Land vehicles – Skates – Wheeled skate
Reexamination Certificate
1998-11-03
2001-07-17
Camby, Richard M. (Department: 3661)
Land vehicles
Skates
Wheeled skate
C280S011231, C301S005302
Reexamination Certificate
active
06260861
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to in-line roller skates.
BACKGROUND OF THE INVENTION
Despite the growing popularity of in-line skating, and advances in in-line skate technology, rapid, controlled stopping has continued to present a problem for skaters of all skill levels. Various stopping devices have been employed on in-line skates, e.g., a braking system located on the toe of the skate (Landers, U.S. Pat. No. 5,207,438), a replaceable brake pad located at the rear of the skate (Roberts, U.S. Pat. No. 5,197,572), and a spring-loaded friction device that engages a skate wheel (Allison, U.S. Pat. No. 5,135,244).
O'Donnell et al. (U.S. Pat. No. 5,401,037) discloses a composite wheel for an in-line skate. The O'Donnell wheel includes a center section made of a hard material having a low coefficient of friction, e.g., high density polyethylene. The center section of the wheel is flanked by side sections made of a relatively soft material having a high coefficient of friction, e.g., cast polyurethane. To stop or reduce speed, a skater using the O'Donnell wheel turns the skates away from the direction of travel, and leans away from the direction of travel, as if on ice skates. This causes a portion of the soft material to engage the ground and generate friction.
SUMMARY OF THE INVENTION
Generally, the invention features an in-line skate wheel that delivers variable traction in response to wheel angle, without sacrificing a smooth ride or wheel durability. Utilizing the variable traction of the wheel, an in-line roller skater can stop safely and reliably. The skater does so in a maneuver similar to an ice-skating maneuver known as the hockey stop. Utilizing the variable traction of the wheel, the snow plow maneuver, which involves turning the toes of both feet inward, to slow forward or backward speed, can also be executed safely and effectively.
The wheel includes: (a) a braking portion including a high friction surface material having a hardness from about 75 to about 95 Shore A, and a coefficient of friction from about 0.45 to about 1.5; and (b) a skating portion including a low friction surface material having a hardness from about 75 to about 95 Shore A, and a coefficient of friction from about 0.1 to about 0.45. The skating portion includes a higher proportion of low friction surface material than the braking portion. Typically, the low friction surface material is arranged around the entire circumference of the wheel.
As a skater initiates a hockey stop, the skating surface of the wheel is in contact with the ground, and the low friction surface material enables the skate to skid or slide momentarily. This momentary sliding prevents the skater from pitching forward uncontrollably. The skater then quickly and smoothly engages the braking surface against the ground. This quickly stops the skater, without loss of balance.
The low friction material and high friction material are similar in hardness. The nearly uniform hardness of the wheel's surface avoids clattering or vibration caused by alternating contact of a hard material and a soft material with the ground. The nearly uniform hardness also inhibits initiation and propagation of tearing.
Preferably, the high friction surface material includes a castable thermoset polymer resin containing an isocyanate-reactive functional group, and the low friction surface material includes a thermoplastic polymer resin containing an isocyanate-reactive functional group. The castable thermoset polymer resin can be cast around the thermoplastic polymer resin. The castable thermoset polymer resin can be, for example, castable thermoset polyurethane, and the thermoplastic polymer resin can be an injection-molded thermoplastic polyurethane.
Preferably, the castable thermoset polyurethane and the injection-molded thermoplastic polyurethane are durably joined, for example,-by covalent bonds. The covalent bonds include, for example, urea linkages or urethane linkages.
The low friction surface material can be in the form of floating insets. The floating insets can be, for example, rods, tubes, or fiber bundles. Alternatively, the low friction surface material can be an inner ring with spokes radiating from the inner ring to the surface of the skating portion of the wheel.
The invention also features a method of making a wheel for an in-line roller skate. The method includes the steps of: (a) providing in a casting mold a low friction surface material consisting of a thermoplastic polymer resin that has a hardness from about 75 Shore A to about 95 Shore A, has a coefficient of friction from about 0.1 to about 0.45, and contains an isocyanate-reactive functional group; and (b) placing into the mold a mixture of a bifunctional isocyanate and a polyol under conditions suitable for polymerization into a thermoset polyurethane having a hardness from about 75 to about 95 Shore A and a coefficient of friction from about 0.45 to about 1.5. The thermoplastic resin can be, for example, thermoplastic polyurethane. The bifunctional isocyanate can be, for example, MDI. The polyol can be, for example, polytetrahydrofuran polyol.
The invention also features an in-line roller skate. The skate includes: (a) a boot; (b) a wheel-mounting frame; and (c) a wheel including: (1) a braking portion including a high friction surface material having a hardness from about 75 to about 95 Shore A, and a coefficient of friction from about 0.45 to about 1.5; and (2) a skating portion including a low friction surface material having a hardness from about 75 to about 95 Shore A, and a coefficient of friction from about 0.1 to about 0.45 Shore A; wherein the skating portion includes a higher proportion of low friction surface material than the braking portions.
As used herein, “braking portion” means the portion of the wheel that can contact the ground during a hockey stop.
As used herein, “coefficient of friction” means a coefficient measured using a normal force (90° angle) of 0.5 pound, against 20-pound bond paper, using an Instron device adjusted to a head speed of 20 inches per minute.
As used herein, “durably joined” materials means materials joined with a bond strength greater than about 50 pounds per linear inch (pli). The pli value is determined according to ASTM D429 method B, modified so that stripping force is applied at an angle of 180° instead of 90°, and Instron head speed is 2 inches per minute. Typically, durably joined materials are joined with a bond strength of greater than about 75 pli.
As used herein, “floating inset” means an inset that is not connected to other insets, either directly, or via an inner ring or hub.
As used herein, “high friction surface material” means a material that has a coefficient of friction from about 0.45 to about 1.5, and is exposed on the surface of a wheel.
As used herein, “isocyanate-reactive” functional group means a functional group that reacts with an isocyanate. Exemplary isocyanate-reactive functional groups are amino groups, amide groups, and hydroxyl groups. Exemplary isocyanates are MDI and TDI.
As used herein, “low friction surface material” means a material that has a coefficient of friction from about 0.1 to about 0.45, and is exposed on the surface of a wheel.
As used herein, “MDI” means a mixture of 4,4′- and 2,4′-diisocyanato diphenylmethane.
As used herein, “skating portion” of a wheel means the portion of the wheel that contacts the ground when the wheel is rolling substantially straight forward or substantially straight backward, during normal skating.
As used herein, “TDI” means a mixture of 2,4- and 2,6-toluene diisocyanate.
As used herein, “thermoplastic polymer resin” means a polymer resin that can be melted or softened in the polymerized form.
As used herein, “thermoset polymer resin” means a polymer resin that decomposes before melting, upon application of heat.
All patents mentioned herein are incorporated by reference in their entirety.
Various features and advantages of the invention will be apparent from the following detailed description and from the claims.
Chiang Albert C.
Roderick John A.
Sipes Charles
Willis David R.
Camby Richard M.
Fish & Richardson P.C.
Mearthane Products Corporation
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