US20070085320A1

US20070085320A1 - Sled with a calf-securing strap

Info

Publication number: US20070085320A1
Application number: US11/610,800
Authority: US
Inventors: David Sellers; Parker Sellers
Original assignee: Mad River Rocket Co
Current assignee: Mad River Rocket Co
Priority date: 2002-12-24
Filing date: 2006-12-14
Publication date: 2007-04-19
Also published as: US7165775B1; US20130307233A1; US8840120B2

Abstract

A sled includes a hull and a strap extending transversely across the hull. The strap extends across the hull at a first longitudinal position selected such that it extends across the calves of a kneeling rider. This enables the rider to kneel erect when riding the sled.

Description

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No. 10/716,032, filed on Nov. 17, 2003, and a continuation-in-part of U.S. patent application Ser. No. 10/329,288, filed on Dec. 24, 2002, the contents of which are herein incorporated by reference in their entirety.

FIELD OF THE INVENTION

The invention relates to sleds, and in particular, to sleds having a restraint system.

BACKGROUND

To a great extent, control over a moving sled is achieved by shifting one's weight. When turning, for example, one leans in the direction of the turn. In negotiating bumpy terrain, one constantly leans forward and backward in an effort to keep the sled on the snow.
In effect, the shifting of one's weight causes small, almost imperceptible perturbations in the position of an imaginary point, referred to as the center-of-mass. A rider's ability to quickly and precisely control these perturbations permits the performance of various stunts or acrobatic maneuvers on the sled.
A rider can shift the center of mass in three dimensions. By leaning to one side, the rider shifts the center-of-mass transversely. Leaning backwards or forwards shifts the center-of-mass longitudinally, Sitting up straight or crouching shifts the center-of-mass vertically.
Known sleds, such as that disclosed in Sellers, U.S. Pat. No. 4,666,171, feature a strap extending transversely across the rider's knees. This strap secures the rider's legs in a flexed position, and thereby limits the rider's ability to vertically adjust the center-of-mass.

SUMMARY

In one aspect, the invention includes a sled having a hull and a strap extending transversely across the hull. The strap extends across the hull at a first longitudinal position selected such that it extends across the calves of a kneeling rider. This enables the rider to kneel erect when riding the sled.
In one embodiment, the strap is adjustable between the first longitudinal position and a second longitudinal position. The second longitudinal position in this case can be selected such that when the strap is extended across the hull the second longitudinal position, it extends across the thighs of a kneeling rider.
Another embodiment includes a first pair of transversely opposed anchor points on opposite sides of the hull for engaging respective first and second ends of the strap. The anchor points are disposed astern of a shin-receiving area on the hull such that the strap extends across the calves of a kneeling rider.
In certain embodiments, an optional second pair of anchor points is disposed to be adjacent to the shin-receiving area. A strap extending between the anchor points of the second pair thus passes across the thighs of a kneeling rider.
In another aspect, the invention includes a sled having a hull and a first pair of transversely opposed anchor points on opposite sides of the hull for engaging respective first and second ends of a strap. The anchor points are disposed such that a strap extending between the anchor points extends across the calves of a kneeling rider.
One embodiment also includes a strap extending across the hull between the anchor points.
In another embodiment, there is a second pair of transversely opposed anchor points on opposite side of the hull for engaging respective first and second ends of a strap. The second pair of anchor points being longitudinally displaced relative to the first pair of anchor points. For example, the second pair of anchor points can be disposed such that a strap extending between the anchor points of the second pair extends across the thighs of the kneeling rider.
These and other features and advantages of the invention will be apparent from the following detailed description and the accompanying figures, in which:
These and other features and advantages of the invention will be apparent from the following detailed description and the figures, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are top and side view of a hull for a sled;
FIG. 3 is a cross-section of the hull shown in FIGS. 1 and 2;
FIGS. 4-6 show a configuration for attaching a strap to the hull;
FIGS. 7-10 show sleds having variable-length straps;
FIG. 11 shows a sled having a strap configured to secure a rider's calves; and
FIGS. 10-14 show sleds having center anchors.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A downhill racing sled suitable for incorporating the features of the invention described with particularity in Sellers, U.S. Pat. No. 4,666,171, the contents of which are herein incorporated by reference.
As shown in FIGS. 1-3, the sled includes a one-piece elongated molded hull 10, preferably of vacuum-molded thermoplastic. The hull 10 has a bow or front-end, which is on the right as viewed in FIGS. 1 and 2, and a stern, or rear-end, which is on the left as viewed in FIGS. 1 and 2. Between the bow end and the stern end are a pair of optional contoured shin pads 40 on which a rider kneels while riding the sled.
The hull 10 presents a generally crescent-shaped profile, best seen in FIG. 2. An upper outwardly rolled molded edge of the hull 10 forms continuous railing or gunwales 12 surrounding the hull 10. The gunwales 12 are raised at the bow to afford handholds and to protect against the intrusion of snow. The bottom of the hull 10 while generally curved in profile as shown in FIG. 2, includes certain features that enhance the sled's performance in deep snow.
Between the two runners 14 and 16, a main central channel 30 extends along a mid-line of the hull 10 from the bow to the stern with progressively increasing depth as shown in FIGS. 2 and 3. The inside ribs 20 and 22 define the edges of the channel 30 and are slightly outwardly flared with gradually increasing spacing at both ends of the hull 10. Inside the hull 10, the molded channel 30 forms a large longitudinal central rib or keel-like hump 32 running down the center of the hull 10. Because of the increasing depth of the snow channel 30 toward the rear of the hull 10, the hump 32 becomes more pronounced toward the rear as shown in phantom in FIG. 2.
Referring now to FIG. 4, side portions of the gunwale 12 are rolled outward to form a lip 56. This lip 56 curls downward to form a rim portion 58 parallel to the hull 10 and separated therefrom by a gap 60. An outboard hole 62 through the rim portion 58 is aligned with an inboard hole 64 through the hull 10. Molded retaining walls 66A-B, seem in isometric view in FIG. 5 flank the inboard hole 64 and extend outward from the hull 10, part way across the gap 60.
A strap 36 has a grommet 68 at each of its two ends, one of which is shown in FIG. 6. To attach the strap 36 to the hull 10, a grommet hole 70 defined by the grommet 60 is aligned with the inboard hole 64. Then, a threaded ½ inch bolt 72 is passed through the grommet hole 70 and through the inboard hole 64. The bolt 72 is long enough to extend through the inboard hole 64 and all the way to the outboard hole 62. Preferably, the bolt 72 extends approximately 3/16 inches beyond the outboard hole 62 to ensure adequate support by the edge of the outboard hole 62.
A nut 74 is then threaded onto the bolt 72 to secure the bolt 72 to the hull 10. When the nut 74 is fully tightened, it comes to rest snugly between the retaining fins 66A-B, as shown in FIG. 8. The retaining fins 66A-B thus limit rotation of the nut 74 in response to torque transmitted by the strap 36. By doing so, the retaining fins 66A-B reduce the likelihood that the nut 74 will loosen during use. The nut 74, the bolt 72, and the walls forming the inboard and outboard holes 62, 64 collectively define a strap anchor 65.
Because of its strength, metal is typically used for making the nut 74 and bolt 72. However, other materials, such as plastic can be used.
A shear force exerted on the strap 36 is transmitted to the hull 10 by the bolt 72. However, the hull 10 supports the bolt 72 at two different points, namely at the edge of the inboard hole 64 and also at the edge of the outboard hole 62. As a result, the strap-anchoring configuration shown in FIGS. 4-6 resists the tendency of the bolt 72 to pivot about a single support in response to a shear force. It does so by resisting shear force using shear resistance provided by the hull 10 at two different support points.
By concealing the nut 74 and bolt 72 from view, the rim portion 58 of the lip provides the hull 10 with a more attractive and streamlined appearance. This appearance can be enhanced by coloring the end of the bolt 72 or by extending the end of the bolt 72 slightly beyond the rim portion 58 so it can be capped.
In addition, by covering the nut 74 and bolt 72, the rim portion 58 also prevents the nut 74 and bolt 72 from snagging on nearby objects, such as the rider's clothing.
In one embodiment, the strap 36 has a length that varies in response to the force exerted thereon. An example of such a strap 36 is an elastic strap as shown in FIG. 7. Another example is a strap 36 having one or more elastic sections 76A-B, as shown in FIG. 8. In this case, the strap 36 has a pair of inelastic grommet sections 78A-B that accommodate the grommets 68 and a central inelastic section 80 for securing the rider. Each grommet section 78A-B is connected to the central inelastic section 80 by a corresponding one of the elastic sections 76A-B. Yet another example, shown in FIG. 9 is a strap 36 having a pair of inelastic grommet sections 78A-B joined by a central elastic section 82.
Preferably, the elasticity of the strap 36, or the elasticity of an elastic section thereof, is such that the strap 36 changes in length by no more than three inches. A strap 36 that is excessively elastic, in which the length changes significantly, will fail to restrain the rider. A strap 36 that has too little elasticity will be uncomfortable in the presence of high g-forces.
The elastic sections can be made of a manufactured fiber in which the fiber-forming substance is a long-chain synthetic polymer comprised of at least 85% of a segmented polyurethane. An exemplary fiber having these properties is presently sold under the name SPANDEX™. The elastic sections can also be made of a manufactured elastic fiber sold under to name SPANDURA™.
The inelastic sections can be made of a manufactured fiber in which the fiber forming substance is a long-chain synthetic polyamide in which less than 85% of the amide-linkages are attached directly (—CO—NH—) to two aliphatic groups. An exemplary fiber having these properties is presently sold under the name NYLON™.
Another embodiment, shown in FIG. 10, features an elastic section 76A in which the elasticity is provided by a spring 84. The spring 84 is sheathed by a fabric jacket 86 (opened to expose the spring 84 in FIG. 10) to protect the rider's clothing from being caught by the spring 84 as it expands and contracts.
The longitudinal position of the strap anchor 65 can be chosen so that the strap 36 extends across the hull 10 above the shin pads 40. In this configuration, the strap 36 extends over the rider's thighs. However, the strap 36 can also be placed astern of the shin pads 40 so that the strap 36 extends over the rider's calves and thereby frees the rider from having to ride with fully flexed knees at all times. A rider thus freed is able to kneel erect or partially erect in the sled, thereby enabling the rider to shift the center-of-mass vertically by a distance that corresponds to the difference between the rider's fully erect position and the rider's fully crouched position.
In FIG. 11, the strap 36 can be switched between a rear pair of strap anchors 65 and a forward pair of strap anchors 88 that are structurally the same as the rear pair of strap anchors 65 but positioned over the shin pads 40. The sled shown in FIG. 11 is thus convertible between the configuration shown in FIG. 11, in which the strap 36 secures the rider's calves, and a configuration in which the strap 36 secures the rider's thighs.
A disadvantage of having a single strap 36 that extends across the hull 10 is that in sharp turns, both of the rider's legs are apt to shift laterally. This causes the center-of-mass of the combined rider and sled to also shift laterally. This lateral shift during a turn undermines the stability of the turn and, in extreme cases, can capsize the sled.
To avoid this difficulty, another embodiment of the sled features a center anchor 90 at the mid-line of the hull 10. An exemplary center anchor 90, shown in FIG. 12, is a longitudinally extending horizontal bar 92 supported over the hull by a vertically-extending bow leg 94A and a vertically-extending stern leg 94B. The bar 92 and the two legs 94A-B define an aperture 96 through which a strap 36 extending transversely across the hull 10 passes. When the strap 36 is looped through the center anchor 90, as shown in FIG. 12, the rider's legs are individually secured. This makes it more difficult for the rider's legs to shift laterally in a sharp turn.
In FIG. 13, the single strap 36 extending across the hull 10 is replaced by a pair of straps 98A, 98B, each one of which extends from a strap anchor 65 to the center anchor 90. This embodiment enables the rider to individually adjust the straps 98A, 98B.
In another embodiment, shown in FIG. 14, the center anchor 90 is molded and/or padded to more closely fit the rider's thighs. This embodiment can be configured to accommodate a single strap 36 looping through an aperture in the center anchor 90 or a pair of straps extending in opposite directions from the center anchor 90 to each of the two sides of the hull 10.
The invention has been described in the context of a specific recreational racing sled. However, the various features of the invention can readily be incorporated other types of recreational sleds.
Having described the invention, and a preferred embodiment thereof, I now claim as being new and secured by letters patent:

Claims

1. A sled comprising:

a hull;

a strap extending transversely across the hull at a first longitudinal position selected such that the strap extends across a calf of a kneeling rider; and

a center anchor coupled to the strap.

2. The sled of claim 1, wherein the strap is adjustable between the first longitudinal position and a second longitudinal position.

3. The sled of claim 2, wherein the second longitudinal position is selected such that the strap, when extended across the hull at the second longitudinal position, extends across a thigh of the kneeling rider.

4. The sled of claim 1, further comprising

a first pair of transversely opposed anchor points on opposite sides of the hull for engaging respective first and second ends of the strap,

the anchor points being disposed astern of a shin-receiving area on the hull such that the strap extends across the calves of a kneeling rider.

5. The sled of claim 4, further comprising a second pair of anchor points disposed over the shin-receiving area such that a strap extending between the anchor points extends across a thigh of a kneeling rider.

6. The sled of claim 1, further comprising means for selectively engaging the strap at one of the first longitudinal position and a second longitudinal position.

7. A sled comprising:

a hull;

a first pair of transversely opposed anchor points on opposite sides of the hull for engaging respective first and second ends of a strap, the anchor points being disposed such that a line extending between the anchor points extends across the calves of a kneeling rider; and

a center anchor for coupling to a strap.

8. The sled of claim 7, further comprising a strap extending across the hull between the anchor points, the strap being coupled to the center anchor.

9. The sled of claim 7, further comprising a second pair of transversely opposed anchor points on opposite side of the hull for engaging respective first and second ends of a strap, the second pair of anchor points being longitudinally displaced relative to the first pair of anchor points.

10. The sled of claim 10, wherein the second pair of anchor points is disposed such that a strap extending between the anchor points of the second pair extends across the thighs of the kneeling rider.

11. The sled of claim 1, wherein the center anchor comprises a structure molded to conform to the rider, the center anchor forming an aperture; and wherein the strap passes through the aperture.

12. The sled of claim 1, wherein the center anchor comprises a horizontal bar extending longitudinally and supported by vertical legs, the horizontal bar and the vertical legs defining an aperture, and wherein the strap passes through the aperture.

13. The sled of claim 1, wherein the strap is detachably coupled to the center anchor.

14. The sled of claim 7, wherein the center anchor comprises a structure molded to conform to the rider, the center structure forming an aperture for receiving a strap.

15. The sled of claim 7, wherein the center anchor comprises a horizontal bar extending supported by vertical legs, the horizontal bar and the vertical legs defining an aperture for receiving a strap.

16. The sled of claim 7, wherein the center anchor is configured for detachable coupling to a strap.