GB2582526A - Free-flex harness - Google Patents

Abstract

A harness for a backpack comprises a support structure (A, fig.1), a strut mechanism 2 and a hip belt (C, fig.1). The strut mechanism resiliently biases the support structure upwards in relation to the hip belt. It is preferably the sole force-transmitting connection between the hip belt and the support structure. The strut mechanism may be laterally flexible and may comprise one or more telescopic struts. A spring 5 may be provided to extend the strut mechanism and a piston and cylinder mechanism 4, 8 may act to damp the extension of the strut mechanism. The strut mechanism may incorporate a Piezo-electric device to generate electricity from the movements. The mechanism reduces bounce of the rucksack, especially while running.

Description

FREE-FLEX HARNESS

Field of the Invention

This invention is a harness for carrying a load, such as a pack. The load to be carried may be any size, form or weight, with the critical elements being the placement of attachment points of the load to the harness and the design of the harness itself.

Background

Existing rucksack designs are based around a waistband and two vertical straps traveling from near or at the base of the pack, up in front of and over the shoulders and down the back into the pack on each side. The weight of the pack contents is transferred downwards into the waistband by attaching the pack directly to the waistband, often assisted by rigid spars transferring load down into the waist-belt.

The intent is for the load to be supported primarily by the waistband, rather than the shoulders, and to minimize the load pulling backwards on the wearer. With only minor variations this design has become prevalent throughout all modern-day rucksacks.

The existing rucksack design as described has several known disadvantages: During typical movements while wearing a rucksack the distance between the top of the shoulder and the hips varies significantly, primarily resulting from movements of the shoulders or as a result of the extension of the spine during bending and twisting. Tests showed the spine extending by about 6cm when moving from upright to touching toes. The straps in existing rucksack designs are vertically load-bearing, and connect to the base of the pack at each side. The variation in distance between the wearer's shoulders and hips means that the weight of the pack constantly shifts between the waistband and the shoulder straps. Typically this results in the waistband shifting upwards off the hips and the harness bouncing on the shoulders, especially during faster movements such as running with the natural response of the wearer typically being to tighten the shoulder straps. As a result the weight of the pack shifts more onto the shoulders, which can lead to rounding of the shoulders, eradicating the natural curvature of the spine and causing excessive strain on both the spine and the muscles of the back. This strain on the back is exacerbated by any "bounce" of the pack created by movements of the wearer (most noticeable while running).

In the existing rucksack design the shoulder straps are intended to carry approximately 30% of the load (the remainder supported by the waistband) and pass over the top of the acromion (the extension of the shoulder-blade that connects to the end of the clavicle bone), which is attached to the main skeletal structure through muscles and other soft tissues. As a result the wearer experiences significant muscle fatigue when wearing the pack for any length of time. Since the acromion is highly mobile with any shoulder movement, any movement of the arms exacerbates this muscle fatigue in the shoulder and back. Additionally the slope of the top of the shoulders and the weight of the rucksack pulling on the shoulder straps pulls the straps backwards and sideways away from the centre of the body.

Attempts have been made to overcome this issue. Chest straps have been introduced to prevent straps from slipping off the shoulders. However these chest straps are neither load-bearing nor designed to prevent the shoulder straps from being vertically load-bearing. North Face have introduced their E-Yap harness which is designed like a bib but worn on the back and put on over the wearer's head. This alleviates some of the strain from the shoulders but cannot be easily put on and cannot be integrated with a waistband, making it only suitable for very light packs (eg. 1 litre hydration packs).

Existing designs pull the entire backpanel of the rucksack against the wearer's back.

This means the rucksack does not accommodate the movements of different parts of the wearer's back relative to each other and also presses against moving parts of the body (most noticeably, the highly mobile shoulder blades). This restricts the wearer's movements and means the wearer's body rubs against the pack, causing discomfort.

Some designs use a tensioned mesh back that creates an air space between the bag and the wearer's back to keep it cool and free of perspiration. However this reduces the load support and exacerbates the problem of load falling significantly behind the wearer. The generic solution has been extra padding, especially over the shoulder-blades. This extra padding alleviates some of the symptoms of discomfort but does not address the root cause and restricts the wearer's movements even more.

The issues described above are exacerbated by faster and/or more extreme movements of the wearer. In most modern running packs the load-bearing waistband and the rigid spars transferring load down into the waist-belt have been sacrificed completely to make a more lightweight pack with the full load supported by the shoulders thereby severely limiting loads that can be realistically carried in these packs.

Summary of the Invention

According to one aspect of the present invention there is provided a harness for a backpack comprising a support structure provided with a strap arrangement for retaining the support structure adjacent a wearer's back, the strap arrangement comprising left and right shoulder straps, each shoulder strap comprising a loop extending from a first position on the support structure on one side of the support structure to a second position below the first position on the same side of the support structure, the straps being interconnected, in use, at the front of the wearer by a releasable buckle comprising left and right buckle components, each loop comprising an upper flexible portion extending from the support structure to an upper fastening point on the respective buckle component and a lower flexible portion extending from the support structure to an attachment point at one end of a link, the other end of the link being connected to a lower fastening point on the respective buckle component, whereby the attachment points of the lower flexible portions are laterally displaceable towards and away from each other.

The loop of each shoulder strap may be made from a substantially inextensible material. The length of each loop may be adjustable.

In one embodiment, buckle components, when engaged with each other, form a rigid interconnection between the loops.

Each link may comprise an inextensible but flexible wand. Each flexible wand may be rigidly connected to the respective buckle component.

According to another aspect of the present invention, there is provided a harness for a backpack comprising a support structure provided with a strap arrangement for retaining the support structure adjacent a wearer's back, the harness also comprising a hip belt connected to the support structure by a strut mechanism which, in use, resiliently biases the support structure upwards with respect to the hip belt.

The strut mechanism may comprise the sole force-transmitting connection between the hip belt and the support structure. In other words, any other connection that may exist between the hip belt and the support structure transfers substantially no force from one to the other.

The strut mechanism may comprise a single upwardly extending strut disposed substantially centrally of a wearer's back when in use. The strut mechanism may comprise a telescopic strut having a piston displaceable in a cylinder, the piston and the cylinder being connected respectively to one and the other of the hip belt and the support structure. The piston may be connected to the respective hip belt or support structure by a piston rod which is laterally flexible. A spring may be provided which acts between the cylinder and the piston in a direction to extend the strut. The strut may include damping means for damping movement of the piston in the extension direction.

The strap arrangement may comprise left and right shoulder straps. Each shoulder strap may comprise a loop extending from a first position on the support structure on one side of the support structure to a second position below the first position on the same side of the support structure. The loop of each shoulder strap may be made from a substantially inextensible material.

The length of each loop is adjustable.

The straps may be interconnected, in use, at the front of the wearer, for example by a releasable buckle comprising left and right buckle components which, when engaged with each other, form a rigid interconnection between the loops. Each loop may comprise an upper flexible portion extending from the support structure to an upper fastening point on the respective buckle component and a lower flexible portion extending from the support structure to an attachment point at one end of a link, the other end of the link being connected to a lower fastening point on the respective buckle component, whereby the attachment points of the lower flexible portions are laterally displaceable towards and away from each other.

Each link may comprise an inextensible but flexible wand, which may be rigidly connected to the respective buckle component.

In embodiments in accordance with the present invention, the benefits of the invention are achieved through separation of the Hip-belt [C] from the Chest Harness [A] to allow them to move independently of each other, and allowing the Hip-belt [C] to remain secure on the wearer's hips and fully support the load while the primary function of the chest harness [A] becomes preventing the load from falling away from the wearer's torso rather than vertical load support. Any connection (including the load itself) between the Chest Harness [A] and the Hip-belt [C] is flexible and free-running in extension.

The narrow Hip-belt [C] and X design of the Chest Harness [A] ensure that the harness is secured at relatively immobile parts of the wearer's skeletal structure to ensure a secure and comfortable fit and significantly reduce restriction of the wearer's movements, rubbing, muscle compression and heat buildup, while the buckle design allows the wearer to still breathe freely.

Finally the use of a sprung, damped system to transfer the weight of the load into the Hip-belt [C] acts as a shock absorber, with the sprung system cushioning the impact of the load on the wearer, and the damping element controlling the movement of the load to reduce rucksack "bounce" and ensure that movement of the load is not destabilizing to the wearer. There are many mechanical solutions for sprung, damped systems such as systems that resist compression including, amongst others, foam padding with elastic properties, torsion, compression or air springs combined with hydraulic or gas pistons, (commonly referred to as shock absorbers or linear decelerators), resistance dampers, or gas struts. Non-compression systems would include, amongst others, using elastic materials to attach the load to the Hip-belt [C] while the Chest Harness [A] connects to the load via a system that allows free vertical movement such as a rail on the Chest Harness [A] with a free-running housing on the load. Each of these have their own particular set of properties and could be applied in this invention to suit different purposes of the Harness.

The load to be carried may comprise a bag as in a traditional rucksack, or may be a piece of rigid equipment, for example cylinders containing a pressurized breathable gas. This invention relates to the carrying harness to which the load (whatever it may be) can be attached.

Embodiments in accordance with the present invention provide a load-carrying harness which facilitates free movement of the wearer, removes the tendency for movement to pull the waistband off the hips, thereby reducing strain and muscle fatigue in the shoulders and back, and reduces "rucksack bounce" by managing the impact of the load on the wearer. It also reduces the feeling of being pulled backwards experienced in existing designs.

For a better understanding of the present invention and to show how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1 shows a rucksack; Figure 2 shows the rucksack of Figure 1 positioned on a wearer; Figure 3 is a sectional view of a sprung, damped system of the rucksack of Figures 1 and 2; Figures 4a and 4b show a strap arrangement of the rucksack of Figures 1 and 2 in different configurations; Figure 5 shows a support frame of an alternative embodiment of a rucksack; Figure 6 shows a harness positioned on a wearer and supporting a gas cylinder.

Below are described three specific embodiments of the invention, demonstrating the common themes of the invention and some of the various mechanical means of achieving them. These are not meant to be exhaustive but merely demonstrate the key elements of the invention that will remain consistent, regardless of the various mechanical solutions used to achieve them.

Throughout this document, the terms left, right, up, down, front and back and similar directional or positional terms refer to the harness when worn by a wearer standing upright, and as perceived by the wearer themselves.

Detailed description of a specific embodiment of the Invention -First Embodiment: Single spar Flexible Spine in this case shown carrying a Rucksack In the first embodiment of the invention shown in Figures 1 to 4, the invention is a carrying harness for a rucksack (ie. The load to be carried consists of the contents of a sack attached to the carrying harness). In this embodiment the invention comprises three elements: A Hip-belt [C] that fits around the wearer's hips and fully supports the load; a strut mechanism in the form of a Flexible Spine [B] that transfers the weight of the load down into the Hip-belt [C]; and a Chest Harness [A] comprising a support structure 9 and a strap arrangement 12, 14&16, and 15 that secures the load to the wearer's upper torso to prevent the load from falling backwards away from the wearer's torso.

The Hip-belt [C] is made of padded material to wrap securely around the top of the hips and spread the load as much as possible across the full width of the wearer's back around the hips and, as far as possible, around to the front of the wearer. It is similar to those found on traditional packs, but is narrower, and can be fitted to mirror the wearer's body shape as closely as possible, because the Hip-belt in the invention will not suffer the tendency to be pulled up off of the wearer's hips as is experienced in traditional designs. To this end the diameter of the top part of the Hip-belt [C] is smaller than the diameter of the bottom part so that it follows the natural concave curvature of the lower lumbar region. The Hip-belt [C] does not extend downwards to the top of the buttocks, nor upwards to the mid-lumbar region, but is narrow to sit across the lower lumbar region, thus ensuring that it is only in contact with parts of the body that do not move relative to each other when the wearer is walking, twisting or bending. The entire weight of the load is transferred via the Flexible Spine [B] into a single point connection [1] into the Hip-belt and is then spread sideways throughout the Hip-belt around onto the hips of the wearer. The connection [1] is at the top of the Hip-belt [C] to maximize the use of the concave curvature of the lumbar region (in laymans' terms the "small of the back") to bring the load as far forward into the wearer's back as possible.

The Flexible Spine [B] connects the Hip-belt [C] to the load. It resists compression but allows extension and is flexible to allow movement laterally, forwards and backwards, and torsionally. The resistance to compression of the Flexible Spine [B] ensures that the weight of the load is fully transferred down into the Hip-belt [C], to be supported on the wearer's hips. The Flexible Spine [B] runs from the top of the Hip-belt [C] at the lowest part of the lumbar region up the full length of the lumbar region to meet the Chest Harness [A] in the thoracic region of the wearer's torso. This ensures that the Flexible Spine [B] covers the full length of the lumbar region where the most flexion and extension of the wearer's own spine will occur during typical movements. The flexibility and free extension of the Flexible Spine [B] enables the load and the Chest Harness [A], to which it is secured, to move independently of the Hip-belt [C] so as to avoid any restriction of the wearer's movements. Note, some extension and flexion occurs in the thoracic region and therefore the Flexible Spine [B] can connect to the Chest Harness [A] higher up in the thoracic region for a more ergonomic fit providing flexion and extension over a greater range of the wearer's spine. However the critical element is facilitating extension and flexibility in the lumbar region.

The Flexible Spine [B]'s resistance to compression and freedom to extend is achieved in the simplest form by using a single vertical support comprising a strut, which may, for example, be in the form of a guiding rod or tube, joining the Hip-belt [C] to the load, where the connector to either the Hip-belt [C] or the Chest Harness [A] runs along the guiding rod or tube within a prescribed distance to accommodate extension of about 6cm. The shortest length of the Flexible Spine [B] (ie with zero extension) between Hip-belt [C] and Chest Harness [A] is sufficiently long that, with the wearer in the upright position, the weight of the load is borne entirely by the Hip-belt [C] and is not supported by the Chest Harness [A] (and by extension then the wearer's own spine). For a guiding rod arrangement the connector to the harness may be a block fixed to the harness with a hole that allows the rod to slide through the block up to the prescribed distance, limited by a stop on the rod that cannot pass through the hole in the block. For a guiding tube one of the connectors to the harness may move along a slit in the tube or the connectors may be fixed to each end of two overlapping tubes that are able to slide over one another to facilitate the extension or compression of the Flexible Spine within a prescribed distance.

In this embodiment (see Figures 1 to 4) a more sophisticated version of the Flexible Spine is shown in which the Flexible Spine has a fixed connection [1] to the Hip-belt [C], the free-running connection between the Harness [A] and the Flexible Spine [B] is a piston [4] within a cylinder [8], and the extension and compression of the Flexible Spine [B] is controlled by a sprung, damped system. An example of how such a sprung, damped system might be fitted to this invention is shown as a cutaway blowup in Figure 3. The Flexible Spine [B] comprises a flexible guiding strut in the form of a rod [2] centrally placed on the wearer's back extending up from the connection into the Hip-belt [1] to connect to a piston [4] sitting within a cylinder [8] that is supported by a compression spring, or series of compression springs [5] that sit between the stop [3] on the guiding rod and the cylinder [8]. The cylinder [8] is connected to the vertical spar [9] of the Chest Harness [A] so that the sprung, damped system sits inside the pack and the vertical spar [9] and its padding protects the wearer's spine from this mechanism. A protective sheath [18] separates the sprung, damped system from the contents of the pack. This protective sheath [18] extends down to a hole [17] in the back panel [13] through which the rod [2] of the Flexible Spine [B] passes to connect into the Hip-belt [C]. The extension of the Flexible Spine [B] is created through the extension of the compression springs [5] so that the springs [5] support the weight of the load throughout the range of extension of the Flexible Spine [B]. The compression springs [5] may be of variable spring rate such that in the fully extended position the spring rate is low and increases as the springs are compressed. Thus the spring rate automatically adjusts for different weights of load.

In this embodiment movement of the load, supported by the springs [5] is damped by controlling the movement of the piston [4] within the cylinder [8]. The head of the piston [4] is flanged so that in the compression stroke, as the weight of the load pushes down on the cylinder [8] and the piston [4] moves towards the top end of the cylinder [8], air can easily escape past the piston head. However in the extension stroke, as the recoil force of the springs [5] push upwards on the cylinder [8] and the piston [4] moves towards the bottom of the cylinder [8] the air pressure above the piston decreases. The greater air pressure below the piston forces the flange of the piston [4] against the sides of the cylinder, thereby restricting the movement of air past the piston [4]. The resulting air pressure differential resists the movement of the piston [4] relative to the cylinder [8] and thereby provides a damping force on the movement of the load and the springs [5] during the extension phase of the cycle. A hole [6] near the top of the cylinder allows air to flow between the atmosphere and the cylinder in either direction. The level of damping provided by a one-way air damper such as this is already velocity dependent to some extent but the damping effect may be varied by changing the size of the hole [6] by means of an adjusting screw [7] housed within the hole [6]. Thus the damping effect can be adjusted between a soft suspension (low damping effect) setting to maximize comfort for slow activities such as walking, and a hard suspension (high damping) setting for faster activities such as running where the extreme movements would otherwise destabilize the wearer.

The one-way air damper (or dashpot) as described above will dampen movement on the extension cycle when the springs are in recoil but not on the compression cycle when the weight of the load is compressing the springs. There are many different mechanical damping systems which could be used as variations on this design from a simple friction damper acting on the guiding rod, to a gas strut or a hydraulic linear decelerator, each with their own individual damping properties but all fundamentally achieving the same result.

To achieve a comfortable fit the optimal distance between the Hip-belt [C] and the Chest Harness [A], with the wearer in a static, upright position, will vary from individual to individual. Also, the required length of the Flexible Spine [B] will vary depending on the load being carried since a heavy load will compress the springs of the shock absorber more than a light load. This necessitates an adjustment mechanism to vary the length of the Flexible Spine [B]. Various established mechanical solutions would solve this problem but in the embodiment shown here the flexible rod [2] includes a screw-thread adjustor [11] at the connection into the Hip-belt [1], allowing the effective length of the Flexible Spine [B] to be increased to accommodate heavier loads (which will compress the springs further) and wearers with longer backs.

The Chest Harness [A] comprises a pair of chest straps, each of which forms a closed loop and includes an upper flexible portion or shoulder strap 12 and a lower flexible portion or abdomen strap 15. When the wearer is standing still and upright the weight of the load pulling on the material of the pack is transmitted by the rigid frame [10] into the vertical spar [9] and acts on the cylinder [8] to compress the springs [5] within the sprung, damped system until static equilibrium is reached.

Provided the screw-thread length adjustor [11] is set sufficiently long, the rigidity of the vertical spar [9] and the frame [10] connecting to the shoulder straps [12] ensures that the weight of the load is transferred directly into the Flexible Spine [B] so that it is supported via the Hip-belt [C], and the shoulder [12] and abdomen straps [15] do not provide any vertical support for the load. From this steady state when the wearer bends forwards a certain amount of the weight of the load will be released from the Flexible Spine [B] as the wearer's inclined back will take some of the weight. The reduced load on the Flexible Spine [B] allows the springs [5] to extend so that the new length of the Flexible Spine [B] matches the increased distance between the Chest Harness [A] and the Hip-belt [C]. The result is that static equilibrium is restored in this new position with the load still supported in part by the Hip-belt [C] and in part by the wearer's inclined back, but not by the shoulder straps [12] of the Chest Harness [A]. Thus the movements of the wearer are unrestricted, no weight is carried by the shoulders, and there are no forces pulling the Hip-belt [C] up off its secure position on the wearer's hips. The range of the piston [4] and the springs [5] needs to accommodate an extension of around 6cm in the spine of an average wearer from fully loaded to fully extended as they move from an upright position to a 'touching toes' position. During typical walking motions the load will move up and down and the kinetic energy will be absorbed and returned by the springs, reducing the impact on the wearer's hips. The damping effect will be slight at these low speeds. During faster movement such as running, the kinetic energy produced by the load moving is far greater. The springs respond to absorb and return this greater energy and, in an un-damped system, would exacerbate the amplitude of the load's cycle. However the damping, which has more effect at greater speeds, controls the movement of the load and the cycle amplitude to keep them within the tolerances of the wearer's natural gait. This is perceived by the wearer as reducing the "bounce" of the rucksack when running.

The Chest Harness [A] is a means of securing the load to the wearer's upper torso to avoid the load falling away from the wearer's back. In this embodiment the Chest Harness [A] may be of an X-harness design securing a vertical spar [9] over the wearer's spine between the shoulder blades. From this vertical spar [9] the Frame [10] extends left and right across the top of the back above the shoulder-blades, to the top corners of the pack which sit higher than the wearer's shoulders, and down the sides of the pack. The shoulder straps [12] extend from this frame over the front of the clavicle bone on either side of the wearer's neck and down across the wearer's chest high up to avoid the pectoral muscles, to a connection or buckle over the sternum, referred to henceforth as the BreatheEZ buckle [14&16]. The abdomen straps [15] are connected to the frame [10] at the lower part of the thoracic region where the frame [10] connects into the bottom of the vertical spar [9], and pass around the rib-cage, to the bottom connections of the BreatheEZ buckle [14&16].

The length of both the shoulder straps [12] and the abdomen straps [15] are adjustable for the comfort of the wearer.

In this embodiment the BreatheEZ buckle [14&16] comprises a left component which joins the left shoulder strap and left abdomen strap, so that when the buckle is unfastened (see Figure 1) the left shoulder strap [12], left component of the buckle [14&16], left abdomen strap [15], and vertical spar [9] over the wearer's spine together form a single continuous loop, and a right component which joins the right shoulder strap and right abdomen strap, so that when the buckle is unfastened the right shoulder strap [12], right component of the buckle [14&16], right abdomen strap [15], and vertical spar [9] over the wearer's spine together form a single continuous loop. The left and right components of the BreatheEZ buckle [14&16] connect together in use by means of the upper section of the buckle [14] and, when connected together in use, the left and right upper sections of the buckle [14] fit together securely as a single, rigid unit lying over the wearer's sternum (as in Figure 4). The BreatheEZ buckle [14&16] is narrow to avoid interfering with the pectoral muscles or breasts of the wearer. The lower section of each left and right component comprises a link in the form of an inextensible but flexible wand or rod [16] extending down to several centimetres (for example at least 8 cm or 10 cm) below the sternum that resists linear forces but is flexible to sideways forces. The left abdomen strap [15] connects to the bottom of this rod [16] on the left buckle component and the right abdomen strap [15] connects to the bottom of this rod [16] on the right buckle component. The shoulder straps [12] connect into the top of the BreatheEZ buckle [14] at an angle. When the buckle is connected in use the forces run diagonally across the wearer's torso from left shoulder strap [12] through the BreatheEZ buckle [14&16] to the right abdomen strap [15], and from the right shoulder strap [12] through the BreatheEZ buckle [14&16] to the left abdomen strap [15] and since all these components are linearly inelastic (including the components of the BreatheEZ buckle[14&16]) these form two close-fitting loops diagonally around the wearer's body securing the Chest Harness [A] to the wearer's torso. The ability of the rods [16] to be displaced laterally allows the gap between the bottom of the left and right rods [16] to increase and decrease with the expansion and contraction of the wearer's rib-cage during breathing. Figure 4a shows the rods [16] in near vertical position when the wearer has fully exhaled while Figure 4b shows the rods [16] pulled apart sideways by the abdomen straps [15] when the wearer has inhaled and the ribcage is fully expanded. Thus the variation in the horizontal distance around the lower part of the wearer's rib-cage during breathing is accommodated while maintaining a materially consistent distance in the diagonal loop comprising left shoulder strap [12], BreatheEZ buckle [14&16] and right abdomen strap [15] and the diagonal loop comprising right shoulder strap [12], BreatheEZ buckle [14&16] and left abdomen strap [15] respectively so that the Chest Harness [A] remains securely fastened to the wearer's torso.

This design ensures that the Chest Harness [A] allows the wearer to breath freely but fits securely around the wearer's torso on parts of the wearer's back and torso that move very little relative to each other, thereby minimizing any shifting of straps, rubbing against the wearer's body, or slack in the Chest Harness [A], whatever movements the wearer makes. Thus any load attached to the harness is securely and comfortably fixed to the wearer's back. Additionally this design sits on the wearer's skeletal structure and avoids large muscle groups, reducing muscle fatigue and strain and facilitating heat loss.

The back panel of the pack [13] is stiff to ensure that the contents of the pack do not press through to interfere with the wearer's body. Padding covers the entire vertical spar [9] and the area across the top of the back above the shoulder blades. This padding both cushions the impact of the harness on immovable parts of the wearer's torso and serves to hold the back panel of the pack [13] away from the wearer's body to ensure that the shoulder blades are free to move unconstrained. This also facilitates heat loss out the side of the pack which may be further improved through channels in the padding. The flexible guiding rod [2] of the Flexible Spine [B] lies between the wearer's back and the pack, passing through the hole [17] in the back panel [13] and down to the Hip-belt [C]. The pack is held slightly away from the wearer's back by the shaping of the frame [10] to ensure the flexible guiding rod [2] is free to move and, together with the stiff backpanel [13] there is no interference with the wearer's back.

Any movement of the wearer while wearing this harness will create mechanical stress on the Flexible Spine [B]. The damping component of the sprung, damped system acts as a shock absorber to dampen these stresses and manage the variation in load (bounce) on the wearer's body by dissipating this kinetic energy. As an optional variant this embodiment may incorporate a Piezo-electric device, or other electrical generator into the sprung, damped system of the Flexible Spine [B] to convert the kinetic energy created by the movements of the load into electrical energy to charge any electric device attached to the pack.

Detailed description of a specific embodiment of the Invention -Second Embodiment: Multiple spar Flexible Spine to form a carrying harness The Flexible Spine [B] may comprise a single vertical support running from a single connection on the Chest Harness [A] down into a single connection into the Hip-belt [C], as shown in the first embodiment (see Figures 1-4) or it may comprise multiple vertical supports and/or multiple connections into the Hip-belt [C] and/or Chest-Harness.

In a second embodiment shown in Figure 5 the Chest Harness [A] and the Hip-belt [C] are largely as described in the first embodiment but the Flexible Spine [B] comprises two Gas struts [19] which connect to the Hip-belt [C] at the sides of the Hips in a hinged connection [20] facilitating forward and backwards motion and extend up to join the Chest Harness [A] at the base of the vertical spar [9]. The use of multiple gas struts [19] to construct the Flexible Spine [B] are different configurations of the same fundamental design but will alter the specific balance of requirements of the components of the Flexible Spine [B]. A single vertical rod [2], worn centrally on the wearer's back, as in the first embodiment, will require considerable flexibility, laterally, forwards and backwards in order to achieve the necessary flexibility to mirror the wearer's own spine. Using two gas struts [19], one on each side, will not require any flexibility laterally in each gas strut [19]. This is because lateral flexibility will be created by the interplay between the two struts, with one extending more than the other to create lateral flexibility in the Flexible Spine [B], while forward and backward and torsional flexibility is achieved through the hinge connections [20] into the Hip-belt [C] combined with differential extension of the struts. Therefore such an arrangement will require the capacity for greater extension in each gas strut [19] but would allow the struts themselves to be rigid. To accommodate different loads and lengths of wearers' backs both Gas struts [19] will require length adjustors [11] to ensure a comfortable fit for the wearer and ensure the Flexible Spine [B] is long enough for the entirety of the weight of the load to be transferred into the Hip-belt [C] and not be supported by the shoulder straps [12].

Using Gas struts automatically creates a sprung, damped system for the Flexible Spine [B]. However as an alternative these could be replaced with rigid rods and sprung, damped systems (such as a hydraulic piston, as described in the first embodiment) where they join the bottom of the vertical spar [9] to achieve the same effect.

In this embodiment the load is unspecified and Figure 5 shows the invention as a stand-alone carrying harness, unencumbered by the load. Since there is no pack requiring a frame, the shoulder straps [12] extend from the vertical spar [9] and are flexible all around the shoulders. The load would be attached to the vertical spar [9] by the attachment points [21]. As with the first embodiment the rigidity of the vertical spar [9] ensures that the entirety of the weight of the load is transferred via the Flexible Spine [B] down into the Hip-belt [C] and not supported by the Shoulder straps [12].

Detailed description of a specific embodiment of the Invention -Third Embodiment: Rucksack secured directly to Hip-belt with rail connection to Chest Harness In a third embodiment, shown in Figure 6, the load (in this case a gas cylinder [23]) is secured directly to the Hip-belt [C] and is connected to the Chest Harness [A] via a free-running connection -in this case a rail [24] on the vertical spar [9] of the Chest Harness [A] and a housing system for the rail [25] secured to the upper part of the cylinder [23].

The load may be secured to the Hip-belt [C] using elastic connections [22] to create a sprung loading system. The housing system for the rail [25] is connected to the load [23] on a swivel so that it can accommodate sideways twisting of the Chest Harness [A] relative to the Hip-belt [C]. Complete separation of Chest Harness [A] and Hip-belt [C] is again achieved and the weight of the load is carried in the Hip-belt [C]. The elastic connection [22] between the load and the Hip-belt may be made of material with memory properties to create a complete sprung, damped invention, or alternatively a damping system (eg. A friction damper) could be incorporated into the housing system [25].

Claims (10)

1. Claims: 1. A harness for a backpack comprising a support structure provided with a strap arrangement for retaining the support structure adjacent a wearer's back, the harness also comprising a hip belt connected to the support structure by a strut mechanism which, in use, resiliently biases the support structure upwards with respect to the hip belt.
2. 2. A harness as claimed in claim 1, in which the strut mechanism comprises the sole force-transmitting connection between the hip belt and the support structure.
3. 3. A harness as claimed in claim 1 or 2, in which the strut mechanism is laterally flexible.
4. 4. A harness as claimed in any one of the preceding claims, in which the strut mechanism comprises one or more telescopic struts
5. 5. A harness as claimed in claim 4, in which a spring acts in a direction to extend the strut mechanism.
6. 6. A harness as claimed in claim 5, in which the strut mechanism includes a means for damping extension of the strut mechanism.
7. 7. A harness as claimed in any one of the preceding claims, in which the strut mechanism comprises a single upwardly extending strut disposed substantially centrally of a wearer's back when in use.
8. 8. A harness as claimed in any one of the preceding claims, in which the strut mechanism comprises a telescopic strut having a piston displaceable in a cylinder, the piston and the cylinder being connected respectively to one and the other of the hip belt and the support structure.
9. 9. A harness as claimed in any one of the preceding claims, in which the strut mechanism incorporates a Piezo-electric device to generate electricity.
10. 10. A backpack comprising a harness in accordance with any one of the preceding claims, and a load secured to the harness.