Patent Publication Number: US-2021170256-A1

Title: Weight stack isolator and selectorized machine incorporating the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a divisional of U.S. application Ser. No. 15/958,287, filed Apr. 20, 2018, the subject matter of which is expressly incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Field of the Disclosure 
     The present disclosure relates generally to selectorized machines, and more particularly to a weight stack isolator for placing under at least a portion of a weight stack of a selectorized machine and to a selectorized machine incorporating the weight stack isolator. 
     2. Description of the Related Art 
     Selectorized machines provide the benefit of selectable resistance while exercising. This flexibility allows a single machine to provide adjustable difficulty to accommodate varying user needs. A typical selectorized machine includes a frame supporting a cable and pulley system, guide rails and a weight stack. The weight stack travels along the guide rails and provides resistance, which is then transmitted by the cable and pulley system to a user during exercises. The weight stack will typically include a plurality of weight plates that can be selectively engaged with the pulley system to adjust resistance. 
     During exercises, the user raises and lowers the engaged weight plates using the cable and pulley system. However, if the weight plates are released prematurely or lowered abruptly, the resulting impact of the engaged weight plates on the unengaged remainder of the weight stack, or on the frame of the selectorized machine, can result in significant noise and vibration. This noise and vibration can propagate into and through the surrounding building structure to nearby areas such as adjacent rooms or floors, which is often undesirable. This noise and vibration can be particularly significant in buildings that were not originally designed to dampen such noise and vibration, such as in buildings that were retrofitted to include workout facilities. Accordingly, options for damping weight plate impacts in selectorized machines are generally desired. 
     It is therefore an object to provide a novel weight stack isolator and selectorized machine incorporating the same. 
     SUMMARY 
     The present disclosure provides a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to be used to limit the scope of the claimed subject matter. 
     In one aspect there is provided a weight stack isolator for positioning under at least a portion of a weight stack of a selectorized machine, the weight stack isolator comprising: an impact damper having at least one rail void therein configured to receive at least one guide rail of the selectorized machine, the impact damper being shaped to at least partially surround a section of the at least one guide rail when received in the at least one rail void, to secure the weight stack isolator to the selectorized machine. 
     In some embodiments, the impact damper may comprise a damping layer and an overlying impact layer. The damping layer and the impact layer may have similar footprints. The impact layer may be formed of resilient rubber, may have a thickness of generally 8 mm and may have a weight of generally 77 kg per 9 m 2 . The damping layer may be formed of a low dynamic modulus elastomer, may have a thickness of generally 50 mm, may have a weight of generally 7 kg per 2 m 2 , and may have a durometer of generally 10. 
     In some embodiments, the impact damper may be shaped to completely surround the section of the at least one guide rail when received in the at least one rail void. The impact damper may have at least one slit extending from an outer perimeter of the impact damper to the at least one rail void. The weight stack isolator may further comprise a bearing plate underlying the impact damper, the bearing plate may have at least one plate void therein extending inwardly from an outer perimeter of the bearing plate in alignment with the at least one slit and the at least one rail void. The bearing plate may be formed of steel and may have a thickness of generally 3 mm. In some embodiments, the at least one guide rail may comprise a plurality of guide rails, the at least one rail void may comprise a plurality of rail voids, each of the rail voids being configured to receive a corresponding one of the guide rails, and the at least one slit may comprise a plurality of slits, each of the slits extending from the outer perimeter of the impact damper to a respective one of the rail voids. 
     In some embodiments, the impact damper may be shaped to partially surround the section of the at least one guide rail when received in the at least one rail void, the at least one rail void may extend inwardly from an outer perimeter of the impact damper and the at least one rail void may be configured to removably receive the at least one guide rail. The weight stack isolator may further comprise a bearing plate underlying the impact damper, the bearing plate may have at least one plate void extending inwardly from an outer perimeter of the bearing plate in alignment with the at least one rail void. The bearing plate may be formed of steel and may have a thickness of generally 3 mm. In some embodiments, the at least one guide rail may comprise a plurality of guide rails and the at least one rail void may comprise a plurality of rail voids, each of the rail voids being configured to receive a corresponding one of the guide rails and each of the rail voids extending inwardly from the outer perimeter of the impact damper. 
     In some embodiments, the weight stack isolator may have a generally similar footprint to that of the bottommost weight in the weight stack. The weight stack isolator may have a selector rod void therein extending at least partially therethrough for receiving a selector rod of the selectorized machine. 
     In one form thereof, the present invention provides a selectorized machine including: a weight stack; at least one guide rail for guiding the weight stack; and a weight stack isolator, as defined in the above summary, positioned under at least a portion of the weight stack. 
     In another form thereof, the present invention provides a weight stack isolator for positioning under at least a portion of a weight stack of a selectorized machine, the weight stack isolator including an impact damper having at least one rail void therein configured to receive at least one guide rail of the selectorized machine, the impact damper being shaped to at least partially surround a section of the at least one guide rail when received in the at least one rail void, to secure the weight stack isolator to the selectorized machine. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned and other features of the disclosure, and the manner of attaining them, will become more apparent and will be better understood by reference to the following description of embodiments of the disclosure taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of a selectorized machine with an installed weight stack isolator; 
         FIG. 2  is a fragmentary view of the selectorized machine of  FIG. 1 , focusing on the weight stack isolator and with the weight stack and selector rod omitted; 
         FIG. 3  is an axonometric view of the weight stack isolator; 
         FIG. 4  is an exploded view of the weight stack isolator; 
         FIG. 5  is an axonometric view of another weight stack isolator; 
         FIG. 6  is an exploded view of the weight stack isolator of  FIG. 5 ; 
         FIG. 7  is an axonometric view of another weight stack isolator; 
         FIG. 8  is an exploded view of the weight stack isolator of  FIG. 7 ; 
         FIG. 9  is an axonometric view of another weight stack isolator; 
         FIG. 10  is an exploded view of the weight stack isolator of  FIG. 9 ; 
         FIG. 11  is an axonometric view of another weight stack isolator; and 
         FIG. 12  is an exploded view of the weight stack isolator of  FIG. 11 . 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the disclosure and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION 
     The foregoing summary, as well as the following detailed description of certain embodiments will be better understood when read in conjunction with the appended drawings. As used herein, an element or feature introduced in the singular and preceded by the word “a” or “an” should be understood as not necessarily excluding the plural of the elements or features. Further, references to “one example” or “one embodiment” are not intended to be interpreted as excluding the existence of additional examples or embodiments that also incorporate the described elements or features. Moreover, unless explicitly stated to the contrary, examples or embodiments “comprising” or “having” or “including” an element or feature or a plurality of elements or features having a particular property may include additional elements or features not having that property. Also, it will be appreciated that the terms “comprises”, “has”, “includes” means “including by not limited to” and the terms “comprising”, “having” and “including” have equivalent meanings. 
     As used herein, the terms “adapted” and “configured” mean that the element or feature is designed and/or intended to perform a given function. Thus, the use of the terms “adapted” and “configured” should not be construed to mean that a given element or feature is simply “capable of” performing a given function but that the element or feature is specifically selected, created, implemented, utilized, and/or designed for the purpose of performing the function. Also, elements or features that are described as being adapted or operative to perform a particular function may additionally or alternatively be described as being configured to perform that function, and vice versa. 
     As used herein, the term “and/or” can include any and all combinations of one or more of the associated listed elements or features. 
     It will be understood that when an element or feature is referred to as being “on”, “attached” to, “connected” to, “coupled” with, “contacting”, etc. another element or feature, that element or feature can be directly on, attached to, connected to, coupled with or contacting the other element or feature or intervening elements may also be present. In contrast, when an element or feature is referred to as being, for example, “directly on”, “directly attached” to, “directly connected” to, “directly coupled” with or “directly contacting” another element of feature, there are no intervening elements or features present. 
     It will be understood that spatially relative terms, such as “under”, “below”, “lower”, “over”, “above”, “upper”, “front”, “back” and the like, may be used herein for ease of description to describe the relationship of an element or feature to another element or feature as illustrated in the figures. The spatially relative terms can however, encompass different orientations in addition to the orientation depicted in the figures. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of ordinary skill in the art to which the subject disclosure pertains. 
     In the following, exemplary weight stack isolators and an exemplary selectorized machine incorporating the same are described. Broadly, the weight stack isolators comprise an impact damper defining at least one rail void configured to receive at least one guide rail of the selectorized machine. The impact damper is shaped to at least partially surround a section of the at least one guide rail when received in the at least one rail void, to secure the weight stack isolator to the selectorized machine. Particular non-limited examples of the weight stack isolators and a selectorized machine incorporating the same will now be described. 
       FIG. 1  illustrates a selectorized machine generally identified by reference character  20 . The selectorized machine  20  comprises a frame  22 , an exercise feature  24  (in this embodiment, a pull-down bar), a cable and pulley system  26 , a selector rod  28 , guide rails  30  and a weight stack  32 . The selectorized machine also includes a seat  34  and may optionally comprise other accessories. A weight stack isolator  36  is installed on the selectorized machine  20  under the weight stack  32 . The frame  22  supports the guide rails  30 , the weight stack  32 , the selector rod  28  and the weight stack isolator  36  in vertical alignment. The frame  22  further supports the exercise feature  24 , the cable and pulley system  26  and the seat  34  in proximity to the weight stack  32 . The weight stack  32  comprises a plurality of weights in the form of plates  38 , and the weight stack isolator  36  is positioned under the bottommost plate  38  of the weight stack  32 . Each plate  38  can be selectively coupled with the selector rod  28  by inserting a selector pin  40  through aligned holes in the plate  38  and selector rod  28 . The selector rod  28  is connected to one end of the cable and pulley system  26  adjacent the weight stack  32 , while the opposite end of the cable and pulley system  26  is connected to the exercise feature  24 . Accordingly, the plates  38  in the weight stack  32  can be selectively engaged or disengaged with the selector rod  28  to vary the resistance on the exercise feature  24 . As will be appreciated, the embodiment of the selectorized machine  20  shown in  FIG. 1  is intended to be illustrative and other selectorized machine configurations and embodiments will be apparent to those skilled in the art. For example, the selectorized machine may comprise a single guide rail or more than two guide rails. In some embodiments the plates  38  in the weight stack  32  may be disks or other shapes or configurations of weights. 
     During use, a user selectively engages a number of the plates  38  with the selector rod  28  to provide a desired amount of resistance on the exercise feature  24  and then interacts with the exercise feature  24  to raise and lower the engaged plates  38  along the guide rails  30  via the cable and pulley system  26  and the selector rod  28 . As the engaged plates  38  are lowered and impact either the remaining unengaged plates  38  or the weight stack isolator  36  directly, the weight stack isolator  36  absorbs or dampens the impact to reduce noise and vibration that is transmitted into the surrounding environment, especially through the frame  22 . 
       FIGS. 2, 3 and 4  better illustrate the weight stack isolator  36 . The weight stack isolator  36  has generally planar top, bottom and side surfaces, and has a rectangular footprint that is generally similar to that of the bottommost plate  38  of the weight stack  32 . The weight stack isolator  36  comprises an impact damper  42  and a bearing plate  44 . The bearing plate  44  underlies the impact damper  42  and may be adhered thereto. During use, the weight stack isolator  36  is positioned under the bottommost plate  38  of the weight stack  32  and surrounds a section of the guide rails  30  to removably secure the weight stack isolator  36  to the selectorized machine  20  under the weight stack  32 . 
     The impact damper  42  comprises a plurality of stacked layers that may be adhered together, including an impact layer  46  and a damping layer  48 . The impact layer  46  overlies the damping layer  48  and protects the damping layer  48  from being directly impacted by the weight stack  32 . The impact layer  46  is formed of resilient rubber, such as recycled rubber. The damping layer  48 , which underlies the impact layer  46 , absorbs or dampens noise and vibration caused by impacts from the weight stack  32  during use. The damping layer  48  is formed of a resilient material with a low dynamic modulus. 
     The impact damper  42  has a plurality of rail voids  50  therein for receiving the guide rails  30  of the selectorized machine  20 . Each of the rail voids  50  is a cutout or through-hole in the impact damper  42  that is sized to receive a corresponding one of the guide rails  30 , and each of the rail voids  50  extends through both the impact layer  46  and the damping layer  48 . The rail voids  50  are laterally spaced apart and cylindrically shaped, i.e. each of the rail voids  50  has a circular horizontal cross-section. It will however be appreciated that in other embodiments, each of the rail voids  50  may have an oval, square, rectangular, oblong or otherwise shaped horizontal cross-section. The impact damper  42  further has a plurality of parallel and planar slits  52  provided therein. Each of the slits  52  extends inwardly from the same side of an outer perimeter of the impact damper  42  to a corresponding one of the rail voids  50  and extends through both the impact layer  46  and the damping layer  48 . As further described below, the impact damper  42  is resiliently flexible to permit the guide rails  30  to pass through the slits  52  and into the rail voids  50 . 
     The bearing plate  44  has a similar footprint to that of the impact damper  42  and has a plurality of plate voids  54  therein for receiving the guide rails  30  of the selectorized machine  20 . Each of the plate voids  54  underlies and is in alignment with one of the rail voids  50  and one of the slits  52  in the impact damper  42 . As illustrated in  FIG. 4 , each of the plate voids  54  is an elongated cutout or slot extending inwardly from an outer perimeter of the bearing plate  44 . Each of the plate voids  54  is sized to receive the corresponding guide rail  30 , and each of the plate voids  54  has a generally rectangular footprint ending in a semi-circular arch opposite the outer perimeter of the bearing plate  44 . The plate voids  54  are laterally spaced apart and extend inwardly from the same side of the outer perimeter of the bearing plate  44 . Each of the plate voids  54  has a width greater than that of the corresponding guide rail  30 , to permit the guide rail  30  to be received in the plate void  54 . The semi-circular arch at the end of each of the plate voids  54  has a curvature similar to that of the corresponding guide rail  30 . 
     The bearing plate  44  is rigid and formed of metal, such as steel, or other rigid material. During use, the bearing plate  44  rest on the frame  22  of the selectorized machine  20  and supports the impact damper  42  above it to spread impacts from the weight stack  32  across the impact damper  42 . Spreading the impact across the impact damper  42  can help to reduce wear and tear on the impact damper  42  and can help to ensure that the impact damper  42  operates within a designed compression range. Operating the impact damper  42  within the designed compression range and reducing wear and tear on the impact damper  42  can help to ensure that the weight stack isolator  36  provides a desired level of damping and can help to increase the useable life of the weight stack isolator  36 . 
     In this embodiment, the weight stack isolator  36  has a selector rod void  56  therein for receiving the selector rod  28  of the selectorized machine  20 . The necessity, location and shape of the selector rod void  56  of course depends on the configuration of the selectorized machine with which the weight stack isolator is intended to be used. For the selectorized machine  20  of  FIG. 1 , the selector rod void  56  is located between the rail voids  50  in the impact damper  42  and between the plate voids  54  in the bearing plate  44 . The selector rod void  56  is cylindrically shaped and extends through both the impact damper  42  and the bearing plate  44 . In other embodiments, the selector rod void  56  may be otherwise shaped and may extend only partway through the weight stack isolator  36 . As will be appreciated, the selector rod void  56  may only be necessary in embodiments where the weight stack isolator  36  underlies the selector rod  28  and the selector rod  28  extends below the weight stack  32 , or extends below the portion of the weight stack  32  overlying the weight stack isolator  36 . Nevertheless, the selector rod void  56  can be included in further embodiments to improve flexibility of the weight stack isolator  36 , to facilitate mass production and/or to achieve a desired level of damping. 
     As described above, the weight stack isolator  36  is adapted for retrofitting to an existing selectorized machine  20 . That is, the selectorized machine  20  may be originally assembled with limited or no noise and vibration damping and thereafter the weight stack isolator  36  can be installed on the selectorized machine  20  to absorb or dampen noise and vibration caused by impacts from the weight stack  32  during use. 
     To install the weight stack isolator  36  on the selectorized machine  20 , the entire weight stack  32  is engaged with the selector rod  28  and then raised using the exercise feature  24 , the cable and pulley system  26  and the selector rod  28 . Typically, this involves inserting the selector pin  40  through the bottommost plate  38  of the weight stack  32  and through the selector rod  28  and then pulling on the exercise feature  24  with one or more persons. However, those skilled in the art will appreciate that other methods for selectively engaging and raising the weight stack  32  can be used depending on the configuration of the selectorized machine  20 . 
     Once the weight stack  32  has been raised, the slits  52  of the weight stack isolator  36  are aligned with the guide rails  30  under the weight stack  32  and the weight stack isolator  36  is forcibly pressed against the guide rails  30 . As the guide rails  30  press against the slits  52 , the impact damper  42  deforms to permit the guide rails  30  to pass through the slits  52  and into the rail voids  50  in the impact damper  42 , as well as into the underlying plate voids  54  in the bearing plate  44 . Receiving the guide rails  30  in the voids  50 ,  54  of the weight stack isolator  36  positions the weight stack isolator  36  under the weight stack  32 . Once the guide rails  30  are received in the rail voids  50  and the plate voids  54 , the impact damper  42  returns to its original shape and surrounds a section of the guide rails  30  to secure the weight stack isolator  36  to the selectorized machine  20  under the weight stack  32 . If necessary, the weight stack isolator  36  can then be lowered on the guide rails  30  until it is supported by the frame  22 , directly or indirectly, and the weight stack  32  can be lowered until it is resting on the weight stack isolator  36 . As will be appreciated, the weight stack isolator  36  can be removed from the selectorized machine  20  by reversing this procedure. 
       FIGS. 5 and 6  illustrate another embodiment of a weight stack isolator generally identified by reference character  136 . The weight stack isolator  136  is similar to the weight stack isolator  36  and like elements are identified by like reference characters, incremented by 100. Similar to weight stack isolator  36 , the weight stack isolator  136  is designed to be retrofitted to the selectorized machine  20 . In this embodiment, the weight stack isolator  136  is configured to be forcibly rotated to install the weight stack isolator  136  on the selectorized machine  20 , as further described below. 
     The weight stack isolator  136  has generally planar top, bottom and side surfaces, and has a rectangular footprint that is generally similar to that of the bottommost plate  38  of the weight stack  32 . The weight stack isolator  136  comprises an impact damper  142  and a bearing plate  144 . The bearing plate  144  underlies the impact damper  142  and may be adhered thereto. During use, the weight stack isolator  136  is positioned under the bottommost plate  38  of the weight stack  32  and surrounds a section of the guide rails  30  to removably secure the weight stack isolator  136  to the selectorized machine  20  under the weight stack  32 . 
     The impact damper  142  comprises a plurality of stacked layers that may be adhered together, including an impact layer  146  and a damping layer  148 . The impact layer  146  overlies the damping layer  148  and protects the damping layer  148  from being directly impacted by the weight stack  32 . The impact layer  146  is formed of resilient rubber, such as recycled rubber. The damping layer  148 , which underlines the impact layer  146 , absorbs or dampens noise and vibration caused by impacts from the weight stack  32  during use. The damping layer  148  is formed of a resilient material with a low dynamic modulus. 
     The impact damper  142  has a plurality of rail voids  150  therein for receiving the guide rails  30  of the selectorized machine  20 . Each of the rail voids  150  is a cutout or through-hole in the impact damper  142  that is sized to receive a corresponding one of the guide rails  30  and each of the rail voids  150  extends through both the impact layer  146  and the damping layer  148 . The rail voids  150  are laterally spaced apart and cylindrically shaped, i.e. each of the rail voids  150  has a circular horizontal cross-section. It will however be appreciated that in other embodiments, each of the rail voids  150  may have an oval, square, rectangular, oblong or otherwise shaped horizontal cross-section. The impact damper  142  further has a plurality of arcuate slits  152  provided therein and extending from opposite sides of the weight stack isolator  136 . Each of the slits  152  extends inwardly from an outer perimeter of the impact damper  142  to a corresponding one of the rail voids  150  and extends through both the impact layer  146  and the damping layer  148 . As further described below, the impact damper  142  is resiliently flexible to permit the guide rails  30  to pass through the slits  152  and into the rail voids  150 . 
     The bearing plate  144  has a similar footprint to that of the impact damper  142  and has a plurality of plate voids  154  therein for receiving the guide rails  30  of the selectorized machine  20 . Each of the plate voids  154  underlies and is in alignment with one of the rail voids  150  and one of the slits  152  in the impact damper  142 . As illustrated in  FIG. 6 , each of the plate voids  154  is an elongated cutout or slot extending inwardly from an outer perimeter of the bearing plate  144 . Each of the plate voids  154  is sized to receive the corresponding guide rail  30 , and each of the plate voids  154  has a generally arcuate footprint ending in a semi-circular arch opposite the outer perimeter of the bearing plate  144 . The plate voids  154  are laterally spaced apart and extend at an angle from opposite sides of the outer perimeter of the bearing plate  144 . Each of the plate voids  154  has a width greater than that of the corresponding guide rail  30 , to permit the guide rail  30  to be received in the plate void  154 , and each semi-circular arch at the end of the plate voids  154  has a curvature similar to that of the corresponding guide rail  30 . 
     The bearing plate  144  is rigid and formed of metal, such as steel, or other rigid material. During use, the bearing plate  144  rest on the frame  22  of the selectorized machine  20  and supports the impact damper  142  above it to spread impacts from the weight stack  32  across the impact damper  142 . Spreading the impact across the impact damper  142  can help to reduce wear and tear on the impact damper  142  and can help to ensure that the impact damper  142  operates within a designed compression range. Operating the impact damper  142  within the designed compression range and reducing wear and tear on the impact damper  142  can help to ensure that the weight stack isolator  136  provides a desired level of damping and can help to increase the useable life of the weight stack isolator  136 . 
     In this embodiment, the weight stack isolator  136  has a selector rod void  156  therein for receiving the selector rod  28  of the selectorized machine  20 . The selector rod void  156  is the same as the selector rod void  56  described above. 
     As described above, weight stack isolator  136  is adapted for retrofitting to an existing selectorized machine  20 . That is, the selectorized machine  20  may be originally assembled with limited or no noise and vibration damping and thereafter the weight stack isolator  136  can be installed on the selectorized machine  20  to absorb or dampen noise and vibration caused by impacts from the weight stack  32  during use. 
     To install the weight stack isolator  136  on the selectorized machine  20 , the entire weight stack  32  is engaged with the selector rod  28  and then raised using the exercise feature  24 , the cable and pulley system  26  and the selector rod  28 . Typically, this involves inserting the selector pin  40  through the bottommost plate  38  of the weight stack  32  and through the selector rod  28  and then pulling on the exercise feature  24  with one or more persons. However, those skilled in the art will appreciate that other methods for selectively engaging and raising the weight stack  32  can be used depending on the configuration of the selectorized machine  20 . 
     Once the weight stack  32  has been raised, the weight stack isolator  136  is positioned under the weight stack  32  in a first orientation intermediate the guide rails  30  of the selectorized machine  20 . In the first orientation, the slits  152  of the weight stack isolator  136  are aligned with the guide rails  30  such that the guide rails  30  press against the slits  152  when the weight stack isolator  136  is rotated in a generally horizontal plane. The weight stack isolator  136  is then forcibly rotated in the generally horizontal plane to forcibly press the guide rails  30  against the slits  152 . As the guide rails  30  press against the slits  152  of the weight stack isolator  136 , the impact damper  142  deforms to permit the guide rails  30  to pass through the slits  152  and into the rail voids  150  in the impact damper  142 , as well as into the underlying plate voids  154  in the bearing plate  144 . The weight stack isolator  136  is forcibly rotated until the weight stack isolator  136  is positioned in a second orientation, where the weight stack isolator  136  bridges the guide rails  30  and where the guide rails  30  are received in the rail voids  150  and the plate voids  154 . Once the guide rails  30  are received in the rail voids  150  and the plate voids  154 , the impact damper  142  returns to its original shape and surrounds a section of the guide rails  30  to removably secure the weight stack isolator  136  to the selectorized machine  20  under the weight stack  32 . If necessary, the weight stack isolator  136  can then be lowered on the guide rails  30  until it is supported by the frame  22 , directly or indirectly, and the weight stack  32  can be lowered until it is resting on the weight stack isolator  136 . As will be appreciated, the weight stack isolator  136  can be removed from the selectorized machine  20  by reversing this procedure. 
       FIGS. 7 and 8  illustrate another embodiment of a weight stack isolator generally identified by reference character  236 . The weight stack isolator  236  is similar to the weight stack isolator  36  and like elements are identified by like reference characters, incremented by 200. Similar to the weight stack isolator  36 , the weight stack isolator  236  is designed to be retrofitted to the selectorized machine  20 . In this embodiment, the weight stack isolator  236  is configured to be rotated in a generally vertical plane to install the weight stack isolator  236  on the selectorized machine  20 , as further described below. 
     The weight stack isolator  236  has generally planar top, bottom and side surfaces, and has a rectangular footprint that is generally similar to that of the bottommost plate  38  of the weight stack  32 . The weight stack isolator  236  comprises an impact damper  242  and a bearing plate  244 . The bearing plate  244  underlies the impact damper  242  and may be adhered thereto. During use, the weight stack isolator  236  is positioned under the bottommost plate  38  of the weight stack  32  and partially surrounds a section of the guide rails  30  to removably secure the weight stack isolator  236  to the selectorized machine  20  under the weight stack  32 . 
     The impact damper  242  comprises a plurality of layers that may be adhered together, including an impact layer  246  and a damping layer  248 . The impact layer  246  overlies the damping layer  248  and protects the damping layer  248  from being directly impacted by the weight stack  32 . The impact layer  246  is formed of resilient rubber, such as recycled rubber. The damping layer  248  underlies the impact layer  246  and absorbs or dampens noise and vibrations caused by impacts from the weight stack  32  during use. The damping layer  248  is formed of a resilient material with a low dynamic modulus. 
     The impact damper  242  has a plurality of rail voids  250  therein for receiving the guide rails  30  of the selectorized machine  20 . As illustrated in  FIGS. 7 and 8 , each of the rail voids  250  is an elongated cutout or slot extending inwardly from an outer perimeter of the impact damper  242 . Each of the rail voids  250  extends inwardly from the outer perimeter of the impact damper  242  and towards the center of the weight stack isolator  236 . Each of the rail voids  250  is sized to receive a corresponding one of the guide rails  30  and extends through both the impact layer  246  and the damping layer  248 . As illustrated in  FIGS. 7 and 8 , each of the rail voids  250  has a generally rectangular footprint ending in a semi-circular arch, opposite the outer perimeter of the impact damper  242 . The rail voids  250  are laterally spaced apart and extend from opposite sides of the outer perimeter of the impact damper  242 . Each of the rail voids  250  has a width greater than that of the corresponding guide rail  30 , to permit the guide rail  30  to be received in the rail void  250 . The semi-circular arch at the end of each of the rail voids  250  has a curvature similar to that of the corresponding guide rail  30 . 
     The bearing plate  244  has a similar footprint to that of the impact damper  242  and has a plurality of plate voids  254  therein for receiving the guide rails  30  of the selectorized machine  20 . Each of the plate voids  254  underlies and is in alignment with one of the rail voids  250  in the impact damper  242 . As illustrated in  FIG. 8 , each of the plate voids  254  is an elongated cutout or slot extending inwardly from an outer perimeter of the bearing plate  244 . Each of the plate voids  254  extends inwardly from the outer perimeter of the bearing plate  254  and towards the center of the weight stack isolator  236 , similar to the rail voids  250 . Each of the plate voids  254  is sized to receive the corresponding guide rail  30 . As illustrated in  FIG. 8 , each of the plate voids  254  has a generally rectangular footprint ending in a semi-circular arch opposite the outer perimeter of the bearing plate  244 . The plate voids  254  are laterally spaced apart and extend from opposite sides of the outer perimeter of the bearing plate  244 . Each of the plate voids  254  has a width greater than that of the corresponding guide rail  30 , to permit the guide rail  30  to be received in the plate void  254 . The semi-circular arch at the end of each of the plate voids  254  has a curvature similar to that of the corresponding guide rail  30 . 
     The bearing plate  244  is rigid and formed of metal, such as steel, or other rigid material. During use, the bearing plate  244  rest on the frame  22  of the selectorized machine  20  and supports the impact damper  242  above it to spread impacts from the weight stack  32  across the impact damper  242 . Spreading the impact across the impact damper  242  can help to reduce wear and tear on the impact damper  242  and can help to ensure that the impact damper  242  operates within a designed compression range. Operating the impact damper  242  within the designed compression range and reducing wear and tear on the impact damper  242  can help to ensure that the weight stack isolator  236  provides a desired level of damping and can help to increase the useable life of the weight stack isolator  236 . 
     In this embodiment, the weight stack isolator  236  has a selector rod void  256  therein for receiving the selector rod  28  of the selectorized machine  20 . The selector rod void  256  is the same as the selector rod void  56  described. 
     As described above, the weight stack isolator  236  is adapted for retrofitting to an existing selectorized machine  20 . That is, the selectorized machine  20  may be originally assembled with limited or no noise and vibration damping and thereafter the weight stack isolator  236  can be installed on the selectorized machine  20  to absorb or dampen noise and vibration caused by impacts from the weight stack  32  during use. 
     To install the weight stack isolator  236  on the selectorized machine  20 , the entire weight stack  32  is engaged with the selector rod  28  and then raised using the exercise feature  24 , the cable and pulley system  26  and the selector rod. Typically, this involves inserting the selector pin  40  through the bottommost plate  38  of the weight stack  32  and through the selector rod  28  and then pulling on the exercise feature  24  with one or more persons. However, those skilled in the art will appreciate that other methods for selectively engaging and raising the weight stack can be used depending on the configuration of the selectorized machine. 
     Once the weight stack  32  has been raised, the weight stack isolator  236  is positioned under the weight stack  32  in a vertical orientation between the guide rails  30  and then rotated into a horizontal orientation, with the bearing plate  244  on the bottom, such that the guide rails  30  are received in the rail voids  250  in the impact damper  242  as well as in the underlying plate voids  254  in the bearing plate  244 . When the guide rails  30  are received in the rail voids  250  and plate voids  254 , the impact damper  242  partially surrounds a section of the guide rails  30  to removably secure the weight stack isolator  236  to the selectorized machine  20  under the weight stack  32 . The weight stack isolator  236  can then be lowered on the guide rails  30  until it is supported by the frame  22 , directly or indirectly, and the weight stack  32  can be lowered until it is resting on the weight stack isolator  236 . As will be appreciated, the weight stack isolator  236  can be removed from the selectorized machine  20  by reversing this procedure. 
       FIGS. 9 and 10  illustrate another embodiment of a weight stack isolator generally identified by reference character  336 . The weight stack isolator  336  is similar to the weight stack isolator  36  and like elements are identified by like reference characters, incremented by 300. In this embodiment, the weight stack isolator  336  is designed to be installed during assembly of the selectorized machine  20  and is fixedly secured under the weight stack  32 . 
     The weight stack isolator  336  has generally planar top, bottom and side surfaces, and has a rectangular footprint that is generally similar to that of the bottommost plate  38  of the weight stack  32 . The weight stack isolator  336  comprises an impact damper  342  and a bearing plate  344 . The bearing plate  344  underlies the impact damper  342  and may be adhered thereto. During use, the weight stack isolator  336  is positioned under the bottommost plate  38  of the weight stack  32  and surrounds a section of the guide rails  30  to secure the weight stack isolator  336  to the selectorized machine  20  under the weight stack  32 . 
     The impact damper  342  comprises a plurality of stacked layers that may be adhered together, including an impact layer  346  and a damping layer  348 . The impact layer  346  overlies the damping layer  348  and protects the damping layer  348  from being directly impacted by the weight stack  32 . The impact layer  346  is formed of resilient rubber, such as recycled rubber. The damping layer  348 , which underlines the impact layer  346 , absorbs or dampens noise and vibration caused by impacts from the weight stack  32  during use. The damping layer  348  is formed of a resilient material with a low dynamic modulus. 
     The impact damper  342  has a plurality of rail voids  350  therein for receiving the guide rails  30  of the selectorized machine  20 . Each of the rail voids  350  is a cutout or through-hole in the impact damper  342  that is sized to receive a corresponding one of the guide rails  30  and each of the rail voids  350  extends through both the impact layer  346  and the damping layer  348 . The rail voids  350  are laterally spaced apart and cylindrically shaped, i.e. each of the rail voids  350  has a circular horizontal cross-section. It will however be appreciated that in other embodiments, each of the rail voids  350  may have an oval, square, rectangular, oblong or otherwise shaped horizontal cross-section. 
     The bearing plate  344  has a similar footprint to that of the impact damper  342  and has a plurality of plate voids  354  therein for receiving the guide rails  30  of the selectorized machine  20 . Each of the plate voids  354  underlies and is in alignment with one of the rail voids  350  in the impact damper  342 . As illustrated in  FIG. 10 , each of the plate voids  354  is a cutout or through-hole that extends through the bearing plate  344 . The plate voids  354  are laterally spaced apart and cylindrically shaped, i.e. each of the plate voids  354  has a circular horizontal cross-section. It will however be appreciated that in other embodiments, each of the plate voids  354  may have an oval, square, rectangular, oblong or otherwise shaped horizontal cross-section. Each of the plate voids  354  is sized to receive the corresponding guide rail  30 , and has a diameter greater than that of the corresponding guide rail  30 . 
     The bearing plate  344  is rigid and formed of metal, such as steel, or other rigid material. During use, the bearing plate  344  rest on the frame  22  of the selectorized machine  20  and supports the impact damper  342  above it to spread impacts from the weight stack  32  across the impact damper  342 . Spreading the impact across the impact damper  342  can help to reduce wear and tear on the impact damper  342  and can help to ensure that the impact damper  342  operates within a designed compression range. Operating the impact damper  342  within the designed compression range and reducing wear and tear on the impact damper  342  can help to ensure that the weight stack isolator  336  provides a desired level of damping and can help to increase the useable life of the weight stack isolator  336 . 
     In this embodiment, the weight stack isolator  336  has a selector rod void  356  therein for receiving the selector rod  28  of the selectorized machine  20 . The selector rod void  356  is the same as the selector rod void  56  described above. 
     As described above, the weight stack isolator  336  is adapted to be installed during assembly of the selectorized machine  20 . During this assembly, the weight stack isolator  336  is positioned under the bottommost plate  38  of the weight stack  32  with the guide rails  30  received in the rail voids  350  in the impact damper  342  as well as in the underlying plate voids  354  in the bearing plate  344 . As a result, the impact damper  342  and the bearing plate  344  surround a section of the guide rails  30  to fixedly secure the weight stack isolator  336  under the weight stack  32 . When the selectorized machine  20  is assembled, the weight stack isolator  336  is supported by the frame  22 , directly or indirectly, and the weight stack  32  rests on the weight stack isolator  336 . 
       FIGS. 11 and 12  illustrate another embodiment of a weight stack isolator generally identified by reference character  436 . The weight stack isolator  436  is similar to the weight stack isolator  36  and like elements are identified by like reference characters, incremented by 400. Similar to weight stack isolator  36 , the weight stack isolator  436  is designed to be retrofitted to the selectorized machine  20 . In this embodiment, the weight stack isolator  436  is adapted to be removably secured to a single one of the guide rails  30  of the selectorized machine  20  and a weight stack isolator  436  is installed on each guide rail  30  of the selectorized machine  20 . 
     The weight stack isolator  436  is cylindrically shaped with generally planar top and bottom surfaces. The weight stack isolator  436  comprises an impact damper  442  and a bearing plate  444 . The bearing plate  444  underlies the impact damper  442  and may be adhered thereto. During use, the weight stack isolator  436  is positioned under the bottommost plate  38  of the weight stack  32  and surrounds a section of one of the guide rails  30  to removably secure the weight stack isolator  436  to the selectorized machine  20  under the weight stack  32 . 
     The impact damper  442  comprises a plurality of stacked layers that may be adhered together, including an impact layer  446  and a damping layer  448 . The impact layer  446  overlies the damping layer  448  and protects the damping layer  448  from being directly impacted by the weight stack  32 . The impact layer  446  is formed of resilient rubber, such as recycled rubber. The damping layer  448 , which underlines the impact layer  446 , absorbs or dampens noise and vibration caused by impacts from the weight stack  32  during use. The damping layer  448  is formed of a resilient material with a low dynamic modulus. 
     The impact damper  442  has a rail void  450  therein for receiving one of the guide rails  30  of the selectorized machine  20 . The rail void  450  is a cutout or through-hole in the impact damper  442  that is sized to receive the one of the guide rails  30  and the rail void  450  extends through both the impact layer  446  and the damping layer  448 . The rail void  150  is cylindrically shaped, i.e. the rail void  450  has a circular horizontal cross-section. It will however be appreciated that in other embodiments, the rail void  450  may have an oval, square, rectangular, oblong or otherwise shaped horizontal cross-section. The impact damper  442  further has a radially extending slit  452  provided therein. The slit  452  extends radially from an outer perimeter of the impact damper  442  to the rail void  450 . The slit  452  extends through both the impact layer  446  and the damping layer  448 . As further described below, the impact damper  442  is resiliently flexible to permit the guide rail  30  to pass through the slit  452  and into the rail void  450 . 
     The bearing plate  444  has a similar footprint to that of the impact damper  442  and has a plate void  454  therein for receiving one of the guide rails  30  of the selectorized machine  20 . The plate void  454  underlies and is in alignment with the rail void  450  and the slit  452  in the impact damper  442 . As illustrated in  FIG. 12 , the plate void  454  is an elongated cutout or slot extending radially inwardly from an outer perimeter of the bearing plate  444 . The plate void  454  is sized to receive the corresponding guide rail  30 , and the plate void  454  has a generally rectangular footprint ending in a semi-circular arch opposite the outer perimeter of the bearing plate  444 . The plate void  454  has a width greater than that of the corresponding guide rail  30 , to permit the guide rail  30  to be received in the plate void  454 . The semi-circular arch at the end of the plate void  454  has a curvature similar to that of the corresponding guide rail  30 . 
     The bearing plate  444  is rigid and formed of metal, such as steel, or other rigid material. During use, the bearing plate  444  rest on the frame  22  of the selectorized machine  20  and supports the impact damper  442  above it to spread impacts from the weight stack  32  across the impact damper  442 . Spreading the impact across the impact damper  442  can help to reduce wear and tear on the impact damper  442  and can help to ensure that the impact damper  442  operates within a designed compression range. Operating the impact damper  442  within the designed compression range and reducing wear and tear on the impact damper  442  can help to ensure that the weight stack isolator  436  provides a desired level of damping and can help to increase the useable life of the weight stack isolator  436 . 
     As described above, the weight stack isolator  436  is adapted for retrofitting to an existing selectorized machine  20 . That is, the selectorized machine  20  may be originally assembled with limited or no noise and vibration damping and thereafter a plurality of the weight stack isolators  436  can be installed (one on each of the guide rails  30 ) to absorb or dampen noise and vibration caused by impacts from the weight stack  20  during use. The weight stack isolator  436  is installed and removed in the same way as the weight stack isolator  36 , described above. 
     It will be appreciated by those skilled in the art that elements have generally similar footprints when their outer perimeters define horizontal two-dimensional areas with the same or nearly the same size and shape, disregarding any voids, slits or the like. 
     It will be appreciated by those skilled in the art that the materials and thicknesses of the various layers in the weight stack isolator will depend on the intended use and application of the weight stack isolator. For example, a weight stack isolator for use in heavy weight applications may have thicker layers or may have layers formed of stiffer or denser materials than those of a weight stack isolator for use in light weight applications. Additionally, it will be appreciated by those skilled in the art that by adjusting the thicknesses and materials of the various layers, the performance of the weight stack isolator can be modified and tailored depending on the intended use and application of the weight stack isolator. In some embodiments, the weight stack isolator may provide vibration isolation efficiencies of up to 99% and/or may provide over 40 dB of noise reduction. 
     In exemplary embodiments of the weight stack isolators shown and described above, the impact layer may have a thickness of 8 mm and may be formed of resilient rubber, such as recycled rubber. The material of the impact layer may have substantially the following properties: weight of approximately 77.1 kg per 9.3 m 2 , wear hardness per DIN 53577 of approximately 4.0 MPa, Shore A hardness per DIN 53505 of 60 (+/−5), compression set per DIN 53517 of approximately 15%, abrasion per DIN 53516 of maximum 200 mm 3 , tensile strength per EN ISO 1798 of approximately 1.5 N/mm 2 , elongation at break per EN ISO 1798 of approximately 90%, coefficient of friction per EN 13893:2002 of μ=0.47 (safe), fire resistance per DIN EN 13501-1 of E fl  (B2), light fastness per DIN EN 105-B02:1999-09 of 2-3, electrostatic properties per DIN EN 1815:1995-06 of 0.5 kV, remaining deformation per EN 433:1994-11 of 0.13 mm and reduction of impact sound pressure level (ΔL w ) per DIN EN ISO 140-8:1998-03 of 18 dB. 
     In exemplary embodiments of the weight stack isolator shown and described above, the damping layer may have a thickness of 51 mm and may be formed of a low dynamic modulus elastomer. The material of the damping layer may have substantially the following properties: durometer of 10, weight of approximately 7 kg per 2 m 2 , mechanical loss factor per DIN 53513 of 0.25, static E-modulus per DIN 53513 of 0.048 N/mm 2 , dynamic E-modulus per DIN 53513 of 0.144 N/mm 2 , static shear modulus per DIN 53513 of 0.04 N/mm 2 , dynamic shear modulus per DIN 53513 of 0.09 N/mm 2 , elongation at break per DIN 53455-6-4 of greater than 400%, resistance to strain of 0.011 N/mm 2 , residual compression set per DIN EN ISO 1856 of less than 5%, tensile strength per DIN 53455-6-4 of greater than 0.35 N/mm 2 , tear resistance per DIN ISO 34-1/A of 0.6 N/mm, rebound elasticity per DIN EN ISO 8370 of 50%, operating temperature of −30 to +70° C. and inflammability per EN ISO 11925-1 of Class E/EN13501-1. The damping layer may exhibit the characteristics set out in Table 1, below. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Damping Layer Characteristics (Exemplary Embodiment) 
               
            
           
           
               
               
               
            
               
                 Load (N/mm 2 ) 
                 Deflection (mm) 
                 Natural Frequency (Hz) 
               
               
                   
               
            
           
           
               
               
               
            
               
                 0.02 
                 9.4 
                 14.6 
               
               
                 0.04 
                 14.4 
                 16.3 
               
               
                 0.06 
                 16.2 
                 17.0 
               
               
                   
               
            
           
         
       
     
     In exemplary embodiments of the weight stack isolator shown and described above, the bearing plate may have a thickness of 3 mm and may be formed of metal, such as steel. 
     Although the impact damper has been shown and described as comprising a plurality of stacked layers, including an impact layer and a damping layer. It will be appreciated that in some embodiments, the impact layer may be omitted. For example, in embodiments where the material of the damping layer is sufficiently resilient to withstand being directly impacted by the weight stack, the impact layer may be omitted and the weight stack may contact damping layer of the impact damper. 
     Although the weight stack isolator has been shown and described as being positioned under the bottommost plate of the weight stack, those skilled in the art will appreciate that in other embodiments the weight stack isolator may be positioned under only a portion of the weight stack. For example, the weight stack isolator may be positioned overlying the bottommost plate of the weight stack and under the remaining portion of the weight stack. In such embodiments, the bearing plate may be omitted from the weight stack isolator and the plate or plates of the weight stack underlying the weight stack isolator may provide support for the impact damper. It will be appreciated that only a portion of the weight stack needs to be raised to install the weight stack isolator in such embodiments. 
     Although the weight stack isolator has been shown and described as having a rectangular footprint that is generally similar to that of the bottommost plate of the weight stack, those skilled in the art will appreciate that in other embodiments the weight stack isolator may have a circular footprint or otherwise shaped footprint. For example, the weight stack isolator may have a footprint that is generally similar to an intermediate plate of the weight stack. Additionally, the weight stack isolator may have a footprint that is not generally similar any plate of the weight stack and may, for example, have a footprint that is larger or smaller than that of the weight stack. 
     Although the bearing plate has been described as having a similar footprint to that of the impact damper, those skilled in the art will appreciate that in other embodiments the bearing plate may have a footprint that differs in shape to that of the impact damper and may, for example, have a footprint that is larger or smaller than that of the impact damper. Additionally, in some embodiments the bearing plate may have a footprint that is similar to an underlying plate of the weight stack. In yet other embodiments, the bearing plate may be omitted entirely, as described above. 
     Although the slits in the impact damper have been shown as narrow in the accompanying drawings, those skilled in the art will appreciate that in other embodiments the slits may be wider to define gaps through which the rail guides pass. Additionally, in some embodiments the width of the slits may be generally equal to or larger than a width or diameter of the rail voids in the impact damper, such that the differentiation between the slits and the rail voids in the impact damper becomes immaterial and the combination of each slit and corresponding rail void can be considered a single void extending inwardly from the outer perimeter of the impact damper. Although the slits have been shown and described as extending from either the same side or opposite sides of the weight stack isolator, it will be appreciated that in other embodiments the slits may extend from adjacent sides of the weight stack isolator or from other combinations of sides. 
     Although the plate voids have been shown and described as extending from either the same side or opposite sides of the bearing plate, it will be appreciated that in other embodiments the plate voids may extend from adjacent sides of the bearing plate or from other combinations of sides. 
     Although each rail void and plate void has been shown and described as receiving one of the guide rails of the selectorized machine, it will be appreciated that in other embodiments each of the rail voids and the plate voids may be sized to receive a plurality of the guide rails. For example, the weight stack isolator may comprise a single rail void in the impact damper that is sized to simultaneously receive all of the guide rails of the selectorized machine. 
     Although embodiments have been described and are shown in the accompanying drawings, it will be appreciated by those skilled in the art that variations and modifications may be made without departing from the scope defined by the appended claims, and the scope of the claims should be given the broadest interpretation consistent with the description and drawings as a whole. 
     While this disclosure has been described as having exemplary designs, the present disclosure can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the disclosure using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this disclosure pertains and which fall within the limits of the appended claims.