Lanyard

A lanyard with attachment members such as a tool holding member, tether key, or carabiner, is provided. The lanyard includes one or more elastic cords within a sheath. The sheath has a much lower elasticity than the elastic cord. The higher spring constant or modulus of elasticity of the sheath limits the total extended length of the lanyard in operation. The elastic cords stretch to absorb the energy of falling equipment up to the length of the outer sheath. The attachment members may be attached to the sheath or may include components of the sheath and or the elastic cord. The lanyard allows for an elastic response to absorb the energy of a falling tool and a restraint to the total extended length of the lanyard.

BACKGROUND OF THE INVENTION

The present invention relates generally to the field of tools. The present invention relates specifically to a lanyard for connecting tools, or batteries, to an anchor point, for example, while working at height. Lanyards are used to attach to/support tools, batteries, components, and/or other equipment to provide security when an operator inadvertently drops the equipment. Lanyards also protect the tool or equipment from damage due to a fall.

SUMMARY OF THE INVENTION

One embodiment of the invention relates to a lanyard. The lanyard includes a first attachment member, a second attachment member, a sheath, and an elastic cord. The sheath includes a first end coupled to the first attachment member and a second end coupled to the second attachment member. The sheath defines an extended length between the first and second ends. The elastic cord has a first elastic cord end and a second elastic cord end. The first elastic cord end and the second elastic cord end are both attached to the first attachment member. The elastic cord defines a loop between the first attachment member and the second attachment member wherein the elastic cord is stretchable between an un-stretched length and stretched length. The un-stretched length is less than the extended length, wherein the elasticity of the sheath is less than the elasticity of the elastic cord.

Another embodiment of the invention relates to a lanyard. The lanyard includes a first attachment member, a second attachment member, a sheath, and four or more separate elastic cords. The sheath includes a first end coupled to the first attachment member and a second end coupled to the second attachment member. The sheath defines an extended length between the first and second ends. The four or more separate elastic cords are disposed within the sheath. Each elastic cord is coupled between the first attachment member and the second attachment member on opposite ends of the sheath. The elastic cord is stretchable between an un-stretched length and a stretched length. The un-stretched length is less than the extended length, such that the elasticity of the sheath is less than the elasticity of the elastic cords.

Another embodiment of the invention relates to a lanyard. The lanyard includes a tool holding member, a carabiner, a sheath, and one or more elastic cords. The sheath includes a first end coupled to the tool holding member and a second end coupled to the carabiner. The second end of the sheath is opposite the first end. The fully extended sheath defines a limiting tensioned length of the lanyard. One or more elastic cords are disposed within the sheath and couple to the tool holding member on a first end of the sheath and the carabiner at a second end of the sheath. The one or more elastic cords have a pre-tensioned length and a tensioned length. The tensioned length of the one or more elastic cords is less than or equal to the limiting tensioned length of the sheath. The limiting tensioned length of the sheath is between a 38% and 115% increase of the pre-tensioned length of the one or more elastic cords.

DETAILED DESCRIPTION

Referring generally to the figures, various embodiments of a lanyard are shown. Lanyards are used as a safety measure to secure tools to an anchor point, for example, while working at height. To enhance safety, a lanyard may couple to tools and tool batteries and tether them when operating the tools at height. Various regulations (e.g., OSHA regulations) may require a lanyard when an operator uses tools height. When a tool is dropped at height, the lanyard couples the tool to an anchor point and prevents the tool from dropping. This prevents a safety hazard and also protects the tool from the destructive influence of the fall.

Lanyards are designed to absorb and dissipate the energy of a fall. Lanyards that are too stiff may break or snap at the attachment points to either the tool or the anchor point or along the lanyard itself. Stiff lanyards allow a predetermined falling length, but often exhibit brittle material behavior and may break unexpectedly along the lanyard or at the attachment members. This brittle-like behavior is due to the stiff lanyards inability to absorb the energy of the falling object. Elastic materials show a far more ductile response to a falling object, but may not be effective in preventing an object from falling a specified distance. For example, a first object with a first weight will fall a different distance than a second object with a second weight when attached to the same elastic lanyard. Many factors, such as the height of the fall, the weight of the supported object, the spring constant of the elastic material, and others, determine the length of the deflection needed to support a falling object with an elastic lanyard. For a reliable lanyard, this unpredictability can be problematic.

Applicant has found that the use of a sheath of a stiff or inelastic material, such as nylon, surrounding an elastic material, such as natural rubber, creates a combination lanyard with the beneficial effects from both materials. The lanyard has a predictable limit to the total deflection defined by the total extended length of the inelastic sheath. In addition, the elastic properties of the cords within the lanyard absorb and dissipate most, if not all, the energy of the fall. This elastic energy dissipation prevents brittle-like fractures at the attachment points or along the sheath of the lanyard. The inelastic material reliably limits the fall distance.

One common attachment member at the ends of a lanyard is a carabiner. Carabiners can quickly attach to an anchor point, a tool, or a tool tether (coupled to or attached to the tool). Carabiners operate a gate in two positions, an open position and a closed position. In the open position, the carabiner may receive a loop or hook. Carabiners can be biased toward the closed position so that when the loop is received, the carabiner closes around the loop and prevents accidental release. However, often the loop is bigger than the gap or opening created by the carabiner, either between the gate and a first end of the carabiner or between the gate and the internal walls of the carabiner. This can cause binding of the loop within the carabiner and may prevent the carabiner from closing around the loop. Applicant has found that maintaining the distance between the gate and the internal walls of the carabiner to be greater than the distance between the gate and an end of the carabiner; lanyard binding is reduced. This is because there is more room for the lanyard loop once it passes through the gate (e.g., more room on the carabiner) than there is between the gate and the end of the carabiner.

As shown inFIGS. 1-4, a lanyard10is provided. The lanyard10includes a sheath14with a first end18and an opposite second end22. The first end18of the sheath14is coupled to a first attachment member24and the second end22is coupled to a second attachment member28. The extended sheath14defines an extended length between the first and second ends18and22of the sheath14. As illustrated inFIGS. 1-4, sheath14is bunched up or kinked about an elastic cord34. Thus the full extended sheath14is greater than the distance shown. The elastic cord34is free to extend within the length of the fully extended sheath14. The full length of the extended sheath14defines a reliable limit for the distance the lanyard10will allow attached equipment to fall.

The sheath14can be made of nylon or other suitable materials. For example, sheath14may be made from natural fibers or wool, cashmere, cotton, silk, linen, hemp, and/or other natural fibers. Sheath14may be made from synthetic fibers such as rayon, polyester, acrylic, acetate, nylon, polyamides, and/or other polymers. In this application, “nylon” will refer to any member of the family of polyamides such as nylon 6,6; nylon 6; nylon 6,12; nylon 5,10; and other polyamides. The sheath14can be formed from a nylon sheet material or a composite material, e.g., nylon and rubber. The sheath14may be formed from less than eighty strands of nylon for every twenty strands of rubber. For example, the sheath14may be formed of seventy-four strands of nylon for every twenty-six strands of rubber. The sheath14may be formed from seventy strands of nylon for every thirty strands of rubber. The sheath14may be formed from sixty strands of nylon for every forty strands of rubber.

In some embodiments, as shown inFIGS. 1, 3, 5 and 6, the lanyard10includes a carabiner26as a first attachment member24and a loop30as a second attachment member28. The loop30can be secured to a power tool, and the carabiner26can be secured to a fixed anchor point such as building, machine, a balcony rail/post, or other mounting structure. In other embodiments, as shown inFIGS. 2 and 4, the lanyard utilizes carabiners26as both the first and second attachment members24and28. In other embodiments, instead of a carabiner26or loop30, the first and second attachment members24and28can be anything capable of securing the lanyard10to a power tool and/or a fixed anchor point. As used herein, a fixed anchor point will refer to any structure that the lanyard is attached to that supports the equipment during a fall. Examples of a fixed anchor point include, but are not limited to, a balcony, a rail or railing, a wall, a support, or other fixed anchor locations for the lanyard.

In some embodiments, as shown inFIGS. 1 and 2, lanyard10may be coupled to a first linking member32and/or a second linking member36. Linking members32and36may have different elastic/inelastic properties than lanyard10. Linking members32and36may be another lanyard10coupled in series. Linking members32and36can be coupled in a semi-permanent fashion (e.g., through one or more swivels48) or in a releasable fashion (e.g., through one or more carabiners26). For example, first linking member32can link the first end18to the first attachment member24, such as the carabiner26, and a second linking member36can link the second end22to the second attachment member28, such as the loop30inFIG. 1or another carabiner26inFIG. 2. The first and second linking members32and36can also be made of nylon, nylon composite (e.g., nylon and rubber composite) or any other suitable material.

As shown inFIGS. 1, 2, and 10, the first linking portion32is comprised of a loop section40and a stitched section44that connects the loop section40to the first end18of the sheath14. As shown inFIGS. 1, 2, 3, 6, 8, 9 and 10the carabiner26can include a swivel48that permits the carabiner26to rotate with respect to the sheath14. In some embodiments, swivel48is fixed and prevents rotation of the carabiner26. In other embodiments, swivel48resists rotation or allows rotation to discrete locations about swivel48. As shown inFIGS. 1, 2, and 10, the loop section40of the first linking member32loops around the swivel48to couple the carabiner26to the first linking member32.

As shown inFIGS. 3 and 4, lanyard10includes an elastic cord34within sheath14. Elastic cord34includes a group of individual elastic strands58of a natural/synthetic rubber or elastomeric material coiled together to form elastic cord34. The elastic cord34may be formed from rubber or other suitable elastic materials. For example, the elastic cord34may be formed of natural rubber, elastomers, elastic polymers, neoprene rubber, unsaturated rubbers (e.g., polyisoprene or nitrile rubber buna-n), saturated rubbers (e.g., ethylene propylene rubber), thermoplastic elastomers (TPE), resilin, elastin, polysulfide rubber, elastolefin, and/or other ductile elastic materials. In addition, a composite sheath14or linking portion32or36may include these materials in proportion to an inelastic material (e.g., nylon). For example, sheath14or linking portion32or36may be formed from less than eighty strands of inelastic material (synthetic or natural, e.g., nylon 6,6) for every twenty strands of an elastic material (synthetic or natural, e.g., polyisoprene or natural rubber).

In some embodiments, as shown inFIG. 3, the elastic cord34is coupled to the first attachment member24(a carabiner26) at the first end18and defines the second attachment member28(a loop30) external to the second end22. Sheath14surrounds the elastic cord34and couples to the carabiner26at the first end18. As shown inFIG. 4, elastic cord34can be coupled to carabiner26at the first end18and another carabiner26at the second end22. For example, a loop30defined by the elastic cord34may be internal to the sheath14, such that loop30couples to attachment member28(e.g., carabiner26) or sheath14(e.g., at sheath end22) and does not form an external loop30. Sheath14may be coupled to the second attachment member28(e.g., carabiner26) to the internal loop30. Sheath14surrounds elastic cord34and couples to the carabiners26at the first end18and second end22. In some embodiments, elastic cord34is coupled to the first and second linking members32and36(e.g., as shown inFIGS. 1 and 2). In the embodiments ofFIGS. 3 and 4, the elastic cord34begins at the first end18and terminates at the second end22of sheath14.

Attachment members24and28may include a carabiner26, a loop30, a latch, a tether key or tether end, a buckle, a fastener, or another attachment to a tool or anchor point. Attachment members24and28may provide an anchor point to lanyard10or be a tool holding member. In operation, the first attachment member24, such as the carabiner26, can be secured to a fixed anchor point, and the second attachment member28, such as the loop30, can be secured to a tool (not shown) used by the operator. In this manner, if and when the operator drops the tool, the tool is elastically supported by the lanyard10up to the extended length of sheath14, which is secured to the anchor point. When the tool reaches the extended length of sheath14, the inelastic response of the sheath14dominates, providing a reliable limit to the distance the falling object travels, regardless of the weight, the height dropped, or other characteristics.

In some embodiments, as shown inFIG. 5, elastic cord34has a first end38, a second elastic cord end42, and a body46defined between the first and second ends38and42. Both the first end38and the second elastic cord end42are coupled to carabiner26. The body46is looped outside of the second end22of the sheath14, such that the body46defines loop30. The elastic cord34extends beyond the sheath14to form the external loop30. As illustrated inFIG. 5loop30is external to sheath14. In some embodiments, loop30is internal to sheath14and couples to an attachment member24or28(such as an inelastic loop30illustrated inFIG. 6or a carabiner26).

For example, inFIG. 5loop30, defined by elastic cord34, is external to the sheath14and defines the second attachment member28. Thus, in this embodiment, loop30is elastic, and there are two elastic portions50and54defined by the body46of one elastic cord34. The elastic portions50and54of body46extend within sheath14between the first and second ends18and22of the sheath14. For example, the first elastic cord end38and the second elastic cord end42are both attached to the first attachment member24, and the elastic cord34defines a loop30between the first attachment member24and the second attachment member28. In other embodiments, loop30, defined by elastic cord34, is internal to the sheath14. The loop30does not extend beyond sheath14but includes elastic portions50and54such that the first elastic cord end38and second elastic cord end42are both attached to sheath14at a first end18. The internal loop30may connect to an attachment member28at the second end22of sheath14.

The elastic cord34may stretch between an un-stretched length and a stretched length. The un-stretched length is less than the fully extended length of sheath14. Thus, sheath14is bunched up or kinked about the elastic cord34. The elasticity of the sheath14is less than the elasticity of the elastic cord34. This configuration enables the elastic cord34to stretch to absorb energy when lanyard10is supporting a falling object. The stretched length of the elastic cord34can vary between the un-stretched length of elastic cord34and the fully extended length of sheath14. Between these limits, the stretched length of the elastic cord34elastically absorbs the kinetic energy of the falling object.

In some embodiments, as shown inFIG. 6, lanyard10includes four or more separate elastic cords34within sheath14. In some embodiments, the four or more elastic cords34may form loops30, such that the first elastic cord end38and second elastic cord end42are both attached to the first attachment member24, and the elastic cords34define a loop30between the first attachment member24and the second attachment member28.

In the embodiment ofFIG. 6, each elastic cord34is separately coupled between attachment members24and28at either end18or22of sheath14. Each elastic cord34is coupled between the first attachment member24and the second attachment member28on the opposite end of sheath14. The elastic cords34are stretchable between an un-stretched length and a stretched length. The un-stretched length is less than the extended length of the sheath14, and the elasticity of sheath14is less than the elasticity of elastic cords34. As illustrated, attachment members24and28are a carabiner26and an inelastic loop30(e.g., nylon and not defined by elastic cords34), but may include any suitable attachment member24or28. In some embodiments, sheath14may include 5, 6, 7, 8, 9, 10, or more separate elastic cords34within the lanyard10separately coupled between attachment members24and28or forming loops30.

In some embodiments, as shown inFIG. 7, elastic cord34includes between thirty-six and fifty elastic strands58. Thus, in embodiments such as the one shown inFIG. 5, because there are two elastic portions50and54within the sheath14, there are effectively between seventy-two and one hundred elastic strands58of rubber between the first and second ends18and22of sheath14, but only thirty-six to fifty elastic strands58within elastic cord34. Similarly, in embodiments such as the one shown inFIG. 6, because there are four separate elastic cords34within the sheath14, there are effectively between one hundred forty-four and two hundred elastic strands58between the first and second ends18and22within sheath14. Additional elastic cords34have between N×36 and N×50 elastic strands58, where N represents the number of elastic cords34within sheath14. For example, five elastic cords34(N=5) have between 5×36=180 and 5×50=250 elastic strands58. In some embodiments, two or more elastic cords34may form a loop30within sheath14to create four or more elastic portions50and54. For example, two elastic cords34may form four elastic portions50and54and comprise between seventy-two and one hundred elastic strands58of rubber.

Carabiner26, as shown inFIGS. 8 and 9, has a body62with a first end66and a second end70which functions as a latch or gate78. Gate78is pivotable over a range of motion82between a first “closed” position and a second “open” position. For example, when gate78moves from the closed position (illustrated inFIGS. 1-6) to the open position (illustrated inFIGS. 7-8), an opening74is formed between gate78and first end66. Opening74is defined when gate78is open between the first end66and second end70of carabiner26.

Carabiner26may be biased towards the closed position. Applying pressure to gate78pivots the gate78between the closed position in which the gate78engages the second end70and the open position, in which the gate78has pivoted the maximum possible distance over the range of motion82, thus maximizing the expanded opening74. Once pressure is released, gate78engages the second end70in the closed position. Gate78can latch and/or lock to the second end70of carabiner26to securely close carabiner26and keep it closed. In some embodiments, gate78is biased by a biasing member, such as a spring (not shown), towards the closed position. Gate78may include a lock or cover (not shown) that rotates or slides to cover second end70and secure gate78in the closed position to prevent accidental opening or release of carabiner26.

The body62of the carabiner26may optionally be attached to swivel48and includes a first end66, a first wall portion86, a second wall portion90, and a second end70. The shape of carabiner26is defined by body62at the first wall portion86and the second wall portion90. The first wall portion86is approximately parallel to the gate78when the gate78is in the closed position and the second wall portion90is linked to the first wall portion86. For example, second wall portion90may make an acute, obtuse, or right angle with first wall portion86. As illustrated, the second wall portion90makes an acute angle with the first wall portion86, which is approximately parallel to gate78in the closed position. Other configurations and embodiments of carabiner26, including non-parallel and/or alternate angles are envisioned.

As shown inFIGS. 8-9, a gate separation distance94is defined as the distance between the gate78and the second end70in the open position where gate78has pivoted the maximum possible distance over the range of motion82and maximized opening74. A wall separation distance98is defined as the minimum distance between the gate78and the first wall portion86or the second wall portion90over the pivotal range of motion82. As illustrated inFIG. 8the horizontal wall separation distance98is less than the vertical wall separation distance98. Thus the wall separation distance98is the horizontal wall separation distance98.

By inspection ofFIGS. 8-9we see two different relationships of the gate separation distance94and wall separation distance98, as defined above. InFIG. 8the minimum wall separation distance98(e.g., horizontal wall separation distance98) is less than the gate separation distance94. InFIG. 9the vertical wall separation distance98in the open position is less than the horizontal wall separation distance98. Therefore the vertical wall separation distance98defines the wall separation distance98. InFIG. 9, the gate separation distance94is less than the minimum (“vertical”) wall separation distance98.

Carabiner26includes gate78pivotably coupled to a first end66of carabiner26. Gate78is configured to clasp a second end70of the carabiner26in a closed position. Rotation of the gate78to an open position defines the minimum wall separation distance98between gate78in the open position and walls86and90of the carabiner26. The open position also defines a gate separation distance94between the second end70of the carabiner26and gate78. In some embodiments, the minimum wall separation distance98between the gate78and walls86and90is greater than the gate separation distance94between the gate78and the second end70of carabiner26.

In the configuration ofFIG. 9, the first wall portion86and second wall portion90are arranged with respect to the gate78such that the wall separation distance98is greater than the gate separation distance94. Thus, in the second position of the gate78, any square or round article, loop, or hook that is large enough to enter the carabiner26through the opening74can move past gate78and allow gate78to move back to the closed position. This allows carabiner26to lock the article or hook securely. In other words, the first wall portion86and second wall portion90are arranged with respect to the gate78such that the article or hook does not force gate78to stay open. Ensuring that the gate separation distance94is less than the minimum wall separation distance98reduces binding and ensures that gate78can return to the closed position. In this manner, the carabiner26ofFIG. 9provides greater ease of use for an operator than the carabiner26ofFIG. 8.

FIGS. 10-19illustrate the lengths of various lanyards10measured in the test.FIGS. 10 and 17define two tested configurations of lanyard10.FIG. 11illustrates the test methodology.FIGS. 12-16illustrate the measured results of the test applied to lanyard10ofFIG. 10.FIGS. 18-19illustrate the measured results of the test applied to lanyard10ofFIG. 17.

As shown inFIG. 10, a total length102of the lanyard10can be broken down into six separate sub-lengths: (1) a length106of the carabiner26; (2) a length110of the loop section40; (3) a length114of the stitched section44; (4) a length118of the elastic cord(s)34(not shown inFIG. 10) between the first and second ends18and22and within the sheath14; (5) a length122of the second linking member36; and (6) a length130of the loop30. The purpose of the test is to see how the elasticity of these lengths varies while supporting various weights dropped from the height of the un-stretched elastic cord(s)34above a fixed anchor point (or 2×'s the unsupported distance of the un-stretched elastic cord(s)34).

FIG. 11shows the positions of the lanyard10both before and after a 2× drop test. The drop test height column of the Table inFIG. 12uses the reference “2×” when referring to the lanyard10being dropped, as indicated by arrow170, from a height174that is two times the un-tensioned length142of the elastic cords34within lanyard10. The un-tensioned length142of the lanyard10shown inFIG. 11corresponds to “Pre-drop total length102” column or the un-tensioned length of the lanyard10for the 2× drop test trials. A dotted line178indicates when the elastic cords34within lanyard10become tensioned and stretch. The test is designed to not extend to the fully extended length of sheath14to test the elastic response of the lanyard10system. For the lanyard10tests ofFIG. 10, tool150is secured to loop30and dropped from an initial position182(2× the un-stretched length of the elastic cord(s)34) to a final position186in which the elastic cord(s)34is fully stretched within sheath14. Carabiner26of lanyard10is secured at the point162. A fully stretched length190of elastic cord(s)34and other components of lanyard10, shown inFIG. 11, corresponds to the “Stretched Total Length102” column in the Table for the 2× drop test height trials.

For each category of weight-rated lanyard10, there are three types of drop tests, as explained below. First, the lanyard10was subjected to a first 2× drop test while supporting the rated weight of the lanyard10and a peak force on the lanyard10was measured for this first drop. Second, the lanyard10was subjected to nine more individual 2× drop tests while supporting the rated weight of lanyard10. For each of these nine additional drops, the peak force on lanyard10was measured. The value listed in the Table inFIG. 12represents the maximum individual peak force measured among the ten total drops, which includes the first drop and the nine subsequent drops supporting the rated weight of lanyard10. Third, lanyard10was subjected to three 2× drop tests while supporting two times the rated weight of lanyard10, and the peak force was measured for each of those three drops. The maximum individual peak force measured among those three drops is listed in the table ofFIG. 12. For example, for the ten-pound weight-rated lanyard10with a total pre-drop length of 921 mm, the peak force of the first drop while supporting ten pounds was 82 lbf., the maximum peak force over ten drops while supporting ten pounds was 123 lbf., and the maximum peak force over three drops while supporting twenty pounds was 268 lbf.

During a drop, the length118of the elastic cord(s)34can change between four separate stages: (1) an initial un-tensioned stage; (2) a tensioned stage when the length of the elastic cord(s)34is less than the length of the unkinked sheath14; (3) a tensioned stage where the length of the elastic cord(s)34is equal to the fully extended length of sheath14; and (4) a fully stretched stage in which the elastic cord(s)34and/or the sheath14become entirely stretched. In the Table above, the initial un-tensioned stage values are represented in the “Un-tensioned length118of elastic cord(s)34” column, and the fully stretched stage values are represented in the “Fully stretched length118of elastic cord(s)34” column.

When the elastic cord(s)34becomes the same length as the unkinked sheath14, it is between 38% and 115% longer than its un-tensioned length. When the elastic cord(s)34becomes the same length as the unkinked sheath14, the sheath14becomes tensioned, and the elastic cord(s)34and the sheath14begin stretching together as a system. As demonstrated in the Table above, the respective lengths of the sheath14and elastic cord(s)34are selected to provide a lower peak force when a weight (e.g., of a tool) is near the lanyards' rated weight and when the weight on the tool150is dropped from a height greater than the un-tensioned length142of lanyard10.

Because the sheath14is inelastic, the fully extended length of sheath14roughly defines a limiting tension length of lanyard10. When the one or more elastic cords34within sheath14are stretched between a pre-tensioned length and a tensioned length, they are unrestrained up to the fully extended length of the sheath14. When the tensioned length reaches the length of the fully extended sheath14, the elastic cords34reach the limiting tension length of lanyard10. Thus, the tensioned length of the elastic cord(s)34is less than or equal to the limiting tensioned length of sheath14. In some embodiments, the limiting tension length of sheath14is between 30% and 125% greater than the pre-tensioned length of the elastic cord(s)34. In some embodiments, the limiting tension length of sheath14is between 38% and 115% greater than the pre-tensioned length of elastic cord(s)34. The limiting tension length of sheath14may be between 45% and 110% of the pre-tensioned length of elastic cord(s)34. The limiting tension length of sheath14may be between 50% and 105% of the pre-tensioned length of elastic cord(s)34. The limiting tension length of sheath14may be between 55% and 100% of the pre-tensioned length of elastic cord(s)34.

In the tests described below, the length of the sheath14was selected to study the elastic properties of the elastic cord(s)34. As such, the length of sheath14was selected to be greater than the elastic response of the lanyard10system to prevent the limiting tensioning length of the sheath14from interfering with the test results.

As shown in the Table inFIG. 12, test data of different weight-rated lanyards10demonstrate the respective stretching lengths of the above six sub-lengths when the lanyards10are subjected to different drop tests. In all of the drop tests listed in the Table ofFIG. 12, the length106of the carabiner26remains constant at 86 mm and does not change as the lanyard10stretches. Similarly, in all of the tests, the length114of the stitched section44of sheath14remains constant at 36 mm and the length122of the second linking member36(e.g., nylon) remains constant at 36 mm. In other words, none of the lengths106,114,122change as the lanyard10is stretched while dropped. Because the sheath14has a large modulus of elasticity (spring constant) and a lower elasticity than the elastic cord(s)34, the sheath14limits the length the lanyard10can stretch.

In another embodiment of a lanyard192shown inFIG. 17, the lanyard192includes, in series, a first carabiner194, a swivel member196, a first linking member198including a loop section202and a stitched section206, a sheath210, a second linking member214including a stitched section218and a loop section222, a second carabiner226, a tether230, and a tether attachment member236. As in previous embodiments, elastic cord(s)34(not shown inFIG. 17) is arranged within sheath210and is coupled between the stitched section206of the first linking member198and the stitched section218of the second linking member214.

As shown inFIG. 17, a total length240of the lanyard192can be broken down into nine separate sub-lengths: (1) a length244of first carabiner194; (2) a length248of loop section202; (3) a length252of stitched section206; (4) an unstretched length256of elastic cord(s)34(not shown inFIG. 17) between the stitched section206of the first linking member198and the stitched section218of the second linking member214and within the sheath210; (5) a length260of the stitched section218; (6) a length264of the loop section222; (7) a length268of the second carabiner226; (8) a length272of the tether230; and (9) a length276of the tether attachment member236. Additionally, total length240can be subdivided into first sub-length280, from first carabiner194to second carabiner226, and a tether230sub-length284, from tether230to tether attachment member236.

The same drop tests illustrated inFIG. 11were performed with lanyard192in the same manner as described above, and the results are listed in a Table shown inFIG. 18. In all of the drop tests listed in the Table ofFIG. 18, the lengths244,268of the first and second carabiners194and226both remain constant at 86 mm and 96 mm, respectively, and do not change as the lanyard192stretches. Similarly, in all of the tests, the length252of the stitched section206of sheath14and the length260of the stitched section218of sheath14both remain constant at 36 mm. In other words, none of the lengths244,252,260and268change as the lanyard192is stretched while dropped. This suggests that the sheath14has a large modulus of elasticity or spring constant and a lower elasticity than the elastic cord(s)34. Thus the length of sheath14defines a practical limit to the total extension of the lanyard10. The elastic cord(s)34is free to stretch and absorb the energy of a fall up to the extended length of sheath14.

FIG. 19illustrates data from the drop tests correlating respectively to the lanyard192, as related to the results shown inFIG. 18. Specifically it shows the percentage elongation of the elastic cord(s)34for 2× tests on (1) the first drop at the rated weight, (2) the maximum elongation after 10 drops at the rated weight, and (3) the maximum elongation after 3 drops at twice the rated weight for lanyard192.