Multi-wheel system for luggage

Abstract

To describe a wheel system configured to smoothly traverse an obstacle and an uneven surface.SOLUTION: A wheel system 100 includes a plurality of wheels having different diameters. The wheels are coupled to a rotary arm 140 that allows the leading and trailing wheels to pivot about a central shaft in response to an impact with an obstacle. The wheel system absorbs a shock and minimizes an interaction of the wheels with the obstacle. The use of the plurality of wheels having different diameters and the rotatable central shaft provides a wheel system compactly designed and having the benefit of smooth rolling.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates generally to luggage, and more particularly to a multi-wheel system for luggage.

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 068,693, filed August 21, 2020, the entire contents of which are incorporated herein by reference in their entirety. [Background technology]

[0003] Individuals use luggage to easily and efficiently transport their belongings when traveling. Many people prefer to use luggage that has some type of wheel system on the bottom, which allows the user to roll the luggage vertically and horizontally across the ground. During use, the luggage may encounter obstacles, including bumps, cracks, or discontinuities in the rolling surface. Upon impact between the luggage wheels and such an obstacle, the obstacle may impart undesirable forces to the wheel system. Furthermore, the ground may also cause the user to abruptly stop as the luggage becomes "stuck" in the obstruction. The impact force between the luggage wheels and the obstacle may result in undesirable effects such as shock, noise, damage to the wheels, rolling of the luggage causing the luggage to tip over, and potential injury to the wrists of the user pulling the luggage. Therefore, there is a need in the art for a wheel system that allows for smooth passage of luggage over cracks or uneven surfaces to enhance an individual's travel experience. [Brief explanation of the drawings]

[0004] This disclosure relates generally to luggage, and more particularly to multi-wheel systems for luggage and related methods.

[0005] [Figure 1] 1 illustrates a perspective view of a multi-wheel system having a central axis.

[0006] [Figure 2] 2 illustrates an exploded view of the multi-wheel system having a central axle of FIG. 1;

[0007] [Figure 3] 1 illustrates a perspective view of a rotating arm.

[0008] [Figure 4] 2 illustrates a side view of the multi-wheel system of FIG. 1;

[0009] [Figure 5] 2 illustrates a side view of the multi-wheel system of FIG. 1 in relation to the ground surface.

[0010] [Figure 6A] 2 illustrates a side view of the multi-wheel system of FIG. 1 overcoming an obstacle above ground level. [Figure 6B] 2 illustrates a side view of the multi-wheel system of FIG. 1 overcoming an obstacle above ground level. [Figure 6C] 2 illustrates a side view of the multi-wheel system of FIG. 1 overcoming an obstacle above ground level. [Figure 6D] 2 illustrates a side view of the multi-wheel system of FIG. 1 overcoming an obstacle above ground level.

[0011] [Figure 7A] Illustrates a side view of the Tawa system in Figure 1 overcoming obstacles below ground level. [Figure 7B] Illustrates a side view of the Tawa system in Figure 1 overcoming obstacles below ground level. [Figure 7C] Illustrates a side view of the Tawa system in Figure 1 overcoming obstacles below ground level. [Figure 7D] Illustrates a side view of the Tawa system in Figure 1 overcoming obstacles below ground level.

[0012] [Figure 8]1 illustrates a top view of a wheel system according to one embodiment.

[0013] [Figure 9] 1 illustrates a top view of a wheel system according to another embodiment.

[0014] [Figure 10] 1 illustrates a perspective view of a wheel according to one embodiment.

[0015] [Figure 11] 1 illustrates an exploded view of the wheel system connection to the luggage body.

[0016] [Figure 12] 1 illustrates a side view of a wheel system associated with luggage via a central axis.

[0017] [Figure 13] 1 illustrates a side view of a wheel system associated with luggage under normal rolling conditions.

[0018] Other aspects of the disclosure will become apparent by consideration of the detailed description and accompanying drawings. DETAILED DESCRIPTION OF THE INVENTION

[0019] Described herein is a wheel system configured for smooth navigation over obstacles and uneven surfaces. The wheel system includes multiple wheels having different diameters coupled to pivoting arms that allow the leading and trailing wheels to pivot about a central axis in response to impact with an obstacle. The wheel system absorbs shock and minimizes wheel interaction with the obstacle. Utilizing multiple wheels having different diameters and a rotatable central axis provides a wheel system with the benefits of smooth rolling in a compact design.

[0020] The terms "first," "second," "third," and "fourth" used herein are used to distinguish between similar elements and do not necessarily describe a particular sequential or chronological order. It is understood that terms so used are interchangeable under appropriate circumstances, for example, so that the embodiments described herein are capable of operating in orders other than those illustrated or otherwise described herein. Furthermore, the terms "comprise" and "have," and any conjugations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, device, or apparatus that includes a list of elements is not necessarily limited to those elements and may include other elements not expressly listed or inherent to such process, method, system, article, device, or apparatus.

[0021] The terms "front," "rear," "top," "bottom," "upper," and "lower" used herein are used for descriptive purposes and are not necessarily used to describe permanent relative positions. It is to be understood that such terms are interchangeable under appropriate circumstances, such that the device, method, and / or article embodiments described herein are operable, for example, in other orientations other than those illustrated or otherwise described herein.

[0022] The terms or phrases "luggage" or "bag" as used herein may be defined as an enclosure configured to hold clothing or personal belongings for transportation. The body of the luggage may be defined by one or more panels forming a general shape, such as, but not limited to, a rectangular prism. The panels may be either hard-shell panels that retain a rigid shape or soft-shell panels that are flexible and foldable. The interior of the luggage may be defined by an interior void formed by the panels. The interior of the bag may be accessible by removable attachments along one or more of the edges or surfaces of the panels. The removable attachments may include zippers, buttons, snaps, or any other means suitable for opening and closing the luggage. The luggage may be defined such that when the bag is in use, the top of the luggage is defined as facing upward, the bottom of the luggage is defined as facing downward, the front of the luggage is defined as facing in the direction the bag is being transported, and the rear of the luggage is defined as facing away from the direction the bag is being transported.

[0023] The term or phrase "focal point" as used herein can be defined as the center point of a wheel. The focal point of each wheel can be located at the center of the wheel's diameter or at the wheel's center of gravity. The focal point of a wheel can be used to describe the position of that wheel relative to other components of a moving wheel system.

[0024] Before any embodiment of this disclosure is described in detail, it should be understood that this disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. This disclosure is capable of other embodiments and of being practiced or carried out in various ways. 1. The entire wheel system

[0025] The wheel system 100 has the ability to smoothly traverse obstacles, such as cracks or bumps in the ground, encountered during use. The wheel system includes three wheels with varying diameters, which allow at least one wheel to contact the ground or an obstacle at any given time. FIGS. 1 and 2 illustrate a wheel system according to this embodiment. The wheel system 100 includes a rotating arm 140 rotatably coupled to a central axle 135 and multiple wheels with varying diameters coupled to the rotating arm 140 by multiple axles. The multiple wheels include a leading wheel 110 with a first diameter D1 coupled to a tip 143 of the arm, a center wheel 120 near a center 142 of the rotating arm 140, and a trailing wheel 130 coupled to a rear end 144 of the rotating arm 140. In use, as the rotating arm 140 rotates about the central axis 135, the leading wheel 110 and trailing wheel 130, which are attached to opposite ends 143, 144 of the arm 140 by leading axles 151 and trailing axles 152, respectively, pivot about the central axis 135 and raise or lower in response to obstacles or discontinuous rolling surfaces. a. Rotating arm

[0026] As discussed above, the wheels are coupled to the swivel arm 140 by a number of axles. The swivel arm 140 links the wheels in a configuration that allows the leading wheel 110 and trailing wheel 130 to be raised or lowered as the arm 140 rotates in response to an obstacle O, while the center wheel 120 rotates solely in place on the central axle 135. Referring to FIG. 3, the swivel arm 140 generally has a long, flat, and straight body 141. The swivel arm 140 includes a number of openings 145a, 145b, and 145c positioned along its length and configured to receive various axles to couple the wheels to the swivel arm 140. The axle mounting locations provide the necessary smooth-rolling functionality for the wheel system 100. As illustrated in FIG. 2, the center wheel 120 is coupled to the swivel arm 140 by the central axle 135, thereby allowing both the center wheel 120 and the swivel arm 140 to rotate about the central axle 135. Because of this configuration, the central wheel 120 does not pivot about the central axis 135 as the swivel arm 140 rotates, but instead remains rotatably mounted about the central axis 135. The central axis 135 can be received by a central opening 145a located near the center of the swivel arm 140. The leading wheel 110 and the trailing wheel 130 are coupled at opposite ends of the swivel arm 140 by a leading axle 151 and a trailing axle 152, respectively. The leading axle 151 is received by a front opening 145b in the swivel arm 140 located near the tip 143 of the arm, while the trailing axle 152 is received by a rear opening 145c in the swivel arm 140 located near the rear end 144 of the arm. The leading and trailing axles provide axes of rotation for the leading and trailing wheels and also allow the leading and trailing wheels to pivot about the central axis 135 as the arm rotates. Leading axle 151 and trailing axle 152 connect leading wheel 110 and trailing wheel 130 to opposite ends of rotating arm 140, which allows leading wheel 110 and trailing wheel 130 to be raised or lowered as arm 140 rotates in response to obstacles O along the ground. b. Central axis

[0027] The central axle 135 serves as the primary attachment point and primary rotation point for the entire luggage system 300. The central axle 135 acts as the primary attachment point by connecting the wheel system 100 to the luggage 300 or other device. The central axle 135 extends from the luggage 300 via the central wheel 120 and the swivel arm 140. The central axle 135 acts as the primary rotation point by allowing the central wheel 120 and the swivel arm 140 to rotate about the same axis. Because the central wheel 120 and the swivel arm 140 are attached to the central axle 135, which is connected to the luggage 300, the central axle 135 transfers the weight of the luggage 300 to the central wheel 120 and / or the swivel arm 140 (depending on the configuration). When the central wheel 120 is in contact with the ground, the central axle 135 transfers most of its weight to the central wheel 120 and some or none of its weight to the swivel arm 140. When the central wheel 120 is not in contact with the ground, the central shaft 135 transmits all of its weight to the rotating arm 140 and none to the central wheel 120. The rotating arm 140 then further transmits its weight to the leading shaft 151 and the trailing shaft 152. c. Leading and trailing shafts

[0028] The leading axle 151 and the trailing axle 152 serve as means for coupling the leading wheel 110 and the trailing wheel 130 to the opposite ends of the pivot arm 140. The leading axle 151 and the trailing axle 152 are attached only to the pivot arm 140 and do not serve as attachment points between the wheel system 100 and the luggage 300 or other devices. Thus, the leading axle 151 and the trailing axle 152 are free to pivot about the central axis 135 independent of the movement of the luggage. The leading wheel 110 and the trailing wheel 130 are configured to rotate freely on the leading axle 151 and the trailing axle 152, respectively.

[0029] When the leading wheel 110 encounters an obstacle O, it raises or lowers accordingly to overcome the obstacle O. Because the leading wheel 110 is connected to the rotating arm 140 via the leading shaft 151, this in turn raises or lowers the leading end 143 of the rotating arm 140 as well. This causes the rotating arm 140 to move in a "see-saw" motion, resulting in the trailing end 144 of the rotating arm 140 raising or lowering in the opposite direction to the leading end 143. This, in turn, raises or lowers the trailing wheel 130, which is connected via the trailing shaft 152, in the opposite direction to the leading wheel 110. For example, as the leading wheel 110 lowers in response to the obstacle O, the trailing end 144 "seesaws" and the trailing wheel 130 rises. Conversely, if the leading wheel 110 rises in response to the obstacle O, the trailing end 144 "seesaws" and the trailing wheel 130 lowers. When the wheel system 100 encounters an obstacle O, the leading wheel 110 and trailing wheel 130 can suspend the center wheel 120 via their axle connections to the rotating arm 140 .

[0030] As discussed above, the central axle 135 carries the load of the luggage 300 or other equipment. When the center wheel 120 is in contact with the ground, the center wheel 120 can support most or all of the load on the central axle 135. In other configurations where the center wheel 120 is not in contact with the ground, such as when the center wheel 120 is suspended above a crack by the pivot arm 140, the pivot arm 140 can carry the load of the central axle 135. In such a configuration, the leading wheel 110 and the trailing wheel 130 can support the pivot arm 140 by virtue of their attachment to either end of the pivot arm 140 via the leading axle 151 and the trailing axle 152. This configuration allows the load of the central axle 135 to be transferred via the pivot arm 140 and distributed between the leading axle 110 and the trailing axle 130. d. Use of the wheel system

[0031] The above-described wheel system 100, or any variation thereof, can be used in a variety of applications. In some embodiments, the wheel system 100 can be used in a push cart, an industrial cart, an industrial dolly, a commercial cart, a commercial dolly, a hand truck, a platform truck, a skateboard truck, a longboard truck, and / or luggage. Alternatively, the apparatus, methods, and articles of manufacture described herein can be applied to any other type of application requiring the smooth passage of a wheel system over uneven surfaces or foreign objects. In many preferred embodiments, the wheel system 100 can be applied to the body of luggage. 2. Wheel Relationship a.Relationship between wheel diameters

[0032] The unique relationship between wheel size and position provides the wheel system 100 with the ability to smoothly traverse obstacles O. As illustrated in FIG. 4 , the leading wheel 110, the center wheel 120, and the trailing wheel 130 are all different sizes. Thus, the leading wheel 110 has a first diameter D1, the center wheel 120 has a second diameter D2 that is different from the first diameter D1, and the trailing wheel 130 has a third diameter D3 that is different from the first diameter D1 and the second diameter D2. The diameters of each wheel decrease from the leading end 143 of the arm to the trailing end 144 of the arm. The first diameter D1 of the leading wheel 110 is larger than the second diameter D2 of the center wheel 120, which is larger than the third diameter D3 of the trailing wheel 130.

[0033] The wheel system 100 has a large leading wheel diameter D1, which allows the system 100 to easily traverse obstacles. The wheel system 100 also has progressively smaller center wheel diameter D2 and trailing wheel diameter D3, which allows the wheel system 100 to be more compact than a similar multi-wheel system in which the center and trailing wheels are the same size as the leading wheel. Generally, when an obstacle is first encountered, wheels with larger diameters traverse such obstacles more easily than wheels with smaller diameters. For obstacles that protrude above the ground, such as bumps, the impact between the bump and a small-diameter wheel occurs at a relatively high point on the wheel, closer to the wheel's center of gravity. This type of impact results in significant forces acting in a direction opposite to the wheel's momentum. Conversely, the impact between a bump and a large-diameter wheel occurs relatively low on the wheel, further away from the wheel's center of gravity. Forces acting against the wheel's momentum in this type of impact are minimized. Similarly, for an obstacle that penetrates the ground, such as a crack, a small diameter wheel will fall further into the crack than a larger diameter wheel. This causes the impact between the crack edge and the small diameter wheel to occur relatively high and close to the center of gravity, resulting in a significant loss of momentum. Conversely, the impact between the crack edge and a large diameter wheel will occur relatively low and away from the center of gravity of the wheel, resulting in an inconspicuous loss of momentum.

[0034] For this reason, the leading wheel 110 is provided with the largest diameter because it is the first wheel in the system 100 to encounter an obstacle during normal use. The center wheel 120 and trailing wheel 130 do not directly interact with obstacles and do not require such large diameters. As discussed above, to create a compact wheel system, it is desirable for the center wheel 120 and trailing wheel 130 to have progressively smaller diameters. The compact wheel arrangement described herein inherently weighs less and takes up less space on the luggage compartment than a similar multi-wheel system that does not have wheels with decreasing diameters.

[0035] Wheel system 100 is configured so that at least one wheel contacts the ground or an obstacle at any given time. Referring to FIG. 5, the bottoms of all three wheels rest on a common surface, designated contact surface 3000. Contact surface 3000 is defined as a horizontal plane tangent to each of leading wheel 110, center wheel 120, and trailing wheel 130. With the bottoms of each wheel resting on the same contact surface 3000, all three wheels can simultaneously contact the ground during normal rolling conditions on a smooth surface. As illustrated in FIG. 5, the surface on which the system rolls can define ground surface 1000. Under normal rolling conditions, contact surface 3000 coincides with ground surface 1000. b. Focus of the wheel

[0036] The size and positioning of the wheels within the wheel system 100 can be further characterized by the location of the center of each wheel. As illustrated in FIG. 5 , each wheel has a geometric center point (hereafter referred to as each wheel's "focal point"). The leading wheel 110 has a first focal point 201 that defines the leading wheel's geometric center point, the center wheel 120 has a second focal point 202 that defines the center wheel's geometric center point, and the trailing wheel 130 has a third focal point 203 that defines the trailing wheel's geometric center point. The first focal point 201, second focal point 202, and third focal point 203 all lie along the same plane, illustrated in FIG. 5 as reference plane 2000. In many embodiments, the reference plane 2000 extends from the leading end 143 to the trailing end 144 through the length of the rotating arm 140. Because each focal point 201, 202, 203 is tied to the same reference plane 2000, the orientation of the reference plane determines the possible relationships between the position and dimensions of each wheel.

[0037] As illustrated in FIG. 5 , the wheel system 100 has a constant acute angle α between the reference surface 2000 and the contact surface 3000 regardless of the configuration of the rotating arm 140. Therefore, the height of the reference surface 2000 relative to the contact surface is greater at points near the leading edge 143 than at points near the trailing edge 144. The greater the angle α, the greater the increase in height of the reference surface 2000 from the trailing edge 144 to the leading edge 143. In many embodiments, the angle α between the contact surface 3000 and the reference surface 2000 can range from 10 to 60 degrees. In some embodiments, the angle α between the contact surface 3000 and the reference surface 2000 can range from 10 to 20 degrees, 20 to 30 degrees, 30 to 40 degrees, 40 to 50 degrees, or 50 to 60 degrees. In other embodiments, the angle α between the contact surface 3000 and the reference surface 2000 can range from 10 to 30 degrees, 15 to 35 degrees, 20 to 40 degrees, 25 to 45 degrees, 30 to 50 degrees, 35 to 55 degrees, or 40 to 60 degrees. For example, the angle α between the contact surface 3000 and the reference surface 2000 can be 20 degrees, 21 degrees, 22 degrees, 23 degrees, 24 degrees, 25 degrees, 26 degrees, 27 degrees, 28 degrees, 29 degrees, 30 degrees, 31 degrees, 32 degrees, 33 degrees, 34 degrees, 35 degrees, 36 degrees, 37 degrees, 38 degrees, 39 degrees, or 40 degrees.

[0038] Referring to FIG. 5 , the position of each focal point along the reference plane 2000 is related to the mounting position between the axle and the rotating arm 140 corresponding to each wheel. In an embodiment in which the leading axle 151 is coupled to the rotating arm 140 at a position substantially close to the leading edge 143, the position of the first focal point 201 in the leading-to-trailing direction of the reference plane 2000 is also substantially close to the leading edge 143. Conversely, in an embodiment in which the leading axle 151 is coupled to the rotating arm 140 at a position farther from the leading edge 143, the position of the first focal point 201 in the leading-to-trailing direction of the reference plane 2000 may be farther from the leading edge 143. Varying the position of each focal point along the reference plane 2000 can change the height of each focal point and, therefore, the required diameter for each wheel. For example, the closer each focal point is to the leading edge 143 of the angled reference plane 2000, the higher the focal point must be and the larger the diameter of the corresponding wheel must be.

[0039] Each of the leading wheel 110, the center wheel 120, and the trailing wheel 130 further defines a focal height. The leading wheel 110 has a first focal height F1 measured as the perpendicular distance between the contact surface 3000 and the first focal point 201. The center wheel 120 has a second focal height F2 measured as the perpendicular distance between the contact surface 3000 and the second focal point 202. The trailing wheel 130 has a third focal height F3 measured as the perpendicular distance between the contact surface 3000 and the third focal point 203. As illustrated in FIG. 5, the first focal height F1 is greater than the second focal height F2, which is greater than the third focal height F3.

[0040] The focal height of each wheel is linear depending on the position of each wheel's focal point in the leading-to-trailing direction. This is due to the fact that the bottom of each wheel is coincident with the contact surface 3000, with the focal point of each wheel positioned on a reference plane 2000 that is at a constant angle α with the contact surface 3000. As illustrated by FIG. 5 , the closer the first focal point 201 is positioned relative to the leading edge 143, the greater the first focal point height F1 must be in order for the bottom of the leading wheel 110 to remain coincident with the contact surface 3000. Similarly, the farther the first focal point 201 is positioned from the leading edge 143, the lower the first focal point height F1 must be. For the same reason, the closer the third focal point 203 is to the trailing edge 144, the lower the third focal point height F3 must be, and the farther the third focal point 203 is from the trailing edge 144, the greater the third focal point height F3 must be. In many embodiments, the second focal point 202 of the central wheel 120 is positioned substantially equidistant from the leading edge 143 and the trailing edge 144. However, in some embodiments, the second focal point 202 can be positioned closer to the leading edge 143 or closer to the trailing edge 144. The second focal point height F2 is greater when positioned closer to the leading edge 143 than when positioned closer to the trailing edge 144.

[0041] In many embodiments, the first focal height F1 can be in the range of 1.5 inches to 3.0 inches. In some embodiments, the first focal height F1 can be in the range of 1.5 inches to 1.75 inches, 1.75 inches to 2.0 inches, 2.0 inches to 2.25 inches, 2.25 inches to 2.5 inches, 2.5 inches to 2.75 inches, or 2.75 inches to 3.0 inches. In other embodiments, the first focal height F1 can be in the range of 1.5 inches to 2.0 inches, 1.75 inches to 2.25 inches, 2.0 inches to 2.5 inches, 2.25 inches to 2.75 inches, or 2.5 inches to 3.0 inches. For example, the first focal height F1 can be 1.5 inches, 1.55 inches, 1.60 inches, 1.65 inches, 1.70 inches, 1.75 inches, 1.80 inches, 1.85 inches, 1.90 inches, 1.95 inches, 2.0 inches, 2.05 inches, 2.10 inches, 2.15 inches, 2.20 inches, 2.25 inches, 2.30 inches, 2.35 inches, 2.40 inches, 2.45 inches, 2.50 inches, 2.55 inches, 2.60 inches, 2.65 inches, 2.70 inches, 2.75 inches, 2.80 inches, 2.85 inches, 2.90 inches, 2.95 inches, or 3.0 inches.

[0042] In many embodiments, the second focal height F2 can range between 0.75 inches and 2.0 inches. In some embodiments, the second focal height F2 can range between 0.75 inches and 1.0 inches, 1.0 inches and 1.25 inches, 1.25 inches and 1.5 inches, 1.5 inches and 1.75 inches, or 1.75 inches and 2.0 inches. In other embodiments, the second focal height F2 can range between 0.75 inches and 1.25 inches, 1.0 inches and 1.5 inches, 1.25 inches and 1.75 inches, or 1.5 inches and 2.0 inches. For example, the second focal height F2 can be 0.75 inches, 0.80 inches, 0.85 inches, 0.90 inches, 0.95 inches, 1.0 inch, 1.05 inches, 1.10 inches, 1.15 inches, 1.20 inches, 1.25 inches, 1.30 inches, 1.35 inches, 1.40 inches, 1.45 inches, 1.50 inches, 1.55 inches, 1.60 inches, 1.65 inches, 1.70 inches, 1.75 inches, 1.80 inches, 1.85 inches, 1.90 inches, 1.95 inches, or 2.0 inches.

[0043] In many embodiments, the third focal height F3 can range between 0.25 inches and 1.5 inches. In some embodiments, the third focal height F3 can range between 0.25 inches and 0.5 inches, 0.5 inches and 1.0 inches, 1.0 inches and 1.25 inches, or 1.25 inches and 1.5 inches. In other embodiments, the third focal height F3 can range between 0.25 inches and 0.75 inches, 0.5 inches and 1.0 inches, 0.75 inches and 1.25 inches, or 1.0 inches and 1.5 inches. For example, the third focal height F3 can be 0.25 inches, 0.30 inches, 0.35 inches, 0.40 inches, 0.45 inches, 0.50 inches, 0.55 inches, 0.60 inches, 0.65 inches, 0.70 inches, 0.75 inches, 0.80 inches, 0.85 inches, 0.90 inches, 0.95 inches, 1.0 inches, 1.05 inches, 1.10 inches, 1.15 inches, 1.20 inches, 1.25 inches, 1.30 inches, 1.35 inches, 1.40 inches, 1.45 inches, or 1.50 inches.

[0044] It should be noted that although the ranges described relative to the first focal height F1, the second focal height F2, and the third focal height F3 partially overlap, the first focal height F1, the second focal height F2, and the third focal height F3 are different from each other. In any particular embodiment, the first focal height F1 is always greater than the second focal height F2, and the second focal height F2 is always greater than the third focal height F3. There are no embodiments in which any of the first focal height F1, the second focal height F2, and / or the third focal height F3 have the same value. 3. Configuration of wheel system over obstacles

[0045] As shown in FIGS. 6-7 , the design of the wheel system 100 allows the luggage to roll smoothly over obstacles or uneven surfaces. The obstacle O is a feature that extends either above and / or below the ground surface 1000. For example, an obstacle O that extends above the ground surface 1000 may be a bump or ledge, while an obstacle O that extends below the ground surface 1000 may be a crack, slit, or crevice. FIG. 6 illustrates the wheel system 100 traveling over an obstacle O above the ground surface 1000, and FIG. 7 illustrates the wheel system 100 traveling over an obstacle O below the ground surface 1000. When the wheel system 100 encounters the obstacle O, the rotating arms 140 of the wheel system 100 allow the leading wheel 110 and the trailing wheel 130 to pivot about the central axis 135. Depending on the obstacle O, the wheel system 100 has a set of configurations while traversing the obstacle O. a. Configuration of the wheel system above the crack

[0046] When the wheel system 100 encounters an obstacle O (i.e., a crack) that extends below the ground surface 1000, the wheel system 100 experiences a set of configurations as the wheel system 100 traverses the obstacle O. The first configuration is defined when the contact surface 3000 is conformal to the ground surface 1000 and all wheels are rolling on the ground surface 1000 before the wheel system 100 interacts with the obstacle O. The second configuration is defined when only the leading wheel 110 interacts with the obstacle O. The leading wheel 110 falls into the crack and the trailing wheel 130 rises because the rotating arm 140 rotates about the central axis 135. The center wheel 120 is still in contact with the ground surface 1000 and supports all of the weight of the luggage 300. Because the center wheel 120 has not fallen into the obstacle O, the user does not notice the crack. In this configuration, the contact surface 3000 of the wheel system 100 is not parallel to the ground surface 1000. A third configuration is defined when the leading wheel 110 exits the obstacle O on the other side. In this configuration, the center wheel 120 is suspended above the obstacle O, and the weight of the luggage 300 is supported only by the leading wheel 110 and the trailing wheel 130. The leading wheel 110 is on one side of the obstacle O, while the trailing wheel 130 is on the other side of the obstacle O. In this configuration, the contact surface 3000 of the wheel system 100 is coincident with the ground surface 1000. A fourth configuration is defined when the center wheel 120 regains contact with the ground surface 1000. The trailing wheel 130 may fall into the crack, and the leading wheel 110 may rise due to the rotating arm 140 rotating about the central axis 135. In the fourth configuration, the contact surface 3000 may not be parallel to or coincident with the ground surface 1000. The center wheel 120 supports all of the weight of the luggage 300. During each of these configurations, the angle α between the reference plane 2000 and the contact surface 3000 remains constant.

[0047] As previously mentioned, this set of configurations allows for smooth navigation over obstacle O, which extends below the ground surface 1000. The set eliminates obstacle O by eliminating or reducing any jolts or sudden movements. The jolts and sudden movements are perceived by the user whenever the center wheel 120 experiences a sudden change in acceleration in the vertical and / or longitudinal directions. For example, if the center wheel 120 suddenly falls into a crack, the center wheel 120 experiences a change in acceleration in the up-down direction. Furthermore, if the center wheel 120 hits the opposite edge of the crack, the center wheel 120 experiences a rapid deceleration in the fore-and-aft direction. However, in the set of configurations defined by the wheel system 100 traversing the crack, the center wheel 120 remains in contact with the ground surface in every configuration, eliminating jolts and sudden movements in the up-and-down direction. Furthermore, because the center wheel 120 does not fall into the crack, the center wheel 120 avoids and does not interact with the opposite edge of the crack. This eliminates any deceleration in the fore-and-aft direction. b. Configuration of the wheel system on the bump

[0048] When the wheel system 100 encounters an obstacle O (i.e., a bump or ledge) that extends above the ground surface 1000, the wheel system 100 experiences a set of configurations as the wheel system 100 traverses the obstacle O. A first configuration is defined such that the contact surface 3000 is conformal to the ground surface 1000 and all wheels are rolling on the ground surface 1000 before the wheel system 100 interacts with the obstacle O. A second configuration is defined by the initial interaction of the leading wheel 110 with the obstacle O. As the leading wheel 110 begins to roll onto the ledge, the arm 140 rotates. As the arm 140 rotates, the middle wheel 120 is then lifted off the ground surface 1000. The weight of the luggage 300 is supported by the leading wheel 110 and the trailing wheel 130. The contact surface 3000 of the wheel system 100 is not parallel to the ground surface 1000. The third configuration is when the leading wheel 110 leaves the obstacle O on the other side. In this configuration, the center wheel 120 is suspended above the obstacle O and the weight of the luggage 300 is supported only by the leading wheel 110 and the trailing wheel 130. The leading wheel 110 is in contact with the ground surface 1000 and the trailing wheel 130 is in contact with the obstacle O. During each of these configurations, the angle α remains constant between the reference plane 2000 and the contact plane 3000.

[0049] As previously mentioned, this set of configurations allows for smooth navigation over an obstacle O that extends above the ground surface 1000. The set overcomes the obstacle O by eliminating or reducing any jolts or jerks. A jolt or jerk is perceived by the user whenever the center wheel 120 experiences a sudden change in acceleration in the up-down (vertical) and / or fore-aft (horizontal) directions. For example, when a conventional wheel contacts a bump, the wheel experiences deceleration not only in the fore-aft direction but also in the up-down direction. However, the design of the exemplary wheel system 100 effectively diffuses the bump, reducing the amount of deceleration perceived by the user. These configurations also effectively diffuse the bump by beginning to raise the center wheel 120 well above the ground surface before it reaches the bump. 4. Lateral wheel offset

[0050] In some embodiments, the wheels can be advantageously offset laterally (side to side) from the rotating arm 140 or from each other to improve stability. In some embodiments, the wheels can be advantageously offset laterally (side to side). By offsetting one or more wheels so that the profiles of the offset wheels overlap, the overall fore-aft distance of the wheel system 100 can be shortened. The leading wheel 110 and trailing wheel 130 can be located on a first side of the rotating arm. As shown in FIGS. 8 and 9, the center wheel 120 can be located on a second side of the rotating arm 140, opposite the first side. Different axes can extend from both surfaces of the rotating arm 140 so that the wheels can be laterally offset from each other. For example, the leading wheel 110 and the trailing wheel 130 may be mounted on an axle extending from one surface of the rotating arm 140, and the central wheel 120 may be mounted on an axle extending from the opposite surface of the arm, so that the rotating arm 140 is positioned between the central wheel 120 and the leading wheel 110 and the trailing wheel 130.

[0051] Laterally spaced wheels allow for a compact design, with the wheel system 100 having a shorter front-to-back distance than if all three wheels were positioned on the same side of the rotating arm 140. This allows for a shorter rotating arm 140 and requires less material. It also allows for overlapping wheels, further reducing the front-to-back distance. Laterally spaced wheels also provide stability by separating the contact points of each wheel with the ground surface 1000. This allows the wheels to engage cracks oriented in any direction relative to the path of travel without disturbance. Conventional luggage consists of only one, generally very narrow, wheel on either side of the luggage. When a user rolls conventional luggage and the luggage engages an elongated crack oriented parallel or nearly parallel to the direction of travel, the narrow wheel can fall all the way into the crack and become stuck, causing the luggage to suddenly rock, fall off the path, or tip over. Such disturbances could cause damage to the luggage and / or injury to the user. Because of the laterally spaced wheels in the present invention, even if one or two of the wheels in a wheelset roll directly over and parallel to the crack, the other wheels spaced laterally from the wheels in the crack will be outside the crack and will continue to roll undisturbed along the ground surface 1000. a.Spacer

[0052] To achieve the desired offset, the wheel system 100 can further include one or more spacers 165, as shown in FIG. 8 . The spacer 165 can be positioned between one or more wheels and the rotating arm 140. The spacer 165 can have a diameter or width smaller than the diameter or width of the adjacent wheels. The spacer 165 can define a central opening. One spacer 165 can be positioned between the leading wheel 110 and the rotating arm 140, such that the spacer 165 receives the leading axle 151 within its opening, securing the leading axle 151 between the wheel 110 and the rotating arm 140. Another spacer 165 can additionally be positioned between the trailing wheel 130 and the rotating arm 140, receiving the trailing axle 152 in a similar manner. In some embodiments, the leading wheel 110 and the trailing wheel 130 can be offset laterally from the rotating arm 140. The width of the one or more spacers 165 can control the distance the wheels are offset from the rotating arm 140. In particular, the spacers 165 can be of different widths to offset the wheels a desired distance from the rotating arm 140. In some embodiments, the spacers 165 can be integral to the rotating arm 140. In other embodiments, the spacers 165 can be integral to one or more of the wheels, as illustrated in Figures 9-10.

[0053] In some embodiments, the width of the one or more spacers 165 can range from about 0.1 inch to 1.0 inch. In some embodiments, the width of the one or more spacers 165 can range from 0.1 inch to 0.25 inch, 0.25 inch to 0.50 inch, 0.5 inch to 0.75 inch, or 0.75 inch to 1.0 inch. In some embodiments, the width of the one or more spacers 165 can range from 0.1 inch to 0.3 inch, 0.2 inch to 0.4 inch, 0.3 inch to 0.5 inch, 0.4 inch to 0.6 inch, 0.5 inch to 0.7 inch, 0.6 inch to 0.8 inch, 0.7 inch to 0.9 inch, or 0.8 inch to 1.0 inch. For example, the width of one or more spacers 165 can be 0.1 inch, 0.15 inch, 0.2 inch, 0.25 inch, 0.3 inch, 0.35 inch, 0.4 inch, 0.45 inch, 0.5 inch, 0.55 inch, 0.6 inch, 0.65 inch, 0.7 inch, 0.75 inch, 0.8 inch, 0.85 inch, 0.9 inch, 0.95 inch, or 1.0 inch. b. Offset distance

[0054] As noted, wheel offset plays an important role in promoting stability and enabling a compact design. Wheel offset can be characterized by the distance between the various planes that house the wheels. A first plane P1, parallel to the swivel arm, is defined through the leading wheel 110 and the trailing wheel 130. A second plane P2 is defined through the midline of the swivel arm 140. A distance A1 between the first plane P1 and the second plane P2 defines the amount by which the leading wheel 110 and the trailing wheel 130 are offset from the swivel arm 140. A third plane P3, parallel to the swivel arm 140, is defined through the center wheel 120. A distance A2 between the second plane P2 and the third plane P3 defines the amount by which the center wheel 120 is offset from the swivel arm 140.

[0055] In many embodiments, the leading wheel 110 and the trailing wheel 130 can be offset laterally from the pivot arm 140 by a distance ranging between 0.25 inches and 1.0 inch. In some embodiments, the leading wheel 110 and the trailing wheel 130 are offset laterally from the pivot arm 140 by a distance ranging between 0.25 inches and 0.40 inches, 0.40 inches and 0.65 inches, 0.65 inches and 0.80 inches, or 0.80 inches and 1.0 inch. In other embodiments, the leading wheel 110 and the trailing wheel 130 are offset laterally from the pivot arm 140 by a distance ranging between 0.25 inches and 0.50 inches, 0.50 inches and 0.75 inches, or 0.75 inches and 1.0 inch. For example, the leading wheel 110 and trailing wheel 130 can be offset laterally from the rotating arm 140 by 0.25 inches, 0.30 inches, 0.35 inches, 0.40 inches, 0.45 inches, 0.50 inches, 0.55 inches, 0.60 inches, 0.65 inches, 0.70 inches, 0.75 inches, 0.80 inches, 0.85 inches, 0.90 inches, 0.95 inches, or 1.0 inch.

[0056] In many embodiments, the central wheel 120 can be offset laterally from the pivot arm 140 by a distance ranging between 0.25 inches and 1.0 inch. In some embodiments, the central wheel 120 is offset laterally from the pivot arm 140 by a distance ranging between 0.25 inches and 0.40 inches, 0.40 inches and 0.65 inches, 0.65 inches and 0.80 inches, or 0.80 inches and 1.0 inch. In other embodiments, the central wheel 120 is offset laterally from the pivot arm 140 by a distance ranging between 0.25 inches and 0.50 inches, 0.50 inches and 0.75 inches, or 0.75 inches and 1.0 inch. For example, the center wheel 120 can be offset laterally from the rotating arm 140 by 0.10 inch, 0.15 inch, 0.20 inch, 0.25 inch, 0.30 inch, 0.35 inch, 0.40 inch, 0.45 inch, 0.50 inch, 0.55 inch, 0.60 inch, 0.65 inch, 0.70 inch, 0.75 inch, 0.80 inch, 0.85 inch, 0.90 inch, 0.95 inch, or 1.0 inch.

[0057] In other embodiments, the leading wheel 110 and the trailing wheel 130 can be offset from the pivot arm 140 at non-uniform distances. For example, the leading wheel 110 can be offset farther from the pivot arm 140 than the trailing wheel 130. Conversely, the trailing wheel 130 can be offset farther from the pivot arm 140 than the leading wheel 110. The staggered offset distances described allow the leading wheel 110 and the trailing wheel 130 to be coupled to the pivot arm 140 in a manner that overlaps and is adjacent to one another. This further reduces the required length of the pivot arm 140, allowing less material to be used. 5. Wheel Description Wheel diameter

[0058] Referring again to FIG. 4 , each wheel may be characterized by a diameter. In some embodiments, the wheels all have different diameters relative to one another. Preferably, the leading wheel 110 may have the largest diameter D1, the trailing wheel 130 may have the smallest diameter D3, and the center wheel 120 may have a diameter D2 that is smaller than the diameter D1 of the leading wheel 110 but larger than the diameter D3 of the trailing wheel 130. The leading wheel 110 is sized with a larger diameter to efficiently overcome obstacles O. The trailing wheel 130 is preferably sized with a smaller diameter to minimize the overall width of the wheel system 100. This allows the wheel system 100 to have a compact design while ensuring functionality.

[0059] In many embodiments, the diameter D1 of the leading wheel 110 can range from 3 inches to 5 inches. In some embodiments, the diameter D1 of the leading wheel 110 can range from 3.0 inches to 3.5 inches, 3.5 inches to 4.0 inches, 4.0 inches to 4.5 inches, or 4.5 inches to 5.0 inches. In other embodiments, the diameter D1 of the leading wheel 110 can range from 3 inches to 4 inches, or 4 inches to 5 inches. For example, the diameter D1 of the leading wheel 110 can be 3 inches, 3.1 inches, 3.2 inches, 3.3 inches, 3.4 inches, 3.5 inches, 3.6 inches, 3.7 inches, 3.8 inches, 3.9 inches, 4.0 inches, 4.1 inches, 4.2 inches, 4.3 inches, 4.4 inches, 4.5 inches, 4.6 inches, 4.7 inches, 4.8 inches, 4.9 inches, or 5.0 inches.

[0060] In many embodiments, the diameter D2 of the center wheel 120 can be between 60% and 90% of the total diameter D1 of the leading wheel 110. In some embodiments, the diameter D2 of the center wheel 120 can be between 60% and 70%, 70% and 80%, or 80% and 90% of the total diameter D1 of the leading wheel 110. In some embodiments, the diameter D2 of the center wheel 120 can be between 60% and 75%, or 75% and 90% of the total diameter D1 of the leading wheel 110. For example, the diameter D2 of the center wheel 120 can be 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, or 90% of the overall diameter D1 of the front wheel 110.

[0061] In many embodiments, the diameter D2 of the center ring 120 can range between 2.0 inches and 4.0 inches. In some embodiments, the diameter D2 of the center ring 120 can range between 2.0 inches and 2.5 inches, 2.5 inches and 3.0 inches, 3.0 inches and 3.5 inches, or 3.5 inches and 4.0 inches. In other embodiments, the diameter D2 of the center ring 120 can range between 2.0 inches and 3.0 inches, or 3.0 inches and 4.0 inches. For example, the diameter D2 of the central wheel 120 can be 2.0 inches, 2.05 inches, 2.15 inches, 2.2 inches, 2.25 inches, 2.3 inches, 2.35 inches, 2.4 inches, 2.45 inches, 2.5 inches, 2.55 inches, 2.6 inches, 2.65 inches, 2.7 inches, 2.75 inches, 2.8 inches, 2.85 inches, 2.9 inches, 2.95 inches, 3.0 inches, 3.05 inches, 3.15 inches, 3.2 inches, 3.25 inches, 3.3 inches, 3.35 inches, 3.4 inches, 3.45 inches, 3.5 inches, 3.55 inches, 3.6 inches, 3.65 inches, 3.7 inches, 3.75 inches, 3.8 inches, 3.85 inches, 3.9 inches, 3.95 inches, or 4.0 inches.

[0062] In many embodiments, the diameter D3 of the trailing wheel 130 can be in the range of between 35% and 65% of the total diameter D1 of the leading wheel 110. In some embodiments, the diameter D3 of the trailing wheel 130 can be in the range of between 35% and 45%, 45% and 55%, or 55% and 65% of the total diameter D1 of the leading wheel 110. In some embodiments, the diameter D3 of the trailing wheel 130 can be in the range of between 35% and 50%, or 50% and 60% of the total diameter D1 of the leading wheel 110. For example, the diameter D3 of the trailing wheel 130 can be 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, or 65% of the overall diameter D1 of the leading wheel 110.

[0063] In many embodiments, the diameter D3 of the trailing wheel 130 can range between 1.0 inch and 3.0 inches. In some embodiments, the diameter D3 of the trailing wheel 130 can range between 1.0 inch and 1.5 inches, 1.5 inches and 2.0 inches, 2.0 inches and 2.5 inches, or 2.5 inches and 3.0 inches. In other embodiments, the diameter D3 of the trailing wheel 130 can range between 1.0 inch and 2.0 inches, or 2.0 inches and 3.0 inches. For example, the diameter D3 of the driven wheel 130 can be 1.0 inch, 1.05 inch, 1.15 inch, 1.2 inch, 1.25 inch, 1.3 inch, 1.35 inch, 1.4 inch, 1.45 inch, 1.5 inch, 1.55 inch, 1.6 inch, 1.65 inch, 1.7 inch, 1.75 inch, 1.8 inch, 1.85 inch, 1.9 inch, 1.95 inch, 2.0 inch, 2.05 inch, 2.15 inch, 2.2 inch, 2.25 inch, 2.3 inch, 2.35 inch, 2.4 inch, 2.45 inch, 2.5 inch, 2.55 inch, 2.6 inch, 2.65 inch, 2.7 inch, 2.75 inch, 2.8 inch, 2.85 inch, 2.9 inch, 2.95 inch, or 3.0 inch. b. Wheel system measurements

[0064] Referring to FIG. 5 , the compact dimensions of the wheel system 100 can be characterized by a maximum height MH and a maximum width MW. The maximum height MH of the wheel system 100 is defined by the diameter D1 of the leading wheel. The maximum width MW can be measured as the distance between the forward-most portion of the leading wheel 110 and the rearward-most portion of the trailing wheel 130. The maximum width MW of the wheel system 100 can be defined by a width equal to or greater than the diameter D1 of the leading wheel 110 plus the diameter D3 of the trailing wheel 130. The location of the wheels on either side of the rotating arm 140 minimizes the maximum width MW, allowing for a more compact design compared to a standard wheel assembly in which the wheels are directly adjacent. The smaller diameter D3 of the trailing wheel 130 further reduces the maximum width MW.

[0065] In many embodiments, the maximum height M H of the wheel system 100 can range between 3.0 inches and 5.0 inches. In some embodiments, the maximum height M H of the wheel system 100 can range between 3.0 inches and 3.5 inches, 3.5 inches and 4.0 inches, 4.0 inches and 4.5 inches, or 4.5 inches and 5.0 inches. In other embodiments, the maximum height M H of the wheel system 100 can range between 3.0 inches and 4.0 inches, or 4.0 inches and 5.0 inches. For example, the maximum height MH of the wheel system 100 can be 3.0 inches, 3.1 inches, 3.2 inches, 3.3 inches, 3.4 inches, 3.5 inches, 3.6 inches, 3.7 inches, 3.8 inches, 3.9 inches, 4.0 inches, 4.1 inches, 4.2 inches, 4.3 inches, 4.4 inches, 4.5 inches, 4.6 inches, 4.7 inches, 4.8 inches, 4.9 inches, or 5.0 inches.

[0066] In many embodiments, the maximum width MW of the wheel system 100 can range between 5.0 inches and 7.0 inches. In some embodiments, the maximum height MH of the wheel system 100 can range between 5.0 inches and 5.5 inches, 5.5 inches and 6.0 inches, 6.0 inches and 6.5 inches, or 6.5 inches and 7.0 inches. In other embodiments, the maximum width MW of the wheel system 100 can range between 5.0 inches and 6.0 inches, or 6.0 inches and 7.0 inches. For example, the maximum width MW of the wheel system 100 can be 5.0 inches, 5.1 inches, 5.2 inches, 5.3 inches, 5.4 inches, 5.5 inches, 5.6 inches, 5.7 inches, 5.8 inches, 5.9 inches, 6.0 inches, 6.1 inches, 6.2 inches, 6.3 inches, 6.4 inches, 6.5 inches, 6.6 inches, 6.7 inches, 6.8 inches, 6.9 inches, or 7.0 inches.

[0067] The maximum width MW of the wheel system 100 depends not only on the fore-aft spacing of the wheels but also on the diameter of the wheels. Referring again to FIG. 4, the fore-aft spacing of the wheels can be characterized by a fore-aft distance A3 measured between the first focal point F1 and the second focal point F2, and a fore-aft distance A4 measured between the second focal point F2 and the third focal point F3. In many embodiments, the respective fore-aft distances A3 and A4 can be substantially similar to one another. In other embodiments, the respective fore-aft distances A3 and A4 can be different.

[0068] In some embodiments, at least one of the front and rear wheel spacing distances A3, A4 can range between 0.5 inches and 2.5 inches. In some embodiments, at least one of the front and rear wheel spacing distances A3, A4 can range between 0.5 inches and 0.75 inches, 0.75 inches and 1.0 inches, 1.0 inches and 1.25 inches, 1.25 inches and 1.5 inches, 1.5 inches and 1.75 inches, 1.75 inches and 2.0 inches, 2.0 inches and 2.25 inches, or 2.25 inches and 2.5 inches. In some embodiments, at least one of the front and rear wheel spacing distances A3, A4 can be in the range of 0.5 inches to 1.0 inches, 0.75 inches to 1.25 inches, 1.0 inches to 1.5 inches, 1.25 inches to 1.75 inches, 1.5 inches to 2.0 inches, 1.75 inches to 2.25 inches, or 2.0 inches to 2.5 inches. For example, at least one of the front and rear wheel spacing distances A3, A4 can be in the range of 0.5 inches, 0.55 inches, 0.6 inches, 0.65 inches, 0.7 inches, 0.75 inches, 0.8 inches, 0.85 inches, 0.9 inches, 0.95 inches, 1.0 inches, 1.05 inches, 1.05 inches, 1.1 inches, 1.15 inches, 1.2 inches, 1.25 inches, 1.3 inches, 1.35 inches, or 1.4 inches. The thickness can be 1.45 inches, 1.5 inches, 1.55 inches, 1.6 inches, 1.65 inches, 1.7 inches, 1.75 inches, 1.8 inches, 1.85 inches, 1.9 inches, 1.95 inches, 2.0 inches, 2.05 inches, 2.1 inches, 2.15 inches, 2.2 inches, 2.25 inches, 2.3 inches, 2.35 inches, 2.4 inches, 2.45 inches, or 2.5 inches.

[0069] As discussed above, wheel system 100 advantageously includes a large leading wheel 110 for easily negotiating obstacles O while maintaining compact overall dimensions. The compact design of wheel system 100 can be characterized by a ratio R defined by the maximum height MH divided by the maximum width MW. The larger the ratio R, the larger the leading wheel 110 will be in proportion to the maximum width MW of system 100. Thus, the ratio R between maximum height MH and maximum width MW is a measure of the balance between wheel system 100's ability to smoothly traverse obstacles O (due to the relatively large leading wheel) and the wheel system's 100's compact dimensions.

[0070] In some embodiments, the ratio R between the maximum height MH and the maximum width MW can be greater than about 5.0. In other embodiments, the ratio R between the maximum height MH and the maximum width MW can be greater than 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, or 0.95. In some embodiments, the ratio R between the maximum height MH and the maximum width MW can be about 0.50, about 0.55, about 0.60, about 0.65, about 0.70, about 0.75, about 0.80, about 0.85, about 0.90, or about 0.95. A wheel system 100 having a ratio R greater than 0.50 is a direct result of having trailing wheels 130 with smaller diameters than leading wheels 119. Wheel systems having similar designs but uniform wheel diameters require a ratio R of less than 0.50 because the maximum width of such systems needs to be at least twice the diameter of the leading wheel to accommodate both leading and trailing wheels having the same diameter.

[0071] The weight of the wheel system 100 may be defined by the sum of the weights of the wheel system 100 features. In many embodiments, the weight of the wheel system 100 may range between 1.0 and 5.0 pounds. In some embodiments, the weight of the wheel system 100 may range between 1.0 and 2.0 pounds, 2.0 and 3.0 pounds, 3.0 and 4.0 pounds, or 4.0 and 5.0 pounds. In other embodiments, the weight of the wheel system 100 may range between 1.0 and 2.5 pounds, or 2.5 and 5.0 pounds. For example, the wheel system 100 may weigh approximately 1.0 pounds, approximately 1.5 pounds, approximately 2.0 pounds, approximately 2.5 pounds, approximately 3.0 pounds, approximately 3.5 pounds, approximately 4.0 pounds, approximately 4.5 pounds, or approximately 5.0 pounds. c. Wheel hardness and material

[0072] Each wheel may be further characterized by hardness and material. One or more wheels may have a similar hardness relative to one or more other wheels. Preferably, all three wheels may have a similar hardness. The hardness of wheel system 100 may be customized to best accommodate the desired function of wheel system 100. Increasing the hardness of a wheel may increase the useful life of the wheel. Conversely, decreasing the hardness of a wheel may increase flexibility and promote smoother rolling over cracks or obstacles. Therefore, the hardness for each wheel may be determined by the intended use of the wheel. For example, a wheel system associated with luggage is used by people during travel and typically has a handle. The desired function of the wheel is to cushion the shock or impact of obstacles that are perceived by the user via the handle. For this reason, a wheel system having shock-absorbing characteristics, such as a relatively lower hardness, further promotes the smooth rolling performance of the wheel system.

[0073] In some embodiments, the hardness of one or more wheels can range from about 78A to 98A. In other embodiments, the hardness of one or more wheels can range from about 78A to 80A, about 80A to 82A, about 82A to 84A, about 84A to 86A, about 86A to 88A, about 88A to 90A, about 90A to 92A, about 92A to 94A, about 94A to 96A, or about 96A to 98A. In some embodiments, the hardness of one or more wheels can be 78A, 79A, 80A, 81A, 82A, 83A, 84A, 85A, 86A, 87A, 88A, 89A, 90A, 91A, 92A, 93A, 94A, 95A, 96A, 97A, or 98A.

[0074] The material of the wheel system 100 can also affect hardness. In many embodiments, one or more wheels can be constructed of a material selected from the group including thermoplastics, thermoplastic polyurethanes, thermosets, aromatic diisocyanates, toluene diisocyanate (TDI), methylene diphenyl diisocyanate (MDI), nylon, polypropylene, polyethylene, or any material suitable for constructing wheels. In some embodiments, the material of the center wheel 120 is the same as the material of the leading wheel 110 and / or trailing wheel 130. In other embodiments, the center wheel 120 can be constructed of a first material selected from the above group, while the leading wheel 110 and / or trailing wheel 130 are constructed of a second material selected from the above group.

[0075] In some embodiments, the wheel system 100 can further include one or more outer rims 155 on one or more wheels. The one or more rims 155 can have a width equal to the width of the wheel to which the rim is connected and a diameter slightly larger than the diameter of the wheel. The rim 155 can surround the wheel and act as a barrier against the ground surface to reduce traction and / or wear on the one or more wheels. The material of the rim 155, like the wheel itself, can be customized depending on the desired use. The outer rim 155 of a given wheel can be the same material as the wheel or a different material. A wide range of material combinations for the one or more wheels and the one or more rims 155 allows for increased functionality depending on the intended use of the wheel system. For example, the outer rim 155 can be constructed of a material with a higher hardness than the wheel, such as nylon, polypropylene, polyethylene, or a material with similar properties selected from the list above. In another example, the outer rim 155 can be constructed of a material having a lower hardness than the wheel, such as rubber or a material having similar properties selected from the list above. An outer rim 155 material having a lower hardness may absorb shock more easily than a harder material, while an outer rim 155 material having a higher hardness may have better durability. The inclusion of the outer rim 155 can allow the outer portion of the wheel that contacts the ground to be softer, while the inner portion of the wheel includes a harder material that provides structural support and durability. d. Hubcap

[0076] In some embodiments, as can be seen in FIG. 11 , the wheel system 100 can further include one or more hub caps 160 on one or more wheels. The one or more hub caps 160 can be coupled to the exterior of the one or more wheels. This can provide the wheel system 100 with a smooth aesthetic and protect the wheels from wear. The one or more hub caps 160 can have any shape that can fit within the outer rim of the one or more wheels. For example, the one or more hub caps 160 can have a circular shape with a diameter complementary to the diameter of the wheel to which the hub cap is attached. In another example, the one or more hub caps can have an X-shape. 6. Alternative Embodiments

[0077] In some embodiments, the leading wheel 110 and the trailing wheel 130 may include multiple components (not shown). The wheel components may have the same diameter so as to contact the ground surface 1000 at the same time. The wheel component of the leading wheel 110 may be coupled to the rotating arm 140 via a leading axle 151. The wheel component of the trailing wheel 130 may be coupled to the rotating arm 140 via a trailing axle 152. In some embodiments, three wheels are coupled to the rotating arm 140 on the same side. In further embodiments, the center wheel 120 may fit between the wheel components of the leading wheel 110 and the trailing wheel 130. For example, a first wheel component of the leading wheel 110 and a first wheel component of the trailing wheel 130 may be coupled to the rotating arm 140 via their respective axles, then the center wheel 120 may be coupled to the rotating arm via a central axle 135, and then a second wheel component of the leading wheel 110 and a second wheel component of the trailing wheel 130 may be coupled to the rotating arm 140 via their respective axles. In this example, the second wheel components of the leading wheel 110 and trailing wheel 130 are offset from the pivot arm 140 by a greater distance than the first wheel components of the leading wheel 110 and trailing wheel 130, allowing the center wheel 120 to fit between them. These wheels are then allowed to partially overlap, reducing the maximum width MW for a compact design. 7. Preferred Luggage Form

[0078] Preferably, the wheel system 100 described herein is applied to a luggage 300, as shown in FIG. 12 . In some embodiments, the luggage 300 may include a handle on the top side of the body for a user to hold and pull the luggage 300 to transport it. The luggage 300 may further include one or more wheel wells 305 formed as recesses from the main body 301 of the luggage. Each wheel well 305 may house a separate wheel system 100. To minimize the external volume of the luggage 300, each wheel well 305 may be formed such that the wheel system 100 housed therein does not extend beyond the outer periphery of the shape of the luggage body 301. As illustrated in FIG. 13 , the wheel wells 305 may be formed near an edge formed by the front and bottom of the luggage 300 so that when the luggage 300 is tilted toward that edge, the wheels are the only parts of the luggage 300 that come into contact with the ground, and the luggage 300 can be rolled. The wheel wells 305 may be formed on opposite sides of each other. Each wheel well 305 may further include an axle receiving opening 306 for connecting the wheel system 100 to the luggage 300. The axle receiving opening 306 may take the form of a hole, a bore, or any other means suitable for receiving and securing an axle. Preferably, the axle receiving opening 306 of the wheel well 305 may receive the central axle 135 such that the center wheel 120 is close to the wheel well 305. In some embodiments, the luggage body may extend above the wheel wells 305, allowing the wheel system 100 to fit internally in the luggage 300. 8. Working Example Example 1

[0079] The acceleration of an exemplary wheel system according to the present invention over a one-inch bump was compared with a control wheel system with two wheels. The exemplary wheel system had two wheel sets (six wheels in total) that further included a leading wheel, a center wheel, and a trailing wheel. The acceleration of these wheel systems was measured by an accelerometer during each trial. Table 1 below displays the results of this comparison. The value displayed for each trial is the average acceleration of the wheel system measured in the opposite direction of motion. A larger magnitude corresponds to a larger change in acceleration and therefore a larger force applied to the wheel system by the bump. The bump causes the wheel system to experience a change in acceleration because the wheel system first experiences a decrease in acceleration due to climbing over the first half of the bump, followed by an increase in acceleration as it descends the second half of the bump. [Table 1]

[0080] The exemplary wheel system experienced 1.40 (G) less acceleration than the control wheel system. This lower acceleration value for the exemplary wheel system means that bumps applied less force to the wheel system. Thus, the exemplary wheel system provides a smoother ride for the user because the user experiences less force as they travel over bumps. Example 2

[0081] The acceleration of an exemplary wheel system according to the present invention over a one-inch expansion crack was compared to a control wheel system with two wheels. The exemplary wheel system had two wheel sets (six wheels in total) that further included a leading wheel, a center wheel, and a trailing wheel. The acceleration of these wheel systems was measured by an accelerometer during each trial. Table 2 below displays the results of this comparison. The number displayed for each trial is the average acceleration of the wheel system measured in the opposite direction of motion (positive numbers correlate to deceleration). A larger magnitude corresponds to a larger change in acceleration and therefore a larger force applied to the wheel system by the crack. The crack causes the wheel system to experience a change in acceleration because the wheels fall and hit the edge of the crack, slowing the wheel system. [Table 2]

[0082] The exemplary wheel system experienced an average acceleration of 4.61 (G) less than the control wheel system. This lower acceleration value for the exemplary wheel system means that less force was applied to the wheel system by the crack. Thus, the exemplary wheel system provides a smoother ride for the user because the user experiences less force as they travel over the crack.

[0083] Substitution of one or more elements recited in a claim is a reconstruction, not a repair. Additionally, benefits, other advantages, and solutions to problems have been described with respect to particular embodiments. However, the benefits, advantages, solutions to problems, and any one or more elements that cause or make more noticeable any benefit, advantage, or solution should not be construed as a critical, necessary, or essential feature or element of any or all of the claimed features.

[0084] Furthermore, embodiments and limitations disclosed herein are not available to the public under the doctrine of public domain if the embodiment and / or limitation (1) is not explicitly claimed in the claims, and (2) is an equivalent or potential equivalent to the explicit elements and / or limitations in the claims under the doctrine of equivalents.

[0085] Various features and advantages of the disclosure are described below.

[0086] (Item 1) A wheel system comprising: a leading wheel having a first diameter and a first focal point; a center wheel having a second diameter and a second focal point; a trailing wheel having a third diameter and a third focal point; a swivel arm; a leading axle; a center axle; and a trailing axle, wherein the first diameter is larger than the second diameter and the second diameter is larger than the third diameter; the swivel arm has a leading end and a trailing end; the leading axle rotatably couples the leading wheel to the leading end of the swivel arm; the trailing axle rotatably couples the trailing wheel to the trailing end of the swivel arm; and the center wheel is rotatably coupled about the center axle. the swivel arm is rotatably coupled about the central axis, the central axis being located between the leading end and the trailing end, the central wheel being located on a first side of the swivel arm, the leading wheel and the trailing wheel being located on a second side of the swivel arm opposite the first side, the swivel arm defining a reference plane extending through the first focal point, the second focal point, and the third focal point, the wheel system defining a contact surface tangent to the leading wheel, the central wheel, and the trailing wheel, the reference plane and the contact surface forming an acute angle.

[0087] (Item 2) The wheel system described in Item 1, wherein the acute angle between the contact surface and the reference surface is between 10 degrees and 60 degrees.

[0088] (Item 3) The wheel system described in Item 2, wherein the acute angle between the contact surface and the reference surface is between 10 degrees and 30 degrees.

[0089] (Item 4) The wheel system described in Item 1, wherein the acute angle between the contact surface and the reference surface is between 10 degrees and 30 degrees.

[0090] (Item 5) The wheel system of item 1, wherein the center wheel is offset from the rotating arm by a distance between 0.40 inches and 0.65 inches.

[0091] (Item 6) The wheel system described in Item 1, wherein the second diameter is between 60% and 90% of the first diameter, and the third diameter is between 35% and 65% of the first diameter.

[0092] (Item 7) The wheel system described in Item 1 further comprises a spacer positioned on at least one of the leading axle, the central axle, and the trailing axle between the rotating arm and at least one of the leading wheel, the central wheel, and the trailing wheel.

[0093] (Item 8) The wheel system of item 7, wherein the spacer has a spacer width between 0.4 inches and 0.6 inches.

[0094] (Item 9) The wheel system described in Item 7, wherein the spacer is integrally formed with the rotating arm.

[0095] (Item 10) The wheel system described in Item 1, wherein the maximum width of the wheel system measured between the front of the leading wheel and the rear of the trailing wheel is between 5.0 inches and 7.0 inches.

[0096] (Item 11) A wheel system comprising: a leading wheel having a first diameter and a first focal point; a center wheel having a second diameter and a second focal point; a trailing wheel having a third diameter and a third focal point; a swivel arm; a leading axle; a center axle; and a trailing axle, wherein the first diameter is larger than the second diameter and the second diameter is larger than the third diameter; the swivel arm has a leading end and a trailing end; the leading axle rotatably couples the leading wheel to the leading end of the swivel arm; the trailing axle rotatably couples the trailing wheel to the trailing end of the swivel arm; the center wheel is rotatably coupled about the center axle; the swivel arm is rotatably coupled about the center axle; the center axle is positioned between the leading end and the trailing end; the center wheel is positioned on a first side of the swivel arm; and the leading wheel and the trailing wheel are rotatably coupled to the swivel arm. a wheel system positioned on a second side opposite the first side, the wheel system defining a contact surface tangent to the leading wheel, the center wheel, and the trailing wheel; the rotating arm defining a reference plane extending through the first focal point, the second focal point, and the third focal point; the first focal point having a first focal height, the second focal point having a second focal height, and the third focal point having a third focal height; the first focal point height, the second focal point height, and the third focal point height being measured as the perpendicular distance between the contact surface and the first focal point, the second focal point, and the third focal point, respectively; and the first focal height being between 1.75 inches and 2.25 inches, the second focal height being between 1.25 inches and 1.75 inches, and the third focal height being between 0.75 inches and 1.25 inches.

[0097] (Item 12) The wheel system of item 11, wherein the leading wheel and the trailing wheel are offset from the rotating arm by a distance between 0.40 inches and 0.65 inches.

[0098] (Item 13) The wheel system of item 11, wherein the center wheel is offset from the rotating arm by a distance between 0.40 inches and 0.65 inches.

[0099] (Item 14) The wheel system described in Item 11, wherein the maximum width of the wheel system measured between the front of the leading wheel and the rear of the trailing wheel is between 5.0 inches and 7.0 inches.

[0100] (Item 15) A luggage bag comprising a luggage body, a wheel well, a central axle, and a wheel system connected to the luggage body by the central axle and housed within the wheel well, the wheel system comprising a leading wheel having a first diameter and a first focal point, a central wheel having a second diameter and a second focal point, a trailing wheel having a third diameter and a third focal point, a swivel arm, a leading axle, and a trailing axle, the swivel arm being rotatably connected about the central axle, the central wheel being rotatably connected about the central axle, the swivel arm having a leading end forward of the central axle and a trailing end rearward of the central axle, the leading axle connecting the leading wheel to the swivel arm, the leading wheel and the trailing wheel are located on a second side of the rotating arm opposite the first side; the first diameter is larger than the second diameter and the second diameter is larger than the third diameter; the rotating arm defines a reference plane extending through the first focal point, the second focal point, and the third focal point; the wheel system defines a contact surface tangent to the leading wheel, the central wheel, and the trailing wheel, and the reference plane and the contact surface form an acute angle.

[0101] (Item 16) The luggage bag according to Item 15, wherein the wheel system housed within the wheel well does not extend beyond the outer periphery of the luggage body.

[0102] (Item 17) The luggage bag according to item 15, wherein the leading wheel and the trailing wheel are offset from the rotating arm by a distance between 0.40 inches and 0.65 inches.

[0103] (Item 18) The luggage bag of item 15, wherein the center wheel is offset from the rotating arm by a distance between 0.40 inches and 0.65 inches.

[0104] (Item 19) The luggage bag according to item 15, wherein the acute angle between the contact surface and the reference surface is between 10 degrees and 60 degrees.

[0105] (Item 20) The luggage bag of claim 19, wherein the acute angle between the contact surface and the reference surface is between 10 and 30 degrees.

[0106] (Item 21) A wheel system includes a leading wheel having a first diameter and a first focal point, a center wheel having a second diameter and a second focal point, a trailing wheel having a third diameter and a third focal point, a swivel arm, a leading axle, a center axle, and a trailing axle, wherein the first diameter is larger than the second diameter and the second diameter is larger than the third diameter, the swivel arm has a leading end and a trailing end, the leading axle rotatably couples the leading wheel to the leading end of the swivel arm, and the trailing axle a trailing wheel rotatably coupled to the rear end of the rotating arm, the central wheel rotatably coupled about the central axis, the rotating arm rotatably coupled about the central axis, the central axis being positioned between the front end and the rear end, the central wheel being positioned on a first side of the rotating arm, the leading wheel and the trailing wheel being positioned on a second side of the rotating arm opposite to the first side, and the rotating arm being configured to rotate around the first focal point, the second focal point, a point at which the wheel system defines a reference plane extending through the third focal point and the third focal point, the wheel system defining a contact surface tangent to the leading wheel, the center wheel, and the trailing wheel, the reference plane and the contact surface forming an acute angle, the wheel system configured to traverse an obstacle located on a ground surface, wherein in a first configuration, the contact surface is coincident with the ground surface, and in a second configuration, the leading wheel interacts with the obstacle such that the contact surface is not parallel to the ground surface and the leading wheel is below the ground surface, the center wheel is on the ground surface, and the trailing wheel is above the ground surface, and the wheel system is configured to traverse an obstacle located on a ground surface, wherein in a first configuration, the contact surface is coincident with the ground surface and the weight of the wheel system is supported by only the leading wheel and the trailing wheel, and in a fourth configuration, the wheel system interacts with the obstacle such that the contact surface is not parallel to the ground surface and the leading wheel is above the ground surface, the center wheel is on the ground surface, and the trailing wheel is below the ground surface.

[0107] (Item 22) The wheel system described in item 21, wherein the maximum width of the wheel system measured between the front of the leading wheel and the rear of the trailing wheel is between 5.0 inches and 7.0 inches.

[0108] (Item 23) The wheel system described in Item 22, wherein the maximum height of the wheel system is defined by the first diameter, and the ratio of the maximum height divided by the maximum width is greater than 0.6.

[0109] (Item 24) The wheel system described in Item 21, wherein the acute angle between the contact surface and the reference surface is between 10 degrees and 60 degrees.

[0110] (Item 25) The wheel system of item 11, wherein the leading wheel and the trailing wheel are offset from the rotating arm by a distance between 0.40 inches and 0.65 inches.

[0111] (Item 26) The wheel system of item 21, wherein the center wheel is offset from the rotating arm by a distance between 0.40 inches and 0.65 inches.

[0112] (Item 27) The wheel system described in Item 21, wherein the second diameter is between 60% and 90% of the first diameter and the third diameter is between 35% and 65% of the first diameter.

[0113] (Item 28) The wheel system described in Item 21, further comprising a spacer positioned on at least one of the leading axle, the central axle, and the trailing axle between the rotating arm and at least one of the leading wheel, the central wheel, and the trailing wheel.

[0114] (Item 29) The wheel system of item 28, wherein the spacer has a spacer width between 0.4 inches and 0.6 inches.

[0115] (Item 30) The wheel system described in Item 28, wherein the spacer is integrally formed with the rotating arm.

[0116] (Item 31) The wheel system described in Item 21, wherein the maximum width of the wheel system measured between the front of the leading wheel and the rear of the trailing wheel is between 5.0 inches and 7.0 inches.

[0117] (Item 32) A wheel system comprising: a leading wheel having a first diameter and a first focal point; a center wheel having a second diameter and a second focal point; a trailing wheel having a third diameter and a third focal point; a swivel arm; a leading axle; a center axle; and a trailing axle, wherein the first diameter is larger than the second diameter and the second diameter is larger than the third diameter; the swivel arm has a leading end and a trailing end; the leading axle rotatably couples the leading wheel to the leading end of the swivel arm; the trailing axle rotatably couples the trailing wheel to the trailing end of the swivel arm; the center wheel is rotatably coupled about the center axle; the swivel arm is rotatably coupled about the center axle; the center axle is positioned between the leading end and the trailing end; the center wheel is positioned on a first side of the swivel arm; and the leading wheel and the trailing wheel are located on the front and rear ends of the swivel arm. a wheel system positioned on a second side opposite the first side, the rotating arm defining a reference plane extending through the first focal point, the second focal point, and the third focal point; the wheel system defining a contact surface tangent to the leading wheel, the center wheel, and the trailing wheel, the reference surface and the contact surface forming an acute angle; the wheel system configured to traverse an obstacle located on a ground surface, wherein in a first configuration, the contact surface coincides with the ground surface; in a second configuration, only the leading wheel interacts with the obstacle, whereby the contact surface is not parallel to the ground surface, the center wheel is above the ground surface, and the rear wheel is on the ground surface; and in a third configuration, only the rear wheel interacts with the obstacle, whereby the contact surface is not parallel to the ground surface, the center wheel is above the ground surface, and the leading wheel is on the ground surface.

Claims

1. 1. A wheel system comprising: a leading wheel having a first diameter and a first focal point; a central ring having a second diameter and a second focal point; a follower wheel having a third diameter and a third focal point; A rotating arm; The tip and A central axis and a driven shaft; the first diameter is greater than the second diameter; the second diameter is greater than the third diameter; the rotating arm having a leading end and a trailing end; the front shaft rotatably connects the front wheel to the tip of the rotating arm, the driven shaft rotatably couples the driven wheel to the rear end of the rotating arm; the central wheel is coupled to be rotatable about the central axis; the rotating arm is coupled to be rotatable about the central axis; the central axis is located between the leading end and the trailing end; the central wheel is positioned on a first side of the rotating arm; the leading wheel and the trailing wheel are positioned on a second side of the rotating arm opposite the first side; the rotating arm defines a reference plane extending through the first focal point, the second focal point, and the third focal point; the wheel system defines contact surfaces for the leading wheel, the center wheel, and the trailing wheel; A wheel system wherein the reference surface and the contact surface form an acute angle.

2. The wheel system of claim 1 , wherein the acute angle between the contact surface and the reference surface is between 10 degrees and 60 degrees.

3. The wheel system of claim 2 , wherein the acute angle between the contact surface and the reference surface is between 10 and 30 degrees.

4. 2. The wheel system of claim 1, wherein the leading wheel and the trailing wheel are offset from the pivot arm by a distance between 0.40 inches and 0.65 inches.

5. 10. The wheel system of claim 1, wherein said center wheel is offset from said pivot arm by a distance between 0.40 inches and 0.65 inches.

6. 2. The wheel system of claim 1, wherein the second diameter is between 60% and 90% of the first diameter and the third diameter is between 35% and 65% of the first diameter.

7. 2. The wheel system of claim 1, further comprising a spacer positioned on at least one of the leading axle, the center axle, and the trailing axle between the rotating arm and at least one of the leading wheel, the center wheel, and the trailing wheel.

8. 8. The wheel system of claim 7, wherein the spacer has a spacer width between 0.4 inches and 0.6 inches.

9. The wheel system of claim 7 , wherein the spacer is integrally formed with the rotating arm.

10. 10. The wheel system of claim 1, wherein the maximum width of the wheel system measured between the front of the leading wheel and the rear of the trailing wheel is between 5.0 inches and 7.0 inches.

11. 1. A wheel system comprising: a leading wheel having a first diameter and a first focal point; a central ring having a second diameter and a second focal point; a follower wheel having a third diameter and a third focal point; A rotating arm; The tip and A central axis and a driven shaft; the first diameter is greater than the second diameter; the second diameter is greater than the third diameter; the rotating arm having a leading end and a trailing end; the front shaft rotatably connects the front wheel to the tip of the rotating arm, the driven shaft rotatably couples the driven wheel to the rear end of the rotating arm; the central wheel is coupled to be rotatable about the central axis; the rotating arm is coupled to be rotatable about the central axis; the central axis is located between the leading end and the trailing end; the central wheel is positioned on a first side of the rotating arm; the leading wheel and the trailing wheel are positioned on a second side of the rotating arm opposite the first side; the wheel system defines contact surfaces for the leading wheel, the center wheel, and the trailing wheel; the rotating arm defines a reference plane extending through the first focal point, the second focal point, and the third focal point; the first focal point has a first focal height, the second focal point has a second focal height, and the third focal point has a third focal height; the first focal height, the second focal height, and the third focal height are measured as vertical distances between the contact surface and the first focal point, the second focal point, and the third focal point, respectively; the first focal height is between 1.75 inches and 2.25 inches; the second focal height is between 1.25 inches and 1.75 inches; The wheel system wherein the third focal height is between 0.75 inches and 1.25 inches.

12. 12. The wheel system of claim 11, wherein the leading wheel and the trailing wheel are offset from the pivot arm by a distance between 0.40 inches and 0.65 inches.

13. 12. The wheel system of claim 11, wherein the center wheel is offset from the pivot arm by a distance between 0.40 inches and 0.65 inches.

14. 12. The wheel system of claim 11, wherein the maximum width of the wheel system measured between the front of the leading wheel and the rear of the trailing wheel is between 5.0 inches and 7.0 inches.

15. A luggage bag, a luggage body, a wheel well, a central axle, and a wheel system coupled to the luggage body by the central axle and housed within the wheel well, the wheel system is a leading wheel having a first diameter and a first focal point; a central ring having a second diameter and a second focal point; a follower wheel having a third diameter and a third focal point; A rotating arm; The tip and a driven shaft; the rotating arm is coupled to be rotatable about the central axis; the central wheel is coupled to be rotatable about the central axis; the rotating arm has a leading end forward of the central shaft and a trailing end rearward of the central shaft; the front shaft rotatably connects the front wheel to the tip of the rotating arm, the driven shaft rotatably couples the driven wheel to the rear end of the rotating arm; the central wheel is positioned on a first side of the rotating arm; the leading wheel and the trailing wheel are positioned on a second side of the rotating arm opposite the first side; the first diameter is greater than the second diameter; the second diameter is greater than the third diameter; the rotating arm defines a reference plane extending through the first focal point, the second focal point, and the third focal point; the wheel system defines contact surfaces for the leading wheel, the center wheel, and the trailing wheel; The reference surface and the contact surface form an acute angle.

16. 16. The luggage bag of claim 15, wherein the wheel system contained within the wheel well does not extend beyond the periphery of the luggage body.

17. 16. The luggage of claim 15, wherein the leading and trailing wheels are offset from the pivot arm by a distance between 0.40 inches and 0.65 inches.

18. 16. The luggage of claim 15, wherein the center wheel is offset from the pivot arm by a distance between 0.40 inches and 0.65 inches.

19. 16. The luggage of claim 15, wherein the acute angle between the contact surface and the reference surface is between 10 and 60 degrees.

20. 20. The luggage of claim 19, wherein the acute angle between the contact surface and the reference surface is between 10 and 30 degrees.

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