Abstract:
A versatile, adjustable stroller for handicapped children, adolescents and adults. The stroller includes a seat assembly and a frame assembly. The frame assembly includes a tilt-in-space block for allowing the seat assembly to be positioned relative to the frame assembly at a multiplicity of angular positions while providing balanced support for the occupant. The back rest of the seat assembly can be positioned at a multiplicity of angular positions while providing proper anatomical alignment and support for an occupant. The seat assembly can be completely removed from the frame assembly and then installed so that the occupant can face in an opposite direction. The stroller is preferably constructed so as to be collapsible for easy transport and/or storage. The tilt-in-space block enables the structural tubing placement, handle bar placement, and tilt-in-space capability to be situated in one plane, thereby making the stroller narrower to provide the maximum amount of access to the environment for the occupant.

Description:
RELATED APPLICATIONS 
     This application is a Continuation of application Ser. No. 09/309,824, filed May 11, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates in general to a stroller, and in particular, to a stroller with a tilt-in-space capability to select the recline angle of the seat assembly of the stroller. 
     A standard wheelchair is perhaps the most common wheeled support structure for handicapped individuals. Although wheelchairs are commonly designed to be readily adaptable to accommodate individuals of different sizes and shape, they often lack the contoured support needed to properly anatomically align and support the occupant. Further, standard wheelchairs frequently have complicated adjustment mechanisms in order to accommodate individuals of different size and weight, and fail to provide any means for varying the spatial orientation of the occupant without disturbing a therapeutically desired seating posture. Lastly, standard wheelchairs by their design and construction are usually restricted as to the type of terrain which can be traversed. For example, they typically have relatively small swivel wheels or coasters secured to their lower front end for mobility, which, because of their size often act as a limitation on the mobility of the wheelchair. 
     Another type of wheeled support structure, although not specifically designed for handicapped individuals, is a baby stroller. A wide variety of baby strollers are presently available, but none appear to satisfactorily combine the above desirable characteristics of a wheeled seat support or stroller for a handicapped individual. Baby strollers are designed to function primarily as wheeled structures for babies and small children. Therefore, such strollers are usually engineered to be of a light construction and often include intricate adjustment or collapse mechanisms which would be unduly cumbersome if enlarged to the size necessary for a wheeled support structure or stroller for an adolescent or adult. Lastly, baby strollers generally lack any contoured support such as that needed to properly anatomically align and support a handicapped individual. 
     Thus, there presently exists a genuine need for a wheeled support structure or stroller capable of properly anatomically aligning and supporting a seated occupant and capable of being adjusted to vary the spatial orientation of the occupant, and yet is easily transportable and storable when not in use. 
     SUMMARY OF THE INVENTION 
     This invention relates to a stroller having tilt-in-space capability. The stroller comprises a frame assembly including a tilt-in-space block having at least one cavity, and a seat assembly including at least one latch pin. The at least one latch pin of the seat assembly is capable of being disposed within the at least one cavity of the tilt-in-space block to allow selection of an angular position of the seat assembly with respect to the frame assembly. 
     In another embodiment of the invention, the stroller comprises a frame assembly including tilt-in-space block and a handle bar block pivotally connected to the tilt-in-space block, and a seat assembly including at least one pivot post capable of being received in the tilt-in-space block. The at least a portion of the handle bar block covers the at least one pivot post when pivoting the handle bar block around the tilt-in-space block, thereby preventing the seat assembly from being removed from the frame assembly when placing the stroller in a folded, down position. 
     In yet another embodiment of the invention, a stroller having tilt-in-space capability comprises a frame assembly including a tilt-in-space block having a plurality of cavities, and a seat assembly including a tilt-in-space latch pin capable of being received in one of the plurality of cavities of the tilt-in-space block of the frame assembly. A first angular position of the seat assembly with respect to the frame assembly can be selected by positioning the tilt-in-space latch pin within one of the plurality of cavities of the tilt-in-space block, and a second angular position of the seat assembly with respect to the frame assembly can be selected by positioning the tilt-in-space latch pin within a different one of the plurality of cavities of the tilt-in-space block. 
     In still yet another embodiment of the invention, a stroller comprises a frame assembly including a handle bar block pivotally connected to a tilt-in-space block, and a seat assembly including at least one pivot post pivotally connected to the tilt-in-space block. The combined thickness of the handle bar block and the tilt-in-space block is about one inch. 
     In another embodiment of the invention, a stroller comprises a frame assembly including tilt-in-space block having a guide slot, and a seat assembly including at least one guide post capable of being received within the guide slot. The least one guide post can prevent the seat assembly from being removed from the frame assembly when the at least one guide post is received within the guide slot. 
     In a further embodiment of the invention, a stroller having anatomically correct pivot points comprises a frame assembly including tilt-in-space block and a handle bar block pivotally connected to the tilt-in-space block, and a seat assembly including at least one pivot post capable of being received in the tilt-in-space block. The pivot post of the seat assembly is located at approximately a center of mass of an occupant when seated in the stroller. 
     Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front perspective view of the stroller with tilt-in-space capability in an unfolded, upright position according to a preferred embodiment of the invention; 
     FIG. 2 is a rear perspective view of the frame assembly of the invention with the seat assembly removed from the frame assembly; 
     FIG. 3 is a cross-sectional view of the tilt-in-space block taken along line  3 — 3  of FIG. 2; 
     FIG. 4 is a front perspective view of the frame assembly of FIG. 2 in a folded, down position; 
     FIG. 5 is a side view of the TIS block when the frame assembly is in an unfolded, upright position; 
     FIG. 6 is a side view of the TIS block when the frame assembly is in a folded, down position; 
     FIG. 7 is a rear perspective view of the seat assembly when in an unfolded, upright position according to the preferred embodiment of the invention; 
     FIG. 8 is a rear perspective view of the seat assembly of FIG. 7 when in the folded, down position; 
     FIG. 9 is a bottom cutaway view of the seat assembly showing the TIS latch mechanism; 
     FIG. 10 is a side cutaway view of the seat assembly and the frame assembly showing the TIS pivot post of the seat assembly being inserted into the TIS block of the frame assembly; and 
     FIG. 11 is a side cutaway view of the seat assembly and the frame assembly of FIG. 10 showing the TIS pivot post of the seat assembly inserted into the TIS block of the frame assembly. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, there is illustrated in FIG. 1 a stroller, shown generally at  10 , according to a preferred embodiment of the invention. The stroller  10  includes a frame assembly, shown generally at  12 , and a seat assembly, shown generally at  14 . For illustrative clarity, the stroller  10  is shown without seat or back cushions. 
     Frame Assembly 
     Referring now to FIGS. 1 through 4, the frame assembly  12  includes a pair of slide tubes  16  connected to a front cross tube  18  by a caster block  20 . The caster block  20  is, in turn, connected to a front wheel assembly, shown generally at  22 , for movably supporting the frame assembly  12 . The pair of slide tubes  16  are also connected to a rear cross tube  24  by a wheel coupling assembly, shown generally at  26 . The wheel coupling assembly  26  is, in turn, connected to a rear wheel assembly, shown generally at  28 , for movably supporting the frame assembly  12 . The frame assembly  12  may also include a platform  29  connected to the slide tubes  16 , the front cross tube  18  and the rear cross tube  24  for providing structural reinforcement to the frame assembly  12 . 
     Each side of the frame assembly  12  includes a front diagonal tube  30  and a wheel lock tube  32 . The front diagonal tube  30  is pivotally connected to the caster block  20  and fixedly attached to a tilt-in-space (TIS) block  34 . The wheel lock tube  32  is pivotally connected to the TIS block  34  by use of a TIS pivot block  35 . A wheel lock mechanism, shown generally at  36 , may be attached to the wheel lock tube  32  for providing a means for locking the rear wheels. This can be accomplished by moving a lever  37  operatively coupled to a brake  39 . Movement of the lever  37  in the upward direction causes the brake  39  to engage the wheel of the rear wheel assembly  28 . Similarly, movement of the lever  37  in the downward direction causes the brake  39  to disengage from the wheel of the rear wheel assembly  28 . An anti-tip tube  38  may be connected to each slide tube  16  for preventing the stroller  10  from tipping too far in the backward direction. A pair of wheels  40  can be rotatably connected to each side of the anti-tip tube  38  to allow the stroller  10  to freely move when the wheels  40  engage the surface on which the stroller  10  is located. 
     The frame assembly  12  also includes a handle bar block, shown generally at  42 , for pivotally connecting a handle bar  44  to the frame assembly  12 . A spring-loaded release knob  46  may be slidably attached to the handle bar  44  to allow the handle bar  44  to pivot over the TIS block  34  when placing the frame assembly  12  in the folded, down position, as shown in FIG.  4 . The release knob  46  will be discussed in further detail below. In addition, the frame assembly  12  includes a latch mechanism, shown generally at  48 , for allowing the rear wheel assemblies  28  to move forward when placing the frame assembly  12  in the folded position. The latch mechanism  48  will not be discussed in further detail. 
     As best seen in FIGS. 2 and 4, the TIS block  34  includes a plurality of apertures or cavities  50 , preferably nineteen, arranged in an arc-like pattern on the side walls  52  of the TIS block  34 . In the preferred embodiment, the cavities  50  are equally spaced by an arc-length of approximately five degrees with respect to each other. It should be appreciated that the invention is not limited by the number or spacing of the cavities, and that the invention can practiced with any number of cavities and any spacing between the cavities. 
     The TIS block  34  also includes a pivot post slot  56  and a guide slot  58 . As best seen in FIG. 3, the pivot post slot  56  includes beveled side walls  60  for receiving a TIS pivot post of the seat assembly  14 . The TIS pivot post is not shown in FIG. 3, but is indicated at  62  in FIGS. 7 and 10. Preferably, the guide slot  58  is substantially T-shaped with a generally straight upper portion  64  and an arc-shaped lower portion  66 . The purpose of the pivot post slot  56  and the guide slot  58  will be discussed below. As shown in FIG. 6, the TIS block  34  also includes an upper cam surface  68  for mating with the lower cam surface  70  of the handle bar block  42  when the handlebar  44  is in the locked, upright position shown in FIG.  2 . In the preferred embodiment, both the TIS block  34  and handle bar block  42  of the stroller  10  have a total thickness of approximately one inch, thereby allowing the maximum amount of access to the environment for the occupant as compared to conventional strollers. 
     Referring now to FIGS. 5 and 6, the frame assembly  12  is illustrated in a locked, upright position. The handle bar  44  includes an lower plug  72  slidably disposed within the handle bar  44 , as indicated by the directional arrows in FIG. 5. A spring  74  is also disposed within the handle bar  44 . An upper plug  75  connected to the release knob  46  is also disposed within the handle bar  44 . A cable  77  is connected to the upper plug  75  and the lower plug  72 . The spring  74  is positioned between the upper plug  75  and the lower plug  72  so as to exert a downward biasing force against the lower plug  72 , thereby positioning the lower plug  72  within a cavity or opening  76  on the upper cam surface  68  of the TIS block  34  when the frame assembly is in the locked, upright position. 
     Referring now to FIG. 6, to position the frame assembly  12  in an unlocked, folded position, an upward biasing force can be exerted by the release knob  46  having a sufficient amount of force to overcome the downward biasing force exerted by the spring  74  on the lower plug  72 , as indicated by the upward directional arrow. As a result, the spring  74  compresses and the lower plug  72  moves upward into the handle bar  44 , as indicated by the phantom arrow. After moving a sufficient distance, the lower plug  72  will no longer be disposed within the opening  76  on the upper cam surface  68  of the TIS block  34 . At this point, the handle bar  44  can be pivoted around the TIS block  34  about a pivot pin  78  defining a pivot axis, A, as indicated by the arcuate-shaped directional arrows. Once the upward biasing force is removed, the bias of the spring  74  causes the lower plug  72  to extend beyond the lower cam surface  70  of the handle bar block  42 . 
     Seat Assembly 
     Referring now to FIG. 7, the seat assembly  14  includes a seat base, shown generally at  82 , and a back rest assembly, shown generally at  84 . The seat base  82  includes upwardly extending side walls  86 , each side wall having the TIS pivot post or arm  62  defining a pivot point, B, for the relative movement of the seat assembly  14  with respect to the frame assembly  12 . It should be noted that the pivot point, B, and the pivot point, A, are both located at the anatomically correct position of the center of mass of the occupant. An armrest  88  may be attached to each side wall  86  for the comfort of the occupant. 
     The back rest assembly  84  includes an outer back rest shell  90  having a pair of lateral pelvic supports  92 . The outer back rest shell  90  also includes a pair of outer vertical slots  94  and a pair of inner vertical slots  96 . The outer slots  94  allow for the selective adjustment of an inner back rest shell  98  vertically along the outer back rest shell  90  by means of adjustable bolts (not shown) that secure the inner back rest shell  98  to the outer back rest shell  90 . The lateral pelvic supports  92  of the outer back rest shell  90  are pivotally secured to the side walls  86  of the seat base  82  using pivot pins  100 , which form a pivot point, C, for the back rest assembly  84  to pivot with respect to the seat base  82 . In a manner similar to the pivot point, B, the pivot point, C, is positioned at an anatomically correct pivot point of the pelvic area of the occupant. A pair of sunshade blocks  102  may be attached to the outer back rest shell  90 . A shell handle  104  can be attached to the pair of sunshade blocks  102  for allowing the user to easily grasp the shell assembly  14 . 
     One feature of the invention is that the seat assembly  14  includes a mechanical locking adjustment mechanism, shown generally at  106 , for positioning the back rest assembly  84  at a selected angle relative to the seat base  82 . The adjustment mechanism  106  includes a hand-operated release grip  108  operatively coupled to a cable  110 . One end of the cable  110  is connected to a coupling  112  that frictionally engages a shaft  114 . The adjustment mechanism  106  is biased to a locked position by use of a biasing means, such as a spring (not shown). When an upward or downward force is applied to the release grip  108 , the cable  110  causes the coupling  112  to no longer frictionally engage the shaft  114 . As a result, the coupling  112  can slide up and down the shaft  114  to infinitely adjust the angle of the back rest assembly  84  with respect to the seat base  82 . When the upward or downward force is no longer applied to the release grip  108 , the biasing means causes the coupling  112  to frictionally engage the shaft  114  to lock the selected angle of the back rest assembly  84  in place. The adjustment mechanism  106  allows the seat assembly  14  to be placed in a folded position by moving the back rest assembly  84  to a fully forward angular position relative to the seat base  82 , as shown in FIG.  8 . 
     Another feature of the invention is that the seat assembly  14  also includes a latch mechanism, shown generally at  116 , for positioning the seat assembly  14  relative to the frame assembly  12  in a multiplicity of selected locations. As best seen in FIG. 9, the latch mechanism  116  includes a hand-operated release grip  118  operatively coupled to a cable  120 . One end of the cable  120  is operatively coupled to an apex of a triangular-shaped TIS activator plate  122 . The TIS activator plate  122  is pivotally mounted to the underside of the seat base  82  by a pivot pin  124 . A pair of TIS linkage rods  126 ,  128  are operatively connected to the other apexes of the triangular-shaped TIS activator plate  122 . The other end of each TIS linkage rod  126 ,  128  is operatively coupled to one end of a latch pin mechanism  130 ,  132 , respectively. The other end of each latch pin mechanism includes a TIS latch pin  134 ,  136 . 
     The latch pin mechanisms  130 ,  132  are positioned at the underside of the seat base  82  such that the TIS latch pins  134 ,  136  protrude from the seat base  82  when the lock pin mechanisms  130 ,  132  are in the locked position. The latch pin mechanisms  130 ,  132  are biased to a locked position by use of a biasing means, such as a spring  138 . The length of the TIS latch pins  134 ,  136  are such that they can be inserted into the cavities  50  on the TIS block  34 . In this manner, the angular position the seat assembly  14  relative to the frame assembly  12  can be selected by applying an upward or downward force on the release grip  118  which causes the TIS activator plate  122  to pivot in a counterclockwise direction (as viewed in FIG.  9 ). This counterclockwise pivoting movement of the TIS activator plate  122  causes the TIS linkage rods  126 ,  128  to move inwardly toward the center of the seat base  82 , which in turn, causes the TIS latch pins  134 ,  136  to also move laterally toward the center of the seat base  82  and retract into their respective latch pin mechanisms  130 ,  132 . 
     When the TIS latch pins  134 ,  136  retract such that they no longer are inserted into the cavities  50  of the TIS block  34 , the seat assembly  14  is in an unlocked position. When in the unlocked position, the seat assembly  14  can pivot about pivot posts  62 , i.e. about pivot point, B, such that the orientation or the angular position of the seat assembly  14  relative to the frame assembly  12  can be moved to the desired angular position. Once the angular position is selected by the stroller attendant, the upward or downward force applied to the release grip  118  can be released such that the bias of the spring  138  causes the TIS activator plate  122  to pivot in a clockwise direction (as viewed in FIG.  9 ). This pivoting movement causes the TIS linkage rods  126 ,  128  to move outwardly from the center of the seat base  82  until the TIS latch pins  134 ,  136  protrude from their respective latch pin mechanisms  130 ,  132  and become disposed within the cavities  50  of the TIS block  34 , thereby locking the seat assembly  14  at the selected angular position. In this manner, the stroller  10  has a tilt-in-space (TIS) capability enabling the stroller attendant to select the desired angular position of the seat assembly  14  with respect to the frame assembly. 
     Referring now to FIGS. 1,  7 ,  8  and  9 , the seat assembly  14  also includes a foot rest assembly, shown generally at  140 , attached to the seat base  82  by a pair of foot rest tubes  142 ,  144 . The foot rest assembly  140  includes a foot bed  146  having side walls  148 ,  150  mounted to a pair of foot bed tubes  152 ,  154 . The foot bed  146  may also include a back wall  149  that functions as a heel stop for the occupant. Each foot bed tube  152 ,  154  is, in turn, pivotally mounted to a knee angle block  156 ,  158 . The knee angle blocks  156 ,  158  are, in turn, attached to the seat base  82  by the foot rest tubes  142 ,  144 . Each knee angle block  156 ,  158  has a forked lower portion  160 ,  162  for receiving a knee angle adjustment bar  164 ,  166  therebetween. A biasing means, such as return springs  168 ,  170 , are positioned between the knee angle adjustment bars  164 ,  166  and the knee angle blocks  156 ,  158  to cause a downward biasing force on the knee angle adjustment bars  164 ,  166 . A knee angle adjustment pin  172 ,  174  are secured to the lower portions  160 ,  162  to span across the forked lower portions  160 ,  162 . A plurality of grooves  176  are located on the bottom of each knee angle adjustment bar  164  and are dimensioned such that the knee angle adjustment pins  172 ,  174  can be seated within the grooves  176  to prevent movement of the knee angle adjustment bars  164 ,  166 . It should be appreciated that the invention is not limited by the number of grooves  176  in the knee angle adjustment bars  164 ,  166 , and that the invention can be practiced with any number of grooves. 
     By applying a sufficient amount of upward force on the knee angle adjustment bars  164 ,  166  to overcome the downward force exerted by the return springs  168 ,  170 , the knee angle adjustment pins  172 ,  174  will no longer be seated in the grooves  176  of the knee angle adjustment bars  164 ,  166 . As a result, the knee angle adjustment bars  164 ,  166  can move relative to the knee angle blocks  156 ,  158 . This relative movement causes pivotal movement of the foot bed  146  until the foot bed  146  is positioned at a selected angular position. When the upward force is no longer applied to the knee angle adjustment bars  164 ,  166 , the downward biasing force of the springs  168 ,  170  cause the knee angle adjustment bars  164 ,  166  to engage the knee angle adjustment pins  172 ,  174 . When the grooves of the knee angle adjustment bars  164 ,  166  are properly aligned with the knee angle adjustment pins  172 ,  174 , the knee angle adjustment pins  172 ,  174  will seat in the grooves  176  to prevent further movement of the knee angle adjustment bars  164 ,  166 . In this manner, the foot rest assembly  140  allows for positioning of the foot bed  146  in a multiplicity of selected angular positions. 
     It should be appreciated that the foot bed tubes  152 ,  154 , as well as, the foot bed  146 , pivot about a pivot axis, D, with respect to the knee angle blocks  156 ,  158  of the foot bed assembly  140 . The pivot axis, D, is positioned to be at an anatomically correct knee position for the occupant to provide the amount of maximum comfort for the occupant. 
     One advantage of the invention is that the seat assembly  14  can be completely removed from the frame assembly  12  by applying an upward or downward force to the release grip  118  such that the TIS latch pins  134 ,  136  no longer are seated within the cavities  50  of the TIS block  34 . By lifting up on the seat assembly  14  by preferably using the shell handle, the seat assembly  14  can be lifted upward until the pivot posts  62  are no longer seated in the pivot post slot  56 . At this point, the seat assembly  14  can be completely removed from the frame assembly  12 . After being completely removed from the frame assembly  12 , the seat assembly  14  can then be positioned in the frame assembly  12  such that the seat assembly  14  is facing in an opposite direction in which the seat assembly  14  was facing before it was removed. In this manner, the occupant can face in an opposite direction in the stroller  10 . 
     To install the seat assembly  14  after being completely removed from the frame assembly  12 , the TIS pivot post  62  and a guide pin  63  on each side of the seat assembly  14  are aligned with the pivot post slot  56  and the guide slot  58 , as shown in FIG.  10 . Then, the TIS pivot post  62  and a guide pin  63  of the seat assembly  14  are inserted into the pivot post slot  56  and the guide slot  58  of the frame assembly  12 , as indicated by the arrows in FIG. 10, until the guide pin  63  enters the guide slot  58  and the TIS pivot post  62  is seated in the pivot post slot  56 , as shown in FIG.  11 . While installing the seat assembly  14  to the frame assembly  12 , the TIS latch pins  134 ,  136  are preferably retracted within their respective latch pin mechanisms  130 ,  132 . However, retraction of the TIS latch pins  134 ,  136  is not necessary during the installation as the side walls  52  of the TIS block  34  can be used to depress the TIS latch pins  134 ,  136  into their respective latch pin mechanisms  130 ,  132 . 
     In the preferred embodiment, the guide pin  63  is offset from the TIS pivot post  62  by an angle, θ, of about twenty degrees with respect to the vertical axis, V, of the seat assembly  14 . As mentioned earlier, the TIS block  34  preferably includes nineteen equally-spaced cavities  50  with an arc-length of approximately five degrees with respect to each other to provide eighteen indexing positions for the stroller  10 . The full range of motion of the seat assembly  14  with respect to the frame assembly  12  is eighteen positions times five degrees, or about ninety degrees. However, because the guide pin  63  is offset from the TIS pivot post  62  by an angle, θ, of about twenty degrees, the maximum angular position of the seat assembly  14  with respect to the frame assembly  12  can be approximately twenty-five degrees in the forward direction and approximately sixty-five degrees in the rearward direction, with respect to the horizontal axis, H. Thus, the offset angle, θ, of the guide pin  63  enables the seat assembly  14  to tilt a greater amount in the rearward direction than in the forward direction. 
     Once the seat assembly  14  is installed onto the frame assembly  12 , the angular position of the seat assembly  14  with respect to the frame assembly  12  can be selected by retracting the TIS latch pins  134 ,  136  into their respective latch pin mechanisms  130 ,  132 . At this point, the seat assembly  14  can be pivoted about the pivot axis, B, as defined by the TIS pivot posts  62 , until the seat assembly  14  is at the desired angular position. 
     It should be noted that once the seat assembly  14  is installed, the seat assembly  14  becomes an integral part of the frame assembly  12 , thereby allowing the seat assembly  14  to accommodate significant loads. It should also be noted that while the seat assembly  14  is pivoting about the pivot axis, B, the guide pin  63  moves along the lower portion  66  of the guide slot  58  of the TIS block  34 , as shown in FIG.  11 . In the event that the seat assembly  14  has been pivoted an excessive amount, the guide pin  63  will abut against the ends  65  of the lower portion  66 , thereby acting as a stop to prevent excessive pivotal movement of the seat assembly  14 . 
     As described above, the stroller  10  having tilt-in-space capability provides several advantageous features in comparison with conventional strollers. One feature is that the TIS block  34  includes a plurality of cavities  50  capable of having the latch pins  134 ,  136  disposed therein. This feature enables the seat assembly  14  to be positioned in a wide range of indexable angular positions with respect to the frame assembly  12 . 
     The invention also provides the feature that the seat assembly  14  pivots with respect to the frame assembly  12  about a pivot axis, B, located at approximately the center of mass of the occupant when seated in the stroller  10 . In the preferred embodiment, the pivot post  62  is positioned approximately 3 to 6 inches forward of the outer back rest shell  90  and approximately 4 to 8 inches above the seat base  82  so that the center of mass of the occupant will coincide with the pivot axis, B, thereby providing stability of the stroller  10 . In addition, the back rest assembly  84  and the foot rest assembly  140  pivot about a pivot axes, C and D, located at approximately anatomically correct positions with respect to the occupant&#39;s pelvic and knee areas, respectively. 
     Another feature of the invention is that the seat assembly  14  can be completely removed from the frame assembly  12 . This feature allows the seat assembly  14  to be positioned in an opposite direction, if desired. It should be noted that the stroller  10  has similar TIS capabilities and stability characteristics, regardless of the direction in which the seat assembly  14  is facing. 
     The invention also provides several important safety features in comparison with conventional strollers. One feature is prevention of the inadvertent removal of the seat assembly  14  from the frame assembly  12  during certain operating conditions. This is accomplished by the handle bar block  42  covering the pivot post  62  when the handle bar  44  is pivoted from the locked, upright position to the unlocked, down position. In addition, the latch pins  134 ,  136  are seated in the cavities  50  and need to be retracted into their respective latch pin mechanisms  130 ,  132  before the seat assembly  14  can be removed from the frame assembly  12 . Further, the guide pin  63  needs to be in same vertical angular alignment with the straight upper portion  64  of the guide slot  58  before the seat assembly  14  can be removed from the frame assembly  12 , even though the TIS latch pins  134 ,  136  are retracted into their respective latch pin mechanisms  130 ,  132 . This prevents inadvertent removal of the seat assembly  14  during adjustment of the angular position of the seat assembly  14  with respect to the frame assembly  12 . It should be also noted that the offset angle, θ, of the guide pin  63  enables the seat assembly  14  to tilt a greater amount in the rearward direction than in the forward direction, thereby decreasing the likelihood that the occupant will fall forward out of the stroller  10 . 
     The invention also provides the feature of providing a maximum amount of access to the environment for the occupant. This can be accomplished because the placement of the slide tubes  16 , the front diagonal tubes  30 , the wheel lock tubes  32 , and the handle bar  44  are all situated within the generally planar space defined by the combined thickness of the TIS block  34  and the handle bar block  42  which have a thickness no greater than about one inch. 
     Still yet another feature of the invention is that the stroller  10  can be easily placed in the folded position for storage. This can be accomplished by moving the back rest assembly  84  and the rear wheel assemblies  28  to the forward position, thereby placing the stroller  10  is a more compact configuration when compared to conventional strollers. 
     In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.