Technical Field

[oooi] The present invention relates to the technical field of load straps for securing loads, especially compactible loads.

Prior Art

[ooo2] Load straps are in common usage to secure loads to the load deck of a vehicle. They commonly take the form of a ratchet strap. The ratchet strap comprises a first, substantially inelastic flexible webbing part which is coiled around a reel supported in a chassis of a ratchet mechanism. The reel is rotatable on an axis. A ratchet drive engages the reel and is further engaged by a lever. Reciprocal operation of the lever with the ratchet engaged causes the reel to rotate in a direction to reel the webbing onto the reel. A release mechanism allows the reel to be released so that the first webbing part can be unwound. A second inelastic flexible webbing part is usually attached to an end of the ratchet mechanism chassis opposite the first webbing part. It is common for the second end to be of adjustable length by means of a buckle, in order to trim the strap for use on a range of load sizes, however once trimmed there is usually no capacity to tighten the second webbing. Hooks or loops are mounted to each end of the webbing parts remote from the ratchet drive to facilitate attachment to fastening eyes or other mounting structures, mounted into the load bed of the vehicle or walls of the vehicle. Once in place the strap can be tightened over the load to press it against the load deck and thus prevent the load from shifting due to the motion of the vehicle. [ooo3] Load straps are also used to attach loads to vehicle roof racks and roof bars. While ratchet straps can be used for this purpose the smaller lighter and more compact nature of such loads tends to encourage the use of straps known as cam straps. These are usually a single length of flexible substantially inelastic webbing with a cam buckle secured at one end. The strap is most commonly used by threading the webbing around the roof bars or elements of the roof rack and over the load before returning the free end of the webbing to the buckle. The free end is threaded through the buckle to form an endless loop around the load. By pulling against the free end of the webbing the loop can be tightened to secure the load. The cam mechanism of the buckle prevents the free end being drawn back by the tension applied to the webbing loop, by the load, until released by the user. The cam buckle conventionally has a release tab designed to facilitate rotating the cam out of engagement with the webbing in order to release the webbing.

[ooo4] Where rigid loads are to be secured a load strap of either type is very effective. However, it is common to transport compactible loads of various types, for example sacks of granular materials in flexible intermediate bulk containers (FIBC) bags (sometimes known as big bags or bulk bags). Such bags are commonly of generally rectangular form and have a maximum capacity of around 800-1 OOOItrs and are commonly used to transport loose granular materials ranging from foodstuffs comprising granular elements, to building materials such as sand and gravel. When loaded onto the flat load bed of a lorry the bulk bags need to be secured since movement of the substantial weight can cause significant handling problems by misbalancing the vehicle, not to mention loss of the load. This is commonly achieved by running one or more spaced cam straps across the top of the bag and securing the fastening hooks to load points in the load bed or vehicle rails before tensioning the straps by operation of the ratchet.

[ooo5] When the load strap is initially tightened the load appears to be secure. However as the vehicle, usually a lorry, truck or van, moves over the uneven road surface vibration transmitted to the load causes the load to shift, especially under the strap where the forces imposed by the strap tension provide additional impetus to the elements of the load. Thus over a period of time during transport the granular elements shift from beneath the strap effectively loosening the strap and rendering the load insecure and mobile. It is therefore commonly necessary for the operator, usually the vehicle driver to stop somewhere, check the load strap tensions and tighten as required. Finding somewhere to stop safely is a problem and the time taken to check and tighten is always a problem.

[ooo6] Tradesmen frequently carry elongate loads strapped to roof bars or a roof rack. Such loads can often consist of a range of elongate materials such as pipe and beams of various material moulded to various cross sections. Such materials are often difficult to arrange in an initially packed configuration when strapped to a roof rack. In consequence a phenomenon similar that previously described for FIBC bags can occur during transit where vibration from the road packs the load more closely and effectively loosens the straps securing the load. [ooo7]. It is also known to use strong elastic members commonly known as bungee cords to secure loads. However these are not approved in many circumstances, they are either not sufficiently strong to secure heavy loads, or if made sufficiently strong are dangerous to handle under tension.

[ooo8] It is the aim of the present invention to provide a load strap which alleviates at least some of the technical problems described above and provides a safe reliable and inexpensive means to secure compactible loads and in-compactible loads.

Summary of Invention

[ooo9] A load strap for securing compactible loads comprising: a compensator having: a first substantially inelastic flexible webbing part, a tension spring having a first end and a second end, a first connector to connect the first end to a first point of the first webbing part, and a second connector to connect the second end to a second point of the first webbing part spaced a span from the first webbing part; the span between the first and second points is substantially longer than the length of the spring so that the span of webbing forms a slack loop when no tension is applied to the webbing and prevents the extension spring from extending beyond the elastic limit of the extension spring when tension is applied to the first webbing part.

[oow] The tension spring may be provided by any suitable elastic member, including at least a coil spring and an elastomeric bungee cord. The coil spring will usually be selected from heavy duty applications capable of securing heavy loads such as the FIBC bags which commonly contain up to 1000kg of material. Elastomeric bungee cord may serve as the tension spring where lower load rated duties are specified. A benefit of the load strap is that tension is only applied to the strap after it is secured to the load points and only over a short span of the webbing, consequently any failure of any component of the strap will dissipate energy from the spring minimising the risk of injury to the user.

[OOH] The spring and compensator webbing also serve as a load strap tension indicator. The tension applied to the strap will be proportionate to the extension of the span, at least until the span is maximally extended. This can help to obviate the application of excessive tension to a load strap with the potential of damage to the load, the strap or the vehicle securing points.

[ooi2] In operation the load strap is secured around the load and to any securing point on the load bed of a vehicle or any form of roof bars or racking system. Tension is applied to the strap until the compensator webbing is fully extended. The tension spring cannot be overextended because of the limits imposed by the inextensible compensator webbing and therefore remains elastic. If the load compacts for any reason the spring takes up the slack thus induced in the webbing and maintains the security of the load.

[0013] In a preferred embodiment of the load strap the first compensator webbing is secured at one end to a ratchet mechanism. A second compensator webbing may then be secured to a reel of the ratchet mechanism. Preferably the ends of each of the first and second compensator webbings remote from the ratchet mechanism are provided with securing fixtures, which may be in the form of hooks, and/or loops adapted to secure to secure points in a vehicle. In an alternative form of the load strap the first webbing part may be provided with a cam locking buckle at one end in order to achieve tension by securing a free end of the webbing part to the buckle.

[ooi4] Where additional load compaction compensation is required more than one compensator may be provided in the first webbing part. In a further variant of the ratchet load strap one or more compensators may be provided in the second webbing part.

Brief Description of Figures

[0015] A load strap for compactible loads constructed in accordance with the present invention will now be described, by way of example only, with reference to the accompanying figures, in which:

Figure 1 is an isometric NW view of a flatbed truck with a load comprising three FIBC bags secured by means of ratchet straps;

Figure 2 is an enlarged isometric NW view of a ratchet strap under maximum tension;

Figure 3 is a view of the ratchet strap of figure 2 relieved of tension;

Figure 4 is a plan view of the ratchet strap of figure 3;

Figure 5 is a plan view of the ratchet strap of figure 2 and

Figure 6 is an isometric NW view of a cam strap.

Detailed Description

[0016] A first embodiment of a load strap for securing compactible loads comprises a compensator 1 having: a first substantially inelastic flexible webbing part 2. A tension spring 3 is provided by a coil spring having a first end 4 and a second end 5. A first connector 6 to connect the first end 4 to a first fix point 7 of the first webbing part, and a second connector 8 to connect the second end 5 to a second fix point 9 of the first webbing part. A hook formation is provided at each of the first and second ends 4, 5 of the tension spring to engage with the corresponding connector.

[ooi7] The span “S” is substantially the length of the first webbing part between the first and second fix points 7 and 9. Each connector is provided by a substantially triangular stiff wire loop. The connector loop 6 is threaded into a sleeve formed transversely in the webbing at the first fix point 7. The connector loop 8 is threaded into a transverse sleeve formed into the webbing at the second fix point 9. The tension coil spring 3 is ended at 4 and 5 with hooks which hook into the connector loops 6 and 8.

[0018] The span S of webbing part 2 between the first and second points 7, 9 is substantially longer than the unstressed length of the spring “R” so that the span of webbing forms a slack loop when no tension is applied to the webbing and prevents the tension spring from extending beyond a predetermined limit. The value of S is selected to ensure that when the tension spring is extended to the maximum extension allowed by the webbing part, as shown in figures 2 and 5 the tension spring cannot be extended beyond the elastic limit for the specified tension spring when tension is applied to the load strap.

[0019] A connector web part 10 is connected to one end of a ratchet reel 11 of conventional design. The length of the connector web may be adjustable by means of a buckle (not shown) which can facilitate connection to the ratchet reel. A further length of webbing 12 extends from the fixed point 9 to a hook 13.

[0020] One end of a reel webbing part 14 is wound on to a reel of the ratchet drive 13. The opposite end of the webbing part is provided with a hook 15. [0021] As shown in figure 1 , the hook 15 can be secured to a load point 16 on the cargo bed of a truck. The webbing part 12 can then be extended sufficiently to be fed over the FIBC bags of sand loaded onto the cargo bed. These would be of much less regular shape than illustrated as the bags are flexible. Tension is applied to the strap by operating the ratchet lever 17 of the ratchet mechanism in the usual way until the tension extends the spring 3 to the limit set by the span of the compensator web 2. If the load shifts and compacts relieving the tension on the load strap the spring acts to draw the strap taught.

[0022], Figure 6 illustrates the compensator 1 deployed in a load strap in the form of a cam strap. The compensator is identical to the compensator of the previous embodiment but the fix points 7 and 9 are attached to a continuous webbing loop 16. A cam buckle 17 is attached to one end of the loop to capture the unadorned opposite free end of the webbing 16. The cam strap - load strap is generally more useful where lighter and smaller loads are to be secured and sufficient tension can be applied by pulling on the free end of the webbing. The operation of the compensator 1 is otherwise similar to the previous embodiment where tension is applied manually to the strap until the tension spring 3 is fully extended to secure the load. If the load packs the tension on the spring 3 causes the spring to contract and compensate for the compaction of the load while maintaining load security.