Abstract:
A belt-like hip-girdling pelvic sling device for maintaining a desired amount of tension surrounding a person&#39;s hips and pelvis to securely support and stabilize a fractured pelvis, including a force-controlled buckle that automatically latches to control the tension and that includes a releasable latching mechanism. The latching mechanism maintains engagement of the buckle with a strap at the required position of the strap with respect to the buckle. The latching mechanism includes a movable member of the buckle that is moved to and latched in a position in which the buckle engages the strap, once a desired amount of tension is reached, limiting and maintaining the required tension.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/733,058 filed Dec. 4, 2012. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to medical emergency equipment, and in particular to a buckle for use in a device for supporting and controlling movement of a patient&#39;s injured pelvis. 
         [0003]    U.S. Pat. Nos. 6,554,784, 7,008,389, and 8,192,383 disclose belt-like hip-girdling pelvis-stabilizing devices each including a buckle and a strap engaged through the buckle so as to place the belt into tension while it encircles a patient&#39;s pelvis. The buckle is arranged to engage the strap when a certain tension has been developed in the portion of the device encircling the patient, to prevent excessive tension in the portion of the device encircling the patient. So long as enough tension is retained in an outer part of the strap, extending beyond the buckle, engagement of the buckle with the strap maintains tension in the belt-like device the while the medical provider applying the device secures the outer part of the strap to the main body of the device. 
         [0004]    In some versions of such a pelvis-stabilizing device the buckle produces an audible click when the correct amount of tension has been achieved, indicating that one or more prongs are exposed within the buckle and have entered into corresponding holes in the strap. If the outer end of the strap in such a buckle is not properly secured to maintain the amount of tension, however, a part of the buckle may move to hide the prongs, retracting them from engagement with the strap and allowing tension in the hip-girdling device to be reduced. 
         [0005]    It is desired, then, to provide a pelvis-stabilizing device including a buckle mechanism that can be used to engage a strap to resist or prevent application of excessive tension, yet to maintain a desired amount of tension in the portion of the device encircling a patient and to facilitate keeping the buckle engaged with the strap while applying the device to a patient, so that tension is retained in the part of the device surrounding the patient while the outer end of the strap is being secured to a main body portion of the device. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention provides a pelvis stabilizing device including a force-controlled buckle which engages a strap once sufficient tension has been achieved in the strap and thus maintains a required tension in the portion of the device encircling a patient&#39;s pelvis. The buckle can maintain tension in the portion of the device encircling a patient even if tension is not continuously maintained in the outer portion of the strap, that is, the portion of the strap extending away from the buckle and which has had to be pulled through the buckle to place into tension the portion of the device encircling the patient. 
         [0007]    In one embodiment of the device the force-controlled buckle consists of at least two components, a frame and a slider. In such a device the slider is mounted movably within an opening defined by the frame. In one embodiment of the buckle the slider&#39;s motion is resisted by a pair of springs that ordinarily keep the slider in a position obscuring the outer ends of a pair of pins or prongs and thus allow a strap to slide along the slider within the opening defined by the frame while tension is being developed in the strap. 
         [0008]    Once a predetermined tension has been developed in the strap the slider is moved by the tension in the strap to a position with respect to the frame exposing the tips of the pins or prongs, and the pins or prongs are extended into corresponding holes provided in the strap and prevent the strap from being placed into greater tension. Upon movement of the slider to a particular position relative to the frame, a latch mechanism engages portions of the slider and the frame with one another and prevents the slider from moving with respect to the frame and again obscuring the prongs, even if tension in the strap is relieved so that the strap no longer holds the slider in its moved position with respect to the frame. 
         [0009]    The latch mechanism is readily released to disengage the slider from the frame, so that the slider can move to its original position in which it obscures the prongs and allows a strap to slide through the buckle. 
         [0010]    In one embodiment, catches are carried on fingers provided on the slider and the fingers are urged by elastic force developed in the fingers to carry the catches into engagement with corresponding receptacles formed in the buckle frame. 
         [0011]    In another embodiment, catches can be provided in the frame and arranged to move into engagement with suitable receptacles in the slider. 
         [0012]    In another embodiment of the buckle respective holes may be provided in the frame and in the slider in respective locations where the holes would be aligned with each other when tension in the strap had reached the required amount to move the slider with respect to the frame far enough to expose the prongs, and a spring-loaded retaining pin can then move into the holes or through the hole and retain the slider in the required position with respect to the frame. 
         [0013]    In yet another embodiment of the buckle, one or more spring-biased levers is carried on the frame and can be moved about a pivot to carry a catch into locking engagement with the slider by an associated spring once the slider has moved. The lever can be manually moved to disengage the catch. 
         [0014]    The foregoing and other features of the invention will be more readily understood upon consideration of the following detailed description of the invention taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is an isometric view of a pelvis-stabilizing device including a tension-retaining force-controlled buckle that is an exemplary embodiment of an aspect of the present invention. 
           [0016]      FIG. 2  is a top plan view showing the pelvis-stabilizing device shown in  FIG. 1  in tension and with the strap shown secured so as to maintain tension and keep the buckle engaged with the strap while the device is in place encircling a person&#39;s pelvis. 
           [0017]      FIG. 3  is an isometric front view of the first and second end portions of the main body of the pelvis-stabilizing device shown in  FIGS. 1 and 2 , illustrating the device secured and under tension around a person. 
           [0018]      FIG. 4  is an isometric view of a buckle that is one embodiment of the buckle included in the pelvis-stabilizing device shown in  FIG. 1  at an enlarged scale. 
           [0019]      FIG. 4A  is a detail view showing a part of the slider and the attached latch-carrying finger of the buckle shown in  FIG. 4 . 
           [0020]      FIG. 5  is a sectional view of the buckle shown in  FIG. 4 , taken along line  5 - 5  of  FIG. 4 , showing the buckle in an engaged condition, when subjected to a predetermined tension to cause the buckle to engage a hole defined in the strap that is part of the pelvis-stabilizing device shown in  FIGS. 1-3 . 
           [0021]      FIG. 6  is a sectional view of the buckle, similar to  FIG. 5 , showing the condition of the buckle before tension has been applied to the buckle by the strap portion of the pelvis-stabilizing device. 
           [0022]      FIG. 7  is a sectional view of the buckle shown in  FIG. 4 , taken along line  7 - 7  of  FIG. 4 , with the buckle in the state in which it is shown in  FIG. 4 . 
           [0023]      FIG. 8  is a sectional view taken along line  8 - 8  of  FIG. 4 , showing the buckle in the state in which it is shown in  FIG. 6 . 
           [0024]    ,  FIG. 9A  is a sectional view of a detail of the buckle as shown in  FIG. 5 , at an enlarged scale. 
           [0025]      FIG. 9B  is a view similar to  FIG. 9A , showing the buckle with its latch between the engaged and disengaged positions. 
           [0026]      FIG. 10  is an isometric view of a buckle that is another embodiment of an aspect of the invention disclosed herein, showing the buckle latched in an engaged condition, as after a predetermined tension has been applied to the buckle by the strap portion of the pelvis-stabilizing device. 
           [0027]      FIG. 10A  is a detail view of a portion of the slider and a catch-carrying finger of the buckle shown in  FIG. 10 . 
           [0028]      FIG. 11  is a sectional view of the buckle shown in  FIG. 10 , taken along line  11 - 11  of  FIG. 10 , showing the buckle latched in an engaged condition. 
           [0029]      FIG. 12  is a view similar to  FIG. 11 , showing the condition of the buckle when disengaged, as before being subjected to a predetermined tension in the strap that is part of the pelvis-stabilizing device shown in  FIGS. 1-3 . 
           [0030]      FIG. 13  is a sectional view of the buckle shown in  FIG. 10 , taken along line  13 - 13  of  FIG. 10 , with the buckle in the state in which it is shown in  FIG. 10 . 
           [0031]      FIG. 14  is an isometric view of a buckle that is a third embodiment of an aspect of the invention disclosed herein. 
           [0032]      FIG. 14A  is a detail view showing a portion of the slider and the latch-carrying finger that is a part of the buckle shown in  FIG. 14 . 
           [0033]      FIG. 15  is a sectional view of the buckle shown in  FIG. 14 , taken along line  15 - 15  of  FIG. 14 , showing the buckle latched in an engaged condition, as when subjected to a predetermined tension to cause the buckle to engage a hole defined in the strap that is part of the pelvis-stabilizing device shown in  FIGS. 1-3 . 
           [0034]      FIG. 16  is a view similar to  FIG. 15 , but showing the condition of the buckle before tension has been applied to the buckle by the strap portion of the pelvis-stabilizing device. 
           [0035]      FIG. 17  is a sectional view of the buckle shown in  FIG. 14 , taken along line  17 - 17  of  FIG. 14 , with the buckle in the state in which it is shown in  FIGS. 14 and 15 . 
           [0036]      FIG. 18  is a sectional view taken along line  18 - 18  of  FIG. 14 , with the buckle shown in the state it is in as shown in  FIG. 16 . 
           [0037]      FIG. 19  is an isometric view of a buckle that is yet another embodiment of an aspect of the invention disclosed herein. 
           [0038]      FIG. 20  is a sectional view of the buckle shown in  FIG. 19 , taken along line  20 - 20 , showing the buckle latched in an engaged condition, as when subjected to a predetermined tension to cause the buckle to engage a hole defined in the strap that is part of the pelvis-stabilizing device shown in  FIGS. 1-3 . 
           [0039]      FIG. 21  is a view similar to  FIG. 20 , showing the buckle in an unengaged state, as before tension has been applied to the buckle by the strap portion of the pelvis-stabilizing device shown in  FIGS. 1-3 . 
           [0040]      FIG. 22  is a sectional view of the buckle shown in  FIG. 19 , taken along line  22 - 22  of  FIG. 19 , with the buckle in the state in which it is shown in  FIGS. 19 and 20 . 
           [0041]      FIG. 23  is a sectional view taken along line  23 - 23  of  FIG. 19 , showing the buckle in the unengaged state in which it is shown in  FIG. 21 . 
           [0042]      FIG. 24  is an isometric view of a buckle that is yet another embodiment of the buckle incorporated in the device shown in  FIGS. 1-3 . 
           [0043]      FIG. 25  is a sectional view taken along line  25 - 25  of  FIG. 24 , showing the buckle latched in an engaged state. 
           [0044]      FIG. 26  is a view similar to  FIG. 25 , showing the buckle in an unengaged state, as before tension has been applied to the buckle by a strap portion of the pelvic stabilizing device showns in  FIGS. 1-3 . 
           [0045]      FIG. 27  is a sectional view taken along line  27 - 27  of  FIG. 24 , showing the buckle in the state in which it is shown in  FIG. 25 . 
           [0046]      FIG. 28  is a sectional view similar to  FIG. 27 , but showing the buckle in the state in which it is shown in  FIG. 26 . 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0047]    Referring now to the drawings which form a part of the disclosure herein, in  FIG. 1  a pelvis supporting and stabilizing device  30  for stabilizing a fractured pelvis, often called a pelvic sling, is shown in a condition in which it is ready for application to a person to provide stabilization and support for a fractured pelvic ring. The device  30  is used by placing it on the person so that it encircles the hip region of the person, as shown in  FIG. 2 . A main body portion  32  is of strong flexible material and has the general shape of a wide belt. A buckle  34  is attached to a first end portion  36  of the main body portion by a small loop  38  of a strap of strong fabric such as woven Nylon webbing that is permanently attached to the first end portion  36 , as by being sewn in securely to it. As used herein, the term “permanently attached” means that removal and reattachment are not easily accomplished by a user and cannot be accomplished readily without the use of equipment similar to that needed for initial manufacture of the pelvic sling  30 . A large loop  40  of fabric which may be similar to that of the small loop  36  may also be attached to the first end portion  36  of the main body so that the large loop  40  can be used as a handle by a person applying the pelvic sling  30  to an injured person, as will be explained more fully presently. 
         [0048]    At a second end portion  42  of the main body portion  32 , opposite the first end portion  36 , an inner end of an elongate flexible strap  44  is permanently attached to the main body portion  32 , as by being sewn, riveted, or thermally or sonically welded securely to the second end portion  42 . The strap  44  may be made of strong fabric such as Nylon webbing and extends longitudinally away from the second end portion  42 , generally aligned with a longitudinal axis  46  of the main body portion. An outer end portion of the strap  44  may include a loop of strong fabric such as nylon webbing attached to an intermediate portion  48  of the strap, so that the loop is available for use as a handle to pull the strap away from the buckle, in applying the pelvic sling  30  to a patient. 
         [0049]    Pairs of holes  50  may be defined in the intermediate portion of the strap  44 . The holes  50  of each pair are aligned with each other transversely across the width  52  of the strap, which may be about 2 inches, for example. Adjacent pairs of holes  50  may be spaced apart evenly longitudinally of the strap at a pitch of, for example, about 0.625 inch, so as to permit the effective circumference of the pelvic sling to be adjusted in increments small enough to provide a desirable amount of tension in the pelvic sling  30  as it encircles a person&#39;s hips to stabilize a fractured pelvis. 
         [0050]    An area  54  of a hook-bearing fastener material, such as that well known under the trademark Velcro®, capable of matingly engaging a corresponding loop-bearing flexible fastener material, may be provided on the second end portion  42  of the main body, and an exterior side of the intermediate portion  48  of the strap may be covered by a layer  56  of a flexible loop-bearing fastener material, securely attached to the strap  44 , as by being sewn to the webbing. Such loop-bearing fastener material ideally may be present along the entire exterior side or face of the strap  44 , the side that is exposed so as to face toward the exterior of the second end portion  42  of the main body portion  32 , and may be present on the inner end of the strap  44 , as shown in  FIGS. 1 and 3 . Thus, when the strap  44  extends through the buckle  34  and is closely alongside the second end portion  42  of the main body portion  32  as shown in  FIGS. 2 and 3 , the hook-and-loop fastener material will secure the strap  44  to the second end portion  42 . 
         [0051]    When the pelvic sling  30  is properly in place on an injured person, it encircles the person&#39;s hips and buttocks, and the first and second end portions  36  and  42  face toward each other, with the strap  44  extending through the buckle  34  and doubled back alongside the second end portion  42  on the exterior of the pelvic sling  30 . 
         [0052]    When the pelvic sling  30  is properly in place, there is a prescribed amount of tension maintained in the main body portion  32  as it encircles the injured person, so that a fracture in the pelvic ring of the person is reduced. This tension is maintained by engagement of the buckle  34  with the strap  44 , as shown in  FIGS. 2 and 3 , where it may be seen that with the desired amount of tension exerted on the buckle  34  by the strap  44 , a pair strap engagement members in the forms of pins  58  extend into the holes  50  in the strap  44 , preventing the strap  44  from moving with respect to the buckle  34 . 
         [0053]    Once the pins  58  engage with the holes  50 , the loop-bearing fastener material  56  on the exterior side of the strap  44  is aligned and mated with hook-bearing fastener material  54  on the exterior side of the second end portion  42  of the main body  32 , thus keeping the strap  44  from being disengaged from the buckle  34 . 
         [0054]    As shown in  FIGS. 4-9 , the buckle  34  is a force-controlled buckle and consists of at least two components, a substantially rigid frame  60  and a sliding block or slider  62  which is mounted in the frame  60  and movable with respect to it. Both the frame  60  and the slider may be molded of suitably strong synthetic plastics resins. With the buckle  34  configured as shown in  FIG. 1-4 , the rigid frame  60  includes a transversely extending bow portion  64  which can be engaged by the small loop  68  of strap material attached to the first end portion  36  of the main body portion  32  of the pelvic sling  30 . The sliding block or slider  62  is movable relative to the buckle frame  60  in a longitudinal direction as indicated by the arrow  66 . The frame  60  defines an opening  68  which is a passageway wide enough to receive the strap  44 , which extends through the opening  68  when the pelvic sling  30  is in use. When there is little tension involved the strap  44  can slide easily along the convexly curved surface of the contact face  70  of the slider  62  as the strap  44  is pulled to tighten the pelvic sling  30  about a person&#39;s pelvis. 
         [0055]    A pair of holes  72  is defined in the slider  62 , and the pins  58  mentioned above with respect to  FIGS. 2 and 3  are aligned with the holes  72  and may extend at least a small distance into the holes. The frame  60  includes a base portion  74 , opposite the bow  64 , from which the pins  58  extend toward the slider  62  as may be seen best in  FIGS. 5-8 . 
         [0056]    A pair of helical springs  76  extends from the base portion to the interior of the slider. Each of the springs may surround a respective one of the pins  58  between the base  74  and the slider  62 . Suitable seats may be provided on the base  74  and the interior of the slider  62  to locate and align the springs. The springs  76  are compressed sufficiently to provide enough force to keep the slider  62  in the position shown in  FIGS. 6 and 8  until a desired amount of tension is created in the pelvic sling  30  by pulling the strap  44  through the opening  68  of the buckle  34 . 
         [0057]    A respective retaining flange  78  extends along the base  74  on each of the opposites sides  80  and  82  side of the frame  60 , and each of the corresponding opposite sides  84  and  86  of the slider  62  includes an inwardly directed retaining lip  88  that engages the respective flange  78  and keeps the slider  62  from moving toward the bow  64  from the position shown in  FIGS. 3 and 4 , thus keeping the springs compressed. The slider  62  may be molded or otherwise formed from a suitable elastic material such as a resilient and tough but generally rigid plastics material so that the opposite sides  84  and  86  of the slider can be sprung apart from each other as the slider is moved into position within the opening defined by the frame, with the lips  88  passing over the flanges  78  to reach the position shown in  FIG. 8 . 
         [0058]    To assist in placing the slider  62  in the position with respect to the frame  60  shown in  FIG. 4 , an assembly cam  90  may be provided on the base  74  of the buckle frame  60  in position to engage the interior of the slider  62  and force the opposite side portions  86  and  88  of the slider  62  apart from each other as the slider  62  is moved within the frame  60  toward the base  74 . The assembly cam  90  thus forces the lips  88  far enough apart so that they can pass over the flanges  78  allowing the slider  62  to move to the position in which the lips can return toward the base  74  and engage the flanges as shown in  FIGS. 6 and 8 . A notch  89  may be provided in one or both of the lips  88  to initially receive the assembly cam  90  and align the slider  62  with the base  74  as the slider  62  is moved into place. 
         [0059]    Substantial tension must be applied to the buckle  34  in use, urging the slider  62  to move in opposition to the springs  76  before the slider  62  begins to move relative to the buckle frame  60 . As may be seen in  FIG. 4A , a pair of guide blocks  91  may engage a portion of the frame  60  to keep the slider  62  properly aligned with the buckle frame  60 . 
         [0060]    Once sufficient tension is provided in the strap  44 , urging the buckle away from the first end portion  36  of the main body portion of the pelvic sling  30 , as the strap  44  is moved further along the convex contact surface  70  of the slider  62 , a pair of holes  50  in the strap  44  will move into alignment with the holes  72  in the slider  62 . This will allow the pins  58  to enter into the holes  50  in the strap  44  as the slider  62  compresses the springs  76  further and moves along the pins  58  toward the base  74  of the frame  60 . 
         [0061]    As may be seen by reference to  FIGS. 4A ,  5 , and  6 , a pair of latch fingers  92  extends from the interior of the slider  62 , parallel with the sides of the frame  60  and toward the base  74  of the frame. The latch fingers  92  extend through correspondingly located through-holes  94  in the base of the frame, and outer ends of the latch fingers  92  are exposed beyond the base  74  of the frame  60 . Each of the latch fingers  92  carries a catch  96  that extends laterally outward toward a respective end of the frame  60 . When the slider  72  is in its unengaged, or first, position, as shown in  FIGS. 6 and 8 , each catch  96  extends into a receptacle that may be in the form of an opening  98  extending through the respective end of the frame. The latch fingers  92  when relaxed may be oriented in slightly divergent directions and thus under small amount of pressure and slightly flexed toward each other inward when the slider  62  is in its relaxed first position with respect to the frame  60  as shown in  FIG. 6 , in which the catches are received in the receptacles  98 . Each catch  96  may have an inclined cam surface  100 , facing away from the convex strap contact face  70  of the slider  62  and thus generally toward the base or outer end of the frame  60 . 
         [0062]    As the slider  62 , urged by the strap  44 , moves from the position shown in  FIG. 6  toward the base portion  74  of the frame  60 , the cam surface  100  engages and rides upon the lower margin of the receptacle  98 , and the cam  100  forces the latch finger  92  inward, disengaging the catch  96  from the receptacle  98  and allowing the catch  96  to ride along a surface extending generally longitudinally of the frame as shown in  FIG. 9B . When the slider  62  has moved a desired distance, far enough to expose the tips of the pins  58  far enough to extend into the holes  50  in the strap  44  and to engage the strap  44  securely to accept and bear the longitudinal forces in the strap, each catch  96  can be moved elastically by the respective latch finger  92  to move beneath the bottom of the frame and engage a latch strike surface  102  at the bottom of the frame locking receptacle. With the catches  96  engaged with the latch strike surfaces  102 , the slider  62  is no longer free to move under the influence of the springs toward the position shown in  FIG. 6  and thus hide the tips of the pins  58  and allow the strap  44  to slide along the convex strap contact face  70  of the slider  62 . This makes it easier for a person placing the pelvic sling  30  on a patient to secure the portion of the strap  44  extending beyond the buckle  34  to the first end portion  36 , using the hook-and-loop fastener materials  54  and  56  previously described, or by some other means. 
         [0063]    When it is desired to release the pelvic sling  30  from a patient, the two latch fingers  92  can be squeezed together as indicated by the arrows  104  in  FIG. 6 , which results in the catches  96  being withdrawn from their respective latch strike surfaces  102 . Once the slider  62  can move at least a slight distance, the tips of the catches  96  will be able to move along the frame as shown in  FIG. 9B  toward the bow  64  of the frame  60 . The slider  62  will then be able to move toward its original, relaxed position with respect to the bow of the frame  60  once tension in the strap  44  is reduced, as by disengaging the hook-and-loop fastener materials  54  and  56  from each other. The slider  62  will then move to the position shown in  FIGS. 6 and 8  and the strap  44  will then be able to again slide along the convex strap contact surface  70  within the frame  60 . 
         [0064]    As may be seen in  FIG. 9A , the catch  96  may have an engagement face  106  defining an acute angle  108  with the fingers  92  to account for flexibility of the finger  92  and thus result in contact of the engagement face  106  against the latch strike surface  102 , rather than a tendency to act as a cam and move the finger  92  in the direction of the arrow  104 . 
         [0065]    Referring next to  FIGS. 10-13 , a buckle  134  is generally similar to the buckle  34 . The buckle  134  has, as shown herein, a set of prongs  136  of the male member of a side release buckle; extending from the bow portion  138 , of the frame  60 , and the configuration and interrelationship between the slider  140  and the base portion  142  of the frame  144  are slightly different. A corresponding female part of a side release buckle (not shown) may be fastened to the first end portion  36  of a main body portion  32  of a pelvic sling  30  by a loop  38 , to receive the prongs  136 , and attach the buckle  134  to the main body portion  32 . In the buckle  134  as shown in  FIGS. 10-13 , there are receptacles  146  for the catches  148  on the respective sides of the base portion  142  of the frame  144 , and a crossbar  150  on each side of the frame  144  includes a strike face  152 . The through-holes  154  in the base of the frame  144  give ample room for the fingers  156  to be squeezed toward each other in the directions of the arrows  157 , to release the catch  148  from the respective latch strike face  152  on each end. As shown best in  FIG. 13 , the strike face and the catch are oriented at an angle  158  to assure that, even allowing for some flexing of the fingers  156  caused by the forces generated in the springs, the catches  148  tend to remain engaged with the strike faces  152  and not to be cammed out of engagement with one another. 
         [0066]    Referring next to  FIGS. 14-18 , a buckle  164 , like the buckle  134 , is generally similar to the bucket  34 . In the buckle  164 , the slider  166  has a pair of fingers  168 , but instead of each finger  168  having an outwardly projecting catch with a cam surface, the fingers  168  are generally flat-sided on both of their inner and outer faces. Each finger  168  has a crossbar  170  that may define a pair of notches  172  between the crossbar  170  and a wide distal end part  174 . As may be seen best in  FIG. 18 , a lower cam surface  176  of each crossbar  170  may be inclined so as to be able to act as a cam against a respective latch strike member, to cause the respective finger  168  to flex inwardly when the slider  166  is forced downward toward the base  182  by tension in the buckle  164  and strap  44 . Each finger  168  extends through a respective through-hole  180  in the base  182  of the frame  184 . Respective catch engagement faces  185 , which may be substantially perpendicular to the respective finger  168  and generally parallel with the base  182  of the frame  184 , can engage each latch strike member  178  when the slider  166  has moved far enough to allow the finger  168  to enter the notch in the latch strike  178 . Once the catch faces  185  have engaged the latch strike faces  178 , the slider  166  is retained in its lowered position with the tips of the pins  58  exposed beyond the convex strap contact  70  surface and engaged in the holes  50  in the strap  44  as described in greater detail above with respect to the buckle  34  and with respect to the pelvic sling  30  as illustrated in FIGS.  1 , 2 , and  3 . 
         [0067]    As shown in  FIGS. 19-23 , a buckle  190  is similar in many respects to the buckle  164  shown in  FIGS. 14-18 , but instead of having a pair of flexible fingers extending from the slider  192 , only a single, centrally located finger  194  is provided. The finger  194  extends through a centrally located through-hole  196  in the base  198  of the buckle frame  200 , where a notch  202  is defined at one side of the through-hole  196  and defines strike faces  204 . Extending on at least one side and shown on both sides of the finger  194  as shown in  FIGS. 16-18 , a crossbar  206  includes a cam surface  208  and latching surface  210  similar to those of the fingers  168  in the previously described buckle  164 . 
         [0068]    To assist in unlatching the slider from the latched, or engaged, position of the slider, a thumb rest  212  is provided on one side of the base portion  198 , facilitating flexing of the finger  194  to disengage the latch and release the slider  192  to move toward the bow end of the frame. The thumb rest  212  also provides a definite indication of which way the finger  194  has to be moved to release it from engagement in the notch  202 . 
         [0069]    Yet another generally similar buckle  220  is shown in  FIGS. 24-31 , where the slider  222  is latched in its latched, strap-engaging, second position state by a pair of catches  224  carried on respective latch levers  226 . Each latch lever  226  is mounted on a pivot pin  228  on the base portion  229  of the frame  230  and biased, as by a spring  232 , toward a position in which a catch  224  carried on the latch lever  226  can engage a corresponding latch strike member  234  carried on the slider  222 , once the slider  222  has been moved, as by tension in a strap  44 , to a strap-engaging position in which the pins  58  protrude from the convex strap contact face  70  of the slider  222 . At least one of the latch strike member  234  and the catch  224  portion of the latch lever  226  may include a cam surface as shown at  236  and  238 , so that as the slider  222  is moved from its original, relaxed, pre-installation position as shown in  FIG. 26  toward the latched strap-engaging state shown in  FIGS. 24 and 25 , the cam  236  or cams  236  and  238  will move the catch  224 , causing the lever  226  to pivot in a first direction as indicated by the arrow  240  to allow the catch  224  to pass by the latch strike member  234 . Once the slider  222  has moved to the strap-engaging second position shown in  FIGS. 24 ,  25 , and  27 , the latch lever spring  232  causes the lever  226  to pivot in the direction opposite that indicated by the arrow  240 , to move the catch  224  into engagement with the latch strike face  242  of the strike member  234 . The catch  224  then retains the slider  22  in the latched engagement position as shown best in  FIGS. 25 and 27 . 
         [0070]    The position of the pivot pin shown in  FIG. 25  is designed, with respect to the frame  230 , and with respect to the selected spring  223 , so as preferably to require a force in the direction of the arrow  240  amounting to about 6 pounds, to move the lever  226  and thus disengage the catch  224  from the latch strike member  234 . The latch lever  226  may be made of a suitably strong synthetic plastic resin or of a metal such as an aluminum or steel alloy. 
         [0071]    The terms and expressions that have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.