Abstract:
A method of use of a rake for gathering material in a raking mode and a picking mode, the method comprising the steps of: pivotally mounting a first rake head and a second rake head between an upper bracket and a lower bracket, said upper bracket being coupled to a handle; articulating said first rake head and said second rake head for axial alignment therebetween to place said rake in said raking mode; engaging a stop mechanism associated with said upper bracket to maintain said rake in said raking mode; and disengaging said stop mechanism and articulating said first rake head and said second rake head to pivot said first rake head and said second rake head towards each other to place said rake in said picking mode.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to tools for gathering and disposing of yard debris and other similar material. 
         [0003]    2. Description of the Related Art 
         [0004]    There are several types of commercially available rakes that can pick up gathered debris, such as leaves, grass cuttings, thatch, flower or plant clippings, even pine needles and cones, and deposit the debris into a collection bag or a wheelbarrow. For example, rakes comprising two rake heads operable to grasp debris are well known. One such rake is a combination of two rakes with their rake heads facing each other and their handles joined scissors style at a point somewhere along their handles. The rake heads are caused to close on the debris by forcing the handles towards each other. Another type of a rake comprises two rake heads, symmetrical in structure, mutually hinged and connected to a handle. The handle supports mechanism for opening and closing the two rake heads, which comprises a pair of cables connected to the rake heads which are pulled or slackened to open and close the rake heads. Yet another rake comprises a sleeve, a first tine head secured on the sleeve, a second tine head rotatably secured on the sleeve and rotatable from an open position to a folded position, and a means for rotating the second tine head towards the first tine head at the folded position. However, these prior art rakes are complicated and difficult to use, non-ergonomic, and also have low pick-up volumes. 
         [0005]    It is an object of the present invention to mitigate or obviate at least one of the above-mentioned disadvantages. 
       SUMMARY OF THE INVENTION 
       [0006]    In one of its aspects, there is provided a rake comprising: 
         [0007]    a handle with an upper portion, an intermediate portion and a lower portion; 
         [0008]    a pair of oppositely disposed frames pivotally attached to said lower portion, said pair of oppositely disposed frames having a plurality of tines; 
         [0009]    an articulating mechanism comprising:
       a pair of rods fixedly coupled to said lower portion;   a handle collar slidable on said handle, said handle collar coupled to a rod collar slidable on one of said pair of rods;   a pair of connector rods hingedly coupled between said collar and said pair of oppositely disposed frames;   whereby sliding said handle collar causes said rod collar to slide in sympathy and provides a force to said pair of connector rods to pivot said pair of oppositely disposed frames towards one other or away from one another.       
 
         [0014]    In another of its aspects, there is provided a method of use of a rake for gathering material in a raking mode and a picking mode, the method comprising the steps of: 
         [0015]    pivotally mounting a first rake head and a second rake head between an upper bracket and a lower bracket, said upper bracket being coupled to a handle; 
         [0016]    articulating said first rake head and said second rake head for axial alignment therebetween to place said rake in said raking mode; 
         [0017]    engaging a stop mechanism associated with said upper bracket to maintain said rake in said raking mode; 
         [0018]    disengaging said stop mechanism and articulating said first rake head and said second rake head to pivot said first rake head and said second rake head towards each other to place said rake in said picking mode. 
         [0019]    Advantageously, the rake facilitates lifting and disposal of debris and provides an articulated frame structure having rake tines such that the articulated frame structure can be moved between an extended open position for the gathering of debris, and a pivoted position wherein the frame structure is pivoted to partially enclose the gathered debris for picking up of same. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    Several preferred embodiments of the present invention will now be described, by way of example only, with reference to the appended drawings in which: 
           [0021]      FIG. 1  shows is a perspective view of a pivoting garden rake in an extended-open position, in one exemplary embodiment; 
           [0022]      FIG. 2  is a profile view of the rake of  FIG. 1  in a closed position, showing a mechanism for opening and closing an articulated frame, proximal and distal pivot brackets, front and rear fixed rods, sliding handle collar, auxiliary sliding rod collar, connecting members and connector rods and tines; 
           [0023]      FIG. 3  is a transverse cross section bottom-up view of the rake of  FIG. 1  taken along line A-A′ showing proximal pivot bracket with partial gear upper pivots, and stop assembly; 
           [0024]      FIG. 4  is a transverse cross section top-bottom view of the rake of  FIG. 1  taken along line B-B′ showing distal bracket with the partial gear lower pivots, and connector rods; 
           [0025]      FIG. 5   a  is a transverse cross section profile view of the rake of  FIG. 1  taken along line C-C′ showing a stop assembly in a disengaged position; 
           [0026]      FIG. 5   b  is a transverse cross section profile view of the rake of  FIG. 1  taken along line C-C′ showing the stop assembly in an engaged position; 
           [0027]      FIG. 6  is a traverse section of the rake of  FIG. 1  taken along line A-A′ showing a bottom up view of the proximal bracket with modified upper pivots, right and left proximal traverse upper arms with modified flat tines and female right and left cylindrical receptors of a modified stop mechanism, in another embodiment; 
           [0028]      FIG. 7  is a traverse section of the rake of  FIG. 1  taken along line B-B′ showing top-bottom view of the distal bracket showing the modified lower pivots, right and left distal traverse lower arms with modified flat tines, in another embodiment; 
           [0029]      FIG. 8   a  is transverse cross section profile view of the rake of  FIG. 1  taken along line C-C′ showing a stop assembly in a disengaged position, in another embodiment; 
           [0030]      FIG. 8   b  is a transverse cross section profile view of the stop assembly of the rake of  FIG. 1  taken along line A-A′, in another embodiment; and 
           [0031]      FIG. 8   c  is transverse cross section profile view of the rake of  FIG. 1  taken along line C-C′ showing the stop assembly in an engaged position, in another embodiment. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0032]    The detailed description of exemplary embodiments of the invention herein makes reference to the accompanying block diagrams and schematic diagrams, which show the exemplary embodiment by way of illustration and its best mode. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be realized and that logical and mechanical changes may be made without departing from the spirit and scope of the invention. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation. For example, the steps recited in any of the method or process descriptions may be executed in any order and are not limited to the order presented. 
         [0033]    Moreover, it should be appreciated that the particular implementations shown and described herein are illustrative of the invention and its best mode and are not intended to otherwise limit the scope of the present invention in any way. 
         [0034]    More particularly, in one exemplary embodiment of the invention, there is provided a pivoting rake frame comprising an elongated handle with a proximal and a distal end. An articulated frame structure having tines is attached to the distal end of the handle for articulated movement between extended-open and the enclosed positions about two axes of articulation or pivoting axis coaxial with the longitudinal axis of the handle. An articulating assembly comprising a set of two pivot brackets with two fixed rods attached to the handle at the distal end allows for the pivoting of the articulated frame structure. A stop mechanism allows the articulated frame structure to remain in an extended-open position for gathering of debris. 
         [0035]    With reference to  FIG. 1 , there is shown a rake, generally designated by the numeral  10 , in one exemplary embodiment. The rake  10  comprises an elongate handle  12  with an upper portion  14 , an intermediate portion  16  and a lower portion  18 . Pivotally attached to lower portion  18  is an articulated frame structure  19  comprising a pair of oppositely disposed rake heads  20 ,  22  having a plurality of tines  24 ,  26 , secured to upper arms  28 ,  30  and lower arms  32 ,  34 . Tines  24 ,  26  are suitably dimensioned and separated for gathering yard debris, such as, leaves, grass cuttings, thatch, flower or plant clippings, even pine needles and cones. Accordingly, tines  24 ,  26  are equally spaced apart and have a generally curved cross section for improved strength and durability. Fixedly coupled to lower portion  18  is articulating mechanism  27  actuated to cause rake heads  20 ,  22  to move, thereby placing rake  10  in a raking mode for gathering debris, or a picking mode for grasping and picking up and/or transporting the debris. 
         [0036]    As shown in  FIGS. 2 and 3 , articulating mechanism  27  comprises a pair of rods  36 ,  38 , fixedly attached between upper pivot bracket  40  coupled to lower portion  18  of handle  12  on outer face  41 , and a lower pivot bracket  42 . The rods  36 ,  38  are received by guiding sockets  43   a ,  43   b  formed with upper pivot bracket  40 , and guiding sockets  43   c ,  43   d  formed in lower pivot bracket  42 . Upper arm  28  comprises a proximal end  44  with a partial gear  46  for rotational movement within socket  47  formed on inner face  48  of bracket  40 , and a free distal end  49 . Correspondingly, upper arm  30  comprises a proximal end  50  with a partial gear  52  for rotational movement within socket  53  (not shown) in bracket  40 , and a free distal end  54 . Partial gears  46 ,  52  are coupled to upper arms  28 ,  30  via linking arms  55 ,  56 , respectively, and comprise gear teeth  57 ,  58  that intermesh. 
         [0037]    Now looking at  FIG. 4 , there is shown lower arms  32 ,  34  of the articulated frame structure  19 . Lower arm  32  comprises a proximal end  60  with a partial gear  62  for rotational movement within socket  63  (not shown) of bracket  42 , and a free distal end  64 . Correspondingly, lower arm  34  comprises a proximal end  66  with a partial gear  68  for rotational movement within socket  69  (not shown) of the bracket  42 , and a free distal end  70 . Connector rod  72  is hingedly attached between rod collar  74  slidable on rod  38  and midpoint of lower arm  32 , while connector rod  76  is also hingedly attached between rod collar  74  and midpoint of lower arm  34 . The sliding motion of rod collar  74  provides a force that causes connector rods  72 ,  76  to induce rotation of partial gears  62 ,  68  within sockets  63 ,  69  of partial gears  62 ,  68 . By virtue of upper arms  28 ,  30  being part of rake heads  20 ,  22 , upper arms  28 ,  30  are forced to rotate in sympathy, and partial gears  46 ,  52  are induced to rotate within sockets  47 ,  53 . 
         [0038]    As can be seen in  FIGS. 1 and 2 , the rest of the articulating mechanism  27  comprises a handle collar  90  slidably attached to handle  12 . In operation, handle collar  90  is grasped by a user to provide a longitudinal force to translate the handle collar  90  along handle  12  between lower portion  18  and intermediate portion  16 . A pair of connecting members  100 ,  102  are coupled between handle collar  90  and rod collar  74 , such that the sliding motion of handle collar  90  is also translated to rod collar  74  to cause angular motion of connector rods  72 ,  76  towards bracket  40 , thereby forcing rake heads  20 ,  22  to pivot. Partial gears  46  and  52 , including partial gears  62  and  68 , co-operate with each other such that rake heads  20 ,  22  are generally axially aligned corresponding to a raking mode; and also co-operate with each other to pivot rake heads  20 ,  22  into an angled configuration corresponding to a picking mode to cage the gathered material for pick up and transport. 
         [0039]    Also part of the articulating mechanism  27  is a stop mechanism  92 , which can be engaged to allow the articulated frame structure  19  to remain rigid and extended open, or disengaged to allow the pair of oppositely disposed rake heads  20 ,  22  to pivot or rotate when required. The stop mechanism  92  includes a partial gear stop wedge  94  actuable to engage and disengage partial gears  46 ,  52 . Accordingly, partial gear stop wedge  94  comprises a plurality of teeth  96  which intermesh with teeth  57 ,  58  of partial gears  46 ,  52  to prevent rotation of partial gears  46 ,  52 . 
         [0040]    Now looking again at  FIG. 4 , bracket  42  is a substantially flat diamond-shaped plate, with guiding sockets  43   c ,  43   d  formed therewith adjacent one pair of opposing vertices. As noted above, guiding sockets  43   c ,  43   d  receive rods  36  and  38  which are fixedly connected to upper pivot bracket  40 . Formed adjacent the other pair of opposing vertices are sockets  63 ,  69  for rotational mounting of partial gears  62 ,  68 . Rod collar  74  includes a pair of eyelets  126 ,  128  on opposite sides of outer wall of rod collar  74 , and eyelets  126 ,  128  include apertures  134 ,  136 . 
         [0041]    Partial gears  62 ,  68  are linked to lower arms  32 ,  34  via linking arms  138 ,  140 , respectively. One half portion of partial gears  62 ,  68  include gear teeth  142 ,  144  formed thereon, while toothless half portions  146 ,  148  of partial gears  62 ,  68  have linking arms  138 ,  140  extending therefrom towards inner faces  150 ,  152  of lower arms  32 ,  34 , respectively. Linking arms  138 ,  140  join inner faces  150 ,  152  at an angle less than 90 degrees such that lower arms  32 ,  34  abut each other at an angle. Tines  24 ,  26  are secured between inner faces  150 ,  152  and outer faces  154 ,  156  of lower arms  32 ,  34 , and tines  24 ,  26  are arched with apex  158 ,  160  touching outer faces  154 ,  156 , and intrados  162 ,  164  facing inner faces  150 ,  152 . About halfway of lower arms  32 ,  34  are eyelets  168 ,  170  perpendicular to inner faces  150 ,  152 , with apertures  172 ,  174  (not shown). Connector rods  72 ,  76  also include eyelets  176 ,  178  at one end, and eyelets  180 ,  182  at another end. Eyelets  176 ,  178  are received by apertures  172 ,  174  of eyelets  168 ,  170  on lower arms  32 ,  34 , while eyelets  180 ,  182  are received by apertures  134 ,  136  of eyelets  126 ,  128  on rod collar  74 . 
         [0042]    As shown in  FIG. 5   a , when stop mechanism  92  is disengaged rake heads  20 ,  22  are able to pivot or rotate toward each other. Accordingly, sliding handle collar  90  is manually operated by applying an axial force which causes the rake heads  20 ,  22  to encase the gathered debris in order to grasp and lift the gathered debris, in a transport mode. The force is applied until the debris has been securely grasped between tines  24 ,  26  of now angled rake heads  20 ,  22 . In more detail, stop mechanism  92  includes pin  181  extending through aperture  182  extending between outer face  41  and inner face  48  of bracket  40 , and moveable through aperture  182 . Pin  181  includes a rectangular cross section in a plane parallel to handle  12  along the entire length of the pin  181 . A frusto-conical handle  186  is connected to a proximal end  190  of pin  181 , and receives a force to slide pin  181  through rectangular aperture  182 . Upper portion  184  of pin  181  includes a plurality of notches  188  extending from a proximal end  190  of pin  181  to substantially midpoint thereof. Bottom portion  192  of pin  181  appears below inner face  48  distal end  196 , and comprise the partial gear stop wedge  94  coupled thereto. Fixedly attached to outer face  41  and adjacent to aperture  182  is an elongate brake actuator  197  operable to lock pin  181  in a particular chosen position. Brake actuator  197  includes an anchor  198  formed with outer face  41 , and biased serrated portion  200  with teeth  202  caused to engage notches  188  to arrest sliding motion of pin  181  through aperture  182 . Biased serrated portion  200  also includes angled lip  204  for receiving a force to overcome the biasing force and release teeth  202  from notches  188 , to permit sliding motion of pin  181 . 
         [0043]    Accordingly, when a downward force is applied to handle  186 , proximal end  190  of pin  181  advances towards outer face  41 , while distal end  196  and partial gear stop wedge  94  advance away from inner face  48  towards partial gears  46 ,  52 . The force is applied until teeth  96  of partial gear stop wedge  94  engage in intermesh contact with the assembly of teeth  57 ,  58  of partial gears  46 ,  52 . Biasing force on serrated portion  200  maintains teeth  202  in notches  188 , thus allowing teeth  96  of partial gear stop wedge  94  to remain in intermesh engagement with the assembly of teeth  57 ,  58  of partial gears  46 ,  52 , as shown in  FIG. 5   b . Accordingly, partial gear stop wedge  94  substantially prevents rotational movements of partial gears  46 ,  52  within sockets  47 ,  53 . Therefore, when raking mode is desired, stop mechanism  92  may be engaged to allow the articulated frame structure  19  to remain rigid and extended open, with pair of oppositely disposed rake heads  20 ,  22  at substantially 180 degrees to each other. 
         [0044]    For transport mode, stop mechanism  92  is disengaged by applying a force on angled lip  204  of serrated portion  200  to overcome the biasing force and release teeth  202  from notches  188 . Concurrently, a pulling force is applied on handle  186  to urge partial gear stop wedge  94  away from partial gears  46 ,  52  until teeth  96  of partial gear stop wedge  94  are free from intermesh contact with teeth assembly  57 ,  58  of partial gears  46 ,  52 , such that partial gears  46 ,  52  are able to freely rotate within sockets  47 ,  53 . Accordingly, rake heads  20 ,  22  are able to pivot or rotate towards each other to encompass the gathered debris. 
         [0045]    A process for transforming rake  10  from a raking mode configuration to a transport mode configuration will now be described. In raking mode configuration as shown in  FIGS. 1 and 3 , rake heads  20 ,  22  are generally axially aligned, such that lower arms  32 ,  34  abut each other at an angle, and likewise upper arms  28 ,  30  abut each other at an angle. Stop mechanism  92  is engaged to allow the articulated frame structure  19  to remain rigid and extended open while raking material. Handle collar  90  is disposed adjacent to lower portion  18  of handle  12 , with connector rods  72 ,  76  being substantially parallel to bottom bracket  42 . Partial gear  46  coupled to upper arm  28  and partial gear  52  of upper arm  30  comprise gear teeth  57 ,  58  that intermesh, as shown in  FIG. 3 ; and toothless half portions  146 ,  148  of partial gears  62 ,  68  face inner faces  150 ,  152  of lower arms  32 ,  34 , while a majority of gear teeth  142 ,  144  face partial gear stop wedge  94 . 
         [0046]    When raked material has been placed in a pile and ready for transport, stop mechanism  92  is disengaged and sliding handle collar  90  is manually operated. Handle collar  90  is grasped by a user&#39;s hand and a force is applied to displace handle collar  90  away from lower portion  18  of handle  12  towards intermediate portion  16 , and that longitudinal force is translated to rod collar  74  to cause angular motion of connector rods  72 ,  76  towards upper bracket  40 . As connector rods  72 ,  76  are hingedly connected between rod collar  74  and midpoint of lower arms  32 ,  34 , the applied force pulls on lower arms  32 ,  34  such that gear teeth  142 ,  144  intermesh and partial gear  62  rotates in an anti-clockwise fashion, while partial gear  68  rotates in an clockwise fashion. The rotating partial gears  62 ,  68  allow rake heads  20 ,  22  to rotate in step with one another. Partial gears  62 ,  68  continue to rotate in sockets  63 ,  69 , and by virtue of upper arms  28 ,  30  being part of rake heads  20 ,  22 , the upper arms  28 ,  30  are forced to rotate in sympathy, and partial gears  46 ,  52  are induced to rotate within sockets  47 ,  53 . 
         [0047]    In another exemplary embodiment, as shown in  FIG. 6 , there is shown a bottom up view of the proximal bracket  40 ′ with upper arm  28 ′ and upper arm  30 ′ hingedly coupled thereto, with a modified stop mechanism  210 , of a rake  10 ′ (not shown). Similar to rake  10 , rake  10 ′ comprises an elongate handle  12 ′ coupled to an articulated frame structure  19 ′ (not shown) comprising a pair of oppositely disposed rake heads  20 ′,  22 ′ (not shown) having a plurality of tines  24 ′,  26 ′, secured to upper arms  28 ′,  30 ′ and lower arms  32 ′,  34 ′. Upper arm  28 ′ comprises a proximal end  44 ′ with a pivot disc  46 ′ for independent rotational movement within socket  47 ′ formed on inner face  48 ′ of bracket  40 ′, and a free distal end  49 ′. Correspondingly upper arm  30 ′ comprises a proximal end  50 ′ with a pivot disc  52 ′ for independent rotational movement within socket  53 ′ (not shown) in bracket  40 ′, and a free distal end  54 ′. Pivot discs  46 ′,  53 ′ are coupled to upper arms  28 ′,  30 ′ via linking arms  55 ′,  56 ′. 
         [0048]    Now looking at  FIG. 7 , lower arm  32 ′ comprises a proximal end  60 ′ with a pivot disc  62 ′ for independent rotational movement within socket  63 ′ (not shown) of bracket  42 ′, and a free distal end  64 ′. Correspondingly lower arm  34 ′ comprises a proximal end  66 ′ with a pivot disc  68 ′ for independent rotational movement within socket  69 ′ (not shown) of the bracket  42 ,′ and a free distal end  70 ′. A connector rod  72 ′ is hingedly attached between a rod collar  74 ′ slidable on rod  38  and midpoint of lower arm  32 ′, while connector rod  76 ′ is also hingedly attached between rod collar  74 ′ and midpoint of lower arm  34 ′. The sliding motion of rod collar  74 ′ provides a force that causes connector rods  72 ′,  76 ′ to induce the rotation of pivot discs  62 ′,  68 ′ about sockets  63 ′,  69 ′ (not shown). By virtue of upper arms  28 ′,  30 ′ being part of rake heads  20 ,  22 , the upper arms  28 ′,  30 ′ are forced to rotate in sympathy, and partial gears  46 ′,  52 ′ are induced to rotate within sockets  47 ′,  53 ′. 
         [0049]    Similar to bracket  42  of  FIG. 4 , bracket  42 ′ is a substantially flat diamond-shaped plate, with guiding sockets  43   c ′,  43   d ′ formed therewith adjacent one pair of opposing vertices. As noted above, guiding sockets  43   c ′,  43   d ′ receive rods  36 ′ and  38 ′ which are fixedly connected to upper pivot bracket  40 ′. Formed adjacent the other pair of opposing vertices are sockets  63 ′,  69 ′ for rotational mounting of partial gears  62 ′,  68 ′. Rod collar  74 ′ includes a pair of eyelets  126 ′,  128 ′ with apertures  134 ′,  136 ′, and disposed on opposite sides of outer wall of rod collar  74 ′. Pivot discs  62 ′,  68 ′ are linked to lower arms  32 ′,  34 ′ via linking arms  138 ′,  140 ′, respectively. Linking arms  138 ′,  140 ′ extend from pivot discs  62 ′,  68 ′ to inner faces  150 ′,  152 ′ of lower arms  32 ′,  34 ′, respectively, at an angle less than 90 degrees such that lower arms  32 ′,  34 ′ abut each other at an angle. Tines  24 ′,  26 ′ are equally spaced and secured between inner faces  150 ′,  152 ′ and outer faces  154 ′,  156 ′ of lower arms  32 ′,  34 ′, and have a flat cross section. About halfway of lower arms  32 ′,  34 ′ are eyelets  168 ′,  170 ′ perpendicular to inner faces  150 ′,  152 ′, with apertures  172 ′,  174 ′. Connector rods  72 ′,  76 ′ also include eyelets  176 ′,  178 ′ at one end, and eyelets  180 ′,  182 ′ at another end. Eyelets  176 ′,  178 ′ are received by apertures  172 ′,  174 ′ of eyelets  168 ′,  170 ′ on lower arms  32 ′,  34 ′, while eyelets  180 ′,  182 ′ are received by apertures  134 ′,  136 ′ of eyelets  126 ′,  128 ′ on rod collar  74 ′. 
         [0050]    Similar to stop mechanism  92 , stop mechanism  210  can be engaged to allow the articulated frame structure  19 ′ (not shown) to remain rigid and extended open or disengaged to allow the pair of oppositely disposed rake heads  20 ′,  22 ′ (not shown) to pivot or rotate when required, as shown in  FIGS. 8   a ,  8   b  and  8   c . When stop mechanism  210  is disengaged and sliding handle collar  90 ′ (not shown) is manually operated, then rake  10 ′ (not shown) is now configured to pivot or rotate to encase the gathered debris in order to provide for lifting the gathered debris, in a transport mode. 
         [0051]    As shown in more detail in  FIG. 8   b , stop mechanism  210  includes pins  222   a ,  222   b  coupled to each other by a connecting member  223 . Pins  222   a ,  222   b  are moveable through apertures  224   a ,  224   b  (not shown) extending between outer face  41 ′ and inner face  48 ′ of bracket  40 ′, as shown in  FIG. 8   a . A frusto-conical handle  228  connected about midpoint of connecting member  223 , and receives a force to slide pins  222   a ,  222   b  through aperture  224   a ,  224   b . An upper portion  226  of pins  222   a ,  222   b  appears above outer face  41 ′, and upper portion  226  of pin  222   a  includes a plurality of notches  230  extending from a proximal end  232   a  of pin  222   a  to substantially midpoint thereof. Bottom portion  234  of pins  222   a ,  222   b  appears below inner face  48 ′ and includes guides  236   a ,  236   b  at distal ends  237   a ,  237   b . Fixedly attached to outer face  41 ′ and adjacent to aperture  224   a  is an elongate brake actuator  238  operable to lock pins  222   a ,  222   b  in a particular chosen position. Brake actuator  238  includes an anchor  240  formed with outer face  41 ′, and biased serrated portion  242  with teeth  244  caused to engage notches  230  to arrest sliding motion of pin  222   a  through aperture  224   a , and hence that of pin  222   b  through aperture  224   b . Biased serrated portion  242  also includes angled lip  245  for receiving a force to overcome the biasing force and release teeth  244  from notches  230  thus allowing sliding motion of pin  222   a , and hence also allows sliding motion of pin  222   b.    
         [0052]    As described above, upper arm  28 ′ comprises a proximal end  44 ′ with a pivot disc  46 ′ for rotational movement within socket  47 ′ formed on inner face  48 ′ of bracket  40 ′, and a free distal end  49 ′, and correspondingly upper arm  30 ′ comprises a proximal end  50 ′ with a pivot disc  52 ′ for rotational movement within socket  53 ′ (not shown) in bracket  40 ′, and a free distal end  54 ′. Formed within linking arm  55 ′ is a female receptacle  246  dimensioned to receive pin  222   a . Correspondingly formed within linking arm  56 ′ is a female receptacle  248  dimensioned to receive pin  222   b . Accordingly, with female receptacles  246 ,  248  aligned with pins  222   a ,  222   b , a pushing force is applied to handle  228 , and proximal ends  232   a ,  232   b  of pins  222   a ,  222   b  advance towards outer face  41 ′, while distal ends  237   a ,  237   b  and guides  236   a ,  236   b  advance away from inner face  48 ′ towards female receptacles  246 ,  248 . The force is applied until a portion of pin  222   a ,  222   b  occupies most of female receptacles  246 ,  248  and remains anchored in both female receptacles  246 ,  248 , thus preventing rotational movement of pivot discs  46 ′,  52 ′ within sockets  47 ′,  53 ′. 
         [0053]    For transport mode, stop mechanism  210  is disengaged by applying a force on angled lip  245  of serrated portion  242  to overcome the biasing force and release teeth  244  from notches  230 . Concurrently, a pulling force is applied on handle  228  to urge the portion of pins  222   a ,  222   b  out of female receptacles  246 ,  248 , until distal ends  237   a ,  237   b  of pins  222   a ,  222   b  are free of female receptacles  246 ,  248 , such that pivot discs  46 ′,  52 ′ are able to freely rotate within sockets  47 ′,  53 ′. 
         [0054]    The preceding detailed description of exemplary embodiments of the invention makes reference to the accompanying drawings, which show the exemplary embodiment by way of illustration. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be realized and that logical and mechanical changes may be made without departing from the spirit and scope of the invention. For example, the steps recited in any of the method or process claims may be executed in any order and are not limited to the order presented. Thus, the preceding detailed description is presented for purposes of illustration only and not of limitation, and the scope of the invention is defined by the preceding description, and with respect to the attached claims.