Patent Publication Number: US-7708672-B2

Title: Incremental weight and selector

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
   The present application is related to co-pending U.S. patent application Ser. No. 12/004,236 filed on the same day herewith by Ronald Gibson, Blakely T. Pennington and David L. Albert and entitled WEIGHT STACK SELECTOR, the full disclosure of which is hereby incorporated by reference. The present application is related to co-pending U.S. patent application Ser. No. 12/004,253 filed on the same day herewith by Ronald Gibson, David E. Dyer and Jonathan M. Stewart and entitled WEIGHT STACK SELECTOR, the full disclosure of which is hereby incorporated by reference. 
   BACKGROUND 
   Stacks of weights are sometimes employed in exercise devices and in other testing or calibration equipment to permit different total weight amounts to be selected for being lifted, dropped or applied. In exercise devices, selection of weights is sometimes performed using a removable pin. Such pins may be lost, misplaced or stolen. Use of the pin is sometimes difficult, tedious and time-consuming. Moreover, fabrication of the weights for use with the pin may be costly. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic illustration of an exercise device including a weight system according to an example embodiment. 
       FIG. 2  is a perspective view of another embodiment of the weight system of  FIG. 1  according to an example embodiment. 
       FIG. 3  is an exploded perspective view of the weight system of  FIG. 2  according to an example embodiment. 
       FIG. 4  is an exploded perspective view of weights and spacers of the weight system of  FIG. 2  according to an example embodiment. 
       FIG. 5  is a partially exploded perspective view of the weight system of  FIG. 2  illustrating a stem and a selector according to an example embodiment. 
       FIG. 6  is an enlarged fragmentary view of a portion of the stem of  FIG. 5  according to an example embodiment. 
       FIG. 7  is a partially exploded top perspective view of the system of  FIG. 2  illustrating a selector in an aligned angular position according to an example embodiment. 
       FIG. 8  is an enlarged fragmentary perspective view illustrating a position indicator of the system of  FIG. 2  according to an example embodiment. 
       FIG. 9  is a bottom perspective view of the system of  FIG. 2  illustrating the selector in a misaligned angular position according to an example embodiment. 
       FIG. 10  is a front perspective view of the system of  FIG. 9  with portions omitted for purposes of illustration according to an example embodiment. 
       FIG. 10A  is a fragmentary top sectional view of a selector of the system of  FIG. 9  in a misaligned weight selected position according to an example embodiment. 
       FIG. 10B  is a fragmentary top sectional view of a selector of the system of  FIG. 9  in an aligned movable position according to an example embodiment. 
       FIG. 11  is a partially exploded top perspective view of the system of  FIG. 2  illustrating an incremental weight selection system according to an example embodiment. 
       FIG. 11A  is a fragmentary top plan view of the system of  FIG. 2  illustrating the incremental weight selection system in a first state in which no incremental weights are engaged according to an example embodiment. 
       FIG. 11B  is a fragmentary top plan view of the system of  FIG. 2  illustrating the incremental weight selection system in a second state in which an incremental weight is engaged according to an example embodiment. 
       FIG. 11C  is a fragmentary top plan view of the system of  FIG. 2  illustrating the incremental weight selection system in a third state in which a plurality of incremental weights are engaged according to an example embodiment. 
       FIG. 11D  is a top perspective view of the system of  FIG. 2  during lifting of weights while the incremental weight selection system is in the third state according to an example embodiment. 
       FIG. 12  is a perspective view of another embodiment of the weight system of  FIG. 1  according to an example embodiment. 
       FIG. 13  is a sectional view of the weight system of  FIG. 12  according to an example embodiment. 
       FIG. 14  is a top perspective view of another embodiment of a selector for the system of  FIG. 2  according to an example embodiment. 
       FIG. 15  is a fragmentary top perspective view of another embodiment of the exercise device of  FIG. 1  according to an example embodiment. 
       FIG. 16  is a fragmentary top plan view of the system of  FIG. 15  illustrating a weight selector in a first state according to an example embodiment. 
       FIG. 17  is a sectional view of the system of  FIG. 16  taken along line  17 - 17  according to an example embodiment. 
       FIG. 18  is a fragmentary top plan view of the system of  FIG. 15  illustrating a weight selector in a second state according to an example embodiment. 
       FIG. 19  is a sectional view of the system of  FIG. 18  taken along line  19 - 19  according to an example embodiment. 
       FIG. 20  is a fragmentary sectional view of the system of  FIG. 19  during lifting of the weights according to an example embodiment. 
       FIG. 21  is a bottom perspective view of another embodiment of the exercise device of  FIG. 1  according to an example embodiment. 
       FIG. 22  is a fragmentary bottom plan view of the system of  FIG. 21  illustrating a weight selector in a first state according to an example embodiment. 
       FIG. 23  is a fragmentary bottom plan view of the system of  FIG. 22  illustrating the weight selector in a second state according to an example embodiment. 
       FIG. 24  is a fragmentary bottom plan view of another embodiment of the exercise device of  FIG. 1  illustrating a weight selector in a first state according to an example embodiment. 
       FIG. 25  is a fragmentary bottom plan view of the system of  FIG. 24  illustrating the weight selector in a second state according to an example embodiment. 
       FIG. 26  is a top perspective view of another embodiment of the weight system of  FIG. 1  according to an example embodiment. 
       FIG. 27A  is a fragmentary top plan view of the system of  FIG. 26  illustrating a main weight selector in a first state according to an example embodiment. 
       FIG. 27B  is a fragmentary top plan view of the system of  FIG. 26  illustrating a main weight selector in a second state according to an example embodiment. 
       FIG. 28A  is a fragmentary top plan view of the system of  FIG. 26  illustrating an incremental weight selection system in a first state in which no incremental weights are engaged according to an example embodiment. 
       FIG. 28B  is a fragmentary top plan view of the system of  FIG. 26  illustrating the incremental mental weight selection system in a second state in which an incremental weight is engaged according to an example embodiment. 
       FIG. 28C  is a fragmentary top plan view of the system of  FIG. 26  illustrating the incremental weight selection system in a third state in which a plurality of incremental weights are engaged according to an example embodiment. 
   

   DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS 
     FIG. 1  schematically illustrates exercise device  20  according to one example embodiment. Exercise device  20  includes weight system  22 , cable system  24  and exercise interface  26 . Weight system  22  comprises a system by which a person may select a total amount of weight to be utilized and ultimately lifted in an exercise. Weight system  22  generally includes main weights  30 , main weight selection system  34 , weight lift  35 , incremental weights  36  and incremental weight selection system  38 . 
   Weights  30  comprise structures having predetermined weight amounts which are configured to be lifted and to provide a mechanical resistance in an exercise. In the particular example illustrated, weights  30  each comprise a solid or hollow plate of one or more metals. In other embodiments, weights  30  may comprise other materials or may comprise encapsulated materials, such as sand, water or other materials. Weights  30  are stacked upon one another such that as a particular weight  30  is being lifted, other weights  30  stacked upon the particular weight  30  are also lifted. 
   As schematically represented in  FIG. 1 , weights  30  each have a front rearwardly and horizontally extending notch or cutout. When stacked upon one another, weights  30  form an elongate continuous channel  67  extending inwardly into each of weights  30 . When stacked, weights  30  further define a multitude of cavities or voids  70  between consecutive weights  30 . Voids  70  each have a floor defined by an underlying weight  30  and a ceiling defined by an overlying weight  30 . In one embodiment, voids  70  are formed by intermediate spacers (not shown) positioned between weights  30 . In another embodiment, such voids  70  are formed by cavities, depressions, recesses and the like directly formed in one or both of opposing faces of consecutive weights  30 . Channel  67  and voids  70  facilitate selection of one or more weights  30  by media weight selection system  34 . 
   Main weight selection system  34  comprises a mechanism configured to permit a person to select one or more of weights  30  for lifting during an exercise. Main weight selection system  34  includes a selector  82  configured to be linearly translated up and down along weights  30  and partially within channel  67  in the direction indicated by arrows  39  to a position horizontally across from or just below a desired lowermost weight to be lifted along with all overlying weights  30 . Selector  82  is configured to be moved between a first position in which selector  82  is inserted into or projects into at least one of voids  70  below a selected lowermost weight to couple the lowermost weight to weight lift and a second position and which selector  82  is withdrawn from any void  70  and his movable along and within channel  67 . 
   For purposes of this disclosure, the term “coupled” shall mean the joining of two members directly or indirectly to one another. Such joining may be stationary in nature or movable in nature. Such joining may be achieved with the two members or the two members and any additional intermediate members being integrally formed as a single unitary body with one another or with the two members or the two members and any additional intermediate member being attached to one another. Such joining may be permanent in nature or alternatively may be removable or releasable in nature. The term “operably coupled” shall mean that two members are directly or indirectly joined such that motion may be transmitted from one member to the other member directly or via intermediate members. 
   Overall, because main weight selection system  34  moves within channel  67  and selectively engages weights by being moved into and out of intermediate voids  70  defined by such weights  30 , easier selection of weights  30  is facilitated and the cost of weight system  22  is reduced. Because main weight selection system  34  utilize a selector  82  that is movable between an inserted position and a withdrawn position with respect to a desired void  70 , weight system  22  does not utilize the insertion of a pin into a cross-drilled bore in a weight. As a result, selection of a particular weight is easier. In addition, weights  30  may omit cross-drilled holes, reducing the number of manufacturing steps and lessening fabrication cost. In addition, because weights  30  may omit such cross drilled holes, weights  30  are more structurally durable. As a result, weights  30  may be formed from alternative, less expensive materials which may not need to withstand such multiple machining steps. 
   Weight lift  35  comprises a structure coupled to main weight selection system  34  which is connected to cable system  24 . In one embodiment, weight lift  35  may itself comprise a cable. For purposes of this disclosure, the term “cable” shall encompass any flexible member, including but not limited to cables, belts, ropes, chains, bands, straps, pivotably connected linkages and the like. Weight lift  35  may also be coupled to an incremental weight  36  by incremental weight selection system  38 . 
   Incremental weights  36  comprise structures or members having a predetermined weight amount that are configured to be selectively coupled to weight lift  35  by incremental weight selection system  38 . In one embodiment, incremental weights  36  each have a weight amount less than a predetermined weight amount of each of main weights  30 . For example, in one embodiment, each of main weights  30  may be 15 pounds while each of incremental weights  36  is 5 pounds. In another embodiment, each of main weights  30  may be 10 pounds while each of incremental weights  36  is 5 pounds. In one embodiment, incremental weights  36  may include a 5 pound incremental weight and a 2.5 pound incremental weight. Incremental weights  36  permit a person to select a total amount of weight for an exercise that is intermediate or between the larger weight increments provided by main weights  30 . 
   As schematically represented in  FIG. 1 , incremental weights  36  longitudinally extend across multiple weights  30 . As a result, incremental weights  36  do not increase the overall height of weight system  22 . In one embodiment, incremental weights  36  comprise rods or bars passing through openings within weights  30  or contained within cutouts along a face of the stack of weights  30 . As a result, incremental weights  36  are more closely positioned relative to a center of mass of the weight stack. Consequently, tipping moments of the stack which could cause friction with the guide rods or other structures that guide movement of the stack are reduced. In yet another embodiment, incremental weights  36  may extend external to the stack of weights  30 . 
   Incremental weight selection system  38  comprises a mechanism configured to selectively add or remove incremental weights  36  from the total amount of weight connected to weight lift  35 . In one embodiment, incremental weight selection system  38  rotates between various positions in which a selected one of supplemental weights  36  are selectively connected to weight lift  35 . For example, in one embodiment, incremental weight selection system  38  may rotate to a first position in which a first incremental weight is connected to weight lift  35 , a second position in which a second incremental weight is additionally connected to weight lift  35  and a third position in which neither the first incremental weight nor the second incremental weight are connected to weight lift  35 . In other embodiments, incremental weight selection system  38  may have other configurations. In still other embodiments, incremental weight  36  and incremental weight selection system  38  may be omitted. 
   Cable system  24  comprises a system of pulleys and cables configured to operably coupled weight lift  35  (and any connected weights  30 ,  36 ) to exercise interface  26 . Cable system  24  may have any of a variety of different sizes, shapes and configurations depending upon exercise interface  26 . In other embodiments, exercise interface  26  may be operably coupled to weight system  22  by other mechanisms. 
   Exercise interface  26  comprises a device or mechanism operably coupled to cable system  24  by which one or more persons may exert force against one or more structures and may move the one or more structures to raise or lift a selected amount of weight provided by weights  30  and/or  36 . Exercise interface  26  may have various configurations depending upon which particular muscles or groups of muscles are to be exercised. Examples of exercise interface  26  include, but are not limited to the following types of exercise machines: abdominal isolator, angled seated calf, abductor, seated leg curl, glute isolator, vertical and horizontal, rear delt/pec fly, lateral raise, shoulder press, vertical press, back extension, seated row, vertical row, pulldown, long pull, seated dip, seated tricep extension, bicep curl, camber curl and bench press. Exercise interface  26  may be provided as part of a multi-station exercise machine, a modular exercise machine or a single station exercise machine. 
   Although weight system  22  has been illustrated and described for use as part of an exercise device  20  additionally including cable system  24  and exercise interface  26  (shown and described with respect to  FIG. 1 ), in other embodiments, weight system  22  may be employed in devices other than exercise devices. For example, weight system  22  may alternatively be employed in testing and calibration systems where it may be desirable to apply different weights, loads or impact forces by selecting one or more weights and by sensing or taking measurements or readings. In such alternative applications, weight system  22  provides a low-cost and simple to use and adjust weights system. 
     FIGS. 2 and 3  illustrate exercise device  120 , another embodiment of exercise device  20  (shown in  FIG. 1 ). Like device  20 , device  120  also includes cable system  24  and exercise interface  26  (both of which are shown and described with respect to device  20 ). Unlike device  20 , device  120  includes weight system  122 , a specific embodiment of weight system  22 .  FIG. 2  is a perspective view of exercise device  120  and weight system  122 .  FIG. 3  is an exploded perspective view of exercise device  120  and weight system  122 . As will be described hereafter, weight system  122  is a relatively low-cost arrangement of components which enables a person to quickly and easily select a desired amount of weight for an exercise routine. 
   Weight system  122  generally includes base  126 , upper guide  127 , guide rods  128 , weights  130 , spacers  132  (shown in  FIG. 3 ), main weight selection system  134 , weight lift  135 , incremental weights  136 A,  136 B (collectively referred to as incremental weights  136 ) and incremental weight selection system  138 . Base  126  comprises an arrangement of components configured to serve as a foundation and support for weight system  122 . Base  126  includes foot  142 , risers  144 , bumpers  146  and dock  148 . Foot  142  supports risers  144  and dock  148 . Although foot  142  is illustrated as a plate, in other embodiments, foot  142  may have other configurations. 
   Bumpers  146  comprise resiliently compressible members positioned between risers  144  and weights  130 . In the example illustrated, additional washers  150  are disposed between risers  144  and bumpers  146 . Bumpers  146  are configured to absorb the impact of weights  130  as weights  130  are dropped or otherwise lowered. In the example embodiment illustrated, bumpers and  146  are each formed from a bulk or mass of rubber. In other embodiments, bumpers and  146  may be formed from other resiliently compressible materials or may include other resiliently compressible members, such as one or more springs. In still other embodiments, bumpers  146  or risers  144  may be omitted. 
   Dock  148  comprises one or more members configured to remotely receive, support and guide portions of main weight selection system  134  and incremental weights  136 . Dock  148  extends from foot  142  and includes main bore  154  and incremental weight bores and  156 . Main bore  154  comprises an opening configured to remotely and slidably receive a lower portion of main weight selection system  134  when weights  130  are not being lifted. As will be described in more detail hereafter, main bore  154  appropriately aligns portions of main weight selection system  134  with weights  130  such that weights  130  may be selectively engaged by main weight selection system  134 . Likewise, incremental weight bores  156  comprise openings configured to remotely and slidably receive lower ends of the incremental weights  136 . As will be described in more detail hereafter, incremental weight bores  156  support incremental weights  136  with respect to incremental weight selection system  138  such that incremental weights  136  may be selectively engaged by incremental weight selection system  138 . Although dock  148  is illustrated as a single unitary or integral structure providing each of bores  154  and  156 , in other embodiments, dock  148  may alternatively comprise distinct individual tubes or structures extending from foot  142 . 
   Upper guide  127  comprises an arrangement of structures or components located on an opposite end of the stack of weights  130  as base  126  that is configured to assist in guiding movement of weights  130  along guide rods  128 . Upper guide  127  includes top plate  157 , incremental weight alignment bushings  158  and guide rod bushings  159 . Top plate  157  serves as a cap for the stack of weights  130 . Top plate  157  supports remaining components of upper guide  127 . In the particular example illustrated, top plate  157  further supports incremental weight selection system  138 . In other embodiments, or guide  127  may be provided at other locations or may be omitted. 
   Incremental weight alignment bushings  158  extend within apertures in top plate  157  and receive an upper portion of incremental weights  136 . Guide rod bushings  159  slidably receive the guide rods  128  and guide movement of weights  130  along guide rods  128 . In particular embodiments, such bushings may be omitted. 
   Guide rods  128  comprise elongate structures extending from foot  142  through weights  130 . Guide rods  128  additionally extend through risers  144  and bumpers  146  and may extend to an upper frame structure (not shown) of exercise device  120 . Guide rods  128  are configured to orient weights  130  and guide movement of weights  130  as they are being lifted or lowered. In particular embodiments, guide rods  128  may have other configurations or may be omitted. 
   Weights  130  comprise structures having predetermined weight amounts which are configured to be lifted and to provide a mechanical resistance in an exercise. In the particular example illustrated, weights  130  each comprise a solid or hollow plate of one or more metals. In other embodiments, weights  130  may comprise other materials or may comprise encapsulated materials, such as sand, water or other materials. Weights  130  are stacked upon one another such that as a particular weight  130  is being lifted, other weights  130  stacked upon the particular weight  130  are also lifted.  FIG. 4  is an exploded view of three consecutively stacked weights  130 . As shown by  FIG. 4 , each weight  130  includes guide rod openings  160 , incremental weight apertures  162 , selector aperture  164  and access channel  166 . Guide rod openings  160  comprise bores passages extending through weight  130 . Openings  160  of weight  130  are further configured to align with one another when weights  130  are stacked upon one another. Openings  160  are configured to receive guide rods  128 . 
   Incremental weight apertures  162  comprise bores or openings through which incremental weights  136  extend. Apertures  162  are configured to be aligned with one another when weights  130  are stacked upon one another. Incremental weight apertures  162  generally direct upward or downward movement of the incremental weights  136  when incremental weights  136  are being lifted or lowered. 
   Although incremental weight apertures  162  are illustrated as being connected to and in communication with selector aperture  164 , in other embodiments, incremental weight apertures  162  may be completely bordered or surrounded by weight  130  or may be provided in other locations. In embodiments where weight system  122  includes a greater or fewer of such incremental weights  136 , each weight  130  may also include a corresponding fewer or greater of such incremental weight apertures  162 . In particular embodiments where incremental weights  136  extend across multiple weights  130  outside or beyond an outer perimeter of weights  130 , incremental weight apertures  162  may be omitted or may alternatively comprise an inwardly extending cut out along the perimeter of each weight  130 . 
   Selector aperture  164  comprises an opening extending through weights  130  and configured to receive portions of main weight selection system  134 . Selector apertures  164  are configured to be aligned with one another when weights  130  are stacked upon one another. As will be described in more detail hereafter, apertures  164  are configured such that when a portion weight selection system  134  is aligned with apertures  164 , that portion of the weight selection system  134  may move through aperture  164  along and across weights  130 . When that portion of weight selection system  134  is moved so as to be out of alignment with apertures  164 , that portion of weight selection system  134  extends into a void formed between consecutive weights  130  such that all weights  130  overlying that portion of weight selection system  134  may be lifted. 
   Access channel  166  comprises an opening or passage extending from a perimeter or edge of each weight  130  inwardly to selector aperture  164 . Access channel  166  extends generally perpendicular to a longitudinal axis along which weights  130  are stacked and along which each of openings  160 , aperture  162  and aperture  164  extend or are aligned. Access channel  166  is configured to permit portions of main weight selection system  134  to project from selector aperture  164  to a location in front of weights  134  for access and manipulation by a person. Access channels  166  aligned with one another, permitting a person to grasp portions of main weight selection system  134  and to move main weight selection system  134  vertically upward and downward through and along a continuous vertical channel  67  formed by the individual access channels  166 . As a result, access channel  166  permits a person to move main weight selection system  134  to one of a plurality of available positions along the stack of weights  130  to select a total number of weights  130  or a total weight amount to be lifted. 
   Spacers  132  comprise one or more structures disposed between weights  130  that are configured to space and separate consecutive or adjacent weights from one another in the vertical direction so as to form voids  170  between consecutive weights  130 . As shown by  FIG. 3 , in the particular example illustrated, spacers  132  comprise annular bushings having a lower cylindrical portion  172 , an annular rim  174  and a through opening  176 . When positioned between consecutive weights  130 , cylindrical portion  172  of spacer  132  extends into opening  160  of an underlying weight  130 , rim  174  forms a shoulder bearing against a top of the underlying weight  130  and an overlying weight  33 , spacing the overlying weight  130  from the top of the underlying weight  130 . Rim  174  spaces consecutive weights by a vertical distance such that the void as a height greater than or equal to that portion of main weight selection system  134  that is received within the void. At the same time, through holes  176  permits one of guide rods  128  to pass through weight  130 , facilitating slidable movement of weights  130  along guide rods  128 . Thus, such bushings serve a dual purpose. 
   In other embodiments, spacers  132  may be provided separately from the bushings that facilitate sliding movement of weights  130  along the guide rods  128 . For example, the bushings shown in  FIG. 3  may alternatively omit rim  174  and extend within openings  160 . In particular embodiments, spacer  132  may comprise washers disposed about guide rods  128  been captured between weights  130 . Separate structures may be mounted to the upper surface, lower surface or both the surfaces of each weight  130 . In particular embodiments, spacer  132  may be fastened, glued, bonded or welded to one or more sources of weight  130 . And yet other embodiments, spacer  132  may be integrally formed as part of a single unitary body with weight  130 . For example, in embodiments where weight  130  comprises a casting of one or more metals, spacer  132  may be cast along with weight  130 . In embodiments where weight  130  comprises an encapsulated material, weight  130  may be molded or otherwise formed in the encasement skin. 
   Although spacers  132  are utilized in the particular example illustrated to form spaces or voids  170  between consecutive weights  130  that extend substantially across an entirety (less the space occupied by spacers  132 ) of a face of each of the consecutive weights  130 , in other embodiments, spaces or voids  170  may be provided in other fashions and may have other surface extents. For example, in another embodiment, voids  170 , which are used to receive a portion of weight selection system  134 , may alternatively comprise a recess, depression or cavity formed or otherwise provided within either the upper surface, the lower surface or both of such surfaces of each weight  130 . In such an embodiment, a majority of either the upper face or the lower face may be in direct contact with the lower face or the upper face, respectively, of a consecutive weight  130 , wherein only the floor or the roof of such recesses of consecutive weights are spaced from one another to form the void. 
   Main weight selection system  134  comprises a mechanism configured to permit a person to select one or more of weights  130  for lifting during an exercise. Main weight selection system  134  includes selector stem  180  and main selector  182 . Selector stem  180  comprises an elongate shaft, bar, rod or other structure coupled to weight lift  135  and movably positioned within selector apertures  164  of weights  130  such that stem  180  may be raised or lowered by weight lift  135 . In the particular example illustrated, stem  180  is coupled to weight lift  135  by incremental weight selection system  138 . As a result, even when no weights  130  are selected, stem  180  and incremental weight selection system  138  provide an initial weight. Stem  180  extends along an axis  183  (shown in  FIG. 5 ) and is configured to slidably support main selector  182  along an axis  183 . Selector stem  180  is configured such that selector  182  may be retained relative to stem  180  at a selected one on a plurality of positions along an axis  183  such that selector  182 , and any engaged weights  130 , will move with movement of stem  180  by weight lift  135 . 
     FIG. 5  illustrates stem  180  in full while  FIG. 6  is an enlarged view of stem  180 . As shown by  FIGS. 5 and 6 , stem  180  includes a tapered end portion  186  and a multitude of segments  188  joined and spaced apart from one another by spacers  190 . End portion  186  is configured to be removably received within bore  154 . End portion  186  generally tapers towards a point along axis  183 . In one embodiment, end portion  186  is at least partially conical. Because end portion  186  is tapered, end portion  186  self centers and aligns itself as it is being lowered into bore  154 . Because end portion  186  aligns itself into bore  154 , other structures or mechanisms otherwise used to provide and precise control over positioning of stem  180  when it is withdrawn from bore  154  when weights  130  are being lifted may be omitted or may be provided with greater tolerances, potentially reducing friction and drag as weights  130  are being lifted to provide a smoother feel. In addition, because end portion  186  aligns itself into bore  154 , part tolerances may be increased, reducing cost. For example, because end portion  186  is tapered and self aligning, guide rods  128  and not necessarily have to maintain precise positional control over stem  180  or both portions at the top of weight system  122  connected to stem  180 , such as incremental weight selection system  138 . As a result, the spacing or gap between guide rods  128  and bushings at an upper end of weight system  122  may be increased, reducing friction providing a smoother lifting of weights  130 . 
   Although tapered end portion  186  is illustrated as being employed with stem  180  which includes segments  188  and spacers  190 , tapered end portion  186  may alternatively be employed in other stems or lifting rods which are selectively connected to weights in a stack in an exercise device. For example, tapered end portion  186  may also be employed in other presently available weight stacks having a central rod or shaft with multiple axially holes that receive a pin that is inserted through corresponding through holes in individual weight plates. In other embodiments, tapered end portion  186  may be semi-bulbous or semi-spherical in shape, may be flat or may be omitted. 
   Segments  188  and spacers  190  alternately extend along axis  183 . Each segment  188  is shaped such that selector  182  may be rotated about axis  83  between a first angular position in selector  182  may be moved or slid along axis  83  without substantial interference from segments  188  and a second angular position in which selector  182  is retained between two consecutive segments  188  along axis  183 . In particular, segment  188  has a cross-sectional shape configured such that each segment  188  may pass through an opening in selector  182  when selector  182  is in a first angular position and is obstructed so as to not pass through the same opening in selector  182  when selector  182  is in the second angular position. In the example illustrated, each of the segments  188  has a non-circular or non-annular cross-sectional shape. In the particular example illustrated, each of the segments  188  as a non-circular cross-sectional shape which corresponds to a cross-sectional shape of the opening through main selector  182 . In the example illustrated, each segment  188  has a generally “+” shaped cross-section. As a result, a segment  188  extends below a larger portion of selector  182  to provide enhanced retention of selector  182  such that weights  130  are better connected to stem  180 . In other embodiments, segment  188  may have other cross-sectional shapes. 
   Each segment  188  further has a height or thickness substantially equal to a height or thickness of an individual weight  130  extending horizontally across from the particular segment  188 . As a result, the gaps  192  provided by spacers  190  are in substantial vertical alignment (horizontally across from) void  170  between weights  130 . In the particular example illustrated in which each weight  130  has substantially the same thickness, each of segments  188  also has substantially the same thickness. In other embodiments in which different weights  130  may have different thicknesses, segment  188  may also have different thicknesses so long as each segment  188  has a thickness with substantially equal to the thickness of the particular weight  130  horizontally across from the particular segment  188 . 
   Spacers  190  comprise portions of stem  180  which extend between segments  188  to separate segments  188 . Spacers  190  each have a height such that a portion of selector  182  may be captured or received between consecutive segments  188 . Each spacer  190  is configured to support and overlying segment  188  such as a top of the segment is substantially horizontally coplanar or coextensive with before of a corresponding void  170  (shown in  FIG. 2 ). According to one embodiment, spacers  190  each have a height substantially equal to a height of a corresponding void  170  (shown in  FIG. 2 ). In the particular example illustrated, each spacer  190  has a height substantially equal to a height of rim  174  of spacer  132  (shown in  FIG. 4 ). Spacers  190  permit selector  182  to rotate between the first and second angular positions. Spacers  190  each have a cross-sectional shape dimension smaller than a cross-sectional shape of segments  188 . 
   In the particular example illustrated, each spacer  190  has a circular cross-sectional shape, facilitating easier rotation of selector  182  when between consecutive segments  188 . In other embodiments, spacers  190  may have other cross-sectional shapes. In the example illustrated, each spacer is integrally formed as a single unitary body with other spacers  190  and with segments  188 . In other embodiments, one or more of spacers  190  or one or more of segments  188  may be independent or distinct structures connected to one another, stacked upon one another or connected to a third supporting structure, such as a support shaft, rod or bar. 
   Selector  182  comprises a mechanism configured to be moved along and at least partially within channel  167  between one of a plurality of multiple selectable positions across from a selected void  170  and to be moved from a withdrawn position to an inserted position in which selector  182  extends between the void and is axially retained relative to stem  180 . As a result, when weight lift  135  exerts a lifting force upon stem  180  to lift stem  180 , selector  182  and any overlying weights  130  are also lifted. In the particular example illustrated, selector  182  is configured to rotate between the inserted position and the withdrawn position. 
   As shown by  FIG. 3 , selector  182  includes housing  200 , bearings  202 , engagement plate  204 , handle  206 , and alignment indicator  208 . Housing  200  comprises a structure configured to house bearings  202  which facilitate sliding movement of selector  182  along stem  180 . In the particular example illustrated, bearings  202  comprise J-Series sleeve bushings contained within housing  200 . Such an embodiment, housing  200  has an internal cylindrical cavity for receiving such bushings. 
   Engagement plate  204  comprises a structure secured to housing  200  which includes engagement projections  210  and opening  212 . In one embodiment, engagement plate  204  is bonded, welded, fastened or otherwise secured to housing  200 . In yet another embodiment, plate  204  is integrally formed as part of a single unitary body with housing  200 . 
   Engagement projections  210  comprise outwardly extending projections having a thickness or height and a length so as to be insertable within voids  170 . In the particular example illustrated, engagement projections  210  comprise outwardly projecting tabs angularly spaced from one another by approximately 180 degrees. As a result, rotation of selector  182  about stem  180  in either direction positions at least one of projections  210  within a corresponding void  170 . In other embodiments, selector  182  may have a single engagement projection  210  or may include greater than one engagement projections  210 . In other embodiments, projections  210  may have other shapes as well. 
   Opening  212  comprises a non-circular opening through plate  204  and in at least partial alignment with the opening or bore within housing  200  and through bearings  202 . Opening  212  is configured such that when selector  182  is in a first angular position or orientation, opening  212  permits stem  180  to pass therethrough, permitting selector  182  to be moved or slid along stem  180 . Opening  212  is further configured such that when selector  182  is in a second angular position or orientation, plate  204  is captured between consecutive segments  188  such a selector  182  is retained along stem  180 . In the particular example illustrated, opening  212  has a shape corresponding to the cross-sectional shape of segments  188 . In the particular example illustrated, opening  212  has a “+” shape. In other embodiments, open  212  may have different shapes and may have shapes distinct from the shape of segments  188 . 
   Handle  206  comprises an extension extending from a first location proximate to housing  200  opening  212  within selector apertures  164  of weights and through access channels  166  of weights  130 . Handle  206  is configured to be manually grasped by a person, permitting a person to rotate opening  212  between the first angular position which opening  212  is in alignment with segments  188  of stem  180  and a second angular position in which opening  212  is out of alignment with segments  188  of stem  180 . Handle  206  further permits a person to manually raise or lower selector  182  along channel  167  when opening  212  has been rotated into alignment with segments  188 . In the particular example illustrated, substantial portion of handle  206  are integrally formed as part of a single unitary body with plate  204 , reducing fabrication and assembly costs. In other embodiments, handle  206  makes and from housing  200  and may have other shapes and configurations. In still other embodiments, handle  206  may be coupled to a powered actuator configured to selectively rotate handle  206  and opening  212  between the first and second angular positions. In one embodiment, exercise device  120  may include a remote control, such as a wired or wireless remote control, for controlling the actuator and for remotely controlling selector  182 . 
   Alignment indicator  208  comprises a mechanism configured to indicate to a person when engagement projections  210  are in alignment with (horizontally across from) one of voids  170 . In the example illustrated, alignment indicator  208  comprises a structure that is resiliently biased in an outward direction from selector  182  into contact with surfaces of weights  130 . Alignment indicator  208  extends into an opposite one of voids  171  across from one of voids  170 . As selector  182  is raised or lowered and indicator  208  is moved from one of voids  170  to another one of voids  170 , alignment indicator  208  resiliently compresses, flexes or otherwise deforms. Alignment indicator  208  provides a clicking sound or a resistance feeling to indicate to a person when selector  182  is in alignment with a selected one of voids  170 . 
   In the particular example illustrated, alignment indicator  208  utilizes a resiliently biased ball. Alignment indicator  208  includes ball detent housing  216  and ball detent  218 . Ball detent housing is welded, bonded, fastened otherwise adhered to housing  200  and receives ball detent  218 . In the example illustrated, ball detent  218  comprises a ½-13 threaded spring ball detent commercially available from McMaster Carr. In other embodiments, alignment indicator  208  may comprise other resiliently biased surfaces. In other embodiments, alignment indicator  28  may be omitted. 
     FIGS. 7-10  illustrate operation of main weight selection system  134 .  FIG. 7  illustrates selector  182  in the aligned angular position in which opening  212  is sufficiently aligned with segments  188  such that selector  182  may be moved vertically through and along channel  167  to vertically position selector  182  across from one of voids  170 .  FIG. 7  illustrates selector  182  initially positioned towards an upper one of weights  130 . 
     FIG. 8  illustrates use of alignment indicator  208  in more detail. As shown by  FIG. 7 , ball detent  218  includes tapered perimeter portions  220  and outwardly projecting resiliently biased ball  222 . In the particular example illustrated, ball  222  rotates between a disengaged position which ball  222  is out of engagement with weights  130  (as shown in  FIG. 8 ) and an engaged position in which ball  222  engages edges of weights  130 . To receive an indication as to when selector  182  is appropriately aligned with one of voids  170 , a person rotates selector  182  to position ball  222  in the engage position. As a result, as selector  182  is raised and lowered, ball  222  alternately projects into a void  170  or is compressed by an intermediate weight  130 . This results in the person receiving either an audible or a tactile sensation indicating when selector  182  is in alignment with one of voids  170  and may be further rotated to a position in which projection  210  may be inserted into one of voids  170 . 
     FIGS. 9 and 10  illustrate selector  182  repositioned to just below a lower most one of weights  130 . As shown by  FIG. 9 , selector  182  is rotated to an annular position such that engagement projections  210  extend below a face of an overlying weight  130 . As shown by  FIG. 10 , this rotation of selector  182  also results in opening  212  being rotated to a misaligned position with respect to segments  188  of stem  180 . As a result, selector  182  is axially retained relative to stem  180 . Thereafter, any lifting of stem  180  by weight lift  135  also results in selector  182  and any overlying weights  130  also being raised or lifted. To select a different total weight amount, a person (1) simply rotates selector  182  back to the aligned position (shown in  FIG. 10A ) and slides selector  182  along channel  167  to position selector  182  across from a selected one of voids  170  and below a selected one of weights  130  and (2) rotates selector  182  to the misaligned angular orientation (shown in  FIG. 10B ). Thus, weight selection is simplified. 
   Weight lift  135  couples weight selection system  134  and incremental weights selection system  138  to cable system  24  (shown in  FIG. 1 ). Weight lift  135  includes bar  235 , cable attachment  237 , fastener  238  (shown in  FIG. 3 ) and cable  239  (shown in  FIG. 2 ). Bar  235  extends through incremental weight selection system  138  and is fixedly coupled to top  157 . Cable attachment  237  is secured to bar  235  by fastener  238 . In other embodiments, weight selection system  134  may be connected to cable system  24  in other manners. 
     FIG. 10  illustrates incremental weights  136  in more detail. As shown by  FIG. 10 , incremental weights  136  comprise elongate rods having a predetermined weight. According to one embodiment, weights  136  have individual weight amounts which are distinct from the individual weight amounts of weights  130 . In one embodiment, weights  130  each have a weight of 15 pounds while both incremental weights  136 A and  136 B have a weight of 5 pounds. In one embodiment, weight  136 A may have an incremental weight amount one-half that of weights  130  and weight  136 B may have an incremental weight amount one-quarter that of weights  130 . For example, in one embodiment, each of weights  130  weighs 10 pounds while incremental weights  136 A and  136 B weigh 5 pounds and 2.5 pounds, respectively. In still other embodiments, weights  136  may have other weight increments distinct from weights  130 . 
   Incremental weights  136  extend through openings  162  (shown in  FIG. 4 ) in weights  130  so as to extend vertically across multiple weights  130 . This results in several advantages. First, weights  136  do not substantially increase the height, width or length of weights system  122 . Second, incremental weights  36  are more closely positioned relative to a center of mass of the weight stack, reducing tipping moments of the stack which could otherwise cause friction with the guide rods  128  or other structures that guide movement of the stack. Third, weights  136  remain partially hidden for a cleaner more compact appearance. As for further shown by  FIG. 10 , weights  136  and a lower end received within bores  156  of the dock  148  and upper ends which include grooves or channels  230  configured to receive portions of incremental weight selection system  138 . 
     FIGS. 3 and 11  illustrate incremental weight selection system  138 . Incremental weight selection system  138  is configured to enable a person to select one or both of weights  136  for addition to the total amount of weight largely determined by main weights  130 . As shown by  FIG. 3 , system  138  includes top  240 , selector  242  and position indicator  244 . Top  240  is mounted to top plate  157  by fasteners  248  so as to capture selector  242  between top  247  and top plate  157 . Top  240  further supports portions of position indicator  244 . Although illustrated as being circular, top  240  man various shapes and configurations. 
   Selector  242  comprises a member configured to be rotated about a central axis of stem  180  so as to selectively engage incremental weights  136 . Selector  242  includes plate  252  and handle  254 . Plate  252  serves as a body for selector  242 . Plate  252  includes slot  258 , catch  260  and catch  262 . Slot  258  comprises an elongate arcuate opening through plate  252  configured to receive fastener  248 . Slot  258  guides rotation of selector  242  about the axis of stem  180 . 
   Catches  260  and  262  comprise generally horizontal hooks or notches formed in plate  252  that are configured to receive upper portions of weights  136  such that portions of plate  252  extend about weights  136  within grooves  230 . Catches  260  and  262  are angularly located with respect to one another such that: (1) selector  242  may be rotated to a first angular position (shown in  FIGS. 11 and 11A ) such that neither catch  260  nor catch  262  is in engagement with incremental weights  136 , (2) selector  242  may be rotated a first angular extent to a second angular position such that catch  260  receives and engages incremental weight  136 A while catch  260  remains disengaged from incremental weight  136 B (shown in  FIG. 11B ) and (3) selector  242  may be rotated a second greater angular extent to a third angular position such that both catch  260  and  262  engage incremental weights  136 A and  136 B, respectively (shown in  FIG. 11C ). By engaging an incremental weights  136 , selector  242  couples incremental weights  136  to top  157 , stem  180  and weight lift  135  to add the weight of one or both of incremental weights  136  to the total weight being lifted. 
   Position indicator  244  provides an audible or tactile feedback to a person indicating the angular positioning of selector  242 . As shown by  FIG. 11 , position indicator  244  includes detents  270 A,  270 B and  270 C (collectively referred to as detents  270 ), ball detent boss or housing  272  and ball detent  274 . Detents  270  comprise depressions or holes formed in plate  252  of selector  242 . Detents  270  correspond to distinct angular positions of selector  242  and cooperate with ball detents  274  to indicate the angular positioning of selector  242 . 
   Ball detent housing  272  is supported by top  240  and houses ball detent  274 . Ball detent  274  comprises a resiliently biased ball configured to be partially received within one of detents  270 . In particular, when the ball of ball detent  274  is within detents  270 A, selector  242  is in a first angular position in which neither of weights  136  is engaged by catches  260 ,  262 . When the ball of ball detent  274  is within detent  270 B, selector  242  is in the second angular position in which catch  260  is in lifting engagement with incremental weight  136 A and catch  262  is out of lifting engagement with incremental weight  136 B. When the ball of ball detent  274  is within detent  270 C, selector  242  is in the third angular position in which catches  260  and  262  are both in lifting engagement with incremental weights  136 A and  136 B, respectively. In other embodiments, other risen only biased judges beside a ball, such as a leaf spring and the like may be employed to resiliently engage one of detents  270  to indicate an angular positioning of selector  242 . In yet other embodiments, position indicator  244  may be omitted. 
     FIG. 11D  illustrates a selected number of weights  157  being lifted while selector  242  is in the third angular position (also shown in  FIG. 11C ) in which both of incremental weights  136  are coupled to weight lift  135 . As shown by  FIG. 11D , during such lifting, both of weights  136  are pulled and lifted through openings  162 . As a result, the weight of incremental weights  136  is added to the total weight being lifted. As noted above, in other embodiments, selector  242  may alternatively be positioned at the second angular position in which only incremental weight  136 A is couple weight lift  135  or the first angular position in which neither of incremental weights  136  is coupled to weight lift  135 . 
   Although incremental weight selection system  138  is illustrated as including two catches  260  and  262  for engaging two incremental weights  136 , in other embodiments, weight system  122  may be provided with a greater or fewer of such incremental weights  136 . Likewise, incremental weight selection system  138  may be configured to selectively engage a greater or fewer of such incremental weights, wherein selector  242  may include additional catches and may have additional or fewer angular positions where different sets of incremental weights are engaged. In yet other embodiments, incremental weights  136  and incremental weight selection system  138  may be omitted or may have other configurations. 
   Although weight system  122  has been illustrated and described as utilizing selector  182  which is generally not removal from stem  180  by a person using weight system  122 , in other embodiments, weight system  122  may include other mechanisms for selecting one or more of weights  130 . For example, in one embodiment, selector  182  may be omitted and replaced with an alternative removable selector that is insertable through channel  167  into retaining engagement with stem  180  while being inserted in a selected one of voids  170 . 
     FIGS. 12 and 13  illustrate exercise device  320 , another embodiment of exercise device  20  (shown in  FIG. 1 ). Like device  20 , device  320  also includes cable system  24  and exercise interface  26  (both of which are shown and described with respect to device  20 ). Unlike device  20 , device  320  includes weight system  322 , a specific embodiment of weight system  22 . Weight system  322  is similar to weight system  122  except that weight system  322  includes of alignment indicator  308  in place of align indicator  208  (described and illustrated above with respect to  FIG. 8 ). Like alignment indicator  208 , alignment indicator  308  comprises a mechanism configured to indicate to a person when engagement projections  210  are in alignment with (horizontally across from) one of voids  170 . In the example illustrated, alignment indicator  308  comprises a structure that is resiliently biased in an outward direction from selector  182  into contact with one of spacers  190  along stem  180 . Alignment indicator  308  extends into an opposite one of spacers  190  across from one of spacers  190 . As selector  182  is raised or lowered and indicator  308  is moved from one of voids  170  to another void  170 , alignment indicator  308  resiliently compresses, flexes or otherwise deforms. Alignment indicator  308  provides a clicking sound or a resistance feeling to indicate to a person when selector  182  is in alignment with a selected one of voids  170 . 
   As shown by  FIG. 13 , alignment indicator  308  utilizes a resiliently biased ball  322 . Alignment indicator  308  includes ball detent housing  316  and ball detent  318 . Ball detent housing is welded, bonded, fastened otherwise adhered to housing  200  and receives ball detent  318 . In the example illustrated, ball detent  318  comprises a ½-13 threaded spring ball detent commercially available from McMaster Carr. In other embodiments, alignment indicator  308  may comprise other resiliently biased surfaces. In other embodiments, alignment indicator  308  may be omitted. 
   Those remaining components of exercise device  320  which correspond to exercise device  120  are numbered similarly. Like exercise device  120 , exercise device  320  provides a relatively low-cost arrangement of components which enables a person to quickly and easily select a desired amount of weight for an exercise routine. 
     FIG. 14  illustrates weight system  422 . Weight system  422  is similar to weight system  122  except that system  422  includes selector  434  (shown in  FIG. 12 ) in lieu of selector  182 . The remaining components of system  422  are shown in  FIGS. 2-11 . Selector  434  is configured to be inserted across and within a selected one of voids  170  and into retaining engagement with stem  180  (shown in  FIG. 5 ). Selector  434  includes prongs  436 ,  438  and handle  440 . Prongs  436 ,  438  comprise tongs or projections separated by an intermediate opening or slot  442 . Prongs  436 ,  438  have a thickness such that prongs  436  and  438  may be received within a void  170  between consecutive weights  130  (shown in  FIG. 2 ). At the same time, opening  442  is configured to extend about one of spacers  190  between consecutive segments  188  of stem  180  (shown in  FIG. 6 ). As a result, selector  434  may be inserted into a selected void  170  and into retaining engaging with stem  180  such that lifting of stem  180  also lifts those weights  130  above a selected void  170 . 
   Handle  440  comprises an extension extending from a thin plate providing prongs  436  and  438 . Handle  430  is configured to extend from prongs  436 ,  438  through and beyond channel  167 . Handle  430  permits a person to insert or withdraw selector  434  in a desired position along the stack of weights  130 . In other embodiments, selector  434  may have other configurations. 
     FIGS. 15-20  illustrate exercise device  520 , another embodiment of exercise device  20  (shown in  FIG. 1 ). Like device  20 , device  520  also includes cable system  24  and exercise interface  26  (both of which are shown and described with respect to device  20 ). Unlike device  20 , device  520  includes weight system  522 , a specific embodiment of weight system  22 . Weight system  522  is similar to weight system  122  in that weight system  522  includes base  126 , upper guide  127 , guide rods  128  and weight lift  135 , each of which is shown and described above with respect to weight system  122 . Unlike weight system  122 , weight system  522  includes weights  530  and the main weight selection system  534  in place of weights  130  and main weight selection system  534 . 
   Weights  530  comprise structures having predetermined weight amounts which are configured to be lifted and to provide a mechanical resistance in an exercise. In the particular example illustrated, weights  530  each comprise a solid or hollow plate of one or more metals. In other embodiments, weights  530  may comprise other materials or may comprise encapsulated materials, such as sand, water or other materials. 
   Weights  530  are stacked upon one another such that as a particular weight  530  is being lifted, other weights  530  stacked upon the particular weight  530  are also lifted.  FIG. 15  illustrates three consecutively stacked weights  530  with the uppermost weight  530  shown being transparent for purposes of illustration. As shown by  FIG. 15 , each weight  530  includes guide rod openings  560 , stem openings  562 , selector aperture  564 , access channel  566  and void  570 . Guide rod openings  560  comprise bores passages extending through each weight  530 . Openings  560  of weights  530  are further configured to align with one another when weights  530  are stacked upon one another. Openings  560  are configured to receive guide rods  128 . Stem opening  562  comprises a generally centrally located opening through weight  530  configured to slidably receive a stem  580  of weights selection system  534 . 
   Selector aperture  564  comprises an opening extending from opening  562  through weight  530  and configured to receive portions of main weight selection system  534 . Selector apertures  564  are configured to be aligned with one another when weights  530  are stacked upon one another. As will be described in more detail hereafter, apertures  564  are configured such that when a portion weight selection system  534  is aligned with or contained within apertures  564 , that portion of the weight selection system  534  may move through aperture  564  along and across weights  530 . When that portion of weight selection system  534  is moved at least partially out of apertures  564 , that portion of weight selection system  534  extends into a void formed between consecutive weights  530  such that all weights  530  overlying that portion of weight selection system  534  may be lifted. 
   Access channel  566  comprises an opening or passage extending from a perimeter or edge of each weight  530  inwardly to selector aperture  564 . Access channel  566  extends generally perpendicular to a longitudinal axis along which weights  530  are stacked and along which each of openings  560  extend or are aligned. Access channel  566  is configured to permit portions of main weight selection system  534  to project from selector aperture  564  to a location in front of weights  534  for access and manipulation by a person. Access channels  566  are aligned with one another, permitting a person to grasp portions of main weight selection system  534  and to move main weight selection system  534  vertically upward and downward through and along a continuous vertical channel  567  formed by the individual access channels  566 . As a result, access channel  566  permits a person to move main weight selection system  534  to one of a plurality of available positions along the stack of weights  530  to select a total number of weights  530  or a total weight amount to be lifted. 
   Void  570  comprises a cavity, depression, recess or other opening configured to receive selector  582  (described below) of main weight selection system  534  when selector  582  is positioned into coupling engagement with stem  580  (described below) of system  534 . In the example illustrated, void  570  is formed upon an underside of each weight  530  adjacent to selector a picture  564  and adjacent to stem  580  of the system  534 . In the example illustrated, void  570  extends on opposite sides of stem  580  facilitating engagement with opposite side of stem  580  by selector  582 . In the example illustrated, void  570  is generally rectangular. In other embodiments, void  570  may alternatively be formed on an upper side of each weight  530 , may extend adjacent to stem  580  by different extents and may have other shapes. Although void  570  is illustrated as a single continuous void, in other embodiments, void  570  may include distinct spaced portions which receive portions of selector  582 . Although void  570  is integrally formed as part of weight  530 , reducing the number of parts and simplifying system  522 , in other embodiments, void  570  may alternatively be formed by spacers position between and spacing opposite surface of consecutive weights  530 . 
   Main weight selection system  534  comprises a mechanism configured to permit a person to select one or more of weights  530  for lifting during an exercise. Main weight selection system  534  includes selector stem  580  and main selector  182 . Selector stem  580  comprises an elongate shaft, bar, rod or other structure coupled to weight lift  135  and movably positioned within selector apertures  564  of weights  530  such that stem  580  may be raised or lowered by weight lift  535 . In the particular example illustrated, stem  580  is coupled to weight lift  135 . Stem  580  extends along an axis  583  and is configured to slidably support main selector  582  along an axis  583 . Selector stem  580  is configured such that selector  582  may be retained relative to stem  580  at a selected one on a plurality of positions along an axis  583  such that selector  582 , and any engaged weights  530 , will move with movement of stem  580  by weight lift  135 . 
   As shown by  FIG. 15 , stem  580  includes a tapered end portion  586  and a multitude of segments  588  joined and spaced apart from one another by spacers  590 . End portion  586  is configured to be removably received within bore  154  (shown in  FIG. 2 ). End portion  586  generally tapers towards a point along axis  583 . In one embodiment, end portion  586  is at least partially conical. Because end portion  586  is tapered, end portion  586  self centers and aligns itself as it is being lowered into bore  154 . Because end portion  586  aligns itself into bore  154 , other structures or mechanisms otherwise used to provide and precise control over positioning of stem  580  when it is withdrawn from bore  154  when weights  530  are being lifted may be omitted or may be provided with greater tolerances, potentially reducing friction and drag as weights  530  are being lifted to provide a smoother feel. In addition, because end portion  186  aligns itself into bore  154 , part tolerances may be increased, reducing cost. For example, because end portion  586  is tapered and self aligning, guide rods  128  do not necessarily have to maintain precise positional control over stem  580  or both portions at the top of weight system  522  connected to stem  580 . As a result, the spacing or gap between guide rods  128  and bushings at an upper end of weight system  522  may be increased, reducing friction providing a smoother lifting of weights  530 . In other embodiments, tapered end portion  186  may be semi-bulbous or semi-spherical in shape, may be flat or may be omitted. 
   Segments  588  and spacers  590  alternately extend along axis  583 . Each segment  588  is shaped such that selector  182  may be vertically moved along to stem  580 . An example illustrated, stem  580  has a circular cross-section reducing fabrication cost and complexity. In other embodiments, stem  580  may have other cross-sections. 
   Each segment  588  further has a height or thickness substantially equal to a height or thickness of an individual weight  530  extending horizontally across from the particular segment  588 . As a result, the gaps  592  provided by spacers  590  are in substantial vertical alignment (horizontally across from) void  570  between weights  530 . In the particular example illustrated in which each weight  530  has substantially the same thickness, each of segments  588  also has substantially the same thickness. In other embodiments in which different weights  530  may have different thicknesses, segment  588  may also have different thicknesses so long as each segment  588  has a thickness with substantially equal to the thickness of the particular weight  530  horizontally across from the particular segment  588 . 
   Spacers  590  comprise portions of stem  580  which extend between segments  588  to separate segments  588 . Spacers  590  each have a height such that a portion of selector  582  may be captured or received between consecutive segments  588 . Each spacer  590  is configured to support and overlying segment  588  such as a top of the segment is substantially horizontally coplanar or coextensive with before of a corresponding void  570  (shown in  FIG. 16 ). According to one embodiment, spacers  590  each have a height substantially equal to a height of a corresponding void  570  (shown in  FIG. 16 ). Spacers  590  permit selector  582  to slide between the first and second positions. Spacers  590  each have a cross-sectional shape dimension smaller than a cross-sectional shape of segments  588 . 
   Selector  582  comprises a mechanism configured to be moved along and at least partially within channel  567  between one of a plurality of multiple selectable positions across from a selected void  570  and to be moved from a withdrawn position to an inserted position in which selector  582  extends between the void and is axially retained relative to stem  580 . As a result, when weight lift  135  exerts a lifting force upon stem  580  to lift stem  580 , selector  582  and any overlying weights  530  are also lifted. In the particular example illustrated, selector  582  is configured to rotate between the inserted position and the withdrawn position. 
   As shown by  FIG. 17 , selector  582  includes support  600  and fork  602 . Support  600  comprises a structure configured to slide along stem  580  along axis  583  while slidably supporting fork  602  for movement in a direction perpendicular to axis  583 . As shown in  FIGS. 19 and 20 , support  600  includes a sleeve  606  and a platform  608 . Sleeve  600  receives stem  580  and extends about stem  580  so as to slide along stem  580 . In one embodiment, sleeve  606  may additionally include internal bearing structures (not shown) that further facilitate slighting movement of sleeve  600  along stem  580 . 
   Platform  608  projects from sleeve  606  and underlies fork  604  across aligned openings  567 . Platform  608  provides a base or deck movably supporting and guiding movement of fork  604  substantial perpendicular to axis  583  and stem  580 . Although platform  608  is illustrated as underlying fork  604 , in other embodiments, platform  604  may alternatively extend over or at least partially contain fork  604 . 
   Fork  604  comprises a structure actuatable or movable along an axis substantially perpendicular to axis  583  between a disengaged position shown in  FIGS. 16 and 17  and a disengaged position shown in  FIGS. 18 and 19 . Fork  604  includes prongs  636 ,  638  and handle  640 . Prongs  636 ,  638  comprise tongs or projections separated by an intermediate opening or slot  642 . Prongs  636 ,  638  have a thickness such that prongs  636  and  638  may be received within a void  570  between consecutive weights  530  (shown in  FIG. 15 ). At the same time, opening  642  is configured to extend about one of spacers  590  between consecutive segments  588  of stem  580  (shown in  FIG. 17 ). As a result, selector  582  may be inserted into a selected void  570  and into retaining engaging with stem  580  such that lifting of stem  580  also lifts those weights  530  above a selected void  570 . 
   Handle  540  comprises an extension extending from prongs  536  and  538 . Handle  530  is configured to extend from prongs  536 ,  538  through and beyond channel  567  (shown in  FIG. 15 ). Handle  530  permits a person to insert or withdraw selector  582  in a desired position along the stack of weights  530 . In other embodiments, selector  582  may have other configurations. 
   In the example illustrated, fork  604  is movably coupled to platform  608  by means of slot  650  and one or more projections  652 . Slot  650  comprises an elongate slot extending along an axis substantially perpendicular to axis  580  in a horizontal plane. Slot  650  receives projections  652 . 
   Projections  652  to comprise structures extending from platform  608  through slot  650 . Projections  652  are configured to slide within slot  650  as fork  604  is moved between the engaged and disengaged positions. Projections  652  cooperate with slot  652  guide movement of fork  604 . 
   In the example illustrated, projections  652  have heads  656  (shown in  FIG. 17 ) which are larger than or wider than slot  650  so as to capture fork  604  and retain fork  604  with respect to platform  608 . According one embodiment, projections  652  comprise fasteners such as screws, bolts or rivets secured to platform  608  and extending through slot  650 . In other embodiments, projections  652  may be integrally formed with platform  608  or of other structures. In still other embodiments, other arrangements may be used to guide movement of fork  604  and retained fork  604  with respect to platform  608 . For example, in another embodiment, platform  608  may include a slot, channel or groove while fork  604  includes a projection received within the slot, channel or groove. 
     FIGS. 16-19  illustrate actuation of fork  604  between the engaged in disengaged positions.  FIGS. 16 and 17  illustrate fork  604  in the disengaged position in which fork  604  has been moved in the direction indicated by arrow  660  to withdraw prongs  636 ,  638  from void  570  and to withdraw stem  580  from opening  642 . As a result, selector  582  may be slid within aligned channels  567  and along stem  580  to position fork  604  across from a desired one of gaps  592  and across from one of spacers  590  which correspond to desired number of overlying weights  530  intended to be lifted. 
   As shown by  FIGS. 18 and 19 , once selector  582  has been moved within and a long openings  564  to a desired position adjacent to and below a desired weight  530 , fork  604  may be moved in a direction perpendicular to axis  583  in a direction indicated by arrow  662  from the disengaged position to the engaged position shown. As a result, opening  642  receives one of spacers  590 . Prongs  636 ,  638  are at least partially received within gap  592  and concurrently project into void  570  connecting the weight  530  providing void  572  stem  580 . 
   As shown by  FIG. 20 , subsequent lifting of stem  580  by pulling upon lift  135  (shown in  FIG. 2 ) results in selector  582  and overlying weights  530  also being lifted. During such lifting in the direction indicated by arrow  668 , sleeve  606  is withdrawn from stem openings  562 . To select a different number of weights  530 , the person simply lowers the currently lifted weights to their at rest position in which the weights rest upon one another and repeats the process shown in  FIGS. 16-19 . Overall, main weight selection system  534  facilitates fast and relatively simple selection of weights with a single hand and without complete separation of selector  582  from weights  530  which could otherwise potentially result in selector  582  becoming lost or misplaced. 
   Although not shown for ease of illustration and discussion, in other embodiments, main weight selection system  534  may include other features noted above. For example, system  534  may additionally include an alignment indicator such as either alignment indicator  208  (shown in  FIG. 8  or a lineman indicator  308  (shown in  FIG. 13 ). With alignment indicator  208 , sleeve  606  or platform  608  would include a resiliently biased projection configured to project between adjacent weights  530  for us to provide a tactile or audible signal as selector  582  is moved across weights  530 . With alignment indicator  308 , sleeve  600  would include a resiliently biased projection configured to engage gaps  592  as selector  582  is moved along stem  580 . Such an alignment indicator  308  would also provide an audible or tactile (feel) signal indicating movement of selector  582  across weights  530  and between different positions aligned with respect to weights  530  and voids  570 . 
   Although exercise device  520  is illustrated as including weights  530 , in other embodiments, weights  530  may additionally be configured to facilitate the additional use of incremental weights  136  and incremental weight selection system  138  described above. In such an embodiment, weights  530  would additionally include openings  162  as shown in  FIG. 4 . In other embodiments, exercise device  520  may be configured to be utilized with other incremental weight selection systems and other incremental weights. In other embodiments, selector  582  and weights  530  may have other configurations. 
     FIGS. 21-23  illustrate exercise device  1020 , another embodiment of exercise device  20  (shown in  FIG. 1 ). Like device  20 , device  1020  also includes cable system  24  and exercise interface  26  (both of which are shown and described with respect to device  20 ). Unlike device  20 , device  520  includes weight system  1022 , a specific embodiment of weight system  22 . Weight system  1022  is similar to weight system  1022  in that weight system  1022  includes base  126 , upper guide  127 , guide rods  128  and weight lift  135 , each of which is shown and described above with respect to weight system  122 . Unlike weight system  122 , weight system  522  includes weights  1030  and the main weight selection system  1034  in place of weights  130  and main weight selection system  534 . 
   Weights  1030  comprise structures having predetermined weight amounts which are configured to be lifted and to provide a mechanical resistance in an exercise. In the particular example illustrated, weights  1030  each comprise a solid or hollow plate of one or more metals. In other embodiments, weights  1030  may comprise other materials or may comprise encapsulated materials, such as sand, water or other materials. 
   Weights  1030  are stacked upon one another such that as a particular weight  1030  is being lifted, other weights  1030  stacked upon the particular weight  1030  are also lifted.  FIG. 21  illustrates three consecutively stacked weights  1030 . As shown by  FIG. 21 , each of weights  1030  includes guide rod openings  160  (shown and described with respect to  FIG. 4 ), stem opening  1062  and access channel  1066 . Stem opening  1062  comprises a generally centrally located opening through weight  5100  configured to slidably receive a stem  1080  of weights selection system  1034 . 
   Access channel  1066  comprises an opening or passage extending from a perimeter or edge of each weight  1030  inwardly to stem opening  160 . Access channel  1066  extends generally perpendicular to a longitudinal axis along which weights  1030  stacked and along stem opening  160  which each of openings  160  (shown in  FIG. 4 ) extend or are aligned. Access channel  1066  is configured to permit portions of main weight selection system  1034  (selector  1082 ) to project to a location in front of weights  1030  for access and manipulation by a person. Access channels  566  further permit movement of portions of main weight selection system  1034 . In the example illustrated, each channel  1066  is formed upon an underside of each weight  1030  adjacent to opening  1062  and adjacent to stem  1080  of the system  1034 . 
   Main weight selection system  1034  comprises a mechanism configured to permit a person to select one or more of weights  1030  for lifting during an exercise. Main weight selection system  1034  includes selector stem  1080  and main selector  1082 . Selector stem  1080  comprises an elongate shaft, bar, rod or other structure coupled to weight lift  135  (shown in Figure) and movably positioned within stem openings  1062  of weights  1030  such that stem  1080  may be raised or lowered by weight lift  135 . Stem  1080  extends along an axis  1083  (shown in  FIG. 22 ) and is configured to slidably support main selector  1082  along an axis  1083 . Selector stem  1080  is configured such that selector  1082  may be retained relative to stem  1080  at a selected one on a plurality of positions along an axis  1083  such that selector  1082 , when engaging weights  1030 , will move with movement of stem  1080  by weight lift  135 . 
   As shown by  FIG. 21 , stem  1080  includes a multitude of segments  1088  joined and spaced apart from one another by spacers  1090 . Segments  1088  and spacers  1090  alternately extend along axis  1083 . Each segment  1088  is shaped such that selector  1082  may be rotated about axis  1083  between a first angular position in which selector  1082  may be moved or slid along axis  1083  without substantial interference from segments  1088  and a second angular position in which selector  1082  is retained between two consecutive segments  1088  along axis  1083 . In particular, segment  1088  has a cross-sectional shape configured such that each segment  1088  may pass through an opening in selector  1082  when selector  1082  is in a first angular position and is obstructed so as to not pass through the same opening in selector  1082  when selector  1082  is in the second angular position. In the example illustrated, each of the segments  1088  has a non-circular or non-annular cross-sectional shape. In the particular example illustrated, each of the segments  1088  has a non-circular cross-sectional shape which corresponds to a cross-sectional shape of the opening through main selector  1082 . In the example illustrated, each segment  1088  has a generally elongated cross-section, such as an oval or rectangle. In other embodiments, segment  188  may have other cross-sectional shapes. 
   Each segment  1088  further has a height or thickness substantially equal to a height or thickness of an individual weight  1030  extending horizontally across from the particular segment  1088 . As a result, selectors  1082  are maintained opposite to gaps  1092  when sandwiched between consecutive weights  1030 . In the particular example illustrated in which each weight  1030  has substantially the same thickness, each of segments  1088  also has substantially the same thickness. In other embodiments in which different weights  1030  may have different thicknesses, segments  1088  may also have different thicknesses so long as each segment  1088  has a thickness with substantially equal to the thickness of the particular weight  1030  horizontally across from the particular segment  1088 . 
   Spacers  1090  comprise portions of stem  1080  which extend between segments  1088  to separate segments  1088 . Spacers  1090  each have a height such that a portion of selector  1082  may be captured or received between consecutive segments  1088 . Each spacer  1090  is configured to support an overlying segment  1088  such as a top of the segment is substantially horizontally coplanar or coextensive with the top of an adjacent weight  1030 . According to one embodiment, spacers  1090  each have a height substantially equal to a height of a corresponding weight  1030 . 
   Selectors  1082  comprises mechanisms associated with each weight  1030  in configured to be rotated between a first position and which selector  1082  couples stem  1080  to the associated weight  1030  and a second position in which the associated weight  1030  is decoupled from stem  1080 . In the example illustrated, selector  1082  rotates or pivots about axis  1083 . Each of selectors  1082  includes an engagement plate  1204  and handle  1206 . 
   Opening  1212  comprises a non-circular opening through plate  1204 . Opening  1212  is configured such that when selector  1082  is in a first angular position or orientation shown in  FIG. 22 , opening  1212  permits stem  1080  to pass therethrough, permitting stem  1080  two removed through and along opening  1062 . Opening  1212  is further configured such that when selector  1082  is in a second angular position or orientation, plate  1204  is captured between consecutive segments  1088  such that selector  1082  is retained along stem  1080 . In the particular example illustrated, opening  1212  has a shape corresponding to the cross-sectional shape of segments  1088 . In the particular example illustrated, opening  1212  has an elongated shape, such as an oval or rectangle. In other embodiments, open  1212  may have different shapes and may have shapes distinct from the shape of segments  1088 . 
   Handle  1206  comprises an extension extending from a plate  1204  through access channels  1066  of weights  1030 . Handle  1206  is configured to be manually grasped by a person, permitting a person to rotate opening  1212  between the first angular position which opening  1212  is in alignment with segments  1088  of stem  1080  as shown in  FIG. 22  and a second angular position in which opening  1212  is out of alignment with segments  1088  of stem  1080  as shown in  FIG. 23 . 
   In the particular example illustrated, a substantial portion of handle  1206  is integrally formed as part of a single unitary body with plate  204 , reducing fabrication and assembly costs. In other embodiments, handle  1206  may have other shapes and configurations. In still other embodiments, handle  1206  may be coupled to a powered actuator configured to selectively rotate handle  1206  and opening  1212  between the first and second angular positions. In one embodiment, exercise device  1020  may include a remote control, such as a wired or wireless remote control, for controlling the actuator and for remotely controlling selector  1082 . 
     FIGS. 24 and 25  illustrate exercise device  1220 , another embodiment of exercise device  20  (shown in  FIG. 1 ). Like device  20 , device  1220  also includes cable system  24  and exercise interface  26  (both of which are shown and described with respect to device  20 ). Unlike device  20 , device  520  includes weight system  1222 , a specific embodiment of weight system  22 . Weight system  1222  is similar to weight system  122  in that weight system  1222  includes base  126 , upper guide  127 , guide rods  128  and weight lift  135 , each of which is shown and described above with respect to weight system  122 . Unlike weight system  122 , weight system  1022  includes weights  1230  and the main weight selection system  1234  in place of weights  1230  and main weight selection system  1234 , respectively. 
   Weights  1230  comprise structures having predetermined weight amounts which are configured to be lifted and to provide a mechanical resistance in an exercise. In the particular example illustrated, weights  1230  each comprise a solid or hollow plate of one or more metals. In other embodiments, weights  1230  may comprise other materials or may comprise encapsulated materials, such as sand, water or other materials. 
   Weights  1230  are stacked upon one another such that as a particular weight  1230  is being lifted, other weights  1230  stacked upon the particular weight  1230  are also lifted. Although not shown, each of weights  1230  includes guide rod openings  160  (shown and described with respect to  FIG. 4 ). In addition, each weight  1230  includes stem opening  1262  and access channel  1266 . Stem opening  1262  comprises a generally centrally located opening through weight  1230  configured to slidably receive a stem  1080  of weights selection system  1234 . 
   Access channel  1266  comprises an opening or passage extending from a perimeter or edge of each weight  1230  inwardly to stem opening  1262 . Access channel  1266  as an L-shaped configuration and extends generally perpendicular to a longitudinal axis along which weights  1230  stacked Access channel  1266  is configured to permit portions of main weight selection system  1234  (selector  1282 ) to project to a location in front of weights  1230  for access and manipulation by a person. Access channels  1266  further permit movement of portions of main weight selection system  1034 . In the example illustrated, each channel  1066  is formed upon an underside of each weight  1230  adjacent to opening  1262  and adjacent to stem  1280  of the system  1234 . In other embodiment, access channel  1266  may alternatively be formed on an upper side of an associated weight  1230  when selector  1282  is attached to the particular weight  1230 . 
   Main weight selection system  1234  comprises a mechanism configured to permit a person to select one or more of weights  1230  for lifting during an exercise. Main weight selection system  1234  includes selector stem  1080  (described above with respect to  FIGS. 21-23 ) and main selector  1282 . 
   Selectors  1282  comprises mechanisms associated with each weight  1230  and configured to be rotated or pivoted between a first position and which selector  1282  couples stem  1080  to the associated weight  1230  and a second position in which the associated weight  1230  is decoupled from stem  1080 . In the example illustrated, selector  1082  rotates or pivots about axis  1283 , an axis parallel to and spaced from axis  1083  of stem  1080 . In the example illustrated, each selector  1282  is pivotably pinned to an associated weight  1230  within access channel  1266 . Each of selectors  1282  includes an engagement plate  1304  and handle  1306 . 
   Engagement plate  1304  comprises a structure including a notch or opening  1312 . Opening  1312  is configured such that when selector  1282  is in a first angular position or orientation shown in  FIG. 24 , opening  1312  is withdrawn from stem  1080 , permitting stem  1080  to pass through the associated weight  1230  such that the associated weight  1230  is not coupled to stem  1080 . Opening  1312  is further configured such that when selector  1282  is in a second angular position or orientation shown in  FIG. 25 , plate  1304  is captured between consecutive segments  1288  such that selector  1282  is retained along stem  1080 . In the particular example illustrated, opening  1312  has a rectangular or U-shape. In other embodiments, opening  1312  may have other shapes. 
   Handle  1306  comprises an extension extending from a plate  1304  through access channels  1266  of weights  1230 . Handle  1306  is configured to be manually grasped by a person, permitting a person to rotate opening  1312  between the first angular position which opening  1312  at least partially receives stem  1080  as shown in  FIG. 24  and a second angular position in which opening  1312  is withdrawn from stem  1080  as shown in  FIG. 25 . 
   In the particular example illustrated, substantial portion of handle  1306  is integrally formed as part of a single unitary body with plate  1304 , reducing fabrication and assembly costs. In other embodiments, handle  1306  may have other shapes and configurations. In still other embodiments, handle  1306  may be coupled to a powered actuator configured to selectively rotate handle  1306  and opening  1312  between the first and second angular positions. In one embodiment, exercise device  1220  may include a remote control, such as a wired or wireless remote control, for controlling the actuator and for remotely controlling selector  1282 . 
   Although not shown for ease of illustration and discussion, in other embodiments, main weight selection systems  1034  and  1234  may include other features noted above. For example, system  534  may additionally include an alignment indicator such as either alignment indicator  208  (shown in  FIG. 8  or alignment indicator  308  (shown in  FIG. 13 ). With alignment indicator  208 , sleeve  606  or platform  608  would include a resiliently biased projection configured to project between adjacent weights  530  for us to provide a tactile or audible signal as selector  582  is moved across weights  530 . With alignment indicator  308 , sleeve  600  would include a resiliently biased projection configured to engage gaps  592  as selector  582  is moved along stem  580 . Such an alignment indicator  308  would also provide an audible or tactile (feel) signal indicating movement of selector  582  across weights  530  and between different positions aligned with respect to weights  530  and voids  570 . 
   Although exercise device  520  is illustrated as including weights  530 , in other embodiments, weights  530  may additionally be configured to facilitate the additional use of incremental weights  136  and incremental weight selection system  138  described above. In such an embodiment, weights  530  would additionally include openings  162  as shown in  FIG. 4 . In other embodiments, exercise device  520  may be configured to be utilized with other incremental weight selection systems and other incremental weights. In other embodiments, selector  582  and weights  530  may have other configurations. 
     FIGS. 26-29  illustrate exercise device  1420 , another embodiment of exercise device  20  (shown in  FIG. 1 ). Like device  20 , device  1420  also includes cable system  24  and exercise interface  26  (both of which are shown and described with respect to device  20 ). Unlike device  20 , device  120  includes weight system  1422 , a specific embodiment of weight system  22 .  FIG. 2  is a perspective view of exercise device  1420  and weight system  1422 . As will be described hereafter, weight system  1422  is a relatively low-cost arrangement of components which enables a person to quickly and easily select a desired amount of weight for an exercise routine. 
   Weight system  1422  generally includes base  1426 , upper guide  127  (described above with respect to system  120 ), guide rods  128  (described above with respect to device  120 ), weights  1430 , main weight selection system  1434 , weight lift  135  (described above with respect to system  120 ), incremental weights  1436 A,  1436 B (collectively referred to as incremental weights  1436 ) and incremental weight selection system  1438 . Base  1426  comprises an arrangement of components configured to serve as a foundation and support for weight system  1422 . Base  1426  includes foot  1442 , risers  1444  and docks  1448 . Foot  1442  supports risers  1444  and docks  1448 . Although foot  1442  is illustrated as a plate, in other embodiments, foot  1442  may have other configurations. 
   Risers  1444  comprise structures extending from foot  1442  that are configured to support guide rods  128 . Rises  1444  further engage a lower side of weights  1470  to elevate the stack of weights  1430 . 
   Docks  1448  comprises one or more members configured to remotely receive, support and guide portions incremental weights  1436 . Dock  1449  extends from foot  1442  and is configured to remove Lee receive a lower portion of stem  580  main weight selection system  1438 . Although docks  1448  and dock  1449  are illustrated as distinct tubular structures, in other embodiments, such docks may have other configurations. 
   Weights  1430  comprise structures having predetermined weight amounts which are configured to be lifted and to provide a mechanical resistance in an exercise. In the particular example illustrated, weights  1430  each comprise a solid or hollow plate of one or more metals. In other embodiments, weights  1430  may comprise other materials or may comprise encapsulated materials, such as sand, water or other materials. Weights  1430  are stacked upon one another such that as a particular weight  1430  is being lifted, other weights  1430  stacked upon the particular weight  1430  are also lifted. Weights  1430  are similar to weights  530  (shown in  FIG. 15 ). As shown by  FIG. 27A , each weight  1430  includes guide rod openings  560  (shown in  FIG. 15 ), incremental weight apertures  1462 , selector aperture  1464  and access channel  1466 . Guide rod openings  160  comprise bores passages extending through weight  1430 . Openings  1460  of weight  130  are further configured to align with one another when weights  1430  are stacked upon one another. Openings  160  are configured to receive guide rods  128 . 
   Incremental weight apertures  1462  comprise bores or openings through which incremental weights  1436  extend. Apertures  1462  are configured to be aligned with one another when weights  1430  are stacked upon one another. Incremental weight apertures  1462  generally direct upward or downward movement of the incremental weights  1436  when incremental weights  1436  are being lifted or lowered. 
   Although incremental weight apertures  1462  are illustrated as comprising distinct apertures, in other embodiments, such apertures  1462  may be connected to one another or may be in communication with selector aperture  1464 . In embodiments where weight system  1422  includes a greater or fewer of such incremental weights  1436 , each weight  1430  may also include a corresponding fewer or greater of such incremental weight apertures  1462 . In particular embodiments where incremental weights  1436  extend across multiple weights  1430  outside or beyond an outer perimeter of weights  1430 , incremental weight apertures  1462  may be omitted or may alternatively comprise an inwardly extending cut out along the perimeter of each weight  1430 . 
   Selector aperture  1464  comprises an opening extending from opening  1462  through weight  1430  and configured to receive portions of main weight selection system  1434 . Selector apertures  1464  are configured to be aligned with one another when weights  1430  are stacked upon one another. As will be described in more detail hereafter, apertures  1464  are configured such that when a portion weight selection system  1434  is aligned with or contained within apertures  1464 , that portion of the weight selection system  1434  may move through aperture  1464  along and across weights  1430 . When that portion of weight selection system  1434  is moved at least partially out of apertures  1464 , that portion of weight selection system  1434  extends into a void formed between consecutive weights  1430  such that all weights  1430  overlying that portion of weight selection system  1434  may be lifted. 
   Access channel  1466  comprises an opening or passage extending from a perimeter or edge of each weight  1430  inwardly to selector aperture  1464 . Access channel  1466  extends generally perpendicular to a longitudinal axis along which weights  1430  are stacked and along which each of openings  1460  extend or are aligned. Access channel  1466  is configured to permit portions of main weight selection system  1434  to project from selector aperture  1464  to a location in front of weights  1430  for access and manipulation by a person. Access channels  1466  are aligned with one another, permitting a person to grasp portions of main weight selection system  1434  and to move main weight selection system  1434  vertically upward and downward through and along a continuous vertical channel  1467  formed by the individual access channels  566 . As a result, access channel  1466  permits a person to move main weight selection system  1434  to one of a plurality of available positions along the stack of weights  1430  to select a total number of weights  1430  or a total weight amount to be lifted. 
   Void  1470  comprises a cavity, depression, recess or other opening configured to receive selector  1482  (described below) of main weight selection system  1434  when selector  1482  is positioned into coupling engagement with stem  580  (described below) of system  1434 . In the example illustrated, void  1470  is formed upon an underside of each weight  1430  below and overlying lip  1471  adjacent to selector aperture  1464  and adjacent to stem  580  of the system  534 . In the example illustrated, void  1470  extends on opposite sides of stem  580  facilitating engagement with opposite side of stem  580  by selector  1482 . In the example illustrated, void  1470  is generally rectangular. In other embodiments, void  1470  may alternatively be formed on an upper side of each weight  1430 , may extend adjacent to stem  580  by different extents and may have other shapes. Although void  1470  is illustrated as a single continuous void, in other embodiments, void  1470  may include distinct spaced portions which receive portions of selector  1482 . Although void  1470  is integrally formed as part of weight  1430 , reducing the number of parts and simplifying system  1422 , in other embodiments, void  1470  may alternatively be formed by spacers position between and spacing opposite surface of consecutive weights  1430 . 
   Main weight selection system  1434  comprises a mechanism configured to permit a person to select one or more of weights  1430  for lifting during an exercise. Main weight selection system  1434  includes selector stem  1480  and main selector  1482 . 
   Selector stem  1480  in substantially similar to selector stem  580 . As shown by  FIG. 26 , stem  1480  includes a multitude of segments  1488  joined and spaced apart from one another by spacers  1490 . 
   Segments  1488  and spacers  1490  alternately extend along axis  483 . Each segment  1488  is shaped such that selector  1482  may be vertically moved along to stem  1480 . In the example illustrated, stem  1480  has a circular cross-section reducing fabrication cost and complexity. In other embodiments, stem  1480  may have other cross-sections. 
   Each segment  1488  further has a height or thickness substantially equal to a height or thickness of an individual weight  1430  extending horizontally across from the particular segment  1488 . As a result, the gaps  1492  provided by spacers  1490  are in substantial vertical alignment (horizontally across from) void  1470  between weights  1430 . In the particular example illustrated in which each weight  1430  has substantially the same thickness, each of segments  1488  also has substantially the same thickness. In other embodiments in which different weights  1430  may have different thicknesses, segment  1488  may also have different thicknesses so long as each segment  1488  has a thickness with substantially equal to the thickness of the particular weight  1430  horizontally across from the particular segment  1488 . 
   Spacers  1490  comprise portions of stem  1480  which extend between segments  1488  to separate segments  1488 . Spacers  1490  each have a height such that a portion of selector  1482  may be captured or received between consecutive segments  1488 . Each spacer  1490  is configured to support and overlying segment  1488  such as a top of the segment is substantially horizontally coplanar or coextensive with before of a corresponding void  1470  (shown in  FIG. 27A ). According to one embodiment, spacers  1490  each have a height substantially equal to a height of a corresponding void  1470  (shown in  FIG. 27A ). Spacers  1490  permit selector  1482  to slide between the first and second positions. Spacers  1490  each have a cross-sectional shape dimension smaller than a cross-sectional shape of segments  1488 . 
   Selector  1482  comprises a mechanism configured to be moved along and at least partially within channel  1467  between one of a plurality of multiple selectable positions across from a selected void  1470  and to be moved from a withdrawn position to an inserted position in which selector  1482  extends between the void and is axially retained relative to stem  1480 . As a result, when weight lift  135  exerts a lifting force upon stem  1480  to lift stem  1480 , selector  1482  and any overlying weights  1430  are also lifted. In the particular example illustrated, selector  1482  is configured to linearly translate or slide between the inserted position and the withdrawn position. 
   As shown by  FIG. 17 , selector  582  includes support  1500  and fork  1502 . Support  1500  comprises a structure configured to slide along stem  1480  along axis  1483  while slidably supporting fork  602  for movement in a direction perpendicular to axis  1483 . Support  1500  includes a sleeve  1506  and a platform  1508 . Sleeve  1500  receives stem  1480  and extends about stem  1480  so as to slide along stem  1480  within the opening formed by lip  1470 . In one embodiment, sleeve  1506  may additionally include internal bearing structures (not shown) that further facilitate slighting movement of sleeve  1500  along stem  1480 . 
   Platform  1508  projects from sleeve  1506  and underlies fork  1504  across aligned openings  1467 . Platform  1508  provides a base or deck movably supporting and guiding movement of fork  1504  substantial perpendicular to axis  1483  and stem  1480 . Although platform  1508  is illustrated as underlying fork  1504 , in other embodiments, platform  1504  may alternatively extend over or at least partially contain fork  1504 . 
   Fork  1504  comprises a structure actuatable or movable along an axis substantially perpendicular to axis  1483  between an engaged position shown in  FIG. 27A  and a disengaged position shown in  FIG. 27B . Fork  1504  includes prongs  1536 ,  1538  and handle  1540 . Prongs  1536 ,  1538  comprise tongs or projections separated by an intermediate opening or slot  1542 . Prongs  1536 ,  1538  have a thickness such that prongs  1536  and  1538  may be received within a void  1470  between consecutive weights  1430 . At the same time, opening  1542  is configured to extend about one of spacers  1490  between consecutive segments  1488  of stem  1480  (shown in  FIG. 26 ). As a result, selector  144482  may be inserted into a selected void  1470  and into retaining engaging with stem  1480  such that lifting of stem  1480  also lifts those weights  1430  above a selected void  1470 . 
   Handle  1540  comprises an extension extending from prongs  1536  and  1538 . Handle  1540  is configured to extend from prongs  1536 ,  1538  through and beyond channel  1567 . Handle  1530  permits a person to insert or withdraw selector  1482  in a desired position along the stack of weights  1430 . In other embodiments, selector  1482  may have other configurations. 
   In the example illustrated, fork  1504  is movably coupled to platform  1508  by means of slot  1550  and one or more projections  1552 . Slot  1550  comprises an elongate slot extending along an axis substantially perpendicular to axis  580  in a horizontal plane. Slot  1550  receives projections  1552 . 
   Projection  1552  to comprises a structure extending from platform  1508  through slot  1550 . Projection  1552  is configured to slide within slot  1550  as fork  1504  is moved between the engaged and disengaged positions. Projections  1552  cooperate with slot  1552  guide movement of fork  1504 . 
   groove while fork  604  includes a projection received within the slot, channel or groove. 
     FIGS. 27A and 27B  illustrate actuation of fork  1504  between the engaged in disengaged positions.  FIG. 27B  illustrates fork  1504  in the disengaged position in which fork  1504  has been moved in the direction indicated by arrow  1560  to withdraw prongs  1536 ,  1538  from void  1470  and to withdraw stem  1480  from opening  1542 . As a result, selector  1482  may be slid within aligned channels  1467  and along stem  1480  to position fork  1504  across from a desired one of gaps  1592  and across from one of spacers  1590  which correspond to desired number of overlying weights  1530  intended to be lifted. 
   As shown by  FIG. 27A , once selector  1482  has been moved within and along openings  1464  to a desired position adjacent to and below a desired weight  1430 , fork  1504  may be moved in a direction perpendicular to axis  580  in a direction indicated by arrow  1562  from the disengaged position to the engaged position shown. As a result, opening  1542  receives one of spacers  1490 . Prongs  1536 ,  1538  are at least partially received within gap  1492  and concurrently project into void  1470  connecting the weight  1430  providing void  1470  to stem  1480 . 
   Although not shown for ease of illustration and discussion, in other embodiments, main weight selection system  1434  may include other features noted above. For example, system  534  may additionally include an alignment indicator such as either alignment indicator  208  (shown in  FIG. 8  or a lineman indicator  308  (shown in  FIG. 13 ). With alignment indicator  208 , sleeve  1506  or platform  1508  would include a resiliently biased projection configured to project between adjacent weights  1430  for us to provide a tactile or audible signal as selector  1482  is moved across weights  1430 . With alignment indicator  308 , sleeve  1500  would include a resiliently biased projection configured to engage gaps  1492  as selector  1482  is moved along stem  1480 . Such an alignment indicator  308  would also provide an audible or tactile (feel) signal indicating movement of selector  1482  across weights  1430  and between different positions aligned with respect to weights  1430  and voids  1470 . 
     FIGS. 28A-28C  illustrate incremental weights  1436  in more detail. As shown by  FIG. 10 , incremental weights  1436  comprise elongate rods having a predetermined weight. According to one embodiment, weights  1436  have individual weight amounts which are distinct from the individual weight amounts of weights  1430 . In one embodiment, weights  1430  have a weight of 15 pounds while each of incremental weights  1436 A and  1436 B have a weight of 5 pounds. In another embodiment, weight  1436 A may have an incremental weight amount one-half that of weights  1430  and weight  1436 B may have an incremental weight amount one-quarter that of weights  1430 . In one embodiment, each of weights  1430  weighs 10 pounds while incremental weights  1436 A and  1436 B weigh 5 pounds and 2.5 pounds, respectively. In still other embodiments, weights  1436  may have other weight increments distinct from weights  1430 . 
   Incremental weights  1436  extend through openings  1462  (shown in  FIG. 27A ) in weights  1430  so as to extend vertically across multiple weights  1430 . As a result, weights  1436  do not substantially increase the height, width or length of weights system  1422 . Weights  1436  remain partially hidden for a cleaner more compact appearance. As for further shown by  FIG. 26 , each of weights  1436  have a lower end received within dock  1448  and upper ends which include grooves or channels  1730  configured to receive portions of incremental weight selection system  1438 . 
   Incremental weight selection system  1438  is configured to enable a person to select one or both of weights  1436  for addition to the total amount of weight largely determined by main weights  1430 . As shown by  FIG. 26 , system  1438  includes top  1640  and selector  1642 . Top  1640  is mounted to top plate  157  by fasteners  1648  which pass through elongated slot in selector  1642  so as to capture selector  1642  between top  1640  and top plate  157  while permitting selector  1642  to slide. Although illustrated as being rectangular, top  1640  man various shapes and configurations. 
   Selector  1642  comprises a member configured to be linearly translated or rotated along an axis substantially perpendicular to axis  580  of stem  180  so as to selectively engage incremental weights  1436 . Selector  1642  includes plate  1652  and handle  1654 . Plate  1652  serves as a body for selector  1642 . Plate  1652  includes slot  1658 , catch  1660  and catch  1662 . Slot  1658  comprises an elongate arcuate opening through plate  1652  configured to receive one of fastener  1648 . Slot  1658  guides in your translation or sliding movement of selector  1642  along axis  1655  which is substantially perpendicular to axis  580  of stem  1480 . 
   Catches  1660  and  1662  comprise generally horizontal slots or notches formed in plate  1652  that are narrower than the upper had portions of weights  1436 . Catches  1660  and  1662  are configured to receive upper portions of weights  1436  such that portions of plate  252  extend about weights  1436  within grooves  1730 . Catches  1660  and  1662  are spaced from one another in a direction along axis  1655  with respect to one another such that: (1) selector  1642  may be linearly translated to a first position (shown in  FIG. 28A ) such that neither catch  1660  nor catch  1662  is in engagement with incremental weights  1436 , (2) selector  1642  may be linearly translated a first linear extent to a second position such that catch  1660  receives and engages incremental weight  1436 A while catch  1660  remains disengaged from incremental weight  1436 B (shown in  FIG. 28B ) and (3) selector  1642  may be linearly translated a second greater linear extent to a third position such that both catch  1660  and  1662  engage incremental weights  1436 A and  1436 B, respectively (shown in  FIG. 28C ). By engaging an incremental weights  1436 , selector  1642  couples incremental weights  1436  to top  157 , stem  1480  and weight lift  135  to add the weight of one or both of incremental weights  1436  to the total weight being lifted. 
   Although incremental weight selection system  1438  is illustrated as including two catches  1660  and  1662  for engaging two incremental weights  1436 , in other embodiments, weight system  1422  may be provided with a greater or fewer of such incremental weights  1436 . Likewise, incremental weight selection system  1438  may be configured to selectively engage a greater or fewer of such incremental weights, wherein selector  1642  may include additional catches and may have additional or fewer positions where different sets of incremental weights are engaged. In yet other embodiments, incremental weights  1436  and incremental weight selection system  1438  may be omitted or may have other configurations. 
   Although the present disclosure has been described with reference to example embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the claimed subject matter. For example, although different example embodiments may have been described as including one or more features providing one or more benefits, it is contemplated that the described features may be interchanged with one another or alternatively be combined with one another in the described example embodiments or in other alternative embodiments. Because the technology of the present disclosure is relatively complex, not all changes in the technology are foreseeable. The present disclosure described with reference to the example embodiments and set forth in the following claims is manifestly intended to be as broad as possible. For example, unless specifically otherwise noted, the claims reciting a single particular element also encompass a plurality of such particular elements.