when the elongate flexible element passes over the supports it is caused to change direction.

16. A fall prevention system according to Claim 15, wherein the member mounting the reel includes two supports, each causing the elongate flexible element to change direction through approximately 90 degrees.

17. A fall prevention system according to any preceding claim, wherein the free end of the elongate flexible element is provided with an attachment means.

18. A fall prevention system according to Claim 17, wherein one of the first and second members is provided with a corresponding attachment means to which the attachment means of the elongate flexible element may attach.

19. A fall prevention system according to any preceding claim, further comprising a pole including means for engaging the elongate flexible element.

20. A fall prevention system according to Claim 19, further including additional supports and/or attachment means adapted to secure the elongate flexible element in the stowed state.

21. A fall prevention system according to Claim 19 or 20, wherein a support is provided to towards the base of one of the first and second members and an attachment means is attached to the other.

22. A vehicle comprising a load carrying surface and a fall prevention system according to any preceding claim.

23. A vehicle according to Claim 22, including elongate flexible element receiving means.

24. A ladder unit comprising a ladder having a pair of spaced apart side members and a plurality of rungs extending therebetween, and a ladder mount, the ladder mount including a bracket attachable to an object, a pair of spaced apart ladder supports each pivotally mounted on the ladder mount and configured to receive a side member of the ladder such that said side members may slide in the ladder support, and a securing means to secure the ladder in a fixed position with respect to the ladder mount.

25. A ladder unit according to Claim 24, wherein the securing means includes at least one locking member.

26. A ladder unit according to Claim 25, wherein a locking member includes a bolt having a locked state and an unlocked state and in the locked state the bolt engages with a part of the ladder or an element having a fixed relationship with the ladder and a part of the ladder mount.

27. A ladder unit according to any of Claims 24 to 26, wherein the securing means includes a part associated with the ladder configured to engage with the ladder mount to secure the ladder in a fixed position with respect to the ladder mount.

28. A ladder unit according to Claim 27, wherein the said part of the securing means is so shaped and dimensional as to engage with a bracket.

29. A ladder unit according to Claim 28, wherein the bracket is situated towards the top of an upright element of the ladder mount.

30. A ladder unit according to any of Claims 26 to 29, wherein the bolt in the locked state engages with a bracket attached to the ladder.

31. A ladder unit according to Claim 30, wherein the bolt is attached to an upright element of the ladder mount.

32. A ladder unit according to Claim 27 or 28, wherein the bracket includes a channel configured to receive the said part of the securing means.

33. A vehicle comprising at least one ladder unit according to any of Claims 24 to

32.

34. A vehicle according to Claim 22 or 23, further comprising at least one ladder unit according to any of Claims 26 to 32.

35. A fall prevention system substantially as shown in, and as described with reference to Figures 1 to 6.

36. A ladder unit substantially as shown in, and as described with reference to, Figures 1 to 10.