Selectable-weight dumbbell handle assembly

Abstract

A handle chassis for a selectable-weight dumbbell includes two opposing abutment plates configured to attach to one or more weight plates. A handle connects to and is positioned between the two abutment plates. A pair of lateral beams is positioned parallel to and on opposing sides of the handle and connects to and is positioned between the two abutment plates. A pair of selector bars is configured to slidably connect to respective ones of the lateral beams and selectively engage a subset of the one or more weight plates adjacent to respective abutment plates. A weight of the handle chassis is ten (10) pounds (4.5 kg) or less. The handle chassis is configured to carry a load attached weight plates of at least eighty (80) pounds (36 kg).

Description

TITLESelectable-weight dumbbell handle assemblyINVENTORJoseph Gerry Larson of Westminster, ColoradoCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority pursuant to 35 U.S.C. § 119(e) of U.S. provisional application no. 63 / 574,168 filed 3 April 2024 entitled “Selectable-weight dumbbell handle assembly,” and U.S. provisional application no. 63 / 706,406 filed 11 October 2024 entitled “Selectable-weight dumbbell handle,” which are hereby incorporated herein by reference in their entireties.TECHNICAL FIELD

[0002] The technology described herein relates to manually operated exercise equipment and particularly to dumbbells.BACKGROUND

[0003] Selectable-weight dumbbells, often referred to as “adjustable dumbbells” or “adjustable-weight dumbbells” allow a user to select a desired weight for easy attachment to a dumbbell handle from among a range of available weights. This weight selectability is typically achieved by providing a number of weight plates of generally uniform mass and form factor and a connection system that easily and quickly allows for connection and disconnection of any of the number of weight plates to the handle. Numerous connection systems have been conceived and implemented with various degrees of success in strength and stability of the dumbbell when loaded with weight plates.

[0004] The information included in this Background section of the specification, including any references cited herein and any description or discussion thereof, is included for technical reference purposes only and is not to be regarded subject matter by which the scope of the invention as defined in the claims is to be bound.SUMMARY

[0005] The technology disclosed herein relates to selectable-weight dumbbell construction. In one example implementation, a handle chassis for a selectable-weight dumbbell is disclosed. The handle chassis can include two opposing abutment plates and a handle. The two opposing abutment plates can each have inner faces and each can be configured to attach to one or more weight plates. The handle can be positioned betweenthe two abutment plates. The handle can be formed as a cylindrical tube with an inner wall and two annular end wall faces flatly abutting against the two abutment plates, respectively. Two cylindrical bushings can be seated against the inner wall within the cylindrical tube of the handle at opposite lateral ends of the handle. An outer edge face of each cylindrical bushing can be positioned to lie in a common plane with a corresponding one of the annular end wall faces of the handle. A perimeter of each cylindrical bushing adjacent to the outer edge face can be beveled toward an outer diameter of the bushing such that an annular recess is formed between the outer edge face and the inner wall of the cylindrical tube. A bead weld can be formed within each annular recess. Each bead weld can be ground flat such that there is a continuous flat surface created by each annular end wall face of the handle, the outer edge face of each cylindrical bushing, and the bead weld to provide increased surface area at an interface between the handle and the inner faces of the two abutment plates to distribute a load between the two abutment plates and the handle. A pair of fasteners can, respectively, connect the two abutment plates to respective lateral ends of the handle by engagement with the cylindrical bushings.

[0006] In another example implementation, a handle chassis for a selectable-weight dumbbell can include two opposing abutment plates and a handle. The two opposing abutment plates can be configured to attach to one or more weight plates. The handle can be connected to and positioned between the two abutment plates. A pair of lateral beams can be positioned parallel to and on opposing sides of the handle and be connected to and positioned between the two abutment plates. A pair of selector bars can be configured to slidably connect to respective ones of the lateral beams and selectively engage a subset of the one or more weight plates adjacent to respective abutment plates. A weight of the handle chassis can be ten (10) pounds (4.5 kg) or less. The handle chassis can be configured to carry a load of attached weight plates of at least eighty (80) pounds (36 kg).

[0007] In an additional example implementation, the handle chassis can further be configured to carry a load of attached weight plates of at least 125 pounds (56.7 kg).

[0008] In an additional example implementation of the handle chassis, each of the lateral beams and each of the selector bars can formed of a same metal material to avoid galling between corresponding lateral beams and selector bars when the selector bars slide with respect to the lateral beams.

[0009] In an additional example implementation of the handle chassis, a bead weld can be formed at an interface between the handle and the abutment plates. The bead weld can be ground flat to provide additional surface area at the interface to distribute a load between the abutment plates and the handle.

[0010] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intendedto identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. A more extensive presentation of features, details, utilities, and advantages of the present invention as defined in the claims is provided in the following written description of various embodiments and implementations and illustrated in the accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements.

[0012] The use of cross-hatching in the accompanying figures is generally provided to indicate a surface of a cross-section cut. The use of contour lines, shading, or stippling in the accompanying figures is generally provided indicate surface features, including curved surfaces or changes in depth, to clarify boundaries between adjacent elements, and to facilitate legibility of the figures. Accordingly, neither the presence nor the absence of crosshatching, contour lines, shading, or stippling conveys or indicates any preference or requirement for particular materials, material properties, element proportions, element dimensions, commonalities of similarly illustrated elements, or any other characteristic, attribute, or property for any element illustrated in the accompanying figures.

[0013] Additionally, it should be understood that the proportions and dimensions (either relative or absolute) of the various features and elements (and collections and groupings thereof) and the boundaries, separations, and positional relationships presented therebetween, are provided in the accompanying figures merely to facilitate an understanding of the various example embodiments described herein and, accordingly, may not necessarily be presented or illustrated to scale, and are not intended to indicate any preference or requirement for an illustrated embodiment to the exclusion of embodiments described with reference thereto.

[0014] FIG. 1 is an isometric view of an example implementation of a selectable-weight dumbbell.

[0015] FIG. 2 is a front elevation view of the selectable-weight dumbbell of FIG. 1.

[0016] FIG. 3 is a top plan view of the selectable-weight dumbbell of FIG. 1.

[0017] FIG. 4 is an isometric view of an example implementation of the selectable-weight dumbbell of FIG. 1 with an alternative add-on weight configuration, and with the handle unit, the add-on weights, and three weight plates on each end selected and removed from a remainder of unselected weight plates resting in a cradle.

[0018] FIG. 5 is a front, right, isometric view in cross section of the selectable weight dumbbell of FIG. 1 as indicated by lines 5-5 in FIG. 3.

[0019] FIG. 6 is a top, front, left isometric view of an example implementation of a handle for the selectable-weight dumbbell of FIG. 1.

[0020] FIG 7 is a top, front, left isometric view in cross section of the handle of FIG. 6 as indicated by lines 7-7 in FIG. 6.

[0021] FIG. 8 is a top, front, left isometric view in cross section of the selectable-weight dumbbell of FIG. 1 as indicated by lines 8-8 in FIG. 2.

[0022] FIG. 9 is a plan view in cross section at a 45° angle of the handle unit of the selectable-weight dumbbell of FIG. 1, with add-on weight features removed, as indicated by lines 9-9 in FIG. 10.

[0023] FIG. 10 is a left side isometric view of the handle unit of the selectable-weight dumbbell of FIG. 1.

[0024] FIG. 11 A is a front, left isometric view in cross section of a single weight plate of the selectable-weight dumbbell of FIG. 1 as indicated by lines 11A-11A in FIG. 4.

[0025] FIG. 11 A is a front, left isometric view in cross section of a single weight plate of the selectable-weight dumbbell of FIG. 1 as indicated by lines 11A-11A in FIG. 4.

[0026] FIG. 11 B is a rear, left isometric view in cross section of a single weight plate of the selectable-weight dumbbell of FIG. 1 as indicated by lines 11 B-11 B in FIG. 4.

[0027] FIG. 12A is a bottom, right isometric view of a roll pin used to secure

[0028] FIG. 12B is a bottom plan view of the roll pin of FIG. 12A.DETAILED DESCRIPTION

[0029] Examples of the present technology are directed to a selectable-weight dumbbell, also referred to in the field as an adjustable-weight dumbbell, or merely an "adjustable dumbbell." The selectable-weight dumbbell has a handle chassis that is configured for attachment to one or more removable weight plates. The entirety of available weight plates define a total possible weight for the adjustable dumbbell. The number of weight plates connected at one time define the weight selected by the user for an exercise. In example implementations, each of the removeable weight plates can be 5 lbs (2.27 kg) such that when a pair of weight plates (one on each end) is selected for attachment to the handle chassis, the selected weight increments by 10 lbs (4.5 kg). It is also possible to select one weight plate on a single end of the handle chassis to increment by 5 lbs (2.27 kg) at a time, but this may be less desirable due to the imbalance such can impart.

[0030] In the example implementations disclosed herein, the selectable-weight dumbbell is considered a "heavy" dumbbell, which means that the total weight of the dumbbell with all weight plates attached exceeds 80 lbs (36 kg) and can in some implementations reach up to 125 lbs (56.7 kg) or more. To support this significant load, the handle chassis of a heavy adjustable dumbbell is traditionally made substantially of steel, including the handle and endplates to which the weight plates attach. Additionally, several reinforcing steel beams typically surround the handle and also connect to the end plates of the chassis to support the heavy total load of the weight plates. This construction results in a heavy handle chassis, usually targeted at 20 lbs (9 kg), for a heavy adjustable dumbbell to support loads of 80 lbs (36 kg) or more. A starting weight of 20 lbs (9 kg) may be undesirable as too heavy for certain exercises, for example, for physical therapy, or for multiple users of a selectable- weight dumbbell of varying strengths.

[0031] The handle chassis provides a core structure capable of supporting such significant weights, while maintaining a very light base weight of 10 lbs (4.5 kg) of the handle chassis itself when no weight plates are attached. The handle chassis includes a central handle with abutment plates attached at each end. To support a heavy load, the components of the handle chassis can be formed of a combination of materials and form factors as described herein to reduce weight and provide adequate rigidity and flexural strength in resistance to the end loads. A pair of selector cases housing respective selector bars can also extend between and connect to the abutment plates at peripheral edges to provide additional rigidity and strength to the handle chassis. The selector bars can be manipulated to interface with one or more of the removeable weight plates on each lateral end of the adjustable dumbbell, respectively, to thereby select the one or more weigh plates. Outer sides of the abutment plates are configured to removably couple to the adjacent weight plates to provide additional support to the selected weight plates. The outer weight plates can also removably couple to each other so that a plurality of outer weights can stack onto each abutment plate of the handle assembly when the adjustable dumbbell is lifted by a user.

[0032] Additionally, inner sides of the abutment plates, or the handle, or a combination of both, can be configured to removably couple to a respective inner add-on weight. The add-on weights are lighter than the outer weight plates, for example, 2.5 lbs (1.13 kg) each and enable smaller weight increments to be added to the handle chassis between larger weight increments of the outer weight plates. Use of light add-on weights closer to the center of mass of the adjustable dumbbell can also be a more effective and balanced way to increment the total selected weight of the adjustable dumbbell in smaller steps, e.g., 2.5-5 lbs (1.13-2.27 kg) than selecting a single weight plate (e.g., of 5 lbs (2.27 kg)) on only one side of the handle chassis, and further from the center of mass, which can cause noticeable imbalance. The add-on weights can be shaped and sized to avoid interference with the handle during use and to locate a center of mass of the inner weights substantially along a longitudinal axis of the handle.

[0033] In some example implementations, the abutment plates can be made from a different material than the handle, the selector case, and the selector bar to reduce theweight of the handle chassis. The abutment plates can also be made of a different material than the weight plates. The choice to use of different materials in the design and construction of the chassis in support of achieving a low weight handle chassis leads to several impediments that are identified and addressed in greater detail herein.

[0034] A cradle can be provided to support the selectable-weight dumbbell and aid in the addition and removal of the weight plates. The cradle facilitates expandability of the selectable-weight dumbbell with additional outer weights as required or desired.

[0035] An overview of the selectable-weight dumbbell 100 (hereinafter, merely dumbbell 100 for brevity) is presented in FIGS. 1-3. The dumbbell 100 is primarily composed of a handle chassis 102 and a plurality of weight plates 104 selectively attachable to each end of the handle chassis 102. The handle chassis 102 as disclosed herein is designed to provide a base weight to the dumbbell 100 of 10 lbs (4.5 kg). In the example implementation shown in the figures, the dumbbell 100 can support at least eleven (11) weight plates 104 of 5 lbs (2.27 kg) on each end of the handle chassis 102, for a total of 110 lbs (50 kg), not including the weight of the handle chassis 102. For the purposes of this disclosure, the term "heavy" hereinafter refers to a load on the dumbbell 100 of at least 80 lbs (36 kg), or 35 lbs (15.75 kg) on each end of the handle chassis 102, and up to or greater than 125 lbs (56.7 kg), or 55 lbs (25 kg) on each end of the handle chassis 102 plus two add-on weights of 2.5 lbs (1.13 kg) each as further described below.

[0036] The handle chassis 102 can be composed of a handle 106 in the form of a substantially cylindrical tube extending between and connected to opposing abutment plates 120a / b at each lateral end. The handle 106 defines the center axis of the dumbbell 100. The handle chassis 102 of example implementations disclosed herein is designed to provide adequate flexural strength between the opposing abutment plates 120a / b to support heavy loads. In example implementations, the handle 106 can be a steel tube (as further described below) with a relatively thin wall, rather than solid steel, to reduce the weight of the handle chassis 102. The outer surface of the handle 106 may be knurled (not shown) for better grip by a user and may further be nickel-plated to provide corrosion resistance, particularly in the presence of salty sweat of a user or location in high humidity climates. The lateral ends of the handle 106 can also support add-on weights 116, 116’ with coupler structures 118, 118’ (see, e.g., FIGS. 1 and 4) attached in part to the handle 106 and in part to the abutment plates 120a / b. As noted, several forms of add-on weights 116, 116’ are depicted in the figures, but are not the focus of this disclosure and will not be described in detail.

[0037] A pair of selector cases 108 extend between and are fixed to perimeter edges of the opposing abutment plates 120a / b. The selector cases 108 are aligned parallel with each other and with the handle 106 on opposing sides of the handle 106 within a horizontal plane.Each selector case 108 is generally rectangular in form, with an outer face and top and bottom sidewalls to form a partial boxlike structure. The back face and lateral ends of each selector case 108 are open. Respective selector beams 122 extend along the back faces of each selector case 108 and are fixed to the back edges of the top and bottoms, e.g., by welds, to form a generally enclosed box with open ends. The selector cases 108 and selector beams 122 can be formed of steel in example embodiments. The selector beams 122 extend beyond the length of the selector case 108 and the lateral ends of the selector beams 122 are fixed to edges of the abutment plates 120a / b, e.g., with set screws. The selector beams 122 and the affixed selector cases 108 provide additional flexure strength and rigidity to the handle chassis 102, in conjunction with the handle 106, to support the heavy load of the weight plates 104.

[0038] A respective selector bar 110 is retained within, slides within, and can extend outward from a lateral end of the boxlike cavities formed by each set of selector cases 108 and selector beams 122. The selector bar 110 can be generally rectangular in form and is configured to interface with one or more weight plates 104 on a respective end of the handle chassis 102 as will be further described below. The selector beams 122 can be made of steel for strength in providing a portion of the support for the load of the selected weight plates 104. Although accounting for a significant portion of the weight of the handle chassis 102, the use of steel for the selector cases 108, the selector bars 110, and the selector beams 122 is desirable for several reasons. A first reason is to provide adequate strength to the handle chassis 102 to carry the heavy load of the weight plates 104. A second reason is to minimize the possibility of galling between the metal surfaces of the selector bars 110 and the selector cases 108 and selector beams 122 as the selector bar 110 slides within and against the inner surfaces thereof. Galling, as used herein, refers to the rough micro- and macroscopic material build-up created by friction between two surfaces rubbing against each other, that further increases friction and prevents smooth movement of the surfaces against each other. The likelihood of galling is greatly reduced if the same material is used for each component. For example, if a lighter-weight material, e.g., aluminum, was used for the selector cases 108 and selector beams 122, and the selector bar 110 remained steel for desired interface strength with the weight plates 104, the likelihood of galling between the materials and loss of effective function over time greatly increases.

[0039] Each of the abutment plates 102a / b in the handle chassis 102 is identical in form factor. In the example implementation shown to best advantage in FIG. 10, the abutment plates 120a / b can have a generally dodecahedron perimeter, although defining several cutouts. On each lateral edge of the abutment plates, a rectangular recess 129 is provided to receive and interface with the selector beam 122 and the selector case 108 as indicatedabove. Further, a pair of shoulders 128 can be formed in lateral edges of the abutment plates 120a / b beneath the rectangular recesses 129. These shoulders 128 can aid in placement in and alignment of the handle chassis 102 in a cradle 130 as suggested in FIG. 4.

[0040] To compensate for the relative heavy weight of the selector bars 110, the selector cases 108, and the selector beams 122 made of steel, the abutment plates 120a / b can be made of a different material, for example, an aluminum grade that has a similar or higher tensile and yield strength as standard grades of mild steel used in manufacturing. As there is no significant frictional movement of a steel component with respect to the abutment plates 120a / b, the use of aluminum for the abutment plates 120a / b can be a good choice to reduce the total weight of the handle chassis 102 to reach the desired 10 lbs (4.5 kg).

[0041] Each abutment plate 120a / b can be cast from an aluminum grade with the desired characteristics stated above. An inner face of each abutment plate 120a / b that interfaces with a respective end of the handle 106 is generally formed as a planar surface. A tab recess 208 may be defined toward the center of the inner face of the abutment plates 120a / b (visible in FIG. 8) for interfacing with features of the handle 106 as further described below. As shown in detail in FIG. 10, the outer face of the abutment plates 120a / b is formed with a plurality of recesses or cavities depressed from an outer surface of the abutment plates 120a / b to further reduce the weight of the abutment plates 120a / b. In the example implementation depicted, the outer faces of the abutment plates 120a / b can define a pair of upper lateral cavities 190a / b, a pair of lower lateral cavities 192a / b, an upper middle cavity 194, and a pair of medial cavities 196a / b. The noted cavities define a perimeter wall 206 forming the dodecahedron shape and several structures within the perimeter wall 206 in relief.

[0042] An island 198 can be formed in the center of the abutment plates 120a / b and can be adjusted in area to decrease or increase the weight of the abutment plates 120a / b to achieve a desired total weight of the handle chassis 102. The island 198 can also define several bore holes that support other components of the handle chassis 102, which will be described further below. Such bore holes include three abutment plate bores 146a / b / c and a center bore 147, which can have a beveled edge. Each of the abutment plate bores 146a / b / c and the center bore 147 can have threaded inner walls. Note that in this disclosure various terms such as hole, bore, through-hole, borehole, opening, gap, slot, or aperture may be used to describe an empty space defined by or formed through a mass or structure. The term “aperture” is used generically herein to refer to any of these other terms.

[0043] A plurality of structural ribs can extend between the island 198 and the perimeter wall 206. In the example implementation of FIG. 10, two upper ribs 200a / b can extend generally upward from the island 198 to the perimeter wall 206, thereby defining the uppermiddle cavity 194 and portions of the upper lateral cavities 192a / b. A lower rib 202 can extend vertically from the island 198 to the perimeter wall 206 and divides the lower later cavities 192a / b from each other. Four medial ribs 204a-d extend laterally (two on each side) between the island 198 and the perimeter wall 206. The medial ribs 204a-d define portions of all the cavities and primarily enclose the medial cavities 196a / b. In particular, the lower ribs 202 can transfer an impact force from the base of the abutment plates 120a / b if the dumbbell 100 is dropped in an orientation of normal usage across the abutment plates 120a / b through the island 198 to the other ribs and thereby to other structural components, e.g., the selector beams 122 to minimize stresses of such impacts.

[0044] As depicted to best advantage in FIGS. 5 and 9, a dovetail plate 124 is attached to an outer face of the right-side abutment plate 120b. The dovetail plate 124 has been removed from the left side abutment plate 120a in FIGS. 5 and 8-10 for exposure of the ribs and cavities within the outer face of the abutment plates. However, the left side abutment plate 120a also includes a dovetail plate 124 connected an outer face thereof. The dovetail plates 124 are the final components of the handle chassis 102. In this example, the dovetail plates 124 are generally formed in the same shape as a perimeter edge of the island 198 and the upper ribs 200a / b such that an inner face of each dovetail plate 124 is fully supported by a corresponding abutment plate 120a / b. The dovetail plates 124 are attached to the respective abutment plates 120a / b by three fasteners 144a / b / c, for example, set screws, that pass-through holes in the dovetail plates 124 that align with the threaded abutment plate bores 146a / b / c in the abutment plates 120a / b described above. The full form factor of the dovetail plates 124 in FIGS. 5 and 9 is depicted, for example in FIGS. 1 and 4, in which identical dovetail plates 124 are attached to the weight plates 104 as further described below. In some example embodiments, all of the dovetail plates 124 can be made of steel. In other example embodiments, the dovetail plates 124 can be made of aluminum or another metal, or from a molded plastic, e.g., a high-density plastic.

[0045] Each of the weight plates 104 is identical and can be formed of iron or steel (e.g., cast or machined) with a dodecahedron perimeter similar to the abutment plates 120a / b. A pair of lateral shoulders 128a can be formed in each of the weight plates 104, similar to the shoulders 128 in the abutment plates 120a / b, to aid in alignment and support of the weight plates 104 when placed in the cradle 130. The weight plates 104 can further define a selection channel 112 in a sidewall thereof. The selection channel 112 is sized and configured to receive the selector bar 110 therein as it extends from the selector case 108 through the rectangular recess 129 in the corresponding abutment plate 120a / b. The distance the selector bar 110 extends from the selector case 108, and thus which of the selector channels 112 of the weight plates 104 the selector bar 110 interfaces with, determines which weight plates 104 will be lifted by the handle chassis 102 and thus theselected weight for the dumbbell 100 for a particular exercise set. The selection of a subset of weight plates 104 is depicted to best advantage in FIG. 4 in which the selector bar 110 on each side of the dumbbell 100 has been extended past the abutment plates 120a / b to interface with the selection channel 112 of three respective selected weight plates 104a. The unselected weight plates 104b remain seated on their base edges and shoulders 128a within the cradle 130.

[0046] The selector bars 110 do not provide the entire structure for carrying the load of the selected weight plates 104a. Rather, the dovetail plates 124 mounted to the abutment plates 120a / b and forming part of each of the weight plates 104 carry and translate a further portion of the load of the selected weight plates 104a to the handle chassis 102. As depicted in FIGS. 4, 11 A, and 11 B, the weight plates 104 are formed by attachment of the dovetail plate 124 to a mass plate 105 by three fasteners 144a / b / c, for example, set screws, that pass through corresponding dovetail bores 143a / b / c in the dovetail plates 124 that align with the threaded plate bores 149a / b / c in the mass plates 105. An outer depth of the dovetail bores 143a / b / c can be beveled as depicted to interface with flat head, beveled bearing surface, set screw fasteners 144a / b / c to both countersink the set screw fasteners 144a / b / c, thereby providing a flat outer surface for the dovetail plates 124, and a tight, centered, interface fit between the set screw fasteners 144a / b / c and the dovetail plates 124 to resist movement between them. The length of the threaded shaft of the set screw fasteners 144a / b / c is less than the length of the threaded plate bores 149a / b / c in the mass plates 105 such that the set screw fasteners 144a / b / c do not protrude from the mass plates 105, thereby maintaining a smooth outer surface of the mass plates 105. The dovetail bores 143a / b / c and the threaded plate bores 149a / b / c are spaced apart and formed along a centered vertical axis in the respective dovetail plates 124 and the mass plates 105 to resist both linear and rotational shear forces between the dovetail plates 124 and the mass plates 105. However, the bores need not be arranged along a common axis to provide a desired force resistance.

[0047] Further, as depicted in FIGS. 4, 11 A, and 11 B, each of the interior faces of the mass plates 105 defines a socket 126 for receiving a respective dovetail plate 124 of an adjacent weight plate 104 or one of the abutment plates 120a / b. The dovetail plates 124 taper in width from top to bottom and have a beveled undercut edge 125 in the perimeter sidewalls thereof. The sockets 126 define an opposing, symmetrical recessed form factor to the dovetail plates 124 and similarly define a beveled undercut recess 127 around a perimeter edge thereof. The dovetail plates 124 thus slide snugly into a respective socket 126 in the mass plate 105 of an adjacent weight plate 104 and the opposing undercut edge 125 and undercut recess 127 interlace to lock the adjacent weight plates 104 together.

[0048] In some implementations, additional shear force resistance between the dovetail plates 124 and the mass plates 105 can be provided. When two flat parts are clamped together with fasteners, shifting between the parts can occur if they are subjected to force that can overcome the static friction of the two parts. In the case of the interface between the mass plates 105 and the dovetail plates 124, slight movement between these parts has been observed during drop tests of heavier weight loads. Dropping the selectable-weight dumbbell 100 with multiple attached weight plates 104 (i.e. , with a heavy load) creates a much greater shock force upon impact that translates through the selected weight plates104a, which can overcome the friction forces between the mass plates 105 and the dovetail plates 124 and cause a slight shift or movement therebetween. This can result in a small misalignment between the dovetail plates 124 attached to a mass plate 105 in a first weight plate 104 and the opposing socket 126 in an adjacent second weight plate 104. This misalignment can translate into difficulty or inability to maintain an aligned vertical orientation between the weight plates 104 for nesting of the dovetail plates 124 in the sockets 126 or easy translation of the selector bar 110 into the selection channel 112 formed in the weight plates.

[0049] A straightforward way to prevent this shifting is to increase the static friction between the two parts. However, increasing the torque on the fasteners 144a / b / c to place them under greater tension, and thus increase the friction, could lead to tensile failure of the fasteners 144a / b / c. Another option is not reliant on the static friction between the parts, but rather uses two or more dowels or similar cylindrical pins to create a mechanical lock between the parts and thereby prevent any lateral movement between the parts. An example implementation is presented in FIGS. 11A-12B in which roll pins 210 are placed within and span aligned through holes in the dovetail plate 124 and the mass plate 105. As depicted in FIGS. 11A and 11 B, dovetail pin holes 145a / b are formed in the dovetail plate 124 and corresponding plate pin holes 151a / b of a common diameter are formed in the mass plate 105 to receive the roll pins 210. In the example implementation depicted, the dovetail pin holes 145a / b are positioned in line with the dovetail bores 143a / b / c and plate pin holes 151a / b are positioned in line with the threaded plate bores 149a / b / c along a centered vertical axis in the respective dovetail plates 124 and the mass plates 105. However, the pin holes 145a / b, 151a / b need not be arranged along a common axis to provide a desired force resistance.

[0050] As indicated, roll pins 210 can be used to connect with and maintain alignment between the dovetail plates 124 and the mass plates 105, particularly when the dumbbell 100 is subject to significant shock forces (e.g., when dropped). An example roll pin 210 is depicted in FIGS. 12A and 12B and can be made of steel or other metal. The roll pin 210 is cylindrical in form with an outer wall 212 of a first diameter that is slightly largerthan the diameters of the pin holes 145a / b, 151a / b and an inner wall 214 of a smaller, second diameter to provide a thickness to the cylindrical form of the roll pin 210. The roll pin 210 also defines a longitudinal gap 216 in the cylindrical wall between the outer wall 212 and the inner wall 214 bounded by edge faces 218a / b. The width of each of the edge faces 218a / b defines the thickness of the wall of the roll pin 210. Each longitudinal end of the roll pin 210 has a flat end face 220 from the inner wall 214 to an intermediate diameter at which point it transitions to a beveled edge 222 tapering to the outer wall 212.

[0051] As noted, the outer diameter of the roll pins 210 is slightly larger than the diameters of the pin holes 145a / b, 151a / b. The roll pins 210 can be radially compressed along a diameter transverse to the gap 216, whereby the width of the gap 216 provides a maximum range of compression. Compression can be provided by an insertion tool or by the interface of the outer wall 212 with the walls of the pin holes 145a / b, 151a / b. By compressing the roll pin 210, insertion into the pin holes 145a / b, 151a / b is assisted. The beveled edges 222 also aid with the insertion of the roll pins 210 into the pin holes 145a / b, 151a / b. The roll pin 210 acts as a spring that expands once the compression is released, or merely presses outward on the pin holes 145a / b, 151a / b during and post insertion therein. The roll pins 210 thereby create a mechanical lock between the mass plate 105 and the dovetail plate 124 that resists rotation of the mass plate 105 and the dovetail plate 124 with respect to each other when exposed to significant shock forces. The roll pins 210 maintain their position within the pin holes 145a / b, 151a / b via both friction force and mechanical spring force and augment the facial friction forces between the mass plate 105 and the dovetail plate 124 to resist movement upon subjecting the dumbbell 100 to large shock forces.

[0052] In one example experiment before the addition of the and corresponding pins, eleven (11) 5 lb (4.54 kg) plates were placed on each side of the handle chassis 102, resulting in a combined weight of 120 lbs (50 kg) on the selectable-weight dumbbell 100. When the dumbbell 100 is dropped at an angle from a height of one half (0.5) meter, each dovetail plate 124 could shift up to 1 degree. This resulted in the furthermost weight plate 104 from the handle chassis 102 being potentially 12 degrees out of alignment when also accounting for the dovetail plate 124 on the abutment plates 120a / b on the handle chassis 102. This misalignment could cause the selector beam 122 to malfunction; each weight plate needs to stay in vertical alignment so the selection Channell 12 through each of the weight plates 104 remains aligned, allowing the selector beam 122 to extend through each of the weight plates 104.

[0053] After press fitting the roll pins 210 into the pin holes 145a / b, 151 a / b, the prior unintended shifting between the mass plates 105 and dovetail plates 124 was prevented. With the addition of the roll pins 210 in the pin holes 145a / b, 151 a / b, the selectable-weightdumbbell 100 passed a drop test experiment of seven (7) drops from one (1) meter. This testing at one (1) meter was in addition to and after seven (7) drops at each increment of 6 inches (0.1524 m) up to the one (1) meter height for a total of 42 drops without any angular shifting between the mass plates 105 and the dovetail plates 124.

[0054] In another example embodiment, a tubular pin (e.g., of steel or other metal) could be used instead of the roll pin 210 and inserted into the pin holes 145a / b, 151a / b. The tubular pin could have a diameter scarcely (i.e., very slightly or minimally) larger than the diameters of the pin holes 145a / b, 151a / b to provide a friction fit therein. However, the retaining force of the friction fit could be less than that of the spring force provided by the roll pins 210. Insertion of the tubular pin could also be more difficult and require an axial insertion force (e.g., a need to hammer it in the pin holes 145a / b, 151 a / b), which could damage the ends of the tubular pin or the faces of the dovetail plate 124 or the weight plate 104. In a similar example embodiment, a solid dowel pin (e.g., of steel or other metal) could be used instead of the roll pin 210. The dowel pin could have similar dimensions to and similarly be friction fit within the pin holes 145a / b, 151 a / b as the tubular pin, but also can have similar drawbacks as the tubular pin.

[0055] In a further example embodiment, a set screw with a cylindrical head could be used instead of the roll pin 210 and inserted into the pin holes 145a / b, 151a / b. In one implementation, the bores of the plate pin holes 151 a / b could be threaded to receive the threaded shaft or the set screw. In such an example embodiment, the diameter of the dovetail pin holes 151 a / b can be larger than the diameter of the plate pin holes151a / b to accommodate a larger diameter head of the set screw. The dovetail plate 24 could then be placed over the cylindrical heads of the set screws, which can be received within the dovetail pin holes 145a / b and form a friction fit interface therewith if the cylindrical heads of the set screws have an outer diameter scarcely larger than the diameter of the dovetail pin holes 145a / b. The dovetail plate 124 could be tapped or pressed into place to receive the cylindrical heads of the set screws in a friction fit interface with the dovetail pin holes 145a / b.

[0056] As the dovetail plates 124 are mounted on the outer faces of the mass plates 105, and the outer faces of the abutment plates 120a / b, the handle chassis 102 will freely lift out of the sockets 126 adjacent weight plates 104 that the dovetail plates 124 of the abutment plates 120a / b interface with. However, when the selector bars 110 extend within the selection channels 112 of one or more weight plates 104, such weight plates become selected weight plates 104a and the load of the selected weight plates 104a is lifted in part by the selector bar 110 interfacing with the selection channels 112. A portion of the load is also carried by the interface between the beveled undercuts of the dovetail plates 124 and the sockets 126, as lateral forces act between the selected weight plates 104a duringexercise movements. The interface between the beveled undercuts of the dovetail plates 124 and the sockets 126 also resist rotational forces between the weight plates 104 and with respect to the handle chassis 102 about the center axis of the dumbbell 100.

[0057] Typically, a user will select the same number of weight plates 104 for attachment to each end of the handle chassis 102 to maintain balance of the dumbbell 100 during an exercise. However, it is possible to select different numbers of weight plates 104 for attachment to each end of the handle chassis 102 if such is desired for some reason.

[0058] FIGS. 5-9 depict in greater detail and example implementation for a construction of the handle 106 and its interface with the abutment plates 120a / b to provide a lightweight, rigid, strong, and secure interface therebetween. As noted above, the goal is to achieve a handle chassis of no more than 10 lbs (4.5 kg) that can support dumbbell weights of up to 125 lbs (56.7 kg) or more. Ensuring a structurally sound interface between the hollow steel handle 106 and the cast aluminum of the abutment plates 120a / b that can withstand the static loads of the weight plates 104, as well as more dynamic stress forces during drop events, is important to success of the handle chassis 102.

[0059] The handle 106 is depicted in isolation in FIG. 6 and a cross-section as indicated in FIG. 6 is presented in FIG. 7. As noted, the handle 106 is formed of a cylindrical tube, e.g., made of steel or other strong metal or alloy, to reduce weight as compared to a solid steel (or other metal) bar. The majority of the length of the handle 106 can be of a constant outer diameter, but in the embodiment depicted, the ends of the handle 106 may step down in outer diameter slightly to form a handle shoulder 164. An annular groove 166 is shown in the figures, which may be provided to receive a snap ring for retention of an add-on weight structure (e.g., add-on weights 116 in Fig. 1 and add-on weights 116' in FIG. 4). Each end of the body of the handle 106 may define an annular end wall face 162. A pair of antirotation tabs 160 extends longitudinally with respect to the axis of the cylindrical tube from circumferentially offset positions on the end wall face 162. In the example embodiment depicted, the anti-rotation tabs are

[0060] A bushing 150 can be inserted into each end of the handle 106. The outer diameter of the bushing can be slightly smaller than, but substantially the same as, the inner diameter of the handle 106 such that the bushing 150 seats snugly against the inner wall 168 of the handle 106. Each bushing 150 defines a threaded bore 154. An outer edge face 156 of the bushing 150 can be positioned to lie in the same plane as the end wall face 162 of the handle 106. An outer wall of each bushing150 can define a pair of lateral, longitudinal grooves. When the outer wall of the bushing 150 interfaces with the inner wall 168 of the handle 106, these grooves can function as weep holes 152 to allow for fluid drainage from within the handle 106, e.g., excess chemicals after a nickel-plating process or merely from exposure to humidity or a wet environment.

[0061] The perimeter of the bushing 150 adjacent to the outer edge face 156 is beveled toward the outer diameter of the bushing 150 to form an annular recess 158 between the outer edge face 156 and the inner wall 168 of the handle 106. As seen to best advantage in FIG. 9, the bushing 150 is welded in place to the inner wall 168 of the handle 106 with a bevel weld bead 188. The bevel weld bead 188 can be laid down around the perimeter of the bushing 150, with the exception of the areas of the weep holes 152 to ensure that such are not blocked. The bevel weld bead 188 is filed or ground flat such that there is a continuous flat surface created by the end wall face of the handle 106, the outer edge face 156 of the bushing 150, and the bevel weld bead 188, resulting in increased surface area of the interface between the handle 106 and the abutment plates 120a / b. This structure is also in contrast to typical bevel welds of inserts within tubing in which the bevel is further recessed within a cavity so that the bead is below an outer surface and no grinding is necessary.

[0062] In some implementations, due to the extension and curvature of the anti-rotation tabs160, it may be difficult to grind down the bevel weld bead 188 if laid adjacent to the antirotation tabs 160. Therefore, it may be desirable to avoid welding adjacent to the antirotation tab 160, as is the case depicted in FIG. 8.

[0063] To assemble the handle 106 to the abutment plates 120a / b, as depicted in FIGS. 5, 8, and 9, the handle 106 is axially centered on the center bore 147 and the antirotation tabs 160 seat within the tab recesses 208 in the inner faces of the abutment plates 120a / b. The flat surface formed by the end wall face 162 of the handle 106, the outer edge face 156 of the bushing 150, and the ground-down bevel weld bead 188 thus seat flush against the inner face of the abutment plates 120a / b. A handle bolt 148 or other fastener is passed through the center bore 147 and screwed into or otherwise fastened to the threaded bore 154 of the bushing 150. As the handle 106 is pulled tight against the abutment plates 120a / b, the larger surface area of the end wall face 162 of the handle 106, the outer edge face 156 of the bushing 150, and the ground-down bevel weld bead 188, as compared to the surface area of the end wall face 162, distribute the load forces from the selected weight plates 104a to the abutment plates 120a / b over a greater area, thus minimizing the possibility of deformation of the inner surfaces of the abutment plates 120a / b at the interface between the aluminum material of the abutment plates 120a / b and the steel tube of the handle 106. Such a deformation could negatively impact the integrity of the joint between the handle 106 and the abutment plates 120a / b and thus the ability of the handle chassis 102 to carry the heavy load of the weight plates 104.

[0064] Other aspects of the dumbbell 100 are depicted in the figures. For example, the selection functionality of the selector bar 110 can be understood with respect to FIG. 8 in particular. The selector case 108 can define a slot 171 through which a selector pin 114extends to interface with the selector bar 110. An annular shelf 176 containing a toroidal magnet 178 can be mounted, e.g., by a weld, to a shaft of the selector pin 114. The annular shelf 176 can seat within an annular wall 180 formed on the back side of a first end of the selector bar 110, the first end being opposite the weight plates 104 to be selected. The selector pin 114 can define a bore hole that passes through the annular shelf 176 and the toroidal magnet 178. A collet 174 can seat on the back side of the annular shelf 176 and be secured to the selector pin 114 by a set screw 172 that passes through the bore hole in the selector pin 114 to engage the collet 174. The collet 174 can have two outer diameters, a larger diameter adjacent to the annular shelf 176 and a smaller diameter extending distally backward therefrom.

[0065] The selector beam 122 defines a longitudinal engagement slot 182 (see FIG. 9) having a perimeter defined by selector depressions 183. The radius of the selector depressions is generally congruent with the radius of the larger outer diameter of the collet 174. The collet 174 is positioned within the engagement slot 182. The selector pin 114 can be manually adjusted (e.g., with a user's fingers) between two positions: an inward locking position in which the larger diameter of the collet 174 interfaces with one of the selector depressions 183 and sliding if the selector bar 110 is inhibited; and an outward position in which the smaller diameter of the collet 174 seats within the engagement slot 182. In the outward position, the collet 174 does not interact with the selector depressions 183 and is thus able to freely move longitudinally within the engagement slot 182. In this configuration of the selector pin 114, the selector bar 110 is free to move back and forth and extend beyond the selector case 108 into the selection channel 112 of the weight plates 104 to engage one or more of the weight plates 104.

[0066] The toroidal magnet is attracted to the selector beam 122 in the first, inward position and holds the selector pin 114 in place with the larger diameter of the collet 174 interfacing with one of the selector depressions 183, thus holding the selector bar 110 in place. It may be noted that a stadium recess 170 can be formed in the selector case about the selector slot 171 to allow the head of the selector pin 114 to recess and be flush with the outer surface of the selector case 108 during performance of an exercise. If a user wishes to adjust the position of the selector bar 110 to add or take away one or more weight plates 104, the user can pull the head of the selector pin 114 from the front or push on the collet 174 from the back side to release the interface of the larger diameter of the collet 174 and the selector depressions 183 and allow the selector bar 110 to slide freely. In this configuration, the toroidal magnet 178 is attracted to the inside surface of the selector case 108 to maintain the selector pin 114 in the disengaged position. The use of the toroidal magnet 178 in the selector pin 114 is another reason to fabricate the selector case 108 and the selector beam 122 out of steel, to provide the magnetic attraction.

[0067] As depicted in FIG. 8, the end of the selector bar 110 adjacent to the annular wall 180 can define a detent socket 186 for receipt of a detent spring 184 and a detent ball (not visible). The detent spring 184 can bias the detent ball against an upper interior surface of the selector case 108, which may define a series of recesses (not visible) aligned with each of the selector depressions 183. The detent ball can pop in and out of the recesses as the selector bar 110 slide forward and backward to provide the user a tactile response as to when the selector pin 114 is aligned with a selector depression 183 and thus the selector bar 110 is appropriately aligned within the selection channel 112 with respect to a weight plate 104.

[0068] In another aspect, a cradle 130, preferably made of steel or other metal (but alternatively could be made of molded plastic), can be provided for storage and ease of use of the dumbbell 100 and selection and storage of the unselected weight plates 104b. The cradle 130 can have a base 140 and sidewalls 141. A pair of cradle pads 142 may be mounted to a top surface of the base 140. The shoulders128a of the weight plates 104 can seat against the sidewalls 141 of the cradle 130 and the bottom edges of the weight plates 104 and the abutment plates 120a / b can seat on the cradle pad 142. The cradle pads 142 may be made of a hard plastic, for example, to create a "softer" landing and reduce loud clanking sounds between the metal of the weight plates and the cradle 130, while still holding up to the weight of the dumbbell 100. An adjustable bookend 132 can be provided at each lateral end of the cradle 130. Each bookend 132 can be adjusted to different positions by removing a fastener 136 (e.g., a set screw) from a foot 134 of the bookend 132 that fixes the bookend 132 to the base 140 of the cradle 130. The bookends 132 can be moved laterally over a different pair of positioning holes 138 in the base 140 and fixed by engaging the fasteners 136 to the new set of positioning holes 138.

[0069] In view of the above description, it can be understood that in one example implementation, a weight plate for a selectable-weight dumbbell can include a mass plate and a dovetail plate. The mass plate can have a first side and a second side and define a first plurality of apertures between the first side and the second side. Each of a first subset of the first plurality of apertures can have threaded cylindrical walls. Each of a second subset of the first plurality of apertures can have smooth cylindrical walls. The second side of the mass plate can define a socket in a dovetail form with a tapered portion of the dovetail form oriented vertically downward. The dovetail plate can have a first side and a second side, which can have a form factor symmetrically opposite to the dovetail form of the socket in the mass plate to fit within and mate with the socket in an identical weight plate. The dovetail plate can further define a second plurality of apertures between the first side and the second side. Each of a first subset of the second plurality of apertures can be positioned to align with respective ones of the first subset of the first plurality of apertures. Each of asecond subset of the second plurality of apertures can be positioned to align with respective ones of the second subset of the first plurality of apertures. A plurality of set screws can be respectively seated within and pass through the first subset of the second plurality of apertures and fastened to the first subset of the first plurality of apertures to thereby fix the dovetail plate to the mass plate. A plurality of cylindrical pins can respectively pass through and frictionally seat within pairs of the second subset of the second plurality of apertures and the second subset of the first plurality of apertures.

[0070] In another example implementation of the weight plate, the plurality of cylindrical pins can be roll pins.

[0071] In another example implementation of the weight plate, the plurality of cylindrical pins can be hollow cylindrical dowel pins.

[0072] In another example implementation of the weight plate, the plurality of cylindrical pins can be solid cylindrical dowel pins.

[0073] In another example implementation, a weight plate for a selectable-weight dumbbell can include a mass plate and a dovetail plate. The mass plate can have a first side and a second side and define a first plurality of apertures between the first side and the second side. A first subset of the first plurality of apertures can have threaded cylindrical walls. A second subset of the first plurality of apertures can have threaded cylindrical walls. The second side of the mass plate can define a socket in a dovetail form with a tapered portion of the dovetail form oriented vertically downward. The dovetail plate can have a first side and a second side. The dovetail plate can have a form factor symmetrically opposite the dovetail form of the socket in the mass plate to fit within and mate with the socket in an identical weight plate. The dovetail plate can further define a second plurality of apertures between the first side and the second side. A first subset of the second plurality of apertures can be positioned to align with respective ones of the first subset of the first plurality of apertures. A second subset of the second plurality of apertures can be positioned to align with respective ones of the second subset of the first plurality of apertures. A first plurality of set screws can be respectively seated within and pass through the first subset of the second plurality of apertures and can be fastened to corresponding ones of the first subset of the first plurality of apertures to thereby fix the dovetail plate to the mass plate. A second plurality of set screws can have cylindrical heads and threaded shafts. The threaded shafts can respectively seat within and be fastened to the second subset of the first plurality of apertures. The cylindrical heads can frictionally seat within corresponding ones of the second subset of the second plurality of apertures.

[0074] All directional references (e.g., proximal, distal, upper, lower, upward, downward, left, right, lateral, longitudinal, front, back, top, bottom, above, below, vertical, horizontal, radial, axial, clockwise, and counterclockwise) are only used for identification purposes to aidthe reader’s understanding of the structures disclosed herein, and do not create limitations, particularly as to the position, orientation, or use of such structures. Connection references (e.g., attached, coupled, connected, and joined) are to be construed broadly and may include intermediate members between a collection of elements and relative movement between elements unless otherwise indicated. As such, connection references do not necessarily infer that two elements are directly connected and in fixed relation to each other. The exemplary drawings are for purposes of illustration only and the dimensions, positions, order, and relative sizes reflected in the drawings attached hereto may vary.

[0075] In addition, any disclosure of components contained within other components or separate from other components should be considered exemplary because multiple other architectures may potentially be implemented to achieve the same functionality, including incorporating all, most, and / or some elements as part of one or more unitary structures and / or separate structures.

[0076] The detailed description set forth above in connection with the appended drawings describes examples and does not represent the only instances that may be implemented or that are within the scope of the claims. The terms “example” and “exemplary,” when used in this description, mean “serving as an example, instance, or illustration,” and not “preferred” or “advantageous over other examples.”

[0077] As used herein, including in the claims, the term “and / or,” when used in a list of two or more items, means that any one of the listed items can be employed by itself, or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A, B, and / or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination. Also, as used herein, including in the claims, “or” as used in a list of items (for example, a list of items prefaced by a phrase such as “at least one of’ or “one or more of”) indicates a disjunctive list such that, for example, a list of “at least one of A, B, or C” means A or B or C or AB or AC or BC or ABC, or A and B and C.

[0078] The above specification, examples and data provide a complete description of the structure and use of exemplary embodiments of the invention as defined in the claims. Although various embodiments of the claimed invention have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, other embodiments using different combinations of elements and structures disclosed herein are contemplated, as other iterations can be determined through ordinary skill based upon the teachings of the present disclosure. It is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative only of particular embodiments and not limiting. Changes in detail or structure may be made without departing from the basic elements of the invention as defined in the following claims.

Claims

CLAIMSWhat is claimed is1. A handle chassis for a selectable-weight dumbbell comprising two opposing abutment plates each with inner faces and each configured to attach to one or more weight plates; a handle positioned between the two abutment plates, wherein the handle is formed as a cylindrical tube having an inner wall and two annular end wall faces flatly abutting against the two abutment plates, respectively; two cylindrical bushings seated against the inner wall within the cylindrical tube of the handle at opposite lateral ends of the handle, wherein an outer edge face of each cylindrical bushing is positioned to lie in a common plane with a corresponding one of the annular end wall faces of the handle; a perimeter of each cylindrical bushing adjacent to the outer edge face is beveled toward an outer diameter of each cylindrical bushing such that an annular recess is formed between the outer edge face and the inner wall of the cylindrical tube; a bead weld formed within each annular recess, wherein each bead weld is ground flat such that there is a continuous flat surface created by each annular end wall face of the handle, the outer edge face of each cylindrical bushing, and the bead weld to provide increased surface area at an interface between the handle and the two abutment plates to distribute a load between the two abutment plates and the handle; and a pair of fasteners that, respectively, connect the two abutment plates to respective lateral ends of the handle by engagement with the cylindrical bushings.

2. The handle chassis of claim 1 further comprising a pair of lateral beams positioned parallel to and on opposing sides of the handle and connected to and positioned between the two abutment plates; and a pair of selector bars configured to slidably connect to respective ones of the lateral beams and selectively engage a subset of the one or more weight plates adjacent to respective abutment plates.

3. The handle chassis of claim 2, wherein each of the lateral beams and each of the selector bars is formed of a same metal material to avoid galling between corresponding lateral beams and selector bars when the selector bars slide with respect to the lateral beams.

4. The handle chassis of claim 3, wherein the same metal material is steel.

5. The handle chassis of claim 1 , wherein the cylindrical bushings have threaded inner walls; and each of the pair of fasteners is a set screw configured to engage the threaded inner walls.

6. The handle chassis of claim 1 , wherein an outer wall of each cylindrical bushing defines one or more longitudinal grooves; and the bead weld is formed to avoid blocking ends of the one or more longitudinal grooves adjacent to the outer edge face of each cylindrical bushing to form one or more weep holes.

7. The handle chassis of claim 1 , wherein a pair of anti-rotation tabs extend longitudinally from each annular end wall face of the handle circumferentially offset from each other; the two abutment plates have inner faces that each define tab recesses corresponding to each pair of anti-rotation tabs; and the anti-rotation tabs seat within a respective, corresponding tab recess.

8. The handle chassis of claim 7, wherein the bead weld is formed to avoid lying adjacent to the anti-rotation tabs.

9. The handle chassis of claim 1 , wherein a weight of the handle chassis is ten (10) pounds (4.5 kg) or less; and the handle chassis is configured to carry a load of attached weight plates of at least eighty (80) pounds (36 kg).

10. The handle chassis of claim 1 , wherein a weight of the handle chassis is ten (10) pounds (4.5 kg) or less; and the handle chassis is configured to carry a load of attached weight plates of at least 125 pounds (56.7 kg).

11. A handle chassis for a selectable-weight dumbbell comprising two opposing abutment plates configured to attach to one or more weight plates; a handle positioned between, and having lateral ends connected to, the two abutment plates; a pair of lateral beams positioned parallel to and on opposing sides of the handle and connected to and positioned between the two abutment plates; and a pair of selector bars configured to slidably connect to respective ones of the lateralbeams and selectively engage a subset of the one or more weight plates adjacent to respective abutment plates, wherein a weight of the handle chassis is ten (10) pounds (4.5 kg) or less; and the handle chassis is configured to carry a load of attached weight plates of at least eighty (80) pounds (36 kg).

12. The handle chassis of claim 11 further configured to carry a load of attached weight plates of at least 125 pounds (56.7 kg).

13. The handle chassis of claim 11, wherein each of the lateral beams and each of the selector bars is formed of a same metal material to avoid galling between corresponding lateral beams and selector bars when the selector bars slide with respect to the lateral beams.

14. The handle chassis of claim 13, wherein the same metal material is steel.

15. The handle chassis of claim 11 further comprising a bead weld at an interface between each lateral end of the handle and each of the two abutment plates, wherein the bead weld is ground flat and provides additional surface area at the interface to distribute a load between the two abutment plates and the handle.

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