Skateboard with multi-wheel chassis

Abstract

A multi-wheel chassis that minimizes the interaction of the wheels with discontinuous and uneven surfaces. The chassis provides a suspension system that absorbs the impact forces caused by uneven surfaces and a unique attack angle that allows for the traversal of obstacles from a variety of angles.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to skateboards, and more particularly to multi-wheel skateboard trucks.

[0002] RELATED APPLICATION DATA

[0003] This application claims the benefit of U.S. Patent Application No. 63 / 045,582, filed June 29, 2020, and U.S. Patent Application No. 63 / 201,491, filed April 30, 2021, the contents of which are incorporated by reference in their entirety. BACKGROUND

[0004] Individuals use and ride skateboards as a convenient and entertaining mode of transportation. Generally, skateboards (or their electric versions) have many advantageous qualities over other self-propelled transportation alternatives, such as skateboards can be easily stored, picked up, and carried. However, typically, when a user rides a skateboard on discontinuous or uneven surfaces including (but not an exhaustive list) cracks, contraction joints, expansion joints, control joints, and bumps, the impact between the wheels and the discontinuous surface applies undesirable forces to the skateboard. This impact force results in adverse effects including noise, impact to the rider, loss of speed, and loss of control of the skateboard, including flipping and crashing. There is a need in the art for a mobile wheel platform that minimizes the interaction of the wheels with discontinuous and uneven surfaces to enhance the individual’s riding experience and satisfaction. SUMMARY

[0005] The present invention relates to a truck comprising:

[0006] - an axle, the axle comprising a first end and a second end spaced apart from the first end, and a longitudinal axis extending from the first end to the second end;

[0007] - a wheel assembly located proximate one of the first end and the second end of the axle and coupled to the axle by a central axle, the first wheel assembly comprising: a central wheel and a horizontal arm, each coupled to the central axle; wherein the horizontal arm is configured to rotate about the central axle and comprises a front hole, a middle hole, and a rear hole; a front axle received by the front hole of the horizontal arm; a rear axle received by the rear hole of the horizontal arm; a plurality of auxiliary wheels comprising: a front wheel fixed to the front axle; a rear wheel fixed to the rear axle;

[0008] - an angle of attack defined between a first reference line tangent to a forward-most and outermost point of the front wheel and a forward-most and outermost point of the center wheel and a second reference line parallel to the longitudinal axis.

[0009] In some embodiments, the angle of attack is between 40 and 45 degrees.

[0010] In some embodiments, the angle of attack is between 42 and 44 degrees.

[0011] In some embodiments, a lateral distance measured parallel to the longitudinal axis between the center wheel and the front wheel is approximately between 1.5 and 2.0 inches.

[0012] In some embodiments, a fore-aft distance between the front axle and the center axle is approximately between 1.5 and 2.0 inches.

[0013] In some embodiments, a fore-aft distance between the center axle and the rear axle is approximately between 1.5 and 2.0 inches.

[0014] In some embodiments, a diameter of the front wheel is approximately between 2.5 and 3.0 inches.

[0015] In some embodiments, the wheel assembly further comprises a spring mechanism configured to limit rotation of the horizontal arm about the center axle; wherein the spring mechanism comprises a spring washer received within a groove of the horizontal arm.

[0016] In some embodiments, the spring washer comprises a body having a perimeter and a center; wherein the spring washer further comprises at least one flexing portion, wherein the flexing portion extends from the perimeter of the spring washer toward the center and is configured to flex outwardly toward the perimeter.

[0017] In some embodiments, the center wheel is spaced further from the suspension axle than the plurality of auxiliary wheels with respect to the longitudinal direction.

[0018] In some embodiments, the front wheel and the rear wheel are equally spaced apart with respect to the longitudinal direction from the suspension axle.

[0019] In some embodiments, the center wheel comprises a center wheel width, wherein each of the plurality of auxiliary wheels comprises an auxiliary wheel width, and wherein the center wheel width is greater than the auxiliary wheel width.

[0020] In some embodiments, the center wheel width is approximately between 1.5 and 1.75 inches, and wherein the auxiliary wheel width is approximately between 0.5 and 0.7 inches.

[0021] The present invention is also directed to a chassis comprising:

[0022] - a suspension axle, a pivot saddle, a base plate, and a plurality of wheels; wherein the suspension axle comprises: a first end and a second end spaced apart from the first end; a longitudinal axis extending between the first end and the second end;

[0023] - a first central axle coupled to the first end and a second central axle coupled to the second end; wherein the first central axle and the second central axle extend along the longitudinal axis;

[0024] - a first central wheel coupled to the first central axle;

[0025] - a second central wheel coupled to the second central axle;

[0026] - an assembly; the assembly comprising: a first horizontal arm coupled to the first central axle and a second horizontal arm coupled to the second central axle;

[0027] wherein the first horizontal arm is configured to couple a first front wheel and a first rear wheel; wherein the second horizontal arm is configured to couple a second front wheel and a second rear wheel; wherein the first horizontal arm is configured to rotate about the first central axle; wherein the second horizontal arm is configured to rotate about the second central axle; wherein the chassis further comprises an angle of attack defined as an angle between a first reference line and a second reference line; wherein the first reference line is tangent to a forwardmost and outermost point of the first front wheel and a forwardmost and outermost point of the first central wheel; and wherein the second reference line is parallel to the longitudinal axis.

[0028] In some embodiments, the angle of attack is between 40 degrees and 45 degrees.

[0029] In some embodiments, the angle of attack is between 42 degrees and 44 degrees.

[0030] In some embodiments, at least the first horizontal arm comprises a groove configured to receive a spring washer; wherein the spring washer comprises a spring geometry configured to limit rotation of the first horizontal arm and the second horizontal arm.

[0031] In some embodiments, the first central wheel and the second central wheel comprise a similar width; wherein the first front wheel, the first rear wheel, the second front wheel, and the second rear wheel comprise a similar width; and wherein the width of the first central wheel and the second central wheel is greater than the width of the first front wheel, the first rear wheel, the second front wheel, and the second rear wheel.

[0032] In some embodiments, the first front wheel and first rear wheel are positioned on a first plane, wherein the first plane is perpendicular to the longitudinal axis; and wherein the first center wheel is positioned on a second plane, wherein the second plane is parallel to the first plane.

[0033] In some embodiments, the first plane is offset from the second plane in the longitudinal direction by a distance of between about 1.5 inches and 2.0 inches; and wherein the second plane is positioned further from the first end of the hanger axis than the first plane. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 A perspective view of a multi-wheel skateboard chassis is shown, according to one embodiment.

[0035] Figure 2 An exploded view of the chassis of Figure 1 is shown.

[0036] Figure 3 An exploded view of the wheel set of the chassis of Figure 1 is shown.

[0037] Figure 4 A top view of the chassis of Figure 1 is shown, showing the attack angle.

[0038] Figure 5 The dimensions and spacing of the wheel set shown in Figure 3 is shown from a top view.

[0039] Figure 6 The dimensions and spacing of the wheel set shown in Figure 3 is shown from a side view.

[0040] Figure 7 A top view of a multi-wheel chassis is shown, according to one embodiment, showing the attack angle for approaching an obstacle at a particular approach angle.

[0041] Figure 8 A top view of the multi-wheel chassis of Figure 7 is shown, showing the attack angle for approaching an obstacle at another approach angle.

[0042] Figure 9 An exploded view of a horizontal arm and corresponding spring insert, according to embodiments of Figure 1 is shown.

[0043] Figure 10 An exploded view of a horizontal arm, spring insert, and hanger of the chassis of Figure 1 is shown.

[0044] Figure 11 A spring washer is shown according to one embodiment of a multi-wheel chassis.

[0045] Figure 12 A spring washer is shown according to an alternative embodiment of a multi-wheel chassis.

[0046] Figure 13 A spring washer is shown according to another alternative embodiment of a multi-wheel chassis.

[0047] Figure 14 A top view of a suspension axle of a chassis is shown according to an embodiment of Figure 1

[0048] Figure 15 A perspective view of a suspension axle of Figure 14

[0049] Figure 16 A perspective view of a base plate of a chassis is shown according to an embodiment of Figure 1

[0050] Figure 17 An exploded view of a suspension axle and base plate assembly of a chassis is shown according to Figure 1

[0051] Figure 18 A perspective view of a horizontal arm of a multi-wheel chassis is shown according to an alternative embodiment. DETAILED DESCRIPTION

[0052] I. Core of the Invention

[0053] Described herein is a multi-wheel skateboard chassis configured to traverse discontinuous surfaces of various shapes and sizes smoothly at a wide range of speeds and in a wide range of directions. What is given below is a multi-wheel skateboard embodiment having a chassis that provides a unique suspension mechanism and a unique arrangement of auxiliary wheels and a central wheel to provide a unique attack angle on a discontinuous surface. The unique suspension system and attack angle of the chassis wheels combine to minimize the impact of the interaction between the wheels and the obstacle or discontinuous surface. The suspension system includes a plurality of wheel groups, where each wheel group includes a central wheel, a plurality of auxiliary wheels, and a rotatable horizontal arm connecting the wheels. The auxiliary wheels are fixed on the front and rear regions 116 of the rotatable horizontal arm and are configured to move up and down in response to the rotation of the horizontal arm in response to an obstacle. In many embodiments, the suspension system further includes a spring mechanism 130 configured to constrain the rotation of the horizontal arm. The attack angle of the chassis is formed by the configuration of the wheels in each wheel group. Specifically, the attack angle depends on the spatial arrangement of the auxiliary wheels relative to the central wheel. The wheel spatial arrangement and attack angle allow the chassis to traverse obstacles smoothly when approaching the obstacle from various directions.

[0054] ​​​​In addition to skateboards, multi-wheel chassis can be used for a variety of applications. For example, in some embodiments, the chassis can be used for wheelbarrows, industrial carts, industrial dollies, commercial carts, commercial dollies, hand trucks, stack trucks, skateboard chassis, longboard chassis, electric skateboard chassis, carts, strollers, and / or luggage. Alternatively, the devices, methods, and articles described herein can be applied to other types of applications requiring a chassis or other mobile wheeled platform that skates through, hoovers, and / or maneuvers around obstacles or foreign objects (i.e., rocks, pebbles, cracks, and / or sidewalk contraction joints).

[0055] The terms or phrases "connect," "connected," "connects," and "connecting" as used herein can be defined as joining two or more elements together, either mechanically or otherwise. The connection (whether mechanical or otherwise) can last for any length of time, such as permanently or semi-permanently or just instantaneously.

[0056] The terms or phrases "link," "linked," "links," and "linking" as used herein can be defined as a relationship between two or more elements in which at least one element affects the other element. The link (whether mechanical or otherwise) can last for any length of time, such as permanently or semi-permanently or just instantaneously.

[0057] The terms or phrases "secure," "secured," "secures," and "securing" as used herein can be defined as firmly fixing or fastening (one or more elements) so that it cannot move or become loose. The securement (whether mechanical or otherwise) can last for any length of time, such as permanently or semi-permanently or just instantaneously.

[0058] The terms or phrases "couple," "coupled," "couples," and "coupling," as used herein, can be defined as connecting two or more elements either mechanically or otherwise in some manner. Coupling, whether mechanical or otherwise, can last for any length of time, such as permanently or semi-permanently or just momentarily. Mechanical coupling and the like should be broadly construed and encompass all types of mechanical couplings. The absence of the words "removably," "removable," or the like near the term "coupled" and the like is not intended to mean that the coupling in question is or is not removable.

[0059] The terms or phrases "skateboard," as used herein, can be defined as a rideable device. The skateboard can be defined by four distinct sections. The top section of the skateboard is defined as the portion of the deck that the user stands on. The bottom section of the skateboard is defined as the portion opposite the top section. Conventionally, the stance of a right foot user is defined as the left foot in front of the right foot. The front section of the skateboard is defined as the portion of the skateboard closest to the user's left foot. The rear section of the skateboard is defined as the portion of the skateboard closest to the user's right foot. The forward direction is defined as the direction of travel of the skateboard when the right foot pushes back on the ground to move the skateboard in the opposite direction. Similarly, when the multi-wheel chassis of the present invention is attached to the deck of the skateboard, the front section of the multi-wheel chassis can be defined as the portion of the chassis disposed closest to the front section of the skateboard, and the rear section of the chassis can be defined as the portion of the chassis disposed closest to the rear section of the skateboard.

[0060] The terms or phrases "ground" or "rolling surface," as used herein, can be defined as the surface on which the wheels of the skateboard typically roll. During typical operation of the skateboard, the ground or rolling surface is considered to be a generally smooth surface. However, in certain locations, the ground or rolling surface can include discontinuities or obstacles that make a portion of the ground or rolling surface non-smooth, such as cracks, bumps, expansion joints, or foreign objects.

[0061] The terms "first," "second," "third," "fourth," and similar terms, where used in the description and claims (if any), are used to distinguish between similar elements and are not necessarily used to describe a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments described herein are capable of operation in other sequences than the one illustrated or otherwise described herein. Furthermore, the terms "comprise," "comprising," "include," "including," and the like are to be construed open-ended, allowing for the inclusion of additional steps, elements, or components within the process, method, system, article, device, or apparatus that the steps, elements, or components are said to comprise.

[0062] The terms "left," "right," "front," "back," "top," "bottom," "over," "under," and similar terms are used in this description and in the claims (if any) to describe the

[0063] "A," "an," "the," "at least one," and "one or more" are used interchangeably to indicate that at least one of the stated items is present; a plurality of such items can be present unless the context clearly indicates otherwise. All numerical values of parameters (e.g., of quantities or conditions) in this specification, including the accompanying claims, are to be understood as modified in all instances by the term "about" unless otherwise indicated in the specification (e.g., the numerical values of parameters are approximations and are already deemed to contain inherent experimental errors for the sake of experimental feasibility). By the term "about," it is meant the stated numerical value allows some slight imprecision (with some approach to exactness in the value; with some leeway in the value). If an imprecision is otherwise stated herein, then "about" means that the described imprecision applies to the value. Otherwise, "about" means that the value can be the exact value, or close to the value, allowing for some acceptable processing tolerance and / or variation inherent in the materials, equipment, and methodologies used to produce the value. Further, the disclosure ranges include the disclosure of all values and further division of the ranges into sub-ranges. Herein, each value and sub-range of a range is disclosed as a separate embodiment. The terms "comprises," "comprising," "includes," "including," and "has," are inclusive and therefore specify the presence of stated items, but do not preclude the presence of further items. As used herein, the term "or" includes any one of the listed items and all combinations of the listed items. The terms first, second, third, etc. are used to differentiate between items, and are not intended to designate a particular order or sequence, unless otherwise stated.

[0064] In many examples used herein, when one or more values, ranges of values, relationships (e.g., position, orientation, etc.), or parameters (e.g., velocity, acceleration, mass, temperature, rotational rate, rotational direction, etc.) are used in conjunction with one or more other values, ranges of values, or parameters, and / or when a condition (e.g., with respect to time) is described, the term “approximately” can be used. In these examples, the use of the word “approximately” can mean that the value, range of values, relationship, parameter, or condition is within ±0.5%, ±1.0%, ±2.0%, ±3.0%, ±5.0%, and / or ±10.0% of the relevant value, range of values, relationship, parameter, or condition, as applicable.

[0065] Before any embodiments of the present disclosure are described in detail, it is to be understood that the present disclosure is not limited in its applications to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The present disclosure is capable of other embodiments and of being practiced or being carried out in various ways.

[0066] Described below are embodiments of a multi-wheel chassis. Figures 1-2 An embodiment of a chassis 100 is shown that includes a unique suspension system and an attack angle a to allow the chassis 100 to smoothly pass over discontinuous surfaces. Generally, the chassis 100 includes a plurality of wheel sets, a wheel set including a rotatable horizontal arm 110 and a plurality of wheels. The chassis 100 also includes a suspension axle 102 for connecting the plurality of wheel sets. The chassis 100 also includes a base plate 170 configured to receive the suspension axle 102 and connect the chassis 100 to an underside of a snowboard deck (not shown). The arrangement of the suspension axle 102 and the base plate 170 will be described in more detail below.

[0067] II. Suspension System

[0068] The plurality of wheel sets form a suspension system that absorbs unwanted impact upon impact with an obstacle and provides a smooth ride over such obstacles. Figure 3 A wheel set of a chassis 100 according to the present disclosure is shown. In many embodiments, each wheel set includes a rotatable horizontal arm 110 coupled to a central axle 108, at least one central wheel 120 rotatably coupled to the central axle 108, and a plurality of secondary wheels coupled to the horizontal arm 110 by a plurality of secondary axles. In many embodiments, each wheel set includes one central wheel 120 and two secondary wheels, including a front wheel 122 and a rear wheel 124. In many embodiments, the chassis 100 includes a pair of wheel sets, the pair of wheel sets being located on either side of the chassis 100 and secured to opposite ends of the suspension axle 102. In many embodiments, each of the pair of wheel sets is secured to either end of the suspension axle 102 and placed along a longitudinal axis 1000 extending from a first end 104 of the suspension axle 102 to a second end 106 of the suspension axle 102.

[0069] The center shaft 108 can be coupled to one end of the suspension shaft 102 and configured to secure both the center wheel 120 and the rotatable horizontal arm 110 thereto. The center shaft 108 can be received by a void 156 formed within the end of the suspension shaft 102 and fixedly coupled therein. In many embodiments, the center wheel 120 forms a hole. The hole is sized to allow the center wheel 120 to be coupled to the center shaft 108 and freely rotate thereabout. This allows the deck to roll smoothly and safely along the center wheel 120 during use.

[0070] The horizontal arm 110 is also rotatably coupled to the center shaft 108. The horizontal arm 110 includes a front region 112 disposed near the front of the chassis 100 (i.e., the portion of the chassis 100 closest to the front of the skateboard), a middle region 114 centered about the center shaft 108, and a rear region 116 disposed opposite the front region 112 and near the rear of the chassis 100. The middle region 114 includes a middle hole 115 that is substantially centered in the horizontal arm 110 and configured to concentrically link, attach, and / or couple the center shaft 108. The middle hole 115 allows the horizontal arm 110 to be coupled to the center shaft 108 and rotate thereabout. In the illustrated embodiment, the auxiliary wheels are attached at either end of the horizontal arm 110 by a plurality of auxiliary shafts 126, 128. As Figure 3 illustrated, the front region 112 is configured to receive the front wheel 122. The front region 112 includes a front hole 113 that is configured to concentrically link, attach, and / or couple the front auxiliary shaft 126 (hereinafter referred to as the “front shaft”). The front shaft 126 is fixedly coupled within the front hole 113 such that the front shaft 126 is restricted from rotating relative to the horizontal arm 110. The front wheel 122 is configured to be secured to the front shaft 126 and allowed to freely rotate thereon. As Figure 3 illustrated, the rear region 116 is configured to receive the rear wheel 124. The rear region 116 includes a rear hole 117 that is configured to concentrically link, attach, and / or couple the rear auxiliary shaft 128 (hereinafter referred to as the “rear shaft”). The rear shaft 128 is fixedly coupled within the rear hole 117 such that the rear shaft 128 is restricted from rotating relative to the horizontal arm 110. The rear wheel 124 is configured to be secured to the rear shaft 128 and allowed to freely rotate thereon. The configuration of the front and rear wheels 122, 124 attached to either end of the horizontal arm 110 by the plurality of auxiliary shafts 126, 128 allows the front and rear wheels 122, 124 to freely roll along the ground during use of the skateboard. The position of the auxiliary shafts 126, 128 to which the front and rear wheels 122, 124 are attached allows the front and rear wheels 122, 124 to move upward or downward as the horizontal arm 110 rotates about the center shaft 108.

[0071] The suspension system creates a "lift" that provides for smooth passage of the chassis 100 over obstacles or discontinuities in the rolling surface. As the chassis 100 rolls along the ground, the horizontal arms 110 can rotate in response to discontinuities in the surface. The rotation of the horizontal arms 110 allows the auxiliary wheels on either end of the horizontal arms 110 to be raised or lowered depending on the terrain of the rolling surface. The freedom of the auxiliary wheels to raise or lower in response to obstacles serves to absorb the shock typically associated with an impact between a wheel and such an obstacle.

[0072] The lift also serves to dynamically distribute load between the center wheel and the auxiliary wheels during use to provide a smoother ride. During normal use as the skateboard rolls along a smooth surface, the center wheel 120 can support the majority of the weight of the rider. However, when the center wheel 120 encounters an obstacle such as a crack, the front wheel 122 and / or the rear wheel 124 can take the majority of the weight of the rider to keep the chassis 100 stable. For example, upon impact with a crack in the rolling surface, the front wheel 122 encounters the crack first. While the front wheel 122 is in the crack, the horizontal arms 110 can rotate to lower the front wheel 122 into the crack. At the same time, the majority of the load of the skateboard is supported by the center wheel 120, which continues to roll along the main rolling surface. When the front wheel 122 exits the crack, the center wheel 120 can enter the crack. The horizontal arms 110 can rotate to raise the front wheel 122 and allow it to continue to roll along the main rolling surface. The center wheel 120 can be suspended above the crack by the horizontal arms 110, rather than falling into the crack and causing the board to decelerate or impact the rider. Because the horizontal arms are supported at either end by the front wheel 122 and the rear wheel 124 rolling on the smooth rolling surface, substantially all of the load of the skateboard is supported between the auxiliary wheels, and little or no load is carried by the center wheel 120. When the center wheel 120 exits the crack, the rear wheel 124 can enter the crack. While the rear wheel 124 is in the crack, the horizontal arms 110 can rotate to lower the rear wheel into the crack. At the same time, the majority of the load of the board is supported by the center wheel 120, which again rolls along the main rolling surface. Because at least one wheel is rolling along the main rolling surface and supporting the majority of the weight of the rider at any given time, the suspension system provides stability to the chassis 100 by allowing the wheelset to act as a single wheel rolling continuously along the smooth surface.

[0073] III. Attack Angle

[0074] The chassis 100 also includes a spatial arrangement between multiple wheels that work with the suspension system to provide smooth passage over obstacles and discontinuous surfaces. This spatial arrangement allows the suspension system to provide lift regardless of the angle at which the skateboard encounters an obstacle. In many embodiments, the center wheel and auxiliary wheels are spaced laterally (i.e., relative to the direction extending along the longitudinal axis 1000) and longitudinally. This spatial arrangement provides a wide base for the chassis 100 and prevents wheels within each given wheelset from simultaneously impacting an obstacle. Therefore, at any given time, at least one wheel in each given wheelset always supports the rider's weight on the primary rolling surface. The spatial relationship between the wheels within a given wheelset can be characterized by the angle of attack α, which will be described in detail below.

[0075] The angle of attack α represents the spatial relationship between the center wheel and the auxiliary wheel of the chassis 100. For example... Figure 4 As shown, the angle of attack α can be defined as the acute angle between a first reference line A connecting the center wheel 120 and the front wheel 122 of a specific wheelset and a second reference line B extending parallel to the longitudinal axis 1000. The first reference line A can connect a first reference point R1 located on the front wheel 122 and a second reference point R2 located on the center wheel 120. The first reference point R1 is the foremost and outermost reference point of the front wheel 122 (i.e., the farthest from the suspension axle 102). Similarly, the second reference point R2 is the foremost and outermost point of the center wheel 120. Different configurations of the front wheel and the center wheel 120 can change the relationship between the first reference point R1 and the second reference point R2, thereby changing the directionality of the first reference line A.

[0076] Because the angle of attack α is related to the positions of the first reference point R1 and the second reference point R2, it depends on the size and position of the center wheel 120 and the front wheel 122. Specifically, different specific configurations of the center wheel 120 and the front wheel 122 produce different angles of attack α in the following aspects: the lateral spacing between the center wheel 120 and the front wheel 122, the front-rear spacing between the center wheel 120 and the front wheel 122, the width of the center wheel 120 and the front wheel 122, and the diameter of the center wheel 120 and the front wheel 122. In this way, the angle of attack α can be manipulated by changing the spatial relationship between the front wheel and the center wheel 120 and / or by changing the diameter and / or width of the front wheel 122 and the center wheel 120. For example, providing a larger lateral distance between the front wheel 122 and the center wheel 120 produces a shallower angle of attack α, while providing a smaller lateral distance between the front wheel 122 and the center wheel 120 produces a steeper angle of attack α. Similarly, changing the diameter and / or width of one or more wheels within the wheelset alters the position of the first reference point R1 and / or the second reference point R2, which in turn changes the orientation of the first reference line A. The diameters and widths of the multiple wheels will be further detailed below.

[0077] In many embodiments, the center wheel 120 is laterally spaced from a plurality of auxiliary wheels to generate an angle of attack α. Typically, the plurality of auxiliary wheels include an "inline" configuration, where the front wheel 122 and the rear wheel 124 are positioned in a straight line from the front to the rear of the chassis 100. The center wheel 120 is not aligned in a straight line with the auxiliary wheels, but is laterally spaced from them. In many embodiments, such as Figure 5 As shown, the center wheel 120 is laterally further away from the suspension axle 102 than the auxiliary wheel, such that the auxiliary wheel is located between the center wheel 120 and the suspension axle 102. In an alternative embodiment (not shown), the center wheel 120 may be laterally closer to the suspension axle 102 than the auxiliary wheel, such that the center wheel 120 is located between the auxiliary wheel and the suspension axle 102. The lateral distance between the auxiliary wheel (particularly the front wheel 122) and the center wheel 120 relative to each other can be characterized by the distance between a pair of planes. The front wheel 122 and the center wheel 120 may each be located on corresponding planes separated by a specific distance in the longitudinal direction. Figure 5 A first plane 2000 is shown extending in the front-rear direction through the center of the center wheel 120. Similarly, a second plane 3000 is shown, extending in the front-rear direction (and thus parallel to the first plane 2000) through the center of the front wheel 122. In many embodiments, the distance P1 between the first plane 2000 and the second plane 3000 is approximately 2.0 inches. In some embodiments, the distance P1 between the first plane 2000 and the second plane 3000 can range between approximately 0.5 inches and 3.0 inches. In some embodiments, the distance P1 between the first plane 2000 and the second plane 3000 ranges between approximately 0.5 inches and 1.0 inches, between approximately 1.0 inches and 1.5 inches, between approximately 1.5 inches and 2.0 inches, between approximately 2.0 inches and 2.5 inches, or between approximately 2.5 inches and 3.0 inches. The distance between planes 2000 and 3000 forms a wheelset in which the center wheel 120 is laterally spaced from the auxiliary wheels. This design provides the wheelset with the required angle of attack α and a wide base.

[0078] The angle of attack α is also determined by the front-to-back distance between adjacent wheels. Figure 6 A front-to-back distance 192 defined between the front wheel 122 and the center wheel 120 is shown, wherein distance 192 is measured as the vertical distance between the axles to which each wheel is attached (i.e., the front axle 126 and the center axle 108). Similarly, a front-to-back distance 194 between the center wheel 120 and the rear wheel 124 can be measured as the vertical distance between the center axle 108 and the rear axle 128 to which each corresponding wheel is attached. In many embodiments, when the front wheel 122 and the rear wheel 124 are fixed near either end of the horizontal arm 110, the front-to-back distances 192, 194 between adjacent wheels depend on the front-to-back length of the horizontal arm 110.

[0079] In many embodiments, the front-to-back distance between any adjacent pair of wheels can be approximately 1.5 inches. In some embodiments, the front-to-back distance between any adjacent pair of wheels can be between approximately 0.5 and 2.5 inches. In some embodiments, the front-to-back distance between adjacent wheels can be between 0.5 and 1.0 inches, between 1.0 and 1.5 inches, between 1.5 and 2.0 inches, or between 2.0 and 2.5 inches. In some embodiments, the front-to-back distance between adjacent wheels can be between 0.5 and 0.75 inches, between 0.75 and 1.0 inches, between 1.0 and 1.25 inches, between 1.25 and 1.5 inches, between 1.5 and 1.75 inches, between 1.75 and 2.0 inches, between 2.0 and 2.25 inches, or between 2.25 and 2.5 inches. In many embodiments, the front-to-back distance 192 between the front wheels 122 and the center wheel 120 can be substantially similar to the front-to-back distance 194 between the center wheel 120 and the rear wheels 124. In other embodiments, the front-to-back distance 192 between the front wheels 122 and the center wheel 120 can be substantially different from the front-to-back distance 194 between the center wheel 120 and the rear wheels 124. The front-to-back distance between adjacent wheels, in part, determines the location of the first reference point Rl and the second reference point R2, and thus affects the angle of attack a.

[0080] The configuration of the center wheel 120 and the front wheels 122, in terms of spacing and the size of each wheel, defines the angle of attack a of the chassis 100. In many embodiments, an angle of attack a between 30 degrees and 60 degrees is desirable to allow the chassis 100 to traverse obstacles smoothly over the widest range of angles. In many embodiments, the angle of attack a of the chassis 100 of the present invention is approximately 45 degrees. In some embodiments, the angle of attack a is between approximately 30 degrees and 60 degrees. In some embodiments, the angle of attack a is between approximately 30 degrees and 35 degrees, between approximately 35 degrees and 40 degrees, between approximately 40 degrees and 45 degrees, between approximately 45 degrees and 50 degrees, between approximately 50 degrees and 55 degrees, or between approximately 55 degrees and 60 degrees. In other embodiments, the angle of attack a is between approximately 30 degrees and 32 degrees, between approximately 32 degrees and 34 degrees, between approximately 34 degrees and 36 degrees, between approximately 36 degrees and 38 degrees, between approximately 38 degrees and 40 degrees, between approximately 40 degrees and 42 degrees, between approximately 42 degrees and 44 degrees, between approximately 44 degrees and 46 degrees, between approximately 46 degrees and 48 degrees, between approximately 48 degrees and 50 degrees, between approximately 50 degrees and 52 degrees, between approximately 52 degrees and 54 degrees, between approximately 54 degrees and 56 degrees, between approximately 56 degrees and 58 degrees, or between approximately 58 degrees and 60 degrees.

[0081] The optimized attack angle a enhances the ability of the chassis 100 to smoothly traverse obstacles of varying sizes while approaching them over a wide range of angles. As shown in Figure 7 and Figure 8 As the skateboard approaches the obstacle 190, an approach angle β can be defined between the chassis 100 and the obstacle 190. The approach angle β can be defined as the acute angle between the obstacle 190 and the direction of travel of the skateboard. More specifically, the approach angle β is formed by a reference line C, which corresponds to the direction of travel of the chassis 100 at the point of impact with the obstacle 190, and a second reference line D, which is tangent to the obstacle 190 at the point of impact. For example, a "straight on" approach of the skateboard to the elongated obstacle 190 will define an approach angle β of approximately 90 degrees, while an approach of the skateboard to the obstacle 190 from any direction other than straight will define an approach angle β substantially less than 90 degrees.

[0082] The attack angle a of the chassis 100 allows the chassis 100 to smoothly traverse obstacles and discontinuities over a wider range of approach angles β than conventional skateboards. Because the center wheel 120 and the front wheels 122 are laterally spaced to form the attack angle a, the chassis 100 essentially includes a wider base than a similar board having an inline wheel configuration or a conventional skateboard that does not form an attack angle. The attack angle reduces the likelihood that multiple wheels in a set will simultaneously impact an obstacle. This provides balance and stability over obstacles of various sizes and orientations by allowing at least one wheel in each set of wheels to contact a regular rolling surface at any given time. In other words, the attack angle a allows for lift to be generated over a wide range of approach angles β.

[0083] When the chassis 100 of the present application encounters an obstacle at any approach angle β, the load generated by the weight of the rider can be transferred between the center wheel and the auxiliary wheels in both the fore-aft direction and the lateral direction. This configuration provides the chassis 100 of the present application with two additional levels of stability over conventional skateboard chassis, which include only a single wheel on either side of the chassis 100. When a conventional chassis encounters an obstacle, the load generated by the weight of the rider cannot be transferred from the wheel, and thus the wheel bears the full impact force of the obstacle. In contrast, the ability to transfer the load between the center wheel 120 and the auxiliary wheels allows the chassis 100 of the present application to absorb the impact force of the obstacle. The ability to transfer the load in multiple directions due to the attack angle a of the chassis 100 provides greater absorption of this force over a wider range of approach angles β.

[0084] Due to the lift of the front and rear wheels 122, 124 as they rotate on the horizontal arm 110 about the central axle 108, the lift effect allows the chassis 100 to smoothly traverse obstacles. In some cases, however, such as when the skateboard is being carried rather than ridden, it can be desirable to selectively limit the rotation of the horizontal arm 110. Doing so can prevent the horizontal arm 110 from freely swinging back and forth, which can cause the wheels to violently hit the underside of the skateboard, when the skateboard is being carried. Referring now to Figures 9-10 The horizontal arm 110 can include a spring mechanism 130 that provides an amount of mechanical interference to control the rotation of the horizontal arm 110 about the axle. In many embodiments, the spring mechanism 130 can include a shim groove 132 formed within the horizontal arm 110 and configured to receive a spring shim 140. The spring shim 140 can be configured to interface and cooperate with one or more components of the chassis 100 to create a "spring effect" that provides resistance to the rotation of the horizontal arm 110 at certain loads. The shim groove 132 can be formed within the middle region 114 of the horizontal arm 110 and can be centered about the middle hole 115 of the horizontal arm 110. In this manner, the middle hole 115 can extend through a portion of the shim groove 132 and the central axle 108 can extend through the entire shim groove 132. Preferably, the shim groove 132 is formed inward from the inward facing surface of the horizontal arm 110, i.e. the side of the horizontal arm 110 that faces the suspension axle 102 when the horizontal arm 110 is secured to the central axle 108. The position and orientation of the spring shim 140 is provided so that the corresponding spring shim 140 is exposed toward the end of the suspension axle 102 that will interface with the geometry of the end of the suspension axle 102 to create the desired spring effect.

[0085] The shim groove 132 can receive a spring shim 140 that is configured to create a spring effect that constrains the rotation of the horizontal arm 110 about the axle. The spring shim 140 can be secured within the groove through the use of mechanical fasteners such as screws or snap fit mechanisms, through the use of adhesives, or through a combination thereof. The spring shim 140 is designed to provide an amount of resistance to the rotation of the horizontal arm 110 to maintain the positioning of the horizontal arm 110 when the skateboard is being carried. Maintaining the positioning of the horizontal arm 110 when the skateboard is being carried in the air protects the skateboard by preventing the secondary wheels from violently hitting the skateboard deck. The spring shim 140 can be configured to limit the rotation of the horizontal arm 110 at relatively light loads while allowing the horizontal arm 110 to rotate at relatively heavy loads. For example, the spring shim 140 can limit the rotation of the horizontal arm 110 at light loads that are typically associated with a user carrying the skateboard and not associated with a user riding the skateboard. The spring shim 140 can also allow the horizontal arm 110 to rotate at heavy loads that are experienced when the skateboard is being ridden over obstacles.

[0086] In many embodiments, such as Figure 9 and Figure 10 As shown, the spring washer 140 is a single, substantially flat piece and is configured to correspond to the shape of the washer recess 132, such that the spring washer 140 is flush with the washer recess 132. The spring washer 140 can be formed from a generally flexible material such as injection-molded plastic. The spring washer 140 can be made of any one or a combination of the following: nylon, polypropylene, polyethylene, thermoplastic resin, thermoplastic polyurethane, thermosetting resin, aromatic diisocyanate, toluene diisocyanate (TDI), methylene diphenyl diisocyanate (MDI), acrylonitrile butadiene styrene (ABS), acetal, steel, steel alloy, or any material suitable for providing the spring washer 140 with the desired geometry and properties. The spring washer 140 is preferably formed of a material with high elongation. High elongation allows the spring washer 140 to easily flex and “bounce.” High elongation materials allow the spring washer 140 to flex and bend in response to forces associated with the use of the base frame 100.

[0087] In many embodiments, the spring washer 140 is configured to engage part of the suspension shaft 102. For example... Figure 10 As shown, the suspension shaft 102 includes a shoulder 150 on each of a first and second end, at which the central shaft 108 is attached. A spring washer 140 is disposed within the horizontal arm 110 such that the spring washer 140 is mounted on the shoulder 150 of the suspension shaft 102. The shoulder 150 and the spring washer 140 may include complementary geometries that, when a force is applied to the horizontal arm 110, the shoulder 150 and the spring washer 140 together produce a desired spring effect. The spring washer 140 includes an internal geometry configured to engage the shoulder 150 and serve as a spring. The internal geometry may include a plurality of holes, extensions, flexures, slots, grooves, notches, and / or any other features configured to engage the central shaft 108 and / or the suspension shaft 102 in a manner that produces the desired spring effect. In many embodiments, the internal geometry may take the form of a cutout through the entire thickness of the spring washer 140, thereby forming one or more holes. In many embodiments, the shoulder 150 may typically be generally cylindrical. In some embodiments, the shoulder 150 includes one or more slots configured to interact between one or more features of the spring washer geometry and provide resistance.

[0088] In one embodiment, refer to Figure 11The spring washer 140 includes a perimeter 141 having a central hole 142 formed therein, a plurality of protrusions 144, and a plurality of cushioning portions 146. The protrusions 144 can extend inwardly from the perimeter 141 of the spring washer 140 toward the central hole 142. In many embodiments, the protrusions 144 are configured to fit within corresponding notches 152 formed in the shoulder 150 of the axle 102. For example, in the illustrated embodiment, the protrusions 144 of the spring washer 140 are generally triangular in shape and are configured to fit with generally triangular shaped notches 152 formed in the shoulder 150 (as shown). During use of the chassis 100 (as a ride or carry board), load on the horizontal arm 110 causes the protrusions 144 to press against the surface of the shoulder 150 and provide resistance to rotation. However, due to the flexibility of the spring washer material, the protrusions 144 will flex under sufficient load to allow rotation of the arm. In many embodiments, the spring washer 140 includes notches 148 formed opposite the protrusions 144. The notches 148 of the spring washer 140 can provide a small space between the perimeter 141 of the spring washer 140 and the washer groove 132, such that the washer is not flush within the groove at the particular location of the notches 148. The space created by the notches 148 provides a greater flexing ability for the protrusions 144 when engaged with the shoulder 150. Figure 10 During use of the chassis 100 (as a ride or carry board), load on the horizontal arm 110 causes the protrusions 144 to press against the surface of the shoulder 150 and provide resistance to rotation. However, due to the flexibility of the spring washer material, the protrusions 144 will flex under sufficient load to allow rotation of the arm. In many embodiments, the spring washer 140 includes notches 148 formed opposite the protrusions 144. The notches 148 of the spring washer 140 can provide a small space between the perimeter 141 of the spring washer 140 and the washer groove 132, such that the washer is not flush within the groove at the particular location of the notches 148. The space created by the notches 148 provides a greater flexing ability for the protrusions 144 when engaged with the shoulder 150.

[0089] The spring washer 140 also includes a plurality of cushioning portions 146 that act as guides to keep the spring washer 140 centered around the shoulder 150 of the axle 102 during use of the chassis 100, thereby providing stable rotation of the horizontal arm 110. In many embodiments, while the cushioning portions 146 abut a portion of the shoulder 150, the contact area between the shoulder 150 and the cushioning portions 146 can be minimal so as not to inhibit rotation of the horizontal arm 110 during regular use of the board. In contrast, the protrusions 144 provide the primary contact area between the spring washer 140 and the shoulder 150. Under sufficient load, the protrusions 144 flex to allow rotation of the horizontal arm 110, and the cushioning portions 146 act to keep the spring washer 140 centered.

[0090] The spring washer 140 can also include a pair of attachment holes 149 located near the perimeter 141. The attachment holes 149 can be configured to receive mechanical fasteners (e.g., screws). The attachment holes 149 provide a location for the spring washer 140 to be secured within the horizontal arm 110 by such mechanical fasteners.

[0091] Figure 12An alternative embodiment of a spring washer 240 according to the present application is shown. The spring washer 240 is similar to the spring washer 140 and includes substantially the same geometry. The spring washer 240 also performs the same function as the spring washer 140, wherein portions of the geometry of the spring washer are configured to provide resistance to rotation when engaged with the shoulder 150 of the suspension axle 102, but flex and allow rotation under sufficient load. Rather than including a protrusion extending inwardly toward the hole 242, the spring washer 240 includes a pair of elongated flex portions 244 extending laterally across the washer. The flex portions 244 can be substantially thin compared to other portions of the washer, allowing the flex portions 244 to flex when engaged with the shoulder 150 of the suspension axle 102. Similar to the notch 148 of the spring washer 140, the flex portions 244 of the spring washer 240 can form a space between the perimeter 241 of the spring washer 240 and the washer recess 132. This space allows the flex portions 244 to flex outwardly when the shoulder 150 is pressed against the flex portions 244. Under sufficient load, the flex portions 244 flex enough to allow the horizontal arm 110 to rotate. In many embodiments, the spring washer 240 also includes a plurality of cushion portions 246 and attachment holes 249 similar to the cushion portions and attachment holes of the spring washer 140.

[0092] Figure 13Another alternative embodiment of a spring washer 340 according to the present application is shown. The spring washer 340 is similar to the spring washers 140 and 240, and includes substantially similar features. The spring washer 340 also performs the same function as the spring washers 140 and 240, in that some portions of the geometry of the spring washer are configured to provide a resistance to rotation when engaged with the shoulder 150 of the suspension axle 102, but flex and allow rotation under sufficient load. The spring washer 340 includes a plurality of elongated protrusions 344 that extend away from the perimeter 341 and are configured to engage a portion of the shoulder 150. The spring washer 340 also includes slots 345 that separate the elongated protrusions 344 from the perimeter 341. The slots 345 allow the elongated protrusions 344 to flex outwardly toward the perimeter 341 when the shoulder 150 is pressed against the elongated protrusions 344. Under sufficient load, the elongated protrusions 344 flex enough to allow the horizontal arm 110 to rotate. The spring washer 340 also includes a cushioning portion 346 that is similar to the cushioning portion 146 of the spring washer 140. However, instead of the cushioning portion 146 creating a small contact area between the cushioning portion 346 and the shoulder 150, the cushioning portion 346 of the spring washer 340 can include an arcuate surface that corresponds to the shape of the shoulder 150 and provides a greater contact area between the cushioning portion 346 and the shoulder 150. This configuration provides additional stability in centering the spring washer 340 with respect to the center axle 108 and the suspension axle 102, while still allowing the horizontal arm 110 to rotate. In some embodiments, the spring washer 340 also includes a plurality of gaps 347 formed between each of the cushioning portions 346 and the elongated protrusions 344. The plurality of gaps 347 can separate the cushioning portions 346 and the elongated protrusions 344 from each other and allow for greater overall flexing within the interior geometry of the spring washer 340.

[0093] The spring washer 140 constrains the rotation of the horizontal arm 110. When the chassis 100 is on the ground, the horizontal arm 110 can be considered to be in a “rest” position. When at rest, the horizontal arm 110 can be generally parallel to the deck of the skateboard, and the wheels can be approximately evenly spaced away from the underside of the deck. When the skateboard is being carried (i.e., when the wheels are not touching the ground), the weight of the wheels exerts a force on the horizontal arm 110, causing the horizontal arm 110 to want to rotate away from the rest position. The geometry of the spring washer 140 can engage with the geometry of the shoulder 150 and limit the rotation of the horizontal arm 110, and the horizontal arm 110 will generally remain in the rest position. By keeping the horizontal arm 110 in the rest position and limiting its rotation, the spring mechanism 130 prevents the wheels from hitting the underside of the deck, which would occur if the horizontal arm 110 were free to rotate while the board is being carried.

[0094] However, during use of the skateboard, it is desirable for the horizontal arm 110 to rotate and create a lifting action in order to allow the multi-wheel chassis 100 to smoothly traverse discontinuities and uneven surfaces. The spring mechanism 130 can allow the horizontal arm 110 to rotate during use of the skateboard. If a sufficient moment is applied to the horizontal arm 110 during use, as would be the case when traversing a crack or uneven surface, the force of the shoulder 150 pressing against the flexible spring washer 140 causes the spring portion to flex, allowing the horizontal arm 110 to rotate and create the desired lifting action.

[0095] In many embodiments, the spring mechanism 130 can include a rotation threshold. The rotation threshold can be defined as the minimum force applied to the horizontal arm 110 at which the spring mechanism 130 allows the horizontal arm 110 to rotate. For example, if the force applied to the horizontal arm 110 is less than the rotation threshold, the spring mechanism 130 restricts rotation of the horizontal arm 110 and maintains the horizontal arm 110 in a stationary position. Conversely, if the force applied to the horizontal arm 110 is greater than the rotation threshold, the spring mechanism 130 allows the horizontal arm 110 to rotate. The rotation threshold can depend on the design of the spring washer 140, particularly the internal geometry and the materials used. Preferably, the spring washer 140 is designed such that the smaller forces associated with carrying the skateboard are below the rotation threshold, while the larger forces associated with a passenger skateboard traversing obstacles and discontinuous surfaces are preferably above the rotation threshold. In some embodiments, the rotation threshold is between about 0.1 foot pounds and 1.5 foot pounds. In some embodiments, the rotation threshold can be between about 0.1 foot pounds and 0.25 foot pounds, between about 0.25 foot pounds and 0.5 foot pounds, between about 0.5 foot pounds and 0.75 foot pounds, between about 0.75 foot pounds and 1.0 foot pounds, or between about 1.0 foot pounds and 1.5 foot pounds. In some embodiments, the rotation threshold can be between about 0.1 foot pounds and 0.4 foot pounds, between about 0.4 foot pounds and 0.7 foot pounds, between about 0.7 foot pounds and 1.1 foot pounds, or between about 1.1 foot pounds and 1.5 foot pounds. The rotation threshold allows the spring mechanism 130 to restrict rotation of the horizontal arm 110 at sufficiently small loads, but yet allows the horizontal arm 110 to rotate at sufficiently large loads.

[0096] In many embodiments, the spring mechanism 130 includes spring washers 140 located within washer grooves 132 formed in the horizontal arm 110. However, in alternative embodiments, the spring mechanism 130 can be integrally formed within the horizontal arm 110, rather than including separate spring washers 140 within the horizontal arm 110. In other words, the horizontal arm 110 can be formed with an integral spring geometry centered about the middle hole 115 that provides the same spring effect as the spring washers of the above-described embodiments. In many such embodiments, the horizontal arm 110 including the integral spring geometry can be formed from a non-metallic material, such as an injection molded plastic material or a composite material. Embodiments of lift arms having integral spring mechanisms will be discussed in further detail below.

[0097] IV. Other Features

[0098] As described above, the multi-wheel chassis 100 includes a suspension axle 102 and a base plate 170 for coupling a plurality of wheel sets and configuring the chassis 100 to be attachable to an underside of a skateboard deck. As shown, the suspension axle 102 is configured to couple the wheel sets to the chassis 100, and the base plate 170 is configured to receive the suspension axle 102 and attach the chassis 100 to the underside of the skateboard deck. Figure 2

[0099] Figure 14 Figure 15 An embodiment of a suspension axle 102 of a multi-wheel chassis 100 is shown. The suspension axle 102 includes a first end 104 and a second end 106 opposite the first end 104. The suspension axle 102 defines a longitudinal axis 1000 extending between the first end 104 and the second end 106, with the first and second ends each located proximate the longitudinal axis 1000. The suspension axle 102 also defines a transverse axis 1100 extending perpendicular to the longitudinal axis 1000. Thus, the transverse axis 1100 corresponds to a fore-aft direction of the suspension axle 102 relative to a front and a rear of the skateboard. In many embodiments, the first and second ends are located proximate a front of the suspension axle 102, while other components of the suspension axle 102, such as a pivot tip 162 or a pivot saddle 172, can be located rearward of the first and second ends. In many embodiments, a maximum width of the suspension axle 102 is located between the first and second ends, such that a front of the suspension axle 102 includes the widest portion of the suspension axle. The first and second ends generally form the widest portion of the suspension axle 102, such that wheel sets attached to the first and second ends are spaced apart from the remainder of the suspension axle 102 and are free to rotate without interference from the suspension axle 102.

[0100] ​​Each of the first end 104 and the second end 106 may include a gap 156 configured to engage the wheelset to the suspension axle 102. The gap 156 is configured to receive the center axle 108 of the wheelset and securely attach the center axle 108 to the suspension axle 102. In many embodiments, the gap 156 is threaded to receive a corresponding threaded portion of the center axle 108. In some embodiments, the gap 156 may include any form of attachment mechanism suitable for securing a portion of the center axle 108 therein, such as snap-fit, adhesive, epoxy, magnet, interlocking attachment mechanism, or combinations thereof.

[0101] As briefly discussed above, the suspension shaft 102 also includes multiple shoulders 150, which are configured to engage the spring washers 140 of the horizontal arm 110 during rotation of the horizontal arm 110. Figure 14 and Figure 15 As shown, the suspension shaft 102 includes a shoulder 150 located at each of the first and second ends 106. In many embodiments, the shoulder 150 protrudes from the end of the suspension shaft 102 such that it can be received within the internal geometry of the spring washer 140. The shoulder 150 includes a geometry configured to correspond to the internal geometry of the spring washer 140, such that the shoulder 150 can engage the spring washer 140 and produce the aforementioned spring effect when the horizontal arm 110 rotates. Figure 14 and Figure 15 As shown in the embodiment, the geometry includes a generally cylindrical shape, but with a plurality of slots 152 around its perimeter. Each slot 152 can be configured to receive a protrusion 144 of a spring washer 140, for example, a protrusion 144 of a spring washer 140. When the horizontal arm 110 rotates about the central axis 108, the surface of the slot 152 can press against the protrusion 144 of the spring washer 140 and limit the rotation of the horizontal arm 110 to at most a certain amount of force.

[0102] In many embodiments, the suspension shaft 102 may be configured to pivot left or right about a portion of the base plate 170 to control the direction of the skateboard during use. When a rider shifts his or her weight to the right or left side of the skateboard, the suspension shaft 102 may pivot about the base plate 170, causing the skateboard to turn left or right. The suspension shaft 102 includes a pivot body 160 configured to engage a pivot collar 164 of the base plate 170 and allow the suspension shaft 102 to pivot. The pivot body 160 may be located rear of the front portion of the suspension shaft 102 and may include a width substantially smaller than the maximum width of the suspension shaft 102. In many embodiments, the pivot body 160 is generally triangular in shape with rounded edges that allow the suspension shaft 102 to pivot about the surface of the pivot collar 164.

[0103] The suspension 102 also includes a pivot tip 162 configured to center the suspension 102 around the substrate 170. In many embodiments, the pivot tip 162 protrudes from the rear portion of the suspension 102. The pivot tip 162 may be received by a portion of the substrate 170 (e.g., a pivot collar 164), which will be described in further detail below. In many embodiments, the pivot tip 162 is generally cylindrical but has a capped or pointed end to allow the suspension 102 to rotate smoothly and / or pivot within the pivot collar 164. The pivot tip 162 may be integrally formed with the suspension 102 to form a continuous suspension structure.

[0104] like Figure 14 As shown, the suspension shaft 102 includes a pin hole 178 that receives a pin 175 or other attachment mechanism to allow the suspension shaft 102 to be connected to one or more other components of the base frame 100, such as the base plate 170. The pin hole 178 may be a through-hole extending through a portion of the suspension shaft body. In many embodiments, the pin hole 178 is substantially located at the center of the suspension shaft 102, near the pivot body 160. In many embodiments, the pin hole 178 is located between the pivot body 160 and the front portion of the suspension shaft 102. The connection between the suspension shaft 102 and the base plate 170 via the pin hole 178 will be described in further detail below.

[0105] The suspension axle 102 can be constructed from any material used for constructing a conventional skateboard chassis. The suspension axle 102 can be constructed from any one or a combination of the following: 8620 alloy steel, S25C steel, carbon steel, maraging steel, 17-4 stainless steel, 1380 stainless steel, 303 stainless steel, stainless steel alloys, brushed steel, tungsten, magnesium, magnesium alloys, titanium, titanium alloys, Ti-6-4, aluminum, aluminum alloys, aluminum 2024, aluminum 3003, aluminum 5052, aluminum 6061, aluminum 7075, ADC-12, aluminum A356, magnesium AZ61A, magnesium AZ80A, magnesium AZ31B, carbon fiber reinforced plastic composites, glass-filled plastic composites, nylon, polyetheretherketone, polyetherimide, polyphenylene sulfide, or any material suitable for manufacturing a suspension axle or skateboard chassis. In many embodiments, the suspension axle 102 can be constructed from aluminum 6061, aluminum A356, or magnesium AZ61A. The material of the suspension shaft 102 may vary based on the intended use and / or desired weight of the suspension shaft 102.

[0106] In some embodiments, the suspension 102 may include one or more weight-reducing features 158. The weight-reducing features 158 may be provided in the form of notches, recesses, gaps, voids, or holes, etc. The weight-reducing features 158 are areas or portions of the suspension 102 without material. The weight-reducing features 158 may be disposed within any portion of the suspension 102, such as the first end 104, the second end 106, the pivot body 160, or the pivot tip 162, substantially near the front or rear of the suspension 102. In many embodiments, the weight-reducing features 158 are disposed within the pivot body 160 because the pivot body 160 is typically the most substantial part of the suspension mass.

[0107] The weight-reducing feature 158 may occupy between about 1% and about 20% of the volume of the suspension shaft 102. In many embodiments, the weight-reducing feature 158 may occupy between about 1% and about 5%, about 5% and about 10%, about 10% and about 15%, or about 15% and about 20% of the volume of the suspension shaft 102. In alternative embodiments, the weight-reducing feature 158 may occupy between about 1%, about 2%, about 3%, about 4%, about 5%, about 6%, about 7%, about 8%, about 9%, about 10%, about 11%, about 12%, about 13%, about 14%, about 15%, about 16%, about 17%, about 18%, about 19%, or about 20% of the volume of the suspension shaft. One or more weight-reducing features 158 allow the mass of the suspension shaft 102 to be kept to a minimum while maintaining structural integrity.

[0108] The base frame 100 also includes a base plate 170 configured to receive the suspension shaft 102 and connect the base frame 100 to the underside of the skateboard surface. The base plate 170 can be mechanically attached to the underside of the skateboard surface using any fastening means, such as screws, bolts, adhesives, snap-fits, or combinations thereof. In many embodiments, such as Figure 16 As shown, the substrate 170 includes a plurality of holes 174 extending through the body of the substrate 170 and configured to receive mechanical fasteners such as bolts or screws. In many embodiments, each of the plurality of holes 174 is located near the outer periphery or outer peripheral edge of the substrate 170. Furthermore, in some embodiments, the holes 174 may be threaded to receive corresponding threaded fasteners. In some embodiments, the substrate 170 may have two, three, four, five, six, or seven holes. In many embodiments, the substrate may include at least four holes 174 to provide sufficient structural rigidity to secure the substrate 170 to the surface of a slide plate.

[0109] The baseplate 170 can be constructed of any material used to construct a conventional skateboard chassis. The baseplate 170 can be comprised of any one or combination of the following: 8620 alloy steel, S25C steel, carbon steel, maraging steel, 17-4 stainless steel, 1380 stainless steel, 303 stainless steel, stainless steel alloy, drawn steel, tungsten, magnesium, magnesium alloy, titanium, titanium alloy, Ti-6-4, aluminum, aluminum alloy, aluminum 2024, aluminum 3003, aluminum 5052, aluminum 6061, aluminum 7075, ADC-12, aluminum A356, magnesium AZ61A, magnesium AZ80A, magnesium AZ31B, carbon fiber reinforced plastic composite, glass filled plastic composite, nylon, polyether ether ketone, polyetherimide, polyphenylene sulfide, or any material suitable for manufacturing a baseplate or skateboard chassis. In many embodiments, the baseplate 170 can be constructed of aluminum 6061, aluminum A356, or magnesium AZ61A. The material of the baseplate 170 can vary based on the intended use of the baseplate 170 and / or the desired weight.

[0110] The baseplate 170 also includes a saddle 172 and a pivot shaft ring 164 extending in a direction opposite the skateboard deck. The saddle 172 forms a base for the pivot body 160 of the suspension axle 102 to rest on and pivot on. In many embodiments, the surface of the saddle 172 is substantially flat. This allows the circular surface and / or the rounded edge of the suspension axle 102 to pivot around the surface of the saddle 172. The saddle 172 can be located near the front of the baseplate 170 and can orient the suspension axle 102 so that the front of the suspension axle 102 is near the front of the baseplate 170 when fully assembled. In many embodiments, the saddle 172 extends away from the skateboard deck at an angle so that the suspension axle 102 is oriented at an angle relative to the skateboard deck. By angling the suspension axle 102 in this manner, the pivoting action of the suspension axle 102 on the saddle 172 causes the wheels to turn left or right. In this way, the rider can control the direction of the skateboard during use by shifting his or her weight to the left or right.

[0111] The saddle 172 also includes a pin receiving port 176. The pin receiving port 176 can take the form of a hole extending through the saddle 172. The pin receiving port 176 is configured to receive a pin 175 that couples the baseplate 170 to the suspension axle 102. In many embodiments, the pin receiving port 176 can be threaded or unthreaded. The geometry of the pin receiving port 176 (i.e., the type of threading, the number of threads, the pitch, etc.) can vary based on the type and geometry of the pin 175.

[0112] A pivot support ring 164 is formed behind the saddle 172 and is configured to receive the pivot tip 162 of the suspension axle 102. The pivot support ring 164 forms a cup-like structure, including one or more inner walls that form a cavity. The pivot support ring 164 is shaped to receive the pivot tip 162 and house the pivot tip 162 within the cavity. When assembled, the pivot support ring 164 helps to center the suspension axle 102 on the base plate 170 by holding the pivot tip 162 within the pivot support ring 164. In many embodiments, the inner walls of the pivot support ring 164 can form a generally cylindrical shape that corresponds to the generally cylindrical shape of the pivot tip 162. In this way, the pivot tip 162 can be held within the pivot support ring 164 while still allowing the pivot tip 162 to rotate within the pivot support ring 164 as the suspension axle 102 pivots.

[0113] Figure 17 A configuration is shown in which the suspension axle 102 and the base plate 170 are coupled. The suspension axle 102 is seated on the base plate 170 and is coupled to the base plate 170 by a pin 175. The suspension axle 102 is seated on the angled saddle 172 such that the suspension axle 102 is oriented at an angle relative to the skateboard deck. The pivot body 160 of the suspension axle 102 rests on the surface of the saddle 172 in a manner that allows the suspension axle 102 to pivot about the saddle 172. In addition, the pivot tip 162 of the suspension axle 102 is inserted into the pivot support ring 164 of the base plate 170 to center the suspension axle 102 relative to the base plate 170.

[0114] The pin receiving port 176 of the saddle 172 is aligned with the pin hole 178 of the suspension axle 102, and each is configured to receive the pin 175. In many embodiments, the pin 175 is a threaded, elongated bolt. The pin 175 extends through each of the pin receiving port 176 and the pin hole 178 to couple the suspension axle 102 and the base plate. In many embodiments, a threaded bolt 180 can be attached to the threaded end of the pin 175 to lock the pin 175 in place and secure the connection between the base plate 170 and the suspension axle 102.

[0115] As described above, the multi-wheel chassis 100 includes one or more horizontal arms 110 for connecting multiple wheels in a wheel set and rotating to provide a lifting action over obstacles and discontinuous surfaces. In many embodiments, the one or more horizontal arms 110 are constructed from a metallic material, a non-metallic material, or some combination thereof. In many embodiments, the one or more horizontal arms 110 can be constructed from any one or combination of: 8620 alloy steel, S25C steel, carbon steel, maraging steel, 17-4 stainless steel, 1380 stainless steel, 303 stainless steel, stainless steel alloy, drawn steel, tungsten, magnesium, magnesium alloy, titanium, titanium alloy, Ti-6-4, aluminum, aluminum alloy, aluminum 2024, aluminum 3003, aluminum 5052, aluminum 6061, aluminum 7075, ADC-12, aluminum A356, magnesium AZ61A, magnesium AZ80A, magnesium AZ31B, carbon fiber reinforced plastic composite, glass filled plastic composite, nylon, polyether ether ketone (PEEK), polyetherimide, polyphenylene sulfide, or any material suitable for manufacturing a component of a skateboard chassis. In many embodiments, the one or more horizontal arms 110 can be constructed from aluminum 6061, aluminum A356, or magnesium AZ61A. In other embodiments, the one or more horizontal arms 110 can be constructed from nylon or carbon fiber reinforced nylon. In some embodiments, the one or more horizontal arms 110 can include a multi-part structure combining a portion formed from carbon fiber reinforced plastic and a portion of plastic without carbon fiber reinforcement.

[0116] As Figure 18 As shown in alternative embodiments, the one or more horizontal arms 210 can include a multi-part structure including a skeleton portion 218 and a shell portion 219. The skeleton portion 218 can be an interior portion of the horizontal arm 210 and can include the primary structural elements of the horizontal arm, including forming the front hole, middle hole, and rear hole of the horizontal arm 210. In this way, the skeleton portion 218 is the only portion of the horizontal arm that directly receives and contacts the plurality of axles of the wheel set. The skeleton portion 218 can be formed from a high-strength material to provide support and durability to the horizontal arm 210. In many embodiments, the skeleton portion 218 can be constructed from a hard plastic, such as a carbon fiber reinforced plastic composite or a glass filled plastic composite, a metallic material, or any other material having sufficient strength to provide support and durability to the horizontal arm 210.

[0117] The shell portion 219 encloses and encapsulates at least a portion of the skeleton portion 218. In many embodiments, the shell portion 219 is constructed of a "softer material" that includes a higher elongation than the skeleton portion 218. In many embodiments, the shell portion 219 is constructed of an injection molded plastic, an unfilled plastic (i.e., a plastic that does not contain carbon fiber or glass reinforcement), nylon, polypropylene, polyethylene, or any other plastic or other material that has a desired elongation. The shell portion 219 can provide protection against failure of the horizontal arm 210. For example, if the skeleton portion 218, which is rigid due to its high strength, is damaged and breaks or completely fails, the high elasticity of the shell portion 219 will allow the surrounding shell portion 219 to elongate rather than break. This construction prevents catastrophic failure of the horizontal arm 210.

[0118] The shell portion 219 can also be constructed to include a spring mechanism 230 integrally formed therein. Due to the ability to injection mold the shell portion 219, the shell portion 219 can be designed to include a spring geometry that is substantially similar to the geometry of the spring shims 140, 240, and 340. The inclusion of the integrally formed spring mechanism 230 within the horizontal arm 210 itself eliminates the need for a separately formed spring shim.

[0119] As noted above, the multi-wheel chassis 100 includes a plurality of wheels, including at least one central wheel 120 and one or more auxiliary wheels. Each wheel can be characterized by a diameter (wheel diameter), a width (wheel width), a hardness (wheel hardness), and a material (wheel material). In many embodiments, the characteristics (diameter, width, hardness, and / or material) of the central wheel 120 can be different than the characteristics of the one or more auxiliary wheels. In other embodiments, the characteristics of the central wheel 120 can be substantially similar to the characteristics of the one or more auxiliary wheels.

[0120] In many embodiments, as shown in FIG. 1, the diameter of the one or more wheels ranges between approximately 1.5 inches and 4.0 inches. In some embodiments, the diameter of the one or more wheels can range between 1.5 inches and 2.0 inches, between 2.0 inches and 2.5 inches, between 2.5 inches and 3.0 inches, between 3.0 inches and 3.5 inches, or between 3.5 inches and 4.0 inches. In some embodiments, the diameter of the one or more wheels can range between 1.5 inches and 1.75 inches, between 1.75 inches and 2.0 inches, between 2.0 inches and 2.25 inches, between 2.25 inches and 2.5 inches, between 2.5 inches and 2.75 inches, between 2.75 inches and 3.0 inches, between 3.0 inches and 3.25 inches, between 3.25 inches and 3.5 inches, between 3.5 inches and 3.75 inches, or between 3.75 inches and 4.0 inches. Figure 6 In many embodiments, as shown in FIG. 1, the diameter of the one or more wheels ranges between approximately 1.5 inches and 4.0 inches. In some embodiments, the diameter of the one or more wheels can range between 1.5 inches and 2.0 inches, between 2.0 inches and 2.5 inches, between 2.5 inches and 3.0 inches, between 3.0 inches and 3.5 inches, or between 3.5 inches and 4.0 inches. In some embodiments, the diameter of the one or more wheels can range between 1.5 inches and 1.75 inches, between 1.75 inches and 2.0 inches, between 2.0 inches and 2.25 inches, between 2.25 inches and 2.5 inches, between 2.5 inches and 2.75 inches, between 2.75 inches and 3.0 inches, between 3.0 inches and 3.25 inches, between 3.25 inches and 3.5 inches, between 3.5 inches and 3.75 inches, or between 3.75 inches and 4.0 inches.

[0121] One or more wheels can have substantially similar diameters relative to another wheel, two or more wheels, three or more wheels, four or more wheels, or five or more wheels. In many embodiments, at least one central wheel 120 can have a substantially similar diameter D1 relative to one or more auxiliary wheels. In some embodiments, one or more auxiliary wheels can have a substantially similar diameter D2 relative to one or more other auxiliary wheels. For example, a front wheel 122 of a particular wheel set can include a substantially similar diameter as a rear wheel 124 of the same wheel set. In other embodiments, one or more auxiliary wheels can have a substantially different diameter D2 relative to one or more other auxiliary wheels. For example, a front wheel 122 of a particular wheel set can include a substantially larger or smaller diameter than a rear wheel 124 of the same wheel set.

[0122] In alternative embodiments, one or more wheels can have substantially different diameters relative to another wheel, two or more wheels, three or more wheels, four or more wheels, or five or more wheels. In many embodiments, at least one central wheel 120 can have a substantially different diameter relative to one or more auxiliary wheels. In some embodiments, the diameter D1 of at least one central wheel 120 can be smaller than the diameter D2 of at least one auxiliary wheel. In some embodiments, the diameter D1 of at least one central wheel 120 can be larger than the diameter D2 of at least one auxiliary wheel. In some embodiments, one or more auxiliary wheels can have a substantially different diameter relative to one or more other auxiliary wheels. For example, a front wheel 122 of a particular wheel set can include a substantially larger or smaller diameter than a rear wheel 124 of the same wheel set.

[0123] The diameter of one or more wheels is important to allow the chassis 100 to traverse obstacles and discontinuous surfaces smoothly. The wheels are sized to have a diameter large enough so that when a given wheel encounters an obstacle, the point along the wheel that contacts the obstacle occurs low enough on the wheel to reduce the impact force between the wheel and the obstacle. As described above, the diameter of one or more wheels also affects the angle of attack a. Reducing or increasing the diameter of a front wheel and / or central wheel 120 changes the positioning of the reference point R1 and / or the reference point R2 relative to each other. Changing the position of the reference points can change the orientation of the reference line A, and affect the angle of attack a formed between the reference line A and the reference line B.

[0124] For example, in some embodiments, each wheel can be provided with a substantially small diameter to provide a substantially steep attack angle a (i.e., an attack angle substantially greater than 45 degrees). In other embodiments, each wheel can be provided with a substantially large diameter to provide a substantially more gradual attack angle a (i.e., an attack angle substantially less than 45 degrees). In some embodiments, each wheel can be provided with a different diameter in order to optimize the attack angle a. In some embodiments, the front wheels 122 can comprise the largest diameter, the center wheels 120 can comprise a diameter D1 that is less than the diameter of the front wheels 122, and the rear wheels 124 can comprise a diameter that is less than both the front wheels 122 and the center wheels 120. Such embodiments with a large front wheel 122 diameter can provide additional advantages when traversing obstacles. The front wheels 122 are typically the first to encounter such obstacles, and providing a large front wheel 122 diameter minimizes the impact between the obstacle and the front wheels 122. As described above, the diameter of each respective wheel can be balanced with the width and spacing of each wheel to optimize the attack angle a.

[0125] In many embodiments, the wheel width of one or more wheels can range between approximately 0.1 inch and 2.5 inches. In some embodiments, the width of one or more wheels can range between approximately 0.1 to 0.5 inches, between 0.5 to 1.0 inches, between 1.0 to 1.5 inches, between 1.5 to 2.0 inches, or between 2.0 to 2.5 inches. In some embodiments, the width of the wheel for one or more wheels can range between approximately 0.1 inch and 0.25 inches, between 0.25 inches and 0.5 inches, between 0.5 inches and 0.75 inches, between 0.75 inches and 1.0 inches, between approximately 1.0 inch and 1.25 inches, between 1.25 inches and 1.5 inches, between 1.5 inches and 1.75 inches, between 1.75 inches and 2.0 inches, between 2.0 inches and 2.25 inches, or between 2.25 inches and 2.5 inches.

[0126] In many embodiments, the width W2 of each auxiliary wheel is substantially the same as the width of the other auxiliary wheels. For example, the rear wheels 124 and the front wheels 122 in a given wheel set typically comprise the same width W2. In many embodiments, the width W2 of the auxiliary wheels is approximately 0.5 inches. In many embodiments, the width W2 of one or more auxiliary wheels can range between approximately 0.1 inch and 1.5 inches. In some embodiments, the width W2 of one or more auxiliary wheels can range between approximately 0.1 inch and 0.3 inches, between 0.3 inches and 0.5 inches, between 0.5 inches and 0.7 inches, between 0.7 inches and 0.9 inches, between 0.9 inches and 1.1 inches, between 1.1 inches and 1.3 inches, and between 1.3 inches and 1.5 inches.

[0127] In many embodiments, the width Wl of the center wheel 120 is greater than the width W2 of the auxiliary wheels. In many embodiments, the width Wl of the center wheel 120 is approximately 1.7 inches. In many embodiments, the width Wl of the center wheel 120 can range between approximately 1.0 and 2.5 inches. In some embodiments, the width Wl of the center wheel 120 can be between 1.0 and 1.25 inches, between 1.25 and 1.5 inches, between 1.5 and 1.75 inches, between 1.75 and 2.0 inches, between 2.0 and 2.25 inches, or between 2.25 and 2.5 inches. When the skateboard is rolling along a smooth rolling surface, the center wheel 120, which generally bears the majority of the load, is provided with a greater width Wl to increase the stability of the chassis 100 as well as to increase the durability of the center wheel 120.

[0128] The respective widths of the wheels, particularly the width of the center wheel and the front wheels 122, affect the angle of attack a. Reducing or increasing the width of the front wheels and / or the center wheel 120 changes the position of the reference point Rl and / or the reference point R2 relative to each other. Changing the position of the reference points can change the orientation of the reference line A and affect the angle of attack a formed between the reference line A and the reference line B.

[0129] In many embodiments, the wheel hardness of each wheel can be determined by the intended use of the wheel and the desired grip ability with the ground. For example, if the user needs to provide sufficient grip to maneuver over uneven or continuous surfaces, sidewalk contraction joints, cracks, cobblestones, rocks, etc., the hardness of one or more wheels, measured on a Shore A hardness scale, can range between approximately 78A-98A. In other embodiments, the hardness of one or more wheels can be between approximately 78A-80A, 80A-82A, 82A-84A, 84A-86A, 86A-88A, 88A-90A, 90A-92A, 92A-94A, 94A-96A, or 96A-98A. In some embodiments, the wheel hardness value can be 78A, 79A, 80A, 81A, 82A, 83A, 84A, 85A, 86A, 87A, 88A, 89A, 90A, 91A, 92A, 93A, 94A, 95A, 96A, 97A, or 98A. To achieve the desired wheel hardness, the plurality of wheels can be composed of various plastics or plastic polyurethane materials of different hardness values.

[0130] In many embodiments, one or more of the wheels can be constructed from a material selected from the group consisting of: thermoplastic resin, thermoplastic polyurethane, thermoset resin, aromatic diisocyanate, toluene diisocyanate (TDI), methylene diphenyl diisocyanate (MDI), nylon, polypropylene, polyethylene, or any material suitable for manufacturing skateboard wheels. In some embodiments, the material of the center wheel 120 is the same as the material of the plurality of auxiliary wheels 122, 124. In other embodiments, the center wheel 120 can be constructed from a first material selected from the group described above, while the plurality of auxiliary wheels 122, 124 are constructed from a second material selected from the group described above. In many embodiments, the center wheel 120 is constructed from a thermoset plastic such as MDI, and the plurality of auxiliary wheels 122, 124 are constructed from TPU.

[0131] V. Electric Skateboard Embodiments

[0132] In some embodiments (not shown), the multi-wheel chassis 100 described herein can be configured for application to an electric skateboard. In many embodiments, the multi-wheel chassis 100 can be configured to receive one or more belts connected to an electric motor. In such embodiments, the belts can connect the electric motor to the center shaft 108, where the motor is configured to drive the center shaft 108 via the one or more belts. The electric motor can impart power to the shaft by driving the belts, which in turn cause the shaft to rotate. In such embodiments, the center wheel 120 of each wheel set can be fixedly attached to the center shaft 108, rather than rotatably attached to the center shaft 108. In this way, the center wheel 120 can rotate and propel the skateboard forward when powered by the electric motor.

[0133] In other embodiments (not shown), the multi-wheel chassis 100 can include one or more wheels configured to receive a hub motor. Each hub motor can be contained within each center wheel 120 and can be coupled to the center shaft 108. In such embodiments, the hub motor can rotate about the center shaft 108, powering and causing the center wheel 120 to rotate. Rotation of the center wheel 120 caused by the hub motor propels the skateboard forward.

[0134] In some embodiments, the multi-wheel chassis 100 can be configured to receive one or more sensors in one of the wheels, one or more shafts, the swing axle 102, or the pivot axle saddle 172. The sensors can communicate with the motor and transmit a signal that controls the speed of the motor when a user steps on the board or shifts weight. In this way, a user can control the speed of the skateboard by leaning forward or backward on the deck of the skateboard.

[0135] VI. Examples

[0136] 1. Example 1

[0137] The exemplary skateboard chassis 100 according to the present application includes a wheel configuration that produces an angle of attack a of 43.72 degrees. The exemplary chassis 100 includes a front-to-rear distance 192 of 1.62 inches between the front wheel 122 and the center wheel 120. The exemplary chassis 100 includes a lateral distance PI of 1.97 inches between a first plane 2000 in which the center wheel 120 is located and a second plane 3000 in which the front wheel 122 is located. The front wheel 122 includes a width W2 of 0.55 inches and a diameter D2 of 2.75 inches. The center wheel 120 includes a width Wl of 1.68 inches and a diameter Dl of 2.76 inches. The respective dimensions and locations of the front wheel 122 and the center wheel 120 of the exemplary chassis 100 position the first reference point Rl and the second reference point R2 such that a line A connecting the first reference point Rl and the second reference point R2 forms an angle of attack a of 43.72 degrees with respect to a reference line B extending parallel to the longitudinal axis.

[0138] 2. Example 2

[0139] Example 1 of an exemplary skateboard according to the present application including a multi-wheel chassis (6 wheels total per chassis) having horizontal arms with spring mechanisms 130 and an angle of attack of 43.72 degrees was compared to a control skateboard including a conventional chassis (2 wheels total per chassis) without any horizontal arms in terms of deceleration over a 1.5 inch bump. In each test, the deceleration experienced by the skateboard during impact with the bump was measured by an accelerometer. Table 1 below shows the results of the comparison. Higher magnitude corresponds to greater deceleration and greater loss of speed.

[0140] Table 1

[0141]

[0142] On average, the exemplary skateboard decelerated 2.28 G less than the control skateboard. This reduction in deceleration on the exemplary skateboard translates to a 58% less loss of speed over the bump than the control skateboard.

[0143] Example 1 of an exemplary skateboard according to the present application including a multi-wheel chassis (6 wheels total per chassis) having horizontal arms with spring mechanisms 130 and an angle of attack of 43.72 degrees was compared to a control skateboard including a conventional chassis (2 wheels total per chassis) without any horizontal arms in terms of deceleration over a 3 inch expansion joint (or crack). In each test, the deceleration experienced by the skateboard during impact with the expansion joint was measured by an accelerometer. Table 2 below shows the results of the comparison. Higher magnitude corresponds to greater deceleration and greater loss of speed.

[0144] Table 2

[0145]

[0146] On average, the exemplary skateboard experienced a deceleration that was 2.12 G less than the control skateboard. This reduced deceleration of the exemplary skateboard translated into a loss of velocity over the crack that was 66% less than the control skateboard.

[0147] The velocity experienced by the exemplary skateboard as shown above over the bump and expansion joint when compared to a skateboard with a conventional chassis provides a user of the multi-wheel chassis skateboard a significantly smoother ride. In addition, the velocity over the obstacle allows the user to exert less energy to travel the same distance compared to a conventional skateboard.

[0148] 3. Example 3

[0149] An exemplary skateboard according to Example 1 of the present application including a multi-wheel chassis (6 wheels total per chassis) having horizontal arms 110 with spring mechanisms 130 and an attack angle of 43.72 degrees was compared to a control skateboard including a conventional chassis (2 wheels total per chassis) without any horizontal arms for deceleration over a 1 inch bump at a plurality of different approach angles. In each trial, the user of the riding skateboard approached the 1 inch bump at a speed of 5.5 miles per hour. In each trial, the deceleration experienced during impact with the bump was measured by an accelerometer mounted on the skateboard. Table 3 below shows the results of the comparison.

[0150] Table 3

[0151]

[0152] For impacts occurring at an approach angle of 90 degrees (essentially perpendicular), the exemplary skateboard experienced a deceleration that was 1.40 G less than the control skateboard on average. This reduced deceleration on the exemplary skateboard translated into a loss of momentum over the bump that was 42% less than the control skateboard. For impacts occurring at an approach angle of 75 degrees (15 degrees from perpendicular), the exemplary skateboard experienced a deceleration that was 0.69 G less than the control skateboard on average. This reduction in deceleration on the exemplary skateboard translated into a loss of momentum over the bump that was 17% less than the control skateboard. For impacts occurring at an approach angle of 60 degrees (30 degrees from perpendicular), the exemplary skateboard experienced a deceleration that was 0.58 G less than the control skateboard on average. This reduction in deceleration on the exemplary skateboard translated into a loss of momentum over the bump that was 14% less than the control skateboard. For impacts occurring at an approach angle of 45 degrees (45 degrees from perpendicular), the exemplary skateboard experienced a deceleration that was 0.27 G less than the control skateboard on average. This reduction in deceleration on the exemplary skateboard translated into a loss of momentum over the bump that was 8% less than the control skateboard.

[0153] The most significant speed retention effect of the example skateboard, when compared to the control skateboard, occurs on impacts closest to the vertical straight on angle. This is due to the suspension system providing lift directly on the hump. The example skateboard experiences the smallest amount of deceleration when approaching the hump straight on, while the control skateboard experiences a significant amount of deceleration when approaching the hump straight on. The user of the example skateboard can approach obstacles straight on and successfully traverse them without a significant loss of speed. This enables the user of the example skateboard to take a more direct route of travel during normal use of the skateboard, thereby reducing the time and distance of travel.

[0154] The example skateboard also exhibits reduced deceleration for non- vertical angles. Even in the case of approaching angles that are as shallow as 45 degrees, which is atypical during use of the skateboard, the example skateboard exhibits significant speed retention when compared to the control skateboard. It can be seen that the attack angle a of the example skateboard provides stability and allows lift to be generated even at extreme angles.

[0155] Substitution of one or more claimed elements constitutes "alterations" rather than "modifications." In addition, benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems and any one or more of the elements that might cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or element of any or all the claims. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.

[0156] Furthermore, the embodiments and limitations disclosed herein are not to be construed as limiting the public under the doctrine of equivalents. (1) if not claimed in the claims; and (2) if the embodiments and / or limitations are incorporated under the doctrine of equivalents to the patentable matter in the claims.

[0157] The various features and advantages of the present disclosure are set forth in the appended claims.

Claims

1. A base frame, comprising: A suspension shaft, the suspension shaft including a first end and a second end spaced apart from the first end, and a longitudinal axis extending from the first end to the second end; A wheel assembly, located near one of the first and second ends of the suspension axle and connected to the suspension axle via a central shaft, the wheel assembly comprising: A center wheel and a horizontal arm, each connected to the central shaft; The horizontal arm is configured to rotate about the central axis and includes a front hole, a middle hole, and a rear hole; Front axle, the front axle being received by the front bore of the horizontal arm; Rear axle, the rear axle being received by the rear bore of the horizontal arm; Multiple auxiliary wheels, the multiple auxiliary wheels including: Front wheel, the front wheel is fixed to the front axle; Rear wheel, the rear wheel being fixed to the rear axle; The angle of attack is defined between a first reference line and a second reference line. The first reference line is tangent to the foremost and outermost point of the front wheel and the foremost and outermost point of the center wheel. The second reference line is parallel to the longitudinal axis. A spring mechanism configured to limit rotation of the horizontal arm about the central axis; wherein the spring mechanism includes a spring washer received within a groove in the horizontal arm, and The spring washer includes a body having a periphery and a center; the spring washer also includes at least one flexural portion, wherein the flexural portion extends from the periphery of the spring washer toward the center and is configured to flex outward toward the periphery.

2. The base frame according to claim 1, wherein, The angle of attack is between 40 and 45 degrees.

3. The base frame according to claim 1, wherein, The angle of attack is between 42 and 44 degrees.

4. The base frame according to claim 1, wherein, The lateral distance between the center wheel and the front wheel, measured parallel to the longitudinal axis, is between 1.5 inches and 2.0 inches.

5. The base frame according to claim 1, wherein, The front-to-back distance between the front axle and the center axle is between 1.5 inches and 2.0 inches.

6. The base frame according to claim 1, wherein, The front-to-back distance between the central axis and the rear axis is between 1.5 inches and 2.0 inches.

7. The base frame according to claim 1, wherein, The diameter of the front wheels is between 2.5 and 3.0 inches.

8. The base frame according to claim 1, wherein, The center wheel is further apart from the suspension axle in the longitudinal direction than the plurality of auxiliary wheels.

9. The base frame according to claim 1, wherein, The front wheel and the rear wheel are equidistant from the axle in the longitudinal direction.

10. The base frame according to claim 9, wherein, The center wheel includes a center wheel width, wherein each of the plurality of auxiliary wheels includes an auxiliary wheel width, and wherein the center wheel width is greater than the auxiliary wheel width.

11. The base frame according to claim 10, wherein, The width of the center wheel is between 1.5 inches and 1.75 inches, and the width of the auxiliary wheel is between 0.5 inches and 0.7 inches.

12. A base frame, comprising: Suspension shaft, pivot saddle, base plate, and multiple wheels; The suspension shaft includes: A first end and a second end spaced apart from the first end; A longitudinal axis extending between the first end and the second end; A first central shaft connected to the first end and a second central shaft connected to the second end; Wherein, the first central axis and the second central axis extend along the longitudinal axis; The first center wheel is connected to the first center shaft; The second center wheel is connected to the second center shaft; Components; the components include: A first horizontal arm connected to the first central axis and a second horizontal arm connected to the second central axis; The first horizontal arm is configured to connect the first front wheel and the first rear wheel; The second horizontal arm is configured to connect the second front wheel and the second rear wheel; The first horizontal arm is configured to rotate about the first central axis; The second horizontal arm is configured to rotate about the second central axis; The chassis also includes an angle of attack, which is defined as the angle between a first reference line and a second reference line. Wherein, the first reference line is tangent to the foremost and outermost point of the first front wheel and the foremost and outermost point of the first center wheel; and wherein, the second reference line is parallel to the longitudinal axis. Wherein, at least the first horizontal arm includes a groove configured to receive a spring washer; The spring washer includes a spring geometry configured to restrict rotation of the first horizontal arm and the second horizontal arm; and The spring washer includes a body having a periphery and a center, and the spring washer further includes at least one flexural portion, wherein the flexural portion extends from the periphery of the spring washer toward the center and is configured to flex outward toward the periphery.

13. The base frame according to claim 12, wherein, The angle of attack is between 40 and 45 degrees.

14. The base frame according to claim 12, wherein, The angle of attack is between 42 and 44 degrees.

15. The base frame according to claim 12, wherein, The first center wheel and the second center wheel have similar widths; Wherein, the first front wheel, the first rear wheel, the second front wheel, and the second rear wheel have similar widths; and The widths of the first center wheel and the second center wheel are greater than the widths of the first front wheel, the first rear wheel, the second front wheel, and the second rear wheel.

16. The base frame according to claim 12, wherein, The first front wheel and the first rear wheel are located on a first plane, wherein the first plane is perpendicular to the longitudinal axis; and The first center wheel is located on the second plane, which is parallel to the first plane.

17. The base frame according to claim 16, wherein, The first plane is offset from the second plane in the longitudinal direction by a distance between 1.5 inches and 2.0 inches; and The second plane is positioned further away from the first end of the suspension shaft than the first plane.

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