Adjustable Load-Distribution Insert for Dual Carrying Straps

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application No. 63/733,840, filed Dec. 13, 2024, the entire disclosure of which is hereby incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

None.

REFERENCE TO SEQUENCE LISTING, TABLE, OR COMPUTER PROGRAM LISTING

None.

FIELD OF THE INVENTION

The invention relates to load-carrying equipment and, more particularly, to inserts for connecting dual shoulder straps to improve comfort, stability, and load distribution on backpacks, weighted vests, and similar carrying systems.

BACKGROUND OF THE INVENTION

Backpacks, weighted vests, and other devices that rely on dual shoulder straps often concentrate downward forces on a user's trapezius muscles. While some products incorporate strap bridges or chest straps, these solutions are typically static, narrow, or lacking adjustability. Known connectors do not:

• • dynamically adjust the spacing between shoulder straps,
  • distribute load over a wider shoulder region,
  • incorporate a flexible body capable of laterally expanding and contracting, or
  • integrate ventilation channels formed by layered and folded flexible materials.

Furthermore, existing products do not provide a simple retrofit kit that attaches externally to existing straps without sewing, cutting, or modifying the load-carrying device.

There remains a need for a flexible, laterally expandable insert positioned between shoulder straps that improves comfort, adapts to users of varying shoulder widths, controls expansion when lifted by the straps, and can be integrated into new products or retrofitted to existing straps.

SUMMARY OF THE INVENTION

The invention provides an adjustable load-distribution insert configured to connect two shoulder straps. The insert includes a flexible body that expands laterally as the user moves, thereby distributing load across a broader shoulder region. A rigid control piece may be included to prevent excessive expansion, especially when the straps are used as a handle to lift the carrier.

In some embodiments, the flexible body includes:

• • an upper flexible layer,
  • a lower flexible layer, and
  • folded portions of the lower layer forming ventilation channels that improve comfort and provide natural elasticity.

A retrofit embodiment includes a flexible connector body and attachment mechanisms that allow the insert to be removably coupled to existing straps without sewing. Attachment mechanisms may include openings through which straps are routed, hook-and-loop systems, buckles, or magnetic couplers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a user wearing a load-carrying device with an integrated insert assembly, showing strap sleeves 150, 151.

FIG. 2 is a perspective view of the insert assembly connecting two shoulder straps via sleeves 150, 151.

FIG. 3 is a perspective view of the insert assembly with rigid control strap 210 configured with an adjustable ladder buckle 220.

FIG. 4A is a cross-section view of a layered flexible body 110 in a relaxed state.

FIG. 4B is a cross-sectional view of a layered flexible body 110 in an expanded state, showing the rigid control piece 210 taut.

FIG. 4C is a side view showing the folded lower flexible layer 110c forming ventilation channels 310.

FIG. 4D is a bottom view of the folded lower flexible layer 110c forming ventilation channels 310.

FIG. 5A is a perspective view of a retrofit kit embodiment of the insert assembly 400 installed on existing shoulder straps.

FIG. 5B is an isolated perspective view of the retrofit kit showing attachment pieces 450, 460 and strap-routing openings 410, 420, 430, 440.

DETAILED DESCRIPTION OF THE INVENTION

The following description refers to the figures, which illustrate example embodiments.

Integrated Insert Embodiments (FIGS. 1-2)

A load-carrying device includes a first shoulder strap 120 and a second shoulder strap 130. An insert assembly 100 connects these straps near the user's upper shoulders.

The insert assembly includes a flexible body 110 attached to the straps via stitching 115 (left) and 116 (right) as shown in FIGS. 1 and 2. In some embodiments, the straps include sleeves 150, 151 that receive ends of the flexible body.

During use, lateral movement of the user's shoulders causes straps 120 and 130 to move apart. Flexible body 110 expands laterally to accommodate this motion, distributing load across a wider area.

Rigid Control Mechanism (FIG. 3)

A rigid control piece optionally overlies or integrates with the flexible body to limit maximum lateral expansion.

The inelastic strap 210 is secured to the main body assembly at a fixed attachment point 240, such as by stitching, and is secured at the opposite end by the adjustable buckle 220.

Inelastic strap 210 defines fixed length. Buckle 220 (ladder-lock, tri-glide, or cam lock) allows users to set expansion limits.

When straps are lifted together, the control piece prevents over-elongation, maintaining handle integrity.

Flexible Body With Ventilation Channels (FIGS. 4A-4D)

The flexible body 110 includes an upper flexible layer 110a and a lower flexible layer 110c.

FIG. 4A—Relaxed State

The layers 110a and 110c are shown in an unexpanded condition. Lower layer 110c includes folded portions forming ventilation channels 310. Rigid control piece 210 is present but slack or unengaged in this state.

FIG. 4B—Expanded State

As straps separate, upper layer 110a and lower layer 110c expand laterally. Rigid control piece 210 becomes taut, defining the maximum lateral expansion of flexible body 110.

Materials may include elastic fabric, elastomeric webbing, TPU laminates, spacer mesh, or woven elastic composites. Rigid piece 210 may include webbing, polymer reinforcement, or composite strips.

FIGS. 4C-4D—Side and Bottom Views

The figures illustrate the folded construction of the lower layer 110c and the geometry forming ventilation channels 310. These channels are formed by folding parts of the lower layer and can be secured with stitching or other methods. This design is intended to increase comfort and give the layer natural elasticity.

Additional Variations

The rigid control piece 210 can be implemented as a separate strap (as in FIG. 3) or as an integrated substantially inelastic layer.

Flexible-Only Embodiment

In some embodiments, the rigid control piece is omitted, leaving only the flexible body to provide expansion. This version maximizes adjustability and is suitable for lightweight applications.

Retrofit Kit Embodiments (FIGS. 5A-5B)

A retrofit kit 400 enables installation onto existing straps without modification.

FIG. 5A—Installed

Straps are routed through attachment mechanisms located on opposite sides of the flexible connector body.

FIG. 5B—Isolated View

A retrofit kit 400 is provided for aftermarket application to existing load-carrying devices with two independent shoulder straps 120, 130. The kit 400 comprises a central flexible connector body 110 and a pair of attachment mechanisms on its lateral sides.

In one embodiment, the attachment mechanisms comprise a first attachment piece 450 permanently secured (e.g., via stitching 115) to a first lateral side of the body 110, and a second attachment piece 460 permanently secured (e.g., via stitching 116) to a second lateral side. These attachment pieces 450, 460 are formed to create two distinct pairs of openings: a first pair 410, 420 and a second pair 430, 440. See FIG. 5B for openings 410, 420, 430, 440.

An optional rigid control strap 210 with a buckle 220 is installed to prevent over-elongation. In this embodiment, the optional rigid control strap 210 is permanently secured to the first attachment piece 450 at the attachment point 240 (e.g., via stitching) and to the adjustable buckle 220 on the second lateral side.

During installation, the first shoulder strap 120 is threaded sequentially through the first pair of openings 410 and 420, and the second shoulder strap 130 is threaded through the second pair 430 and 440. This configuration, where each strap passes through two separate openings, stabilizes the straps 120, 130, preventing them from twisting, rolling, or shifting during user movement.

The attachment pieces 450, 460 may be curved to better conform to and distribute load evenly across a user's shoulder region, including the trapezius muscles. Furthermore, the bottom surface of the attachment pieces 450 and 460 may be ventilated (e.g., via channels 310) to facilitate airflow.

The primary functional advantage is personalized load distribution. The kit 400 dissipates the downward force of the straps—which would otherwise concentrate on narrow areas—across the broader, robust areas of the shoulders. This enables the user to carry a load with significantly improved comfort. The entire kit 400 attaches externally without modifying the original load-carrying device.

In variations, alternative attachment mechanisms may be used, such as hook-and-loop fasteners, adjustable strap buckles, or magnetic couplers, to secure the flexible connector body 110 to the shoulder straps 120, 130.

Additional Variations

The invention may include any of the following variations:

• • 1. Alternative shapes such as tapered, curved, or Y-shaped inserts.
  • 2. Alternative channel geometries including zig-zag folds or molded elastomer channels.
  • 3. Different layered materials including mesh, foam, elastic composites, or TPU films.
  • 4. Alternative rigid control systems including segmented plates or dual limiters.
  • 5. Various retrofit attachment mechanisms including buckles, loop-through tunnels, or magnetic couplers.

These remain within the scope of the invention as defined by the claims.