Patent Publication Number: US-6669299-B2

Title: Fold-flat seat hinge assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 09/825,411 filed on Apr. 3, 2001, now U.S. Pat. No. 6,544,362. The disclosure of the above application is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates generally to seat back adjustment mechanisms and more particularly to a seat back adjustment mechanism that enables a seat back to be locked in a forward fold-down position to remain substantially horizontal. 
     2. Discussion 
     Vehicle markets such as mini-van and sport utility are extremely competitive and a focus for improvement by automobile manufacturers. Specifically, automobile manufacturers seek to improve the overall utility and comfort of the vehicles in these markets in pursuit of attracting and keeping customers. One important feature is a flexible vehicle interior. Flexibility, in this sense, refers to the interior&#39;s ability to provide seating that may be modified to suit a particular customer&#39;s needs. For example, a customer might desire the removal of a rear seat to provide increased cargo space, while maintaining a middle seat or seats for additional passengers. Additionally, a passenger might desire the seat back of a front or middle seat to fold down, providing a work space while traveling. As such, a passenger could place a laptop computer on the folded down seat back or use the folded down seat back as a small desk for writing or reading. 
     As is known in the art, a seat back may be reclined to various recline positions providing occupant comfort. Concurrently, the seat back may be dumped to a fold forward position for providing improved access to a vehicle interior or a work space, as discussed above. Traditional seat back adjustment mechanisms retain a specific disadvantage in that the recline position of the seat back, prior to folding the seat back forward, defines the fold forward position of the seat back relative to horizontal. For example, if the seat back is in a fully reclined position prior to being folded forward, in the fold forward position the seat back will be at a substantial angle relative to horizontal. This is undesirable, particularly in the case of using the seat back as a work space. 
     It is therefore desirable in the industry to provide a fold-forward adjustment mechanism for use with a seat back that enables an operator to fold the seat back in a generally horizontal or fold-flat position regardless of the initial reclined position of the seat back relative to the seat. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention provides a seat adjustment mechanism including an arm rotatably defining a first locking shoulder, a sector plate rotatably supported by the arm and defining a second locking shoulder having a lock recess, a locking member selectively engaging at least one of the first and second locking shoulders, a quadrant rotatably supported by the arm and slidably supporting the locking member for locking the quadrant in one of a first and second position relative to the arm and a cam plate rotatably supported by the quadrant for selectively engaging the locking member for locking the quadrant in one of the first and second positions. In the first position the locking member is biased against the first locking shoulder and in the second position the locking member is biased into the lock recess. A gear assembly is preferably provided and operably supported by the quadrant for actuation of the cam plate. The gear assembly preferably includes a first gear plate rotatably supported by the quadrant and a second gear plate in meshed engagement with the first gear plate and in operable communication with the cam plate for selectively imparting rotation of the cam plate. 
     Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims, taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of an adjustment mechanism according to the present invention; 
     FIG. 2 is an exploded perspective view of the adjustment mechanism; 
     FIG. 3 is a side view illustrating the adjustment mechanism of FIGS. 1 and 2 in a first position; 
     FIG. 4 is a side view illustrating the adjustment mechanism of FIGS. 1 and 2 in a second position; 
     FIG. 5 is a exploded perspective view of a second embodiment of the adjustment mechanism of the present invention; 
     FIGS. 6 a ,  6   b  and  6   c  are side schematic views of a seat assembly including the adjustment mechanism of the present invention illustrating a seat back in various positions relative a seat; 
     FIG. 7 is a side view of a seat assembly with a seat back in a forward-folded position relative a seat according to the present invention; 
     FIG. 8 is a side view of a third embodiment of the adjustment mechanism of the present invention; 
     FIG. 9 is an exploded view of a third embodiment of the adjustment mechanism of the present invention; 
     FIG. 10 is a side view of a fourth embodiment of the adjustment mechanism of the present invention; 
     FIG. 11 is an exploded view of a fourth embodiment of the adjustment mechanism of the present invention; 
     FIG. 12 is a side view of a third embodiment of the adjustment mechanism of the present invention in a first position; 
     FIG. 13 is a side view of a third embodiment of the adjustment mechanism of the present invention in a second position; 
     FIG. 14 is a side view of a fifth embodiment of the adjustment mechanism of the present invention; and 
     FIG. 15 is an exploded view of a fifth embodiment of the adjustment mechanism of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With particular reference to FIGS. 1 and 2, an adjustment mechanism  10  for use with a seat assembly is shown. The adjustment mechanism  10  generally includes an arm  12  disposed between and pivotally mounted relative to a quadrant  14  including inner and outer plates  18 , 20  and selectively locked relative to the quadrant  14  by a locking member  22 . The locking member  22  is selectively engaged by a cam plate  24 . 
     A first end of the arm  12  includes a portion  16  having a plurality of pawl teeth  26 . A second end of arm  12  includes an aperture  28  for connecting to a linear recliner mechanism and an aperture  29  is included for providing a pivot axis for the adjustment mechanism  10  (see FIGS. 6 a  through  7 ). The first end of the arm  12  further includes a shoulder  30  having a first side surface  32 , a top surface  34 , and a second side surface  36 . The first side surface  32  forms a corner  38  of the arm  12  at a junction with a top surface  39 . 
     The arm  12  is disposed between and rotatably supports the inner and outer plates  18 , 20  on a first pivot  40 . The first pivot  40  is received through an aperture  42  of the arm  12 . The first pivot  40  includes first and second cylindrical extensions  44 , 46  that are receivable into and supported by first and second apertures  48 , 50 , respectively. The first pivot  40  further includes a support bearing  52  that extends radially and is disposed between the first and second cylindrical extensions  44 , 46 . The support bearing  52  includes a bearing surface  54  which is received into the aperture  42  for rotatably supporting the quadrant  14  relative to the arm  12 . 
     The cam plate  24  is also disposed between the inner and outer plates  18 , 20  and is rotatably supported by a second pivot  56  received through a central aperture  58  of the cam plate  24 . The second pivot  56  includes first and second cylindrical extensions  60 , 62  that are receivable into and supported by first and second apertures  64 , 66 , respectively. The second pivot  56  also includes a support bearing  68  that extends radially and is disposed between the first and second cylindrical extensions  60 , 62 . The support bearing  68  includes a bearing surface  70  which is received into the aperture  58  for rotatably supporting the cam plate  24 . 
     One end of the cam plate  24  includes a cam surface  72 . An opposite end of the cam plate  24  includes an aperture  74  for anchoring a first end of a spring  76  and the inner plate  18  includes an aperture  75  for anchoring a second end of the spring  76 . The spring  76  rotationally biases the cam plate  24  in a first rotational direction, which biases the cam surface  72  toward the locking member  22 , which, in turn, is forced toward the corner  38  and against the first side surface  32  of the arm  12 . In this position, the quadrant  14  is held in a first upright position relative to the arm  12 . A cross member  78  includes cylindrical extensions  80 , 82  received into apertures  84 , 86 , respectively, of the inner and outer plates  18 , 20 . The cross member  78  contacts a face  79  of the arm  12  for prohibiting reward rotation of the quadrant  14  relative to the arm  12 . 
     The locking member  22  is a wedge-shaped member having a arcuate surface  88  at a wide end for engaging the cam surface  72  of the cam plate  24  and a notch  90  disposed in a narrow end. The notch  90  is adapted to engage the pawl teeth  26  of the arm  12  for locking the quadrant  14  relative the arm  12 . Ribs  92 , 94  extend perpendicularly from faces  96 , 98  of the locking member  22 . The ribs  92 , 94  are slidably supported within slots  100 , 102  of the inner and outer plates  18 , 20 , respectively, enabling the locking member  22  to slide therebetween. The locking member  22  slides in the slots  100 , 102  as it interfaces between the arm  12  and the cam plate  24 . The cam plate  24  acts on the arcuate surface  88  to bias the locking member  22  against the arm  12 . 
     With particular reference to FIGS. 1,  3  and  4 , the operation of the adjustment mechanism  10  will be described in detail. In a first preferred embodiment, the adjustment mechanism  10  enables the quadrant  14  to pivot forward, relative to the arm  12 , and lock in a plurality of forwardly inclined positions. To fold the quadrant  14  forward, the cam plate  24  is rotated against the biasing force of the spring  76 , forcing the cam surface  72  to slide along and then move away from the arcuate surface  88  of the locking member  22 . Thus, the ribs  92 , 94  of the locking member  22  are free to slide in the slots  100 , 102  of the inner and outer housing plates  18 , 20  as the locking member  22  moves from a recessed position adjacent to the first side surface  32  to a raised position on the top surface  38  of the shoulder  30 . Specifically, as the cam plate  24  rotates against the bias of the spring  76 , the locking member  22  is pinched between the first side surface  32  of arm  12  and the slots  100 , 102 . As the cam surface  72  is moved out of blocking engagement with the locking member  22 , upward movement of locking member  22  is unrestricted. As the quadrant  14  is rotated, the walls defining the slots  100 , 102  of the inner and outer housing plates  18 , 20  push the locking member  22  upward within slots  100 , 102  until the locking member  22  slides over onto the top surface  38 . Continued forward rotation of the quadrant  14  causes the locking member  22  to slide along the top surface  38 , as best seen in FIG.  3 . Once the locking member  22  is on the top surface  38 , the cam plate  24  may be released wherein the spring  76  again biases the cam plate  24  in the first rotational direction. The cam surface  72  again biases the locking member  22  within the slots  100 , 102  pushing the locking member  22  against the top surface  38 . 
     Once the quadrant  14  has rotated sufficiently forward, the locking member  22  slides off of the top surface  38  and onto the pawl teeth portion  16 . Due to the bias of the cam plate  24 , the locking member  22  immediately engages the first pawl tooth  26 , wherein the quadrant  14  is held in a first forward inclined position relative to the arm  12 . 
     A plurality of alternative forward lock positions may be achieved by again operating the cam plate  24  to disengage the arcuate surface  88  of the locking member  22 . Once disengaged, the locking member  22  is movable across the pawl teeth portion  16  until a desired position has been achieved. Upon achieving a desired position, the cam plate  24  is released, again biasing the locking member  22  into engagement with a particular tooth  26  of the pawl teeth portion  16 . 
     To return the quadrant  14  to an upright position, relative to the arm  12 , the cam plate  24  is again rotated against the biasing force of spring  76  to disengage the cam plate  24  from the locking member  22 . As the quadrant  14  rotates rearwardly, the locking member  22  moves from a recessed position adjacent to the second side surface  36  to a raised position on the top surface  38  of the shoulder  30 . Specifically, the locking member  22  is pinched between the second side surface  36  of the arm  12  and the slots  100 , 102  until the locking member  22  slides onto the top surface  38  of the arm  12 . Once the locking member  22  is on the top surface  38 , the cam plate  24  may be released wherein the spring  76  again biases the cam plate  24  in the first rotational direction. Thus, the cam surface  72  biases the locking member  22  within the slots  100 , 102  to force the locking member  22  against the top surface  38 . After the quadrant  14  is rotated sufficiently rearward, the bias of the cam plate  24  causes the locking member  22  to slide within slots  100 , 102 , toward the corner  38  and against first side surface  32 , thereby locking the quadrant  14  in an upright position. 
     With reference to FIG. 5, a second preferred embodiment of the present invention is indicated as adjustment mechanism  110 . The adjustment mechanism  110  generally includes an arm  112  disposed between and pivotally mounted to a quadrant  114  including inner and outer plates  116 , 118 . The quadrant  114  is selectively locked relative to the arm  112  by a locking member  120  that is selectively engaged by a cam plate  122 . 
     A first end of the arm  112  includes a first corner  124 , a second corner  126 , a first side surface  128 , a first top surface  130 , a second top surface  132 , an arcuate surface  134 , a second side surface  136 , and a third top surface  138 . The first corner  124  is formed at the intersection of the first side surface  128  and the third top surface  138 . The second corner  126  is formed at the intersection of the second top surface  132  and the second side surface  136 . A second end of the arm  112  includes a first aperture  140  for providing a pivot axis and a second aperture  142  for connecting to a linear recliner mechanism (see FIGS. 6 a  through  7 ). The arm  112  rotatably supports the inner and outer plates  116 , 118  on a first pivot  144 . 
     The first pivot  144  includes first and second cylindrical extensions  146 , 148  that are received into and supported by apertures  150 , 152  in the inner and outer housing plates  116 , 118 . The first pivot  144  also includes a radially extending support bearing  154  that includes a bearing surface  156 . The first pivot  144  is received through an aperture  158  of the arm  112 , whereby the first pivot  144  rotatably supports the quadrant  114  relative to the arm  112 . 
     The cam plate  122  is also disposed between the inner and outer housing plates  116 , 118  and is rotatably supported therebetween by a second pivot  160  received through a central aperture  162  of the cam plate  122 . The second pivot  160  includes first and second cylindrical extensions  164 , 166  that are received into and supported by apertures  168 , 170  in the inner and outer plates  116 , 118 , respectively. The second pivot  160  also includes a radially extending support bearing  172  that includes a bearing surface  174 . The second pivot  160  is received through the aperture  162  of the arm  112 , whereby the second pivot  160  rotatably supports the quadrant  114  about the bearing surface  174 . 
     One end of the cam plate  122  includes a cam surface  176  and an opposite end of the cam plate  122  includes an aperture  178  for anchoring a first end of a spring  180 . The spring  180  is connected between the cam plate  122  and an aperture  181  formed through a tab  182 . Tab  182  is formed along a top surface of the inner plate  116 . The spring  180  rotationally biases the cam plate  122  in a first direction causing the cam surface  176  to bias the locking member  120  toward the first corner  124  and against first side surface  128  of the arm  112 . When the locking member is in this position, the inner and outer plates  116 , 118  are held in a first upright position relative to the arm  112 . 
     The locking member  120  interfaces between the arm  112  and the cam plate  122  and includes an arcuate surface  184  for engaging the cam surface  176  of the cam plate  122 . The cam plate  122  acts on the arcuate surface  184  to bias the locking member  120  against the arm  112 . Ribs  186 , 188  extend perpendicularly from respective faces  190 , 192  of the locking member  120 . The ribs  186 , 188  are slidably supported within slots  194 , 196  of the inner and outer plates  116 , 118 , enabling the locking member  120  to slide therebetween. 
     As previously described, the quadrant  114  can be folded forward relative to the arm  112  and locked in a single forwardly inclined position. To fold the quadrant  114  forward, the cam plate  122  is rotated in a second direction against the bias direction of the spring  180 . As the cam plate  122  rotates in the second direction, the cam surface  176  slides along and then moves away from the arcuate surface  184  of the locking member  120 , thus freeing the locking member  120  to slide in the slots  194 , 196  of the inner and outer plates  116 , 118  as it moves from a recessed position adjacent to the first side surface  128  to an outward position on the first top surface  130  of the arm  112 . Specifically, as the cam plate  122  rotates against the bias of the spring  180 , the locking member  120  is pinched between the first side surface  128  of the arm  112  and slots  194 , 196 . As the cam surface  176  is moved from blocking the locking member  120 , upward movement of the locking member  120  is unrestricted. The walls defining the slots  194 , 196  of the inner and outer plates  116 , 118  push the locking member  120  upwards within slots  194 , 196  until the locking member  120  slides over onto the first top surface  130  of the arm  112 . Once the locking member  120  is on the first top surface  130 , the cam plate  122  can be released so the spring  180  again biases the cam plate  122  in the first rotational direction, further biasing the locking member  120  against the first top surface  130 . 
     After sufficient forward rotation of the quadrant  114 , the locking member  120  slides off of the first top surface  130  and into the second corner  126 . The locking member  120  is biased into engagement with the second corner  126  by the cam plate  122 . The engagement of the locking member  120  and the second corner  126  holds the quadrant  114  in a forward position relative to the arm  112 . 
     The quadrant  114  may be rotated further forward by again rotating the cam plate  122  against the bias of the spring  180 , relieving engagement of the cam plate  122  and the locking member  120 . The quadrant  114  rotates forward, pinching the locking member  120  between the slots  194 , 196  and the second top surface  132 . Again, the walls defining the slots  194 , 196  push the locking member  120  upward within the slots  194 , 196  until locking member  120  slides over onto the arcuate surface  134 . Once the locking member  120  is in contact with the arcuate surface  134 , the cam plate  122  can again be released wherein the spring  180  biases the cam plate  122 . As a result, the cam surface  176  again pushes the locking member  120  downward in the slots  194 , 196 , biasing the locking member  120  against the arcuate surface  134 . By rotating the quadrant  114  sufficiently backward, the locking member  120  can be again positioned within the second corner  126 , locking the quadrant  114  in the first forward position. 
     The quadrant  114  may be rotated backward to the initial upright position by again operating the cam plate  122  against the bias of the spring  180 , thus disengaging the cam plate  122  from the locking member  64 . As the quadrant  114  rotates backward, the locking member  120  is pinched between the slots  194 , 196  and the second side surface  136 , pushing the locking member  120  upward in the slots  194 , 196  and over onto the first top surface  130 . Upon sufficient backward rotation of the quadrant  114 , the locking member  120  is pushed downward into engagement with the first corner  124  by the cam plate  122 . Thus, the quadrant  114  is locked in the first upright position. 
     With reference to FIGS. 6 a ,  6   b ,  6   c  and  7 , implementation of adjustment mechanism  10  in a seat assembly  200  is shown. The seat assembly  200  includes a seat back  202 , a seat  204 , the adjustment mechanism  10  and a linear recliner mechanism  206 . The linear recliner mechanism  206  includes a handle  208  and is of a type commonly known in the art. The linear recliner mechanism  206  is operable to pivot the seat back  202  relative to seat  204  and to lock the seat back  202  in a plurality of reclined positions. The seat back  202  is shown in an upright position, a first reclined position and a second reclined position, in FIGS. 6 a ,  6   b  and  6   c , respectively. As the seat back  202  reclines rearwardly, the adjustment mechanism  10  rotates about a pivot axis  210 . The quadrant  14  of the adjustment mechanism  10  mount the seat back  202  to the seat  204  through the arm  12 . The adjustment mechanism  10  is operable in any reclined position of seat back  202 , by a handle  212 , to fold the seat back  202  forward relative to the seat  204 . FIG. 7 illustrates a fold-forward position of seat back  202  from the first reclined position shown in FIG. 6 b . It should be noted, however, that while the adjustment mechanism  10  was used in the above description, the adjustment mechanism  110  may substitute in accordance with the invention. 
     With reference to FIGS. 8 and 9, a third preferred embodiment of the present invention is indicated as adjustment mechanism  310 . The adjustment mechanism  310  generally includes an arm  312  disposed between and pivotally mounted to a quadrant  314  including inner and outer plates  318 ,  320 . The quadrant  314  is selectively locked relative to the arm  312  by a locking member  322  that is selectively engaged by a cam plate  324 . The cam plate  324  is actuated through a gear assembly  323 . 
     A first end of the arm  312  includes a portion  316  having a plurality of pawl teeth  326 . A second end of arm  312  includes an aperture  328  for connecting to a linear recliner mechanism and an aperture  397  is included for providing a pivot axis for the adjustment mechanism  310  (see FIGS.  8  and  9 ). The first end of the arm  312  further includes a shoulder  330  having a first side surface  332 , a top surface  334 , and a second side surface  336 . The first side surface  332  forms a corner  338  of the arm  312  at a junction with a top surface  339 . 
     The arm  312  is disposed between and rotatably supports the inner and outer plates  318 , 320  on a first pivot  340 . The first pivot  340  is received through an aperture  342  of the arm  312 . The first pivot  340  includes first and second cylindrical extensions  344 , 346  that are receivable into and supported by first and second apertures  348 , 350 , respectively. The first pivot  340  further includes a support bearing  352  that extends radially and is disposed between the first and second cylindrical extensions  344 , 346 . The support bearing  352  includes a bearing surface  354  which is received into the aperture  342  for rotatably supporting the quadrant  314  relative to the arm  312 . 
     The gear assembly includes the cam plate  324  rotatably supported between the inner and outer plates  318 , 320 , and first and second gear plates  325 , 327 , each rotatably supported between the inner and outer plates  318 , 320 . The cam plate  324  is rotatably supported by a second pivot  356  received through a central aperture  358  of the cam plate  324 . The second pivot  356  includes first and second cylindrical extensions  360 , 362  that are receivable into and supported by first and second apertures  364 , 366 , respectively. The second pivot  356  also includes a support bearing  368  that extends radially and is disposed between the first and second cylindrical extensions  360 , 362 . The support bearing  368  includes a bearing surface  370  which is received into the aperture  358  for rotatably supporting the cam plate  324 . 
     The first gear plate  325  includes a central portion  331  and an actuation arm  333  and a cable release aperture  374  for interconnection with a cable (not shown). The first gear plate  325  further includes a series of teeth  335  radially extending from the central portion  331  for meshed engagement with the second gear plate  327  as will be discussed further below. The central portion  331  further includes a cylindrical post  337  formed therein for rotatable attachment to the inner plate  320  of the quadrant  314 . The cylindrical post  337  includes a bearing surface and is received through an aperture  341  formed in the inner plate  318 . While the present invention includes a cylindrical post  337  that is formed within the first gear plate  325  it is anticipated that the cylindrical post  337  could be a separate member attached to the first gear plate  325  by suitable means and should be considered within the scope of the present invention. 
     The second gear plate  327  includes a central portion  343  and a reaction arm  345  having an engagement face  371 . The central portion  343  includes a series of teeth  347  radially extending therefrom for meshed engagement with the first gear plate  325 , as will be discussed further below. The central portion  343  further includes first and second cylindrical posts  349 , 351  formed therein for rotatable attachment to the inner and outer plates  318 , 320  of the quadrant  314 . A first end of a coil spring  376  attaches to the second cylindrical post  351  and an aperture  375  of the outer plate  320  for anchoring a second end of the spring  376 . The spring  376  rotationally biases the second gear plate  327  in a first rotational direction to bias a cam surface  372  toward the locking member  322 , which, in turn, is forced toward the corner  338  and against the first side surface  332  of the arm  312 . In this position, the quadrant  314  is held in a first upright position relative to the arm  312 . The first and second cylindrical posts  349 , 351  include bearing surfaces and are received through apertures  353 , 355  formed in the inner and outer plates  318 , 320 . While the present invention includes cylindrical posts  349 , 351  that are formed within the second gear plate  327  it is anticipated that the cylindrical posts  349 , 351  could be separate members attached to the second gear plate  327  by suitable means and should be considered within the scope of the present invention. The reaction arm  345  includes an engagement face  357  for interaction with the cam plate  324  during actuation of the adjustment mechanism  310 . 
     The cam plate  324  includes an attachment aperture  358  formed therethrough, a first arm  361  having a cam surface  372  and a second arm  363  having an engagement face  365  for interaction with the second gear plate  327  during actuation of the adjustment mechanism  310 . A cross member  378  includes cylindrical extensions  380 , 382  received into apertures  384 , 386 , respectively, of the inner and outer plates  318 , 320 . The cross member  378  contacts a face  339  of the arm  312  for prohibiting reward rotation of the quadrant  314  relative to the arm  312 . 
     The locking member  322  is a wedge-shaped member having an arcuate surface  388  at a wide end for engaging the cam surface  372  of the cam plate  324  and a notch  390  disposed in a narrow end. The notch  390  is adapted to engage the pawl teeth  326  of the arm  312  for locking the quadrant  314  relative the arm  312 . Ribs  392 , 394  extend perpendicularly from faces  396 , 398  of the locking member  322 . The ribs  392 , 394  are slidably supported within slots  3100 , 3102  of the inner and outer plates  318 , 320 , respectively, enabling the locking member  322  to slide therebetween. The locking member  322  slides in the slots  3100 , 3102  as it interfaces between the arm  312  and the cam plate  324 . The cam plate  324  acts on the arcuate surface  388  to bias the locking member  322  against the arm  312 . 
     With continued reference to FIGS. 8 and 9, operation of the adjustment mechanism  310  will be described in detail. In the first preferred embodiment, the adjustment mechanism  310  enables the quadrant  314  to pivot forward, relative to the arm  312 , and lock in a plurality of forwardly inclined positions. To fold the quadrant  314  forward, a force is applied to the actuation arm  333  of the first gear plate  325 . The applied force causes the first gear plate  325  to rotate, which subsequently rotates the second gear plate  327  against the bias of the spring  376 . Rotation of the second gear plate  327  releases the engagement face  371  of the reaction arm  345  from the first arm  361  of the cam plate  324 . Further rotation of the second gear plate  327  causes the reaction arm  345  to react against the second arm  363  of the cam plate  324 . Engagement of the second gear plate  327  and the second arm  363  of the cam plate  324  causes the cam plate  324  to rotate, forcing the cam surface  372  to slide along and disengage the arcuate surface  388  of the locking member  322 . Thus, the ribs  392 , 394  of the locking member  322  are free to slide in the slots  3100 , 3102  of the inner and outer housing plates  318 , 320  as the locking member  322  moves from a recessed position adjacent to the first side surface  332  to a raised position on the top surface  338  of the shoulder  330 . More specifically, as the cam plate  324  rotates, the locking member  322  is pinched between the first side surface  332  of arm  312  and the slots  3100 , 3102 . As the cam surface  372  is moved out of blocking engagement with the locking member  322 , upward movement of locking member  322  is unrestricted. As the quadrant  314  is rotated, the walls defining the slots  3100 , 3102  of the inner and outer housing plates  318 , 320  push the locking member  322  upward within slots  3100 , 3102  until the locking member  322  slides over onto the top surface  338 . Continued forward rotation of the quadrant  314  causes the locking member  322  to slide along the top surface  338 , as best seen in FIG.  8 . Once the locking member  322  is on the top surface  338 , the first gear plate  325  may be released, wherein the spring  376  again biases the second gear plate  327  in the first rotational direction, inducing the first gear plate  325  to rotate and also releasing the cam plate  324  for engagement with the locking member  322 . The cam surface  372  again biases the locking member  322  within the slots  3100 , 3102  pushing the locking member  322  against the top surface  338 . 
     Once the quadrant  314  has rotated sufficiently forward, the locking member  322  slides off of the top surface  338  and onto the pawl teeth portion  316 . Due to the force from the cam plate  324 , the locking member  322  immediately engages the first pawl tooth  326 , wherein the quadrant  314  is held in a first forward inclined position relative to the arm  312 . 
     A plurality of alternative forward lock positions may be achieved by again operating the first gear plate  325  to disengage the arcuate surface  388  of the locking member  322 . Once disengaged, the locking member  322  is movable across the pawl teeth portion  316  until a desired position has been achieved. Upon achieving a desired position, the first gear plate  325  is released, again biasing the locking member  322  into engagement with a particular tooth  326  of the pawl teeth portion  316 . 
     To return the quadrant  314  to an upright position, relative to the arm  312 , the first gear plate  325  is again rotated, thereby causing the second gear plate  327  to rotate against the biasing force of spring  376  causing the cam plate  324  to rotate such that the cam plate  324  disengages from the locking member  322 . As the quadrant  314  rotates rearwardly, the locking member  322  moves from a recessed position adjacent to the second side surface  336  to a raised position on the top surface  338  of the shoulder  330 . Specifically, the locking member  322  is pinched between the second side surface  336  of the arm  312  and the slots  3100 , 3102  until the locking member  322  slides onto the top surface  338  of the arm  312 . Once the locking member  322  is on the top surface  338 , the first gear plate  325  may be released, wherein the spring  376  again biases the second gear plate  327  in the first rotational direction allowing the first gear plate  325  to rotate and also causing the cam plate  324  to be released. Thus, the cam surface  372  biases the locking member  322  within the slots  3100 ,  3102  to force the locking member  322  against the top surface  338 . After the quadrant  314  is rotated sufficiently rearward, the bias of the cam plate  324  causes the locking member  322  to slide within slots  3100 ,  3102 , toward the corner  338  and against first side surface  332 , thereby locking the quadrant  314  in an upright position. 
     The gear assembly  323  improves the operation of the adjustment mechanism  310  be effectively reducing the force required disengage the cam plate  124  from the locking member  322 . Further, the gear assembly  323  prevents any jerking or jolting motion upon disengagement of the locking member  322  from the first side surface  332  of the arm  312  by actuating the cam  324  through the movement of the first and second gear plates  325 , 327  as opposed to applying a force directly to the cam itself  324 . 
     With reference to FIGS. 10 and 11, a fourth preferred embodiment of the present invention is indicated as adjustment mechanism  410 . The adjustment mechanism  410  generally includes an arm assembly  413  disposed between and pivotally mounted to a quadrant  414  including inner and outer plates  418 , 420 . The quadrant  414  is selectively locked relative to the arm assembly by a locking member  422  that is selectively engaged by a cam plate  424 . 
     The arm assembly  413  includes an arm  412 , a link  415  and a sector plate  417 . A first end of the arm  412  includes a first corner  419 , a second corner  411 , a third corner  421 , a first side surface  423 , a second side surface  425 , a third side surface  427 , a top surface  429 , and an arcuate surface  431 . The first side surface  423 , second side surface  425  and top surface  429  form a locking shoulder. The first corner  419  is formed at the base of the first side surface  423  opposite the top surface  429 . The second corner  419  is formed at the intersection of the second side surface  425  and the arcuate surface  431 . The arcuate surface  431  is formed between the second corner  411  and the third corner  421 . The third corner  423  is formed at the intersection of the third side  427  and the arcuate surface  431 . A second end of the arm  412  includes a first aperture  497  for providing a pivot axis and a second aperture  428  for connecting to a linear recliner mechanism. 
     The arm  412  is disposed between and rotatably supports the inner and outer plates  418 , 420  on a first pivot  440 . The first pivot  440  is received through an aperture  442  of the arm  412 . The first pivot  440  includes first and second cylindrical extensions  444 , 446  that are receivable into and supported by first and second apertures  448 , 450 , respectively. The first pivot  440  further includes a support bearing  452  that extends radially and is disposed between the first and second cylindrical extensions  444 , 446 . The support bearing  452  includes a bearing surface  454  that is received into the aperture  442  for rotatably supporting the quadrant  414  relative to the arm  412 . The sector plate  417  is also rotatably supported by the first pivot  440  and is disposed between the arm  412  and the inner plate  418 . 
     The sector plate  417  includes an aperture  433 , a locking member recess  435 , a first corner  437 , a second corner  439 , a first side  441 , a second side  443 , a third side  445 , an arcuate surface  447  and a top surface  449 . The first corner  437  is formed at the intersection of the arcuate surface  447  and the first side  441 . The second corner  439  is formed at the base of the locking member recess  435  by the intersection of the second side  443  and the third side  445 . The first side  441 , second side  443  and top surface  449  form a locking shoulder. The first pivot  440  is received through the aperture  433  for rotatably supporting the sector plate  417 . An aperture is formed at an opposite end of the sector plate  417  from the locking member recess  435  for attachment of the link  415  thereto. The link  415  includes a first end and a second end with apertures  451 , 453  formed therethrough. The first end of the link  415  is rotatably attached to the sector plate  417  and the second end of the link  417  is rotatably attached to a fixed external structure (not shown). 
     The cam plate  422  is disposed between the inner and outer housing plates  418 , 420  and is rotatably supported therebetween by a second pivot  460  received through a central aperture  462  of the cam plate  422 . The second pivot  460  includes first and second cylindrical extensions  464 , 466  that are received into and supported by apertures  468 , 470  in the inner and outer plates  418 , 420 , respectively. The second pivot  460  also includes a radially extending support bearing  472  that includes a bearing surface  477 . The second pivot  460  is received through the aperture  462  of the arm  412 , whereby the second pivot  460  rotatably supports the quadrant  414  about the bearing surface  477 . 
     One end of the cam plate  424  includes a cam surface  472 . A second end of the cam plate  424  includes an aperture  474  for anchoring a first end of a spring  476  and the inner plate  418  includes an aperture  475  for anchoring a second end of the spring  476 . The spring  476  rotationally biases the cam plate  424  in a first rotational direction, which biases the cam surface  472  toward the locking member  422 , which, in turn, is forced toward the corner and against the first side surface of the arm  412 . In this position, the quadrant  414  is held in a first upright position relative to the arm  412 . A cross member  478  includes cylindrical extensions  480 , 482  received into apertures  484 , 486 , respectively, of the inner and outer plates  418 , 420 . The cross member  478  contacts a face of the arm  412  for prohibiting reward rotation of the quadrant  414  relative to the arm  412 . 
     The locking member  422  is a wedge-shaped member having an arcuate surface  488  at a wide end for engaging the cam surface  472  of the cam plate  424  and a peak  490  disposed in a narrow end. The peak  490  is adapted to engage the locking member recess of the sector plate for locking the quadrant  414  relative the arm  412 . Ribs  492 , 494  extend perpendicularly from faces  496 , 498  of the locking member  422 . The ribs  492 , 494  are slidably supported within slots  4100 , 4102  of the inner and outer plates  418 , 420 , respectively, enabling the locking member  422  to slide therebetween. The locking member  422  slides in the slots  4100 , 4102  as it interfaces between the arm assembly and the cam plate  424 . The cam plate  424  acts on the arcuate surface  488  to bias the locking member  422  against the arm  412 . 
     With further reference to FIGS. 12 and 13, operation of the adjustment mechanism  410  will be described in detail. In a fourth preferred embodiment, the adjustment mechanism  410  enables the quadrant  414  to pivot forward, relative to the arm  412 , and lock in a horizontal or fold-flat position. To fold the quadrant  414  forward, the cam plate  424  is rotated against the biasing force of the spring  476 , forcing the cam surface  472  to slide along and disengage the arcuate surface  488  of the locking member  422 . Thus, the ribs  492 , 494  of the locking member  422  are free to slide in the slots  4100 , 4102  of the inner and outer housing plates  418 , 420  as the locking member  422  moves from a recessed position adjacent to the first side surface  423  to a raised position on the top surface  429  of the arm  412 . Specifically, as the cam plate  424  rotates against the bias of the spring  476 , the locking member  422  is pinched between the first side surface  423  of the arm  412  and the slots  4100 , 4102 . As the cam surface  472  is moved out of blocking engagement with the locking member  422 , upward movement of locking member  422  is unrestricted. As the quadrant  414  is rotated, the walls defining the slots  4100 , 4102  of the inner and outer housing plates  418 , 420  push the locking member  422  upward within slots  4100 , 4102  until the locking member  422  slides over onto the top surface  429  of the arm  412 . Continued forward rotation of the quadrant  414  causes the locking member  422  to slide along the top surface  429  of the arm  412  and eventually transfer from the top surface  429  of the arm  412  to the top surface  449  of the sector plate  417 . Once the locking member  422  is on the top surface  429 , 449  of either the arm  412  or the sector plate  417 , the cam plate  424  may be released wherein the spring  476  again biases the cam plate  424  in the first rotational direction. The cam surface  472  again biases the locking member  422  within the slots  4100 , 4102  pushing the locking member  422  against the top surface  429 , 449  of either the arm  412  or the sector plate  417 , or both, depending upon the forward position of the quadrant  414  at the time the cam plate  424  is released. 
     Once the quadrant  414  has rotated sufficiently forward, the locking member  422  slides off of the top surface  449  of the sector plate  417  and into the locking member recess  435 . Due to the bias of the cam plate  424 , the locking member  422  immediately engages the locking member recess  435 , wherein the back surface  485  of the quadrant  414  is held in a relatively horizontal or fold-flat position. 
     The point on the sector plate  417  where the locking member  422  transfers from the top surface  429  of the arm  412  to the top surface  449  of the sector plate  417  is governed by the relative initial relationship between the arm  412  and the quadrant  414 . As best shown in FIG. 12, the relative angle X of the arm to a horizontal surface determines the angle Y between the arm  412  and the quadrant  414 , and subsequently the distance the locking member  422  must travel over the sector plate  417  before reaching the locking member recess  435 . Specifically, when the arm  412  is rotated (due to reclining), the link  415  rotates the sector plate  417  such that the orientation of the locking member  422 , relative to the horizontal surface remains constant for enabling the back surface  485  of the quadrant  414  to remain horizontal. However, the relative position of the link  415  to the arm  412  changes and the relative position of the sector plate  417  to both the arm  412  and quadrant  414  also changes as the arm  412  is rotated. For example, as the initial angle Y between the arm  412  and the bottom surface  495  of the quadrant  414  increases, the distance between the second side  423  of the arm  412  and the second side  443  of the sector plate  417  decreases as indicated in FIGS. 12 and 13 as Q. Thus, the greater the initial angle Y (or lower the angle X) between the arm  412  and the bottom surface  495  of the quadrant  414 , the shorter the distance the locking member  422  must travel over the top surface  449  of the sector plate  417  to reach the locking member recess  435 . The relative rotation of the sector plate  417  and the arm  412 , through the connection of the link  415 , allows the relative position of the sector plate  417  to the quadrant  414  to change for correspondingly maintaining the back surface  485  of the quadrant  414  in a relatively horizontal position. 
     To return the quadrant  414  to an upright position, relative to the arm  412 , the cam plate  424  is again rotated against the biasing force of spring  476  to disengage the cam plate  424  from the locking member  422 . As the quadrant  414  rotates rearwardly, the locking member  422  moves from a recessed position in the locking member recess  435  to a raised position on the top surface  449  of the sector plate  417 . Specifically, the locking member  422  is engaged in the locking member recess  435  and the slots  4100 , 4102  until the locking member  422  slides onto the top surface  449  of the sector plate  417 . Once the locking member  422  is on the top surface  449 , 429  of either the sector plate  417  or the arm  412 , the cam plate  424  may be released wherein the spring  476  again biases the cam plate  424  in the first rotational direction. Thus, the cam surface  472  biases the locking member  422  within the slots  4100 , 4102  to force the locking member  422  against the top surface  449 , 429  of either the sector plate  417  or the arm  412 . After the quadrant  414  is rotated sufficiently rearward, the locking member  422  transfers from the top surface  449  of the sector plate  417  to the top surface  429  of the arm  412 . The relative distance the locking member  422  must travel Q before transferring from the top surface  449  of the sector plate  417  to the top surface  429  of the arm  412  depends on the initial angle Y between the arm  412  and the quadrant  414  as previously discussed. After the quadrant  414  is rotated sufficiently rearward, the bias of the cam plate  424  causes the locking member  422  to slide within slots  4100 , 4102 , toward the first corner  419  of the arm  412  and against first side surface  423 , thereby locking the quadrant  414  in an upright position. 
     With particular reference to FIGS. 14 and 15, a fifth preferred embodiment of the present invention is indicated as adjustment mechanism  510 . The adjustment mechanism  510  generally includes an arm assembly  513  disposed between and pivotally mounted to a quadrant  514  including inner and outer plates  518 , 520 . The quadrant  514  is selectively locked relative to the arm assembly  513  by a locking member  522  that is selectively engaged by a cam plate  522  that is actuated through a gear assembly  523 . 
     The gear assembly  523  includes the cam plate  524  rotatably supported between the inner and outer plates  518 , 520 , and first and second gear plates  525 , 527  each rotatably supported between the inner and outer plates  518 , 520 . The cam plate  524  is rotatably supported by a second pivot  556  received through a central aperture  558  of the cam plate  524 . The second pivot  556  includes first and second cylindrical extensions  560 , 562  that are receivable into and supported by first and second apertures  564 , 566 , respectively. The second pivot  556  also includes a support bearing  568  that extends radially and is disposed between the first and second cylindrical extensions  560 , 562 . The support bearing  568  includes a bearing surface  570  that is received into the aperture  558  for rotatably supporting the cam plate  524 . 
     The first gear plate  525  includes a central portion  531  and an actuation arm  533  and a cable release aperture  574  for interconnection with a cable (not shown). The first gear plate  525  further includes a series of teeth  535  radially extending from the central portion  531  for meshed engagement with the second gear plate  527  as will be discussed further below. The central portion  531  further includes a cylindrical post  537  formed therein for rotatable attachment to the inner plate  520  of the quadrant  514 . The cylindrical post  537  includes a bearing surface and is received through an aperture  541  formed in the inner plate  318 . While the present invention includes a cylindrical post  537  that is formed within the first gear plate  525  it is anticipated that the cylindrical post  537  could be a separate member attached to the first gear plate  525  by suitable means and should be considered within the scope of the present invention. 
     The second gear plate  527  includes a central portion  543  and a reaction arm  545  having an engagement face  571 . The central portion  543  includes a series of teeth  547  radially extending therefrom for meshed engagement with the first gear plate  525  as will be discussed further below. The central portion  543  further includes first and second cylindrical posts  549 , 551  formed therein for rotatable attachment to the inner and outer plates  518 , 520  of the quadrant  514 . A first end of a coil spring  576  attaches to the second cylindrical post  551  and the outer plate  520  includes an aperture  575  for anchoring a second end of the spring  576 . The spring  576  rotationally biases the second gear plate  527  in a first rotational direction, which in turn rotates the first gear plate  525  in a second rotational direction thereby biasing a cam surface  572  toward the locking member  522 , which, in turn, is forced toward a corner  538  and against a first side surface  532  of the arm  512 . In this position, the quadrant  514  is held in a first upright position relative to the arm  512 . The first and second cylindrical posts  549 , 551  include bearing surfaces and are received through apertures  553 , 555  formed in the inner and outer plates  518 , 520 . While the present invention includes cylindrical posts  549 , 551  that are formed within the second gear plate  527  it is anticipated that the cylindrical posts  549 , 551  could be separate members attached to the second gear plate  527  by suitable means and should be considered within the scope of the present invention. The reaction arm  545  includes an engagement face  557  for interaction with the cam plate  524  during actuation of the adjustment mechanism  510 . 
     The cam plate  524  includes an attachment aperture  558  formed therethrough, a first arm  561  having a cam surface  572  and a second arm  563  having an engagement face  565  for interaction with the second gear plate  527  during actuation of the adjustment mechanism  510 . A cross member  578  includes cylindrical extensions  580 , 582  received into apertures  584 , 586 , respectively, of the inner and outer plates  518 , 520 . The cross member  578  contacts a face  579  of the arm  512  for prohibiting reward rotation of the quadrant  514  relative to the arm  512 . 
     The locking member  522  is a wedge-shaped member having a arcuate surface  588  at a wide end for engaging the cam surface  572  of the cam plate  524  and a peak  590  disposed in a narrow end. The peak  590  is adapted to engage the locking member recess for locking the quadrant  514  relative the arm  3512 . Ribs  592 , 594  extend perpendicularly from faces  596 , 598  of the locking member  522 . The ribs  592 , 594  are slidably supported within slots  5100 , 5102  of the inner and outer plates  518 , 520 , respectively, enabling the locking member  522  to slide therebetween. The locking member  522  slides in the slots  5100 , 5102  as it interfaces between the arm  512  and the cam plate  524 . The cam plate  524  acts on the arcuate surface  588  to bias the locking member  522  against the arm  512  and the sector plate  517 . 
     The arm assembly  513  includes an arm  512 , a link  515  and a sector plate  517 . A first end of the arm includes a first corner  519 , a second corner  511 , a third corner  521 , a first side surface  523 , a second side surface  525 , a third side surface  427 , a top surface  429 , and an arcuate surface  431 . The first side surface  523 , second side surface  525  and top surface  529  form a locking shoulder. The first corner  519  is formed at the base of the first side  523  opposite the top surface  529 . The second corner  511  is formed at the intersection of the second side surface  525  and the arcuate surface  531 . The arcuate surface  531  is formed between the second corner  511  and the third corner  521 . The third corner  523  is formed at the intersection of the third side  527  and the arcuate surface  531 . A second end of the arm  512  includes a first aperture  597  for providing a pivot axis and a second aperture  528  for connecting to a linear recliner mechanism. 
     The arm  512  is disposed between and rotatably supports the inner and outer plates  518 , 520  on a first pivot  540 . The first pivot  540  is received through an aperture  542  of the arm  512 . The first pivot  540  includes first and second cylindrical extensions  544 , 546  that are receivable into and supported by first and second apertures  548 , 550 , respectively. The first pivot  540  further includes a support bearing  552  that extends radially and is disposed between the first and second cylindrical extensions  544 , 546 . The support bearing  552  includes a bearing surface  554  that is received into the aperture  542  for rotatably supporting the quadrant  514  relative to the arm  512 . The sector plate is also rotatably supported by the first pivot  540  and is disposed between the arm  512  and the inner plate  518 . 
     The sector plate  517  includes an aperture  533 , a locking member recess  535 , a first corner  537 , a second corner  539 , a first side  541 , a second side  543 , a third side  545 , an arcuate surface  547  and a top surface  549 . The first side  541 , second side  543  and top surface  549  form a locking shoulder. The first corner  537  is formed at the intersection of the arcuate surface  547  and the first side  541 . The second corner  539  is formed at the base of the locking member recess  535  by the intersection of the second side  543  and the third side  545 . The first pivot  540  is received through the aperture  533  for rotatably supporting the sector plate  517 . An aperture is formed at an opposite end of the sector plate  517  from the locking member recess  535  for attachment of the link  515  thereto. The link  515  includes a first end and a second end with apertures  551 , 553  formed therethrough. The first end of the link  515  is rotatably attached to the sector plate  517  and the second end of the link  517  is rotatably attached to a fixed external structure (not shown). 
     With particular reference to FIGS. 14 and 15, operation of the adjustment mechanism  510  will be described in detail. In a fifth preferred embodiment, the adjustment mechanism  510  enables the quadrant  514  to pivot forward relative to the arm  512  and lock in a horizontal or fold-flat position. To fold the quadrant  514  forward, a force is applied to the actuation arm  533  of the first gear plate  525 . The applied force causes the first gear plate  525  to rotate, which subsequently rotates the second gear plate  527  against the bias of the spring  576 . Rotation of the second gear plate  527  releases the engagement face  571  of the reaction arm  545  from the first arm  561  of the cam plate  524 . Further rotation of the second gear plate  527  causes the reaction arm  545  to react against the second arm  563  of the cam plate  524 . Engagement of the second gear plate  527  and the second arm  563  of the cam plate  524  induces the cam plate  524  to rotate, forcing the cam surface  572  to disengage the arcuate surface  588  of the locking member  522 . Thus, the ribs  592 , 594  of the locking member  522  are free to slide in the slots  5100 , 5102  of the inner and outer housing plates  518 , 520  as the locking member  522  moves from a recessed position adjacent to the first side surface  523  to a raised position on the top surface  529  of the arm  512 . 
     Specifically, as the cam plate  524  rotates against the bias of the spring  576 , the locking member  522  is pinched between the first side surface  523  of the arm  512  and the slots  5100 , 5102 . As the cam surface  572  is moved out of blocking engagement with the locking member  522 , upward movement of locking member  522  is unrestricted. As the quadrant  514  is rotated, the walls defining the slots  5100 , 5102  of the inner and outer housing plates  518 , 520  push the locking member  522  upward within slots  5100 , 5102  until the locking member  522  slides over onto the top surface  529  of the arm  512 . Continued forward rotation of the quadrant  514  causes the locking member  522  to slide along the top surface  529  of the arm  512  and eventually transfer from the top surface  529  of the arm  512  to the top surface  549  of the sector plate  517 , a portion thereof overlapping. Once the locking member  522  is on the top surface  529 , 549  of either the arm  512  or the sector plate  517 , the first gear plate  525  may be released, wherein the spring  576  again biases the second gear plate  527  in the first rotational direction, allowing the first gear plate  525  to rotate and also causing the cam plate  524  to be released. The cam surface  572  again biases the locking member  522  within the slots  5100 , 5102 , pushing the locking member  522  against the top surface  529 , 549  of either the arm  512  or the sector plate  517  or both, depending on the forward movement of the quadrant  514  at the time the first gear plate  525  is released. 
     Once the quadrant  514  has rotated sufficiently forward, the locking member  522  slides off of the top surface  549  of the sector plate  517  and into the locking member recess  535 . Due to the force of the cam plate  524 , the locking member  522  immediately engages the locking member recess  535 , wherein the back surface  585  of the quadrant  514  is held in a relatively horizontal or fold-flat position. 
     The point on the sector plate  517  where the locking member  522  transfers from the top surface  529  of the arm  512  to the top surface  519  of the sector plate  517  is governed by the relative initial relationship between the arm  512  and the quadrant  514 . The relative angle X (reference FIGS. 12 and 13) of the arm  512  to a horizontal surface determines the angle Y (reference FIGS. 12 and 13) between the arm  512  and the quadrant  514 , and subsequently the distance Q (reference FIGS. 12 and 13) the locking member  522  must travel over the sector plate  517  before reaching the locking member recess  535 . When the arm  512  is rotated, the link  515  rotates the sector plate  517  such that the orientation of the locking member  522 , relative to the horizontal surface remains constant for enabling the back surface  585  of the quadrant  514  to remain horizontal. However, the relative position of the link  515  to the arm  512  changes and, thus, the relative position of the sector plate  517  to the arm  512  also changes as the arm  512  is rotated. For example, as the initial angle Y between the arm  512  and the bottom surface  595  of the quadrant  514  increases between the second side  525  of the arm  512  and the second side  543  of the sector plate  517  decreases. Thus, the greater the initial angle Y between the arm  512  and the bottom surface  595  of the quadrant  514 , the shorter the distance the locking member  522  must travel over the top surface  549  of the sector plate  517  to reach the locking member recess  535 . The relative rotation of the sector plate  517  and the arm  512 , through the connection of the link  515 , allows the relative position of the sector plate  517  to the quadrant  514  to change for correspondingly maintaining the back surface  585  of the quadrant  514  in a relatively horizontal position. 
     To return the quadrant  514  to an upright position relative to the arm  512 , the first gear plate  525  is again rotated, thereby causing the second gear plate  527  to rotate against the biasing force of spring  576  causing the cam plate  524  to rotate such that the cam plate  524  disengages from the locking member  522 . As the quadrant  514  rotates rearwardly, the locking member  522  moves from a recessed position in the locking member recess  535  to a raised position on the top surface  549  of the sector plate  517 . Specifically, the locking member  522  is engaged in the locking member recess  535  and the slots  5100 , 5102  until the locking member  522  slides onto the top surface  549  of the sector plate  517 . Once the locking member  522  is on the top surface  549 , 529  of either the sector plate  549  or the arm  512 , the first gear plate  525  may be released, wherein the spring  576  again biases the second gear plate  527  in the first rotational direction, allowing the first gear plate  525  to rotate, and also causing the cam plate  524  to rotate. Thus, the cam surface  572  again biases the locking member  522  within the slots  5100 , 5102  to force the locking member  522  against the top surface  549 , 529  of either the sector plate  517  or the arm  512 . 
     After the quadrant  514  is rotated sufficiently rearward, the locking member  522  transfers from the top surface  549  of the sector plate  517  to the top surface  529  of the arm  512 . The relative distance the locking member  522  must travel before transferring from the top surface  549  of the sector plate  517  to the top surface  549  of the arm  512  depends on the initial angle Y between the arm  512  and the quadrant  514  as previously discussed. After the quadrant  514  is rotated sufficiently rearward, the bias of the cam plate  524  causes the locking member  522  to slide within slots  5100 , 5102 , toward the first corner  519  of the arm  512  and against first side surface  523 , thereby locking the quadrant  514  in an upright position. 
     It will be understood that the third, fourth and fifth embodiments of the adjustment mechanism  310 ,  410 ,  510  may be adapted for use in a seat assembly, similarly as that described for seat assembly  200  of FIGS. 6 a ,  6   b ,  6   c  and  7 . Therefore, a detailed description is foregone. In general, the recliner mechanism  310  enables an operator to more easily disengage the locking member  322 , via a gear reduction through first and second gear plates  325 , 327 , for folding the seat back  202  relative to the seat  204  in one of a number of fold-forward positions. The recliner mechanism  410  enables the seat back  202  to maintain a constant fold-forward, horizontal position, regardless of a recline position of the recliner mechanism  410  to the seat  204 . The recliner mechanism  510 , combines the features of the recliner mechanisms  310 , 410  for enabling easier disengagement of the locking member  522  and maintaining a constant fold-forward, horizontal position, regardless of a recline position of the recliner mechanism  510  to the seat  204 . 
     While the invention has been described in the specification and illustrated in the drawings with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention as defined in the claims. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment illustrated by the drawings and described in the specification as the best mode presently contemplated for carrying out this invention, but that the invention will include any embodiments falling within the description of the appended claims.