Abstract:
A selector of a selectorized dumbbell comprises a keyboard having a plurality of keys that can be depressed into a weight selecting position. In this weight selecting position, a cam actuator on each key forces a pair of connecting pins apart to couple a particular weight to the handle. Preferably, to minimize the risk of accidental weight detachment from the handle, a pair of keys and two pairs of connecting pins couple each weight to the handle in a redundant fashion. The pins in each pair slide apart from one another to couple a weight to the handle and slide towards one another to uncouple a weight from the handle with the sliding motion of the pins being perpendicular to the axis of a hand grip of the handle.

Description:
TECHNICAL FIELD 
     This invention relates to a selectorized dumbbell having a selector that the user manipulates to adjust the mass of the dumbbell by coupling desired numbers of weight plates to each end of a handle. More particularly, this invention relates to a selector that couples the weight plates to the handle in an easy, intuitive and secure fashion. 
     BACKGROUND OF THE INVENTION 
     Selectorized dumbbells overcome the cost and space obstacles presented by traditional dumbbells. In a selectorized dumbbell, a plurality of weights nest together. The weights provide a stack of nested left weight plates and a stack of nested right weight plates. The left and right stacks of weight plates are separated from one another by a gap. 
     In a selectorized dumbbell, a handle is inserted into the gap between the left and right stacks of weight plates. A selector is then manipulated to determine how many of the left and right weight plates of the weights are coupled to the left and right ends of the handle. Once the selector is positioned to pick up a selected number of weights, the handle can then be lifted by the user from between the stacks of weight plates. The selected number of weights will rise with the handle to be used in performing various exercises with the dumbbell. 
     In a typical selectorized dumbbell, an insertable connecting pin comprises the selector to determine which weights are coupled to the handle. The connecting pin is inserted into various different positions relative to the handle and/or the weights. The position of the pin determines how many weights are picked up by the handle. The pin is often coupled to the dumbbell handle by a tether so that it will not be lost. 
     The use of an insertable pin is an effective selector for a selectorized dumbbell. However, it must be on hand to be effective. If it is lost, then no weights can be coupled to the handle until the pin is found or a replacement pin is purchased. While the pin is usually tethered to the handle to minimize the chances that the pin will be lost, the tether itself can get in the way of the user and can be bothersome to some users. 
     In addition, if the pin becomes inadvertently disconnected in some way while the user is exercising, then the weights that had been coupled to the handle by the pin may detach from the handle and fall to the floor. This poses a risk of injury to the user or to a bystander. In addition, the weights may be damaged if they drop to the floor from too high a height. While the instances of a pin becoming disconnected while the dumbbell is being used are rare, they are not totally unknown. 
     Moreover, using a single pin to couple different numbers of weights to the handle means that the pin must be strong enough to hold all of the weights that could possibly be loaded onto the handle. In other words, if the selectorized dumbbell has a maximum mass of 50 pounds when fully loaded, then the connecting pin has to support this maximum mass without deflecting or being broken. While one connecting pin used in a selectorized dumbbell is U-shaped having a pair of connecting prongs, nonetheless this double pronged structure must still be strong enough to support the maximum mass of the dumbbell. Thus, traditional connecting pins used in selectorized dumbbells necessarily have to be fairly large and robust. 
     Finally, some users can be unfamiliar with where and how to properly insert the connecting pin. If the connecting pin is not fully inserted or is improperly inserted, there may be a danger that the pin will become disconnected. This gives rise to the various disadvantages noted earlier. 
     Accordingly, there is a need in the art for a selectorized dumbbell having a selector that is easier and more intuitive to use, that is permanently carried on the handle, and that couples the various weights to the handle in a secure and foolproof manner that minimizes the risk that any weights can be accidentally or inadvertently detached from the handle. 
     SUMMARY OF THE INVENTION 
     One aspect of this invention relates to a selectorized dumbbell. The selectorized dumbbell comprises a plurality of nested weights, a handle, and a selector for coupling selected numbers of weights to the handle. The selector includes a keyboard that is operable by a user to select the weights that are to be coupled to the handle. 
     Another aspect of this invention relates to a selectorized dumbbell which comprises an array of nested weights comprising a stack of nested left weight plates and a stack of nested right weight plates. A handle is provided having a left end and a right end. A selector couples selected numbers of left weight plates to the left end of the handle and selected numbers of right weight plates to the right end of the handle. The selector includes a plurality of keys equal to the number of the weight plates with the keys being placed on a keyboard in an arrangement corresponding to that of the array of nested left and right weight plates. The keys are selectively actuable by a user such that actuation of a key in the keyboard selects for coupling to the handle that weight plate whose position in the array of weight plates is the same as the position of the actuated key in the keyboard. 
     Yet another aspect of this invention relates to a selectorized dumbbell which comprises a plurality of nested weights, a handle, and a selector for coupling selected numbers of weights to the handle. The selector includes a plurality of connecting pins. At least one separate and discrete connecting pin is used to couple each weight to the handle. 
     An additional aspect of this invention relates to a selectorized dumbbell which comprises a plurality of nested weights, a handle, and a selector for coupling selected numbers of weights to the handle. The selector includes a pin array having a plurality of connecting pins whose length increases from one pin to the next. 
     A further aspect of this invention relates to a selectorized dumbbell which comprises a plurality of nested weights which provide a set of nested left weight plates and a set of nested right weight plates separated by a gap. The weights include apertures therein. A handle is provided having a hand grip. The handle is insertable into the gap between the sets of nested left and right weight plates with the handle extending along an axis that is substantially perpendicular to that of the weight plates. A selector is provided for coupling selected numbers of weights to the handle. The selector includes a plurality of individually movable connecting pins carried on the handle with the connecting pins being received in the apertures for connecting the weights to the handle. The apertures and connecting pins are configured to permit the handle to be inserted into the gap in a first position or in a second position that is 180° reversed from the first position without affecting the ability of the apertures and the connecting pins to couple the weights to the handle. 
     One more aspect of this invention relates to a selectorized dumbbell which comprises a plurality of nested weights, a handle, and a selector for coupling selected numbers of weights to the handle. The selector includes a plurality of individually movable connecting pins that can be bi-stably retained in either a first weight coupling position or a second weight uncoupling position. Spring biasing acts on the pins such that the pins cannot be left in an intermediate position between the first and second positions since the spring biasing will then act on the pins to return the pins to one of the first and second positions thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       This invention will be described more completely in the following Detailed Description, when taken in conjunction with the following drawings, in which like reference numerals refer to like elements throughout. 
         FIG. 1  is a perspective view of one embodiment of a selectorized dumbbell according to this invention, particularly illustrating the keys of the keyboard selector located beneath the hand grip of the handle; 
         FIG. 2  is a front elevational view of the selectorized dumbbell of  FIG. 1 ; 
         FIG. 3  is a top plan view of the selectorized dumbbell of  FIG. 1 ; 
         FIG. 4  is a bottom plan view of the selectorized dumbbell of  FIG. 1 ; 
         FIG. 5  is a perspective view of the bottom of the handle of the selectorized dumbbell of  FIG. 1 , particularly illustrating the front and back arrays of connecting pins of the selector; 
         FIG. 6  is an enlarged perspective view of the selector of the selectorized dumbbell of  FIG. 1 , particularly illustrating the keyboard with one of the weight selection keys thereof shown in a raised non-selecting position and the remaining keys thereof being located in a lowered selecting position; 
         FIG. 7  is a cross-sectional view through the selector of  FIG. 6 , particularly illustrating the selector raised above the weight frame of an uncoupled weight with the key that controls the pair of connecting pins for this weight being located in its raised non-selecting position with the pins retracted towards one another; 
         FIG. 8  is a cross-sectional view similar to  FIG. 7 , but particularly illustrating the selector having been lowered into the weight frame of the weight shown in  FIG. 7  and with the key that controls the pair of connecting pins for this weight now shown in its lowered selecting position with the pins extended away from one another to extend into the weight frame of the weight to couple this weight to the handle; 
         FIG. 9  is a perspective view of the connecting rails that form part of the weight frame of each weight, particularly illustrating the pin receiving apertures on the different weight frames and how the weight frames formed by the connecting rails nest inside one another; and 
         FIG. 10  is a side elevational view of the connecting rails shown in  FIG. 9 , but illustrating the connecting rails in an exploded condition to better illustrate the offset placement of the pin receiving apertures on the different weight frames as well as the pin clearance slots on the different weight frames. 
     
    
    
     DETAILED DESCRIPTION 
     One embodiment of a selectorized dumbbell according to this invention is illustrated generally as  2  in  FIG. 1 . Dumbbell  2  is similar to that shown in the Applicants&#39; U.S. Pat. No. 5,769,762, which is hereby incorporated by reference. Dumbbell  2  is also similar to that shown in the Applicants&#39; published U.S. patent application 2004/0162198, which is also hereby incorporated by reference. Only those features of dumbbell  2  which relate to this invention will be described in detail herein. The materials incorporated by reference above can supply other information regarding the general structure and operation of dumbbell  2  in the event the reader hereof desires or requires such information. 
     The Nested Weights of the Dumbbell 
     Dumbbell  2  has six nested weights  4   a - 4   f . See  FIG. 4 . The first weight  4   a  is the innermost weight in the array of nested weights in that it is the shortest and the narrowest weight  4 . The second weight  4   b  is the next outer weight in the array of nested weights  4  in that the second weight  4   b  is a bit longer and wider than the first weight  4   a  to allow the first weight  4   a  to nest within the second weight  4   b . Each adjacent weight  4  continues to be a bit longer and wider than the adjoining inner weight  4  until one reaches the sixth or last weight  4   f  in the array. The weight  4   f  is the longest and widest of the weights  4 . 
     Referring to  FIGS. 1-4 , each weight  4  preferably includes a pair of spaced apart weight plates  6 . Weights  4  thus collectively provide a stack of six nested left weight plates  6   l  and a stack of six nested right weight plates  6   r . Each weight  4  includes one left weight plate  6   l  and one right weight plate  6   r . The number of nested weights  4 , and thus the number of nested left and right weight plates  6   l  and  6   r , can obviously vary. 
     Each weight  4  comprises a weight frame  32  for joining one left weight plate  6   l  and one right weight plate  6   r  together in the spaced apart orientation. Weight frame  32  comprises generally upright front and back walls  31   f  and  31   b . Front and back walls  31   f  and  31   b  are formed by the elongated main bodies of a pair of steel rails, namely a front rail  30   f  and a back rail  30   b . Each steel rail  30  has inturned opposite ends  34 . 
     Weight frame  32  also comprises a pair of carriers  14  secured to opposite ends of rails  30 . One carrier  14  holds the left weight plate  6   l  and the other carrier  14  holds the right weight plate  6   r . Thus, each weight  4  includes a pair of rails  20 , a pair of carriers  14 , and a pair of weight plates comprising one left weight plate  6   l  and one right weight plate  6   r . 
     Each carrier  14  is made in two halves  14   a  and  14   b  as indicated in  FIG. 4  by the parting line  15  between halves  14   a ,  14   b . The inturned ends  34  of rails  30  are bolted between carrier halves  14   a ,  14   b  to attach rails  30  to carriers  14  to thereby make up one weight frame  32 . Each carrier  14  includes a pair of upwardly extending arms  12  with one arm  12  being provided on each carrier half  14   a  or  14   b . A single weight plate  6  is held between the arms  12  of each carrier  14  by a cross hub (not shown) formed on arms  12  extending through a central hole (not shown) in each weight plate  6 . A fastener, such as a bolt  26 , is used to secure arms  12  together with weight plate  6  held therebetween. 
     Weight frames  32  of weights  4  are progressively longer from side to side as one proceeds from the innermost weight  4   a  to the outermost weight  4   b . Thus, the left and right weight plates  6   l  and  6   r  of each weight  4  are progressively spaced further and further apart. This is what provides the stack of nested left weight plates  6   l  and the stack of nested right weight plates  6   r  separated from one another by a gap. This gap is long enough to allow a handle  8 , which will be described in more detail hereafter, to be dropped down or inserted into the gap between the separated stacks of nested left and right weight plates  6   l  and  6   r . 
     In addition, weight frames  32  of weights  4  are progressively wider from front to back as one proceeds from the innermost weight  4  to the outermost weight  4 . Thus, the front walls  31   f  of each weight frame  32 , which are formed respectively by front rails  30   f , nest closely adjacent one another. Similarly, the back walls  31   b  of each weight frame  32 , which are formed respectively by back rails  30   b , also nest closely adjacent one another. See  FIG. 9  which shows the two nested stacks of front and back walls  31   f  and  31   b  separated from one another across the front to back width of dumbbell  2 . As will be described hereafter, front and back walls  31  of weight frames  32  have apertures  80  that coact with a selector  10  to determine which weights are coupled to handle  8 . 
     The construction of weights  4  can vary. For example, each carrier  14  could comprise an integral, single ear or tongue bent up out of each end of a metallic, channel shaped weight frame as shown in the published patent application earlier incorporated by reference herein. Alternatively, weight plates  6  could simply be welded to opposite ends of a metallic weight frame without using an intervening carrier  14  as shown in the issued patent earlier incorporated by reference herein. Moreover, each weight  4  could comprise only a single weight plate  6  rather than a construction which employs two spaced weight plates  6 . In this latter alternative, the stacks of nested left and right weight plates  6  would be provided simply by a plurality of separate weights  4  grouped into such stacks. 
     The Handle of the Dumbbell 
     Handle  8  of dumbbell  2  includes a pair of generally vertically extending ends  40  that are spaced apart a distance at least slightly less than the distance between weight plates  6   l  and  6   r  of innermost weight  4   a . A hand grip  42  extends between and is secured to ends  40  of handle  8 . Hand grip  42  extends along the longest axis of dumbbell  2  such that hand grip  42  is perpendicular to weight plates  6 . As is well known for selectorized dumbbells, handle  8  can be dropped down between the stacks of nested left and right weight plates  6   l  and  6   r  to couple desired numbers of such weight plates to ends  40  of handle  8 . 
     A space  44  is provided between each end  40  of handle  8  and the left weight plate  6   l  and the right weight plate  6   r  of innermost weight  4   a . This permits an auxiliary weight (not shown) to be fastened to the outside of each end  40  of handle  8  by any suitable means. For example, the auxiliary weight could simply be bolted to the outside of each end  40  of handle  8 . When so affixed, one auxiliary weight would be located in each space  44 . 
     Each auxiliary weight will preferably be approximately ½ the weight of each weight plate  6  and thus approximately ¼ of the weight of each entire weight  4 . This provides an incremental adjustment capability to dumbbell  2  to permit the user to select increments in between the usual exercise masses provided by dumbbell  2 . For example, if the auxiliary weights are in use, the user is able to select 15 pounds instead of 10 pounds, 25 pounds instead of 20 pounds, and so on. Alternatively, the spaces  44  shown in the drawings between each end of handle  8  and the left and right weight plates  6   l  and  6   r  of the innermost weight  4   a  could be eliminated. In this case, each end  40  of handle  8  would be closely adjacent against the left and right weight plates  6   l  and  6   r  of the innermost weight  4   a . 
     Ends  40  of handle  8  are also connected at their bottoms by a floor  46 . Floor  46  serves as a mount or support for selector  10 . Preferably, floor  46  overlies substantially the entire front to back width of dumbbell  2  with the underside of floor  46  resting on top of the front and back rails  30  of the various weight frames  32 . The front of floor  46  includes an L-shaped guard  48 , whose purpose will be described in more detail hereafter. 
     The Selector of the Dumbbell 
     Dumbbell  2  of this invention includes a novel selector  10  for coupling weights  4  to handle  8 . Selector  10  is carried on floor  46  of handle  8 . Selector  10  comprises a keyboard  50  having a plurality of side by side weight selection keys k. Selector  10  also comprises a plurality of weight connecting pins  52  that are actuated by movement of weight selection keys k. Keys k and connecting pins  52  together couple desired numbers of weights  4  to handle  8  of dumbbell  2  to selectively vary the exercise mass. 
     Referring now to  FIGS. 6-9 , keyboard  50  of selector  10  is carried atop floor  46  of handle  8  to be easily accessible to the user. Keyboard  50  comprises a plurality of keys k that are pivotally mounted on a pivot shaft  54  carried along the back side of floor  46 . Each key k extends across floor  46  from its connection to pivot shaft  56  to terminate in a front end  58  adjacent to and overlying front walls  31   f  of weight frames  32 . Preferably, keys k are long enough so that front ends  58  of keys k project forwardly past the front edge of floor  46  and past front walls  31   f  of weight frames  32 . This enables a user to place a finger beneath front end  58  of each key to lift up on key k when so desired. 
     Each key k in keyboard  50  can be lifted into a raised position shown in  FIGS. 6 and 7 . In this raised position, key k is inclined upwardly relative to floor  46  and abuts with the underside of a bridge  60  that overlies front ends  58  of keys k. The raised position of key k is a weight non-selecting position. Each key k in keyboard  50  can also be pushed down or depressed into a lowered position shown in  FIG. 8 . In this lowered position, key k lies flat atop floor  46 . The lowered position of key k is a weight selecting position. 
     There are two weight selection keys k for each nested weight of dumbbell  2 . Because there are six weights, there are twelve keys k. Keys k are arranged from side to side across keyboard  50  in the following pattern when looking at the front of keyboard  50  and when going from left to right:
 
12 10 8 6 4 2 1 3 5 7 9 11   Numbered Key Pattern.
 
Keys k 1  and k 2  are used to select the innermost weight  4   a , keys k 3  and k 4  are used to select the next outer weight  4   b  comprising the second weight  4  in the array of nested weights  4 , keys k 5  and k 6  select the third weight  4   c , and so on with keys k 11  and k 12  selecting the outermost weight  4   f .
 
     Depressing only one key k in each pair of keys k is effective to select the corresponding weight  4  for coupling to handle  8 . For example, referring to  FIGS. 6 and 7 , both keys k in the key pairs for the first five weights  4   a - 4   e  are shown depressed into their weight selecting positions. However, for the key pair comprising keys k 11  and k 12  for the sixth and outermost weight  4   f , key k 11  is shown in its raised non-selecting position while key k 12  is shown in its depressed selecting position. Nonetheless, the sixth weight  4   f  will still be selected just like the first five weights  4   a - 4   e  and will be coupled to handle  8  such that handle  8  when lifted will carry all six weights  4   a - 4   f  with it. 
     The use of a pair of keys k to select each weight  4  for coupling to handle  8  is a safety feature. If only a single key k were used and that key k were inadvertently lifted when dumbbell  2  was in use, it would be possible for the weight corresponding to that key k to become detached from handle  8 . However, it is highly unlikely that both keys k in a particular pair used to select a particular weight would be inadvertently dislodged or lifted at the same time. Thus, by using a pair of keys k for each weight  4  with either key k alone being sufficient to select the weight, the chances of unintentionally uncoupling a particular weight  4  from handle  8  are diminished. However, if so desired, keyboard  50  could be arranged with only six keys k for selecting the six different weights  4   a - 4   f , with the added safety provided by the key pairs then being absent. 
     Another safety feature is a positive interlock between keys k in which the left or even numbered keys are interlocked together and the right or odd numbered keys are also interlocked together. The term “interlock” or “interlocked” in this regard means that depressing any one of the interlocked keys requires that all of the inboard keys in the interlocked set must also be depressed. 
     To illustrate the interlock principle, assume we are looking at just the six interlocked left keys as follows:
 
12 10 8 6 4 2.
 
If the user depresses key k 6 , then keys k 4  and k 2  (i.e. the keys that are inboard of key k 6  in the set of interlocked left keys) must also be depressed. The same principle applies to the odd numbered keys as follows:
 
1 3 5 7 9 11.
 
For example, if the user depresses key k 7 , then the three inboard keys k 1 , k 3  and k 5  must also be depressed. The interlock functions only one way however, namely when keys k are being depressed. If in the last example key k 7  is being lifted, then keys k 1 , k 3  and k 5  are not required to be lifted as well. They can remain depressed.
 
     The interlock of the even numbered keys to one another and the odd numbered keys to one another is achieved by a inwardly extending lateral tab  62  on all but the innermost key in each set of interlocked keys. Tab  62  is designed to fit into an upwardly facing mating recess  64  on all but the outermost key in each set of interlocked keys. Thus, again taking the example of the odd numbered keys:
 
1 3 5 7 9 11,
 
then keys k 3 , k 5 , k 7 , k 9  and k 11  all have lateral tabs  62  on their inner sides while keys k 1 , k 3 , k 5 , k 7 , and k 9  all have upwardly facing mating recesses  64  in their outer sides to receive the inwardly extending lateral tabs  62  on the adjacent keys k.  FIG. 6  shows one such tab  62  on the raised key k 11  that will engage in recess  64  on the inner adjacent key k 9 . The same tab/recess arrangement is used on the even numbered keys.
 
     If one assumes that all of keys k are initially in their raised non-selecting positions, depressing any even or odd numbered key will force or depress all of the remaining and inboard even or odd numbered keys down as well. This is due to the interaction of each tab  62  with recess  64  in each adjacent key. For example, referring once again to the odd numbered keys:
 
1 3 5 7 9 11,
 
assume all keys k are raised and then key k 5  is depressed. If key k 5  is depressed, then tab  62  on key k 5  will push downwardly on recess  64  in key k 3  to depress key k 3 , and tab  62  on key k 3  will also push downwardly on recess  64  in key k 1  to depress key k 1 . Thus, pushing down any key in either the odd or even numbered sets of keys necessarily depresses the other inboard keys in the same set of keys.
 
     As will be described hereafter, keys k are acted upon by a spring bias such that the user must depress keys k against the spring bias. If a user pushes down on one key in the odd or even numbered sets of keys, the user must overcome the bias on that key as well as the bias on all of the inboard keys in that interlocked set. This is fairly easy to do if one, two or perhaps three keys are being pushed down or depressed simultaneously, However, it becomes more difficult to do if one attempts to depress all six keys by just pushing down on the outermost key in the set, e.g. if one attempts to depress keys
 
1 3 5 7 9 11
 
just by pushing down on key k 11 . In this situation, the user would push down keys k in groups beginning with the inner keys and working out to the outer keys. For example, the user would first push down keys k 1  and k 3 , then move out and push down keys k 5  and k 7  next, and then finally move further out and push down keys k 9  and k 11  last.
 
     If desired, indicia could be provided somewhere on handle  8  for use with keys k to indicate how much dumbbell  2  weighs when particular pairs of keys are depressed. For example, indicia could be printed, stamped or molded on the top of bridge  60  to overlie the raised outer end  58  of each key k when key k is in its raised non-selecting position. Assuming the nominal weight of handle  8  is 5 pounds and each weight adds 10 pounds to handle  8 , then bridge  60  would be labelled to show the six different exercise masses that could be selected. The indicia on bridge  60  could be in the following pattern corresponding to the pattern of the keys k: 
     
       
         
               
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                   
               
             
             
               
                 65 
                 55 
                 45 
                 35 
                 25 
                 15 
                 15 
                 25 
                 35 
                 45 
                 55 
                 65 
                 Indicia Pattern; 
               
               
                 12 
                 10 
                 8 
                 6 
                 4 
                 2 
                 1 
                 3 
                 5 
                 7 
                 9 
                 11 
                 Key Pattern. 
               
               
                   
               
             
          
         
       
     
     Thus, a user would know which keys to depress to pick a particular exercise mass. If the user wanted dumbbell  2  to weigh 35 pounds in the above example, then the user would depress the following keys from the odd and even numbered sets of keys:
 
6 4 2 1 3 5.
 
If the user wanted only 15 pounds, then the user would depress only the following keys:
 
2 1.
 
     The nature of the indicia placed on bridge  60  could obviously vary. In addition, instead of indicia printed on bridge  60  or some other portion of handle  8 , keys k could themselves be labelled or color coded to indicate the various weights that can be selected. 
     Each key k includes a downwardly pointing, double lobed cam actuator  66  on the underside thereof. Cam actuator  66  has a rounded front cam lobe  67   f  and a rounded back cam lobe  67   b . In addition, cam actuator  66  includes a recessed detent  65  above each of the front and back cam lobes  67   f  and  67   b . 
     Cam actuators  66  on all keys k are received over in a slot  68  in floor  46  of handle  8 . In the raised non-selecting position of a key k, the cam actuator  66  carried by that key k is raised upwardly relative to floor  46  of handle  8  such that cam actuator  66  projects only a small distance into slot  68 . This is shown in  FIG. 7 . In the lowered selecting position of key k, cam actuator  66  is lowered downwardly relative to floor  46  of handle  8  such that cam actuator  66  now projects a greater distance downwardly into slot  68 . This is shown in  FIG. 8 . 
     Cam actuator  66  on each key k operates on a pair of front and back connecting pins  52   f  and  52   b . There are twelve keys k with twelve cam actuators  66  so there are twelve pairs of front and back connecting pins  52   f  and  52   b . Thus, there are twelve front connecting pins  52   f  contained in a front pin array  70   f  on a front pin block  72   f  on the underside of floor  46  of handle  8 . Similarly, there are twelve back connecting pins contained  52   b  in a back pin array  70   b  on a back pin block  72   b  on the underside of floor  46  of handle  8 . See  FIG. 5  which illustrates both the front and back pin arrays  70   f  and  70   b  contained on the underside of floor  46  of handle  8 . 
     Each connecting pin  52  has an arrow shaped head  74  connected to an outwardly extending shaft  76 . Shaft  76  of pin  52  passes through a bore in that pin block  72  in which pin  52  is slidably contained. A spring  78  is compressed between the inner side of pin block  72  and the back side of head  74  of pin  52 . Spring  78  biases pin  52  inwardly relative to floor  46  of handle  8  to move head  74  of pin  52  towards the center of floor  46 . 
     Head  74  of pin  52  abuts against one of the cam lobes  67  on cam actuator  66  of key k. Head  74  of front connecting pin  52   f  abuts against front cam lobe  67   f  on cam actuator  66  while head  74  of back connecting pin  52   b  abuts against back cam lobe  67   b  on cam actuator  66 . This is depicted in  FIGS. 7 and 8  which show how heads  74  of the front and back connecting pins  52   f  and  52   b  in each pair point inwardly towards one another to ride on the oppositely disposed cam lobes  67   f  and  67   b  of cam actuator  66 . 
     When each key k is in its raised non-selecting position, cam actuator  66  is raised sufficiently so that the front and back connecting pins  52   f  and  52   b  controlled by that cam actuator  66  are able to slide towards one another. Heads  74  of pins  52  are able to contact or closely approach one another. The bias of springs  78  urges pins  52  inwardly towards one another. In the non-selecting position as shown in  FIG. 7 , the outer ends of shafts  76  of pins  52  are retracted into the front and back pin blocks  72 . 
     If the user now depresses key k, as shown in  FIG. 8 , the front and back connecting pins  52   f  and  52   b  in this pair of pins  52  move or slide apart in opposite directions from one another. This is caused by the increasing depth of the cam profiles of the front and back cam lobes  67   f  and  67   b , namely connecting pins  52  get cammed apart by cam actuator  66  as key k is forced downwardly. Once key k is fully depressed, the front and back cam lobes have slipped below heads  74  of pins  52  and heads  74  of pins  52  are now held in detents  65  located immediately above cam lobes  67 . In this position, shafts  76  of connecting pins  52  have now been extended or projected out of the front and back pin blocks  72 . The outer ends of shafts  76  are now exposed and can be used to couple one weight  4  to handle  8 . 
     As shown in  FIGS. 9 and 10 , the front and back walls  31  of each weight frame  32  of each weight  4  have apertures  80  therein for receiving the outer ends of shafts  76  of connecting pins  52  when such shafts project outwardly from the front and back pin blocks. In other words, for each pair of connecting pins  52 , there is one aperture  80  in each front wall  31   f  and one aperture  80  in each back wall  31   b  of each weight frame  32 . Because selector  10  desirably uses two keys k to select each weight  4 , and because each key k actuates its own separate pair of connecting pins  52 , there are actually two apertures  80  on each of the front and back walls  31   f  and  31   b  of each weight frame  32 . Thus, when the pair of keys k used to select each weight  4  are both depressed, a total of four connecting pins  52  project through a total of four apertures  80  on each weight  4 . 
     Apertures  80  in front and back walls  31  of the nested weight frames  32  are staggered in a chevron like manner as shown in  FIGS. 9 and 10 . In other words, beginning with weight frame  32  of innermost weight  4   a , the two apertures  80  in wall  31  are arranged at the center of wall  31 . Apertures  80  in wall  31  of the next outer weight  4   b  are slightly spread apart from one another to lie on either side of apertures  80  in the first weight  4   a . Similarly, apertures  80  in wall  31  of the third weight  4   c  are further spread apart from one another to lie on either side of apertures  80  in the second weight  4   b , and so on all the way out to the sixth and outermost weight  4   f . Thus, looking at  FIG. 9 , one can see that apertures  80  are arranged along the inclined sides of a chevron shape. Apertures  80  are identical whether one is describing the front walls  31   f  or the back walls  31   b  of each weight frame  32 . 
     Each front and back wall  31  also include a pair of slots  82  outboard of apertures  80  in front and back walls  31 . These outboard slots  82  are sized and arranged to allow for the passage of the connecting pins  52  used for the other outer weights  4 . For example, referring to wall  31  of weight frame  32  of innermost weight  4   a , two large outboard slots  82  are provided on either side of the two central apertures  80 . These outboard slots  80  are placed in front of all of apertures  80  in the walls  31  of the other weights  4   b - 4   f  such that these apertures are exposed to receive their own respective connecting pins  52 . In other words, outboard slots  82  are needed to prevent one weight  4  from blocking access to the apertures  80  in the other outer weights  4 . 
     The size and location of outboard slots  82  used for pin clearance necessarily vary from weight to weight. Referring to  FIG. 10  and looking at wall  31  of the second weight  4   b , outboard slots  82  are shorter and further out than slots  82  in the first weight  4   a . Similarly, looking at wall  31  of the third weight  4   c , outboard slots  82  are still shorter and further out than outboard slots  82  in the second weight  4   b , and so on all the way out to the outermost or sixth weight  4   f . This last weight has no slots  82  outboard of apertures  80  therein since there are no other weights that are nested outside of the last weight  4   f . 
     In addition to outboard slots  82 , walls  31  of weights  4 , except for walls  31  of the first or innermost weight  4   a , also have a slot or slots  84  inboard of apertures  80 . Inboard slots  84  lie immediately behind apertures  80  in the preceding weight  4 . In other words, the single inboard slot  84  in the second weight  4   b  lies immediately behind the two apertures  80  in the first weight  4   a  The pair of inboard slots  84  in the third weight  4   c  lie immediately behind the two apertures  80  in the second weight  4   b  and so on. 
     Inboard slots  84  allow the outer ends of shafts  76  of connecting pins  52  used to couple the preceding weight to project into inboard slots  84  to accommodate small tolerance variations in the length of shafts  76 . In other words, it is not critical that each shaft be closely controlled as to length. If one shaft  76  is a bit longer than another, the longer shaft  76  will simply extend slightly into the inboard slot or slots  84  provided therefor in the following weight  4 . 
     As seen most clearly in  FIG. 5 , shafts  76  of the various connecting pins  52  also have a progressively varying length as one proceeds from connecting pins  52  used for the innermost weight  4   a  to connecting pins  52  used for the outermost weight  4   f . Thus, the outer ends of shafts  76  of connecting pins  52  in both the front and back pin arrays  70   f  and  70   b  also have a chevron shape similar to the chevron shape of apertures  80  in walls  31  of weight frames  32 . This is desirable since the travel or distance that each pin  52  must be thrown in order to couple to its respective weight  4  is approximately the same. Thus, heads  74  of pins  52 , and the profiles of the cam lobes  67  on cam actuators  66 , can be identical irrespective of which pins  52  in the arrays  70  are being actuated. 
     In addition, because of the increasing length of shafts  76  of pins  52 , the shafts  76  of the pins for the outer weights  4  necessarily overlie the side walls  31  of the inner weights  4 . However, this overlying is permitted because of the outboard slots  82  in the side walls  31 . 
     With selector  10  of this invention, connecting pins  52  in the front and back pin arrays  70   f  and  70   b  must be aligned with the various apertures  80  in front and back walls  31   f  and  31   b  of weight frames  32 . If they are misaligned, a pin  52  may not properly enter its respective aperture  80 . Desirably, weight frames  32  and selector  10  will simply be manufactured precisely enough to ensure such alignment. 
     However, if need be, various ways could be utilized to ensure alignment to permit proper pin and aperture registration. As shown in  FIGS. 9 and 10 , weight frame  32  of the outermost weight  4   f  can include a pair of alignment bars  86  extending between front and back walls  31   f  and  31   b  thereof. Each weight frame  32  of the inner weights  4   a  - 4   e  would include a pair of downwardly facing alignment notches  88  in front and back walls  31  for receiving alignment bars  86 . Thus, when all six weights are nested together, notches  88  in the inner five weights  4   a - 4   e  will be received on alignment bars  86  of the sixth weight  4   f  to ensure that all of the apertures  80  will be properly aligned with connecting pins  52  to smoothly receive connecting pins  52 . Alignment bars  86  could also be provided on a stand for holding dumbbell  2  in which case even the outermost weight  4   f  would include the alignment notches  88 . 
     Other ways of dealing with this alignment issue could be utilized. The outer ends of shafts  76  of connecting pins  52  could be chamfered to make pins  52  self aligning in apertures  80 . Alternatively, apertures  80  themselves could be elongated or oval in nature to provide extra tolerance for receiving shafts  76  of connecting pins  52 . 
     Selector  10  of this invention is intuitive and easy to use. The user will easily and quickly understand that all that needs to be done is to depress keys k for whatever exercise mass is desired. This intuitive understanding is enhanced since the twelve keys in the key pattern, namely keys:
 
12 10 8 6 4 2 1 3 5 7 9 11
 
correspond visually and operationally to the six left weight plates  6   l  and the six right weight plates  6   r . In effect, the user is looking at the weight plates as the user looks at the keyboard. If the user wants to select the three inner left weight plates  6   l  and the three inner right weight plates  6   r  of the first three inner weights  4   a - 4   c , the user need only depress the corresponding three left inner keys k 6 , k 4 , k 2  and the three right inner keys k 1 , k 3 , k 5 . These are simply the keys which occupy the same positions in keyboard  50  as do the desired nested left and right weight plates  6   l  and  6   r  within the entire assembly of weights  4 .
 
     There is also no need to have a separate connecting pin that needs to be manually inserted into different slots or locations on handle  8  or on weight frames  32 . Keyboard  50  is always in place and never changes location on handle  8 . Keyboard  50  simply invites the user to press down those keys k that are needed to select the desired weights  4 . 
     In addition, weights  4  in dumbbell  2  are now individually pinned or coupled to handle  8  using discrete connecting pins  52  dedicated to the coupling of each weight  4 . If three weights  4  are coupled to handle  8 , a total of twelve pins  52  (four pins  52  per weight) take the load, instead of only a single or double pronged connecting pin as in prior art selectorized dumbbells. Thus, connecting pins  52  can be made lighter and smaller and can even be molded out of a rigid plastic material, thereby facilitating permanent placement on handle  8 , since they individually need not carry an extremely heavy load. Pins  52  could also be molded out of a UHMW-PE material that would deform without breaking when such pins  52  see an impact load. The number of connecting pins used increases with the increasing weight of dumbbell  2 . 
     In addition, the keyboard/connecting pin arrangement shown herein is believed to be safer and more reliable in operation. Because two keys k are used to couple each weight  4  to handle  8  using two pairs of front and back connecting pins  52 , it is unlikely that both keys k would be inadvertently disengaged at the same time. Thus, even if one key k were inadvertently lifted, the other key will remain depressed with its pair of connecting pins  52  still coupling the selected weight to handle  8 . The presence of the L-shaped guard  48  on the front of floor  46  of handle  8  further protects keys k from accidentally being pushed up or lifted by banging the front side of dumbbell  2  down onto the edge of a stand, workout bench or rack. The impact will be taken by guard  48  and not keys k. 
     The spring bias on connecting pins  52  also ensures that each key k is positively held in either the lowered selecting position or the raised non-selecting position. If a key k is only partially depressed and then released, the spring bias on connecting pins  52  will act on the cam lobes to cause key k to return all the way back up to its raised non-selecting position. Key k must be firmly depressed all the way to its lowered selecting position in order to be retained therein with heads  74  of connecting pins  52  then held in the detents  65  located above the cam lobes  67 . Thus, keys k are held in bi-stable positions comprising either the raised or lowered positions and cannot be inadvertently disposed or hung up in between such positions. 
     Pin arrays  70  are mirror images relative to one another. In addition, the pins  52  in each array  70  are disposed in mirror images along each side of the chevron. Moreover, apertures  80  are disposed in mirror image sets in the front and rear side walls. Thus, if a user picks up handle  8  with some weights  4  attached, and then inadvertently replaces handle  8  in a reversed position that is 180° offset from the position in which handle  8  was picked up, it will not matter to the proper functioning of dumbbell  2 . All the apertures  80  and connecting pins  52  will still be properly aligned regardless of whether handle  8  is reversed when it is set back down between the stacks of nested left and right weight plates  6 . 
     The ability of selector  10  to work properly whether handle  8  is reversed or not when it is set down between the stacks of nested left and right weight plates  6  is desirable. In a showroom setting, users who are unfamiliar with the equipment will often replace handle  8  in a 180° reversed position. If the selector  10  were designed so that it would not properly work if this were to occur, i.e. if handle  8  always had to be replaced in the same orientation as when it was picked up, this would give the erroneous impression that the dumbbell was broken. Having a dumbbell whose selector  10  will function exactly the same in either possible position of handle  8  avoids giving this impression and is also much easier to use since the user need not pay attention to the precise position of handle  8 . 
     It would be possible for only a single key k and pair of connecting pins  52  arranged on the centerline of the innermost weight  4   a  to be used in place of the pair of keys k 1  and k 2  and the dual pairs of connecting pins  52 . Such a single key k would lie exactly along the apex of the chevron shape of the front and back pin arrays  70 . Such a construction would still provide a reversible handle  8  as described above. However, it is preferred that the innermost weight  4   a  use a pair of keys so that its operation is like that of all the other weights. 
     Various modifications of this invention will be apparent to those skilled in the art. For example, weight frames  32  could be split in half such that each left weight plate  6   l  is no longer coupled to each right weight plate  6   r . Each left weight plate  6   l  would be individually coupled to handle  8  using one of the even numbered keys k and each right weight plate  6   r  would be similarly individually coupled using the odd numbered keys k. Such an arrangement would allow different numbers of weight plates to be simultaneously coupled to the left and right ends of handle  8 . 
     In addition, while apertures  80  have been shown as being contained within the height of side walls  31 , apertures  80  could be provided in tabs that project upwardly from the top edges of side walls  31 . In this case, the outboard and inboard slots  82  and  84 , respectively, would not need to be present as the open spaces above the side walls on either side of the tabs would serve the same purposes as slots  82  and  84 . 
     Thus, the scope of this invention is to be limited only by the appended claims.