Abstract:
A quick release mechanism and headpiece for use with a respirator. The quick release mechanism uses a cam latch pivotally attached to a yoke to control the tension in an upper tension strap. In the latched position the upper tension strap traverses the yoke to support and seal the respirator mask against the face of the wearer. In the unlatched position the upper tension straps loosely support the mask below the chin of the wearer in a parked position. In one embodiment, a guide is provided on the yoke to ensure that the mask may be consistently donned and doffed with minimal effort (e.g., potential one-handed donning and doffing). An opening may also be provided in the face mask and optionally in the yoke, and a filter may be disposed within the opening to provide the desired filtration of inhaled gases.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuing application of co-pending application Ser. No. 09/608,899, filed Jun. 30, 2000, which is a continuation-in-part application of copending application Ser. No. 09/255,601, filed Feb. 22, 1999, now U.S. Pat. No. 6,338,342 both of which are specifically incorporated by reference herein. 
    
    
     BACKGROUND 
     Respirators are worn by persons subjected to unpleasant or noxious environments. A common type of respirator is the half mask respirator, which comprises a cup type mask supported by a yoke attached to two sets of straps. One set of straps, the upper set, is designed to rest on the crown of the head of a wearer. The second, lower, set is designed to wrap around the back of the neck of the wearer. The upper set is generally attached to a broadened flexible strap, commonly known as a cradle, that fits over, or cradles, the crown of the head. The upper strap is generally adjustably attached between the facepiece and cradle by a buckle having an adjusting mechanism such as a D-ring for tightening the strap against the head. A D-ring, as is well known in the industry, generally requires that a wearer use two hands to manipulate the D-ring to adjust the length of the strap during donning or doffing often proving to be challenging to the wearer. The lower strap generally includes a fastening element including a hook and slot arrangement and further includes an adjustment mechanism such as a D-ring. 
     A wearer typically puts on (dons) the respirator by clipping the lower straps behind the neck and then lifting the cradle up onto the top of the crown while simultaneously guiding the mask and yoke portion, or facepiece, into position on the face. The straps are then manipulated through the D-rings and adjusted until a good fit is achieved and a successful face seal check is performed. Removal, or doffing, of the respirator is performed opposite the donning operation wherein the lower straps are unbuckled and the cradle is removed from the head while the facepiece is withdrawn from the face of the wearer. 
     In the course of an average day, a worker required to wear a respirator may don and doff the respirator up to 20 times. The donning procedures of current art respirators, including adjustment and face seal check, are viewed by many wearers as being complex and cumbersome. In some cases wearers forego the donning procedure when it is perceived that the task they are to perform would take less time than the donning procedure. The donning procedure is further complicated by other protective equipment such as goggles, glasses, earmuffs, hats and hard hats that need to be removed in order to don or doff the respirator. 
     The doffing of current respirators is viewed by many wearers as an equally cumbersome task. In order to remove the respirator, even for short periods, the lower strap must be unbuckled and the cradle lifted off the head as described herein above. A temporary removal, or parking, of the respirator is performed by slipping the cradle off the back of the head and allowing the facepiece to drop in front of the wearer wherein the respirator is supported by the lower strap around the neck of the wearer. Both the complete doffing and the parking of the respirator are further hampered by the inclusion of safety equipment as set forth herein above. 
     Another problem with prior art respirators results when respirators rely on upper straps having no elongation. Over time, latching of rigid straps causes material fatigue in the mask and may cause breakage of the mask during donning. 
     Another problem with prior art respirators is that the strap attachments, as well as tightening and release mechanisms, cause point loads in the facepiece making them uncomfortable to the wearer. 
     Accordingly, there remains a need in the art for a respirator that may be easily and conveniently donned, doffed and parked without discomfort to the wearer. 
     SUMMARY 
     The above discussed and other drawbacks and deficiencies of the prior art are overcome or alleviated by the present respirator headpiece and quick release respirator mechanism. In one embodiment, the quick release respirator mechanism includes a yoke attached to the respirator face mask. An over center cam latch is pivotally attached to the yoke. At least one strap is attached to the latch, such that actuation of the latch to a latched position increases tension in the strap, which supports and seals the respirator mask against the face of the wearer. In one embodiment, a guide is provided on the yoke to ensure that the mask may be consistently donned and doffed with minimal effort (e.g., potential one-handed donning and doffing). An opening may also be provided in the face mask and optionally in the yoke, and a filter may be disposed within the opening to provide the desired filtration of inhaled gases. 
     The above discussed and other features and advantages will be appreciated and understood by those skilled in the art from the following detailed description and drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring now to the drawings wherein like elements are numbered alike in the several FIGURES: 
     FIG. 1 is a front perspective view of a respirator showing the unlatched position; 
     FIG. 2 is an expanded perspective illustration of a respirator facepiece showing the facepiece in an exploded view; 
     FIG. 3 is a side perspective view illustrating the parts comprising a hinge lock for the latch mechanism; 
     FIG. 4 is a top, left side perspective view of a respirator showing an unlatched position; 
     FIG. 5 is a side perspective view of a respirator showing an unlatched position; 
     FIG. 6 is a front perspective view of a respirator face showing a latched position; 
     FIG. 7 is a rear perspective view of a respirator showing a rear aspect of a facepiece and showing strap points of engagement with the yoke; 
     FIG. 8 is a perspective view of the inside surface of a headpiece; 
     FIG. 9 is a front cross sectional view of the headpiece of FIG. 8 along lines  2 — 2 ; 
     FIG. 10 is a side cross sectional view of the headpiece of FIG. 8 along lines  4 — 4 ; 
     FIG. 11 is a top perspective view of a sorbent cartridge shell component; 
     FIG. 12 is a top perspective view of a sorbent cartridge cap component; 
     FIG. 13 is a side perspective view of the sorbent cartridge cap of FIG. 12; 
     FIG. 14 is a rear perspective view of a second cartridge shell component; 
     FIG. 15 is a top perspective view of a standalone filter cartridge shell component; 
     FIG. 16 is a rear perspective view of a filter cartridge cap component; 
     FIG. 17 is a top perspective view of a disc filter base component; 
     FIG. 18 is a rear perspective view of a disc filter cover component; and 
     FIG. 19 is a front perspective of a respirator in a parked position. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1 an exemplary respirator is generally shown at  10 . The respirator  10  incorporates a quick release mechanism  12  into a facepiece support system, the quick release mechanism  12  including a yoke  14  and a cam latch  16  pivotally attached to the yoke  14  via hinge pins  18 ,  20  (shown in FIG.  2 ). A facepiece  22  is supported by the yoke  14  to fit the facepiece  22  against the face of a wearer. Alternately, the facepiece support system may comprise a facemask/support piece (not shown) such that the facepiece  22  and yoke  14  are integrally molded into a single element by a known process, such as by dual shot molding or over-molding, among others. 
     The respirator  10  further may include sorbent material  24 ,  26  ( 26  is shown in FIG. 2) positioned on opposite sides of the facepiece  22 . The yoke  14  attaches to the facepiece  22  in a removable snap fit fashion against a button type stud ( 62  in FIG. 2) similar to that of prior art respirators. Sorbent material  24 ,  26  is disposed within sorbent cartridge shells  28 ,  30  underneath sorbent cartridge caps  32 ,  34 . 
     Referring again to FIG. 1, the exemplary cam latch  16  further includes a relief cut  36  accommodating an exhalation valve housing  38  while the cam latch  16  is in the latched position (shown generally at  40  in FIG.  6 ). The cam latch  16  further includes first and second relief cuts  42 ,  44  configured to accept a loop of the upper strap  46 . (Alternately, independent straps may be attached at the first and second relief cuts  42 ,  44 ) The upper strap  46  extends over a portion of the yoke  14  and through first and second strap guides  48 ,  50 , positioned above the cam latch  16 . The upper strap  46  further extends to attach to first and second relief cuts  52 ,  54  in the headpiece  56 . Thus, the cam latch  16  and headpiece  56  are connected, such that downward motion  58  of the cam latch  16  draws the facepiece  22  closer to the headpiece  56 , and upward motion  60  of the cam latch  16  relaxes tension in the upper strap  46 , allowing the facepiece  22  to fall away from the headpiece  56  into a parked position. 
     Turning to FIG. 2, an exploded view of exemplary facepiece  22  is shown illustrating a partially pre-assembled state. The facepiece includes a button type stud  62  configured to engage a relief cut  64  on the yoke  14 . Similarly, the facepiece  22  includes a button type stud  66  configured to engage a relief cut (not shown) on the yoke  14 . The facepiece  22  further includes a centrally located hole  68  configured to accept the exhalation valve seat  70 . Exhalation valve housing  38  receives an exhalation valve  71 , which further includes a retaining pin  72  sized to engage a retaining hole  74  disposed within the exhalation valve seat  70  (which may snap into the facepiece  22  or be integrally molded into the facepiece  22  by a known process). 
     Referring again to FIG. 2, an exemplary facepiece  22  may further include first and second side holes  76 ,  78  configured to accept first and second cartridge/filter retainers  80 ,  82 . The first and second cartridge/filter retainers  80 ,  82  are shown tethered by a connecting material  84  such that they may be easily installed from the interior of the facepiece  22  and urged outwardly through the first and second side holes  76 ,  78 . Alternately, the cartridge/filter retainers  80 ,  82  may be integrally molded into the facepiece  22  by any known process. 
     Referring again to FIG. 2, exemplary first and second cartridge/filter retainers further include a plurality of raised portions  86  configured to engage and retain a portion of the first and second sorbent cartridge shells  28 ,  30 . Sorbent material  26  is shown provided within the sorbent cartridge shell  30  underneath the sorbent cartridge cap  34 . 
     Referring again to FIG. 2, the exemplary yoke  14  may include first and second strap cinchers  88 ,  90  ( 88  shown in FIG.  4 ), positioned below the cam latch  16  and configured to accept the lower neck straps  92 ,  94  (shown in FIG.  4 ). As shown, the respirator  10  may incorporate two neck straps  92 ,  94 . However, the present respirator  10  may include a single neck strap (not shown), configured to slip over the head of the wearer or configured to engage the yoke with a mechanical fit, such as a snap-in buckle (not shown). 
     The exemplary first and second strap cinchers  88 ,  90  include a post  96  (best shown in FIG. 3) around which a length of strap material is looped and a tooth member  98  (best shown in FIG.  3 ), which holds the looped strap material in place and retains tension on the strap as it is tightened. Though the yoke  14  are illustrated including the first and second strap cinchers, the lower straps  92 ,  94  may be attached through the posts  96  by any suitable method such as by being sewn, glued, riveted, or looped through a conventional D-ring (not shown), among others. The yoke  14  also includes first and second hinge pin-retaining holes  100  (not shown),  102  configured to accept the hinge pins  18 ,  20 . 
     Referring again to FIG. 2, the exemplary yoke  14  further includes snap locks  104 , 106  formed or otherwise provided on the outer surface of the yoke  14  proximal to the hinge pins  18 ,  20 . Turning to FIG. 3, the snap locks are sized and configured to receive notched portions  108  (not shown),  110  on the underside of the cam latch  16  proximal to the hinge pins  18 ,  20 . The snap locks  104 ,  106  and notched portions  108 ,  110  provide secure engagement of the cam latch  16  in the latched position. Preferably snap locks  104 ,  106  and notched portions  108 ,  110  are configured such that an audible snap will occur when the cam latch  16  is engaged. 
     Turning now to FIG. 4, an exemplary respirator  10  is shown illustrating an unlatched position. The upper strap  46  extends from the cam latch  16  and through the first and second strap guides  48 ,  50  to attach to headpiece  56  at relief cuts  52 ,  54 . The lower straps  92 ,  94  extend from the first and second strap cinchers  88 ,  90  and attach to the neck catch  112 . 
     In one embodiment, the upper strap  46  comprises a resilient strap material having the flexibility to trace out the path from headpiece  56  through the yoke  14  to the cam latch  16  in both the latched and unlatched positions. Similarly, the lower straps  92 ,  94  may comprise an elastic material. As used herein, the term strap includes material having any physical cross-section, including rectangular, trapezoidal, circular and elliptical, among others. As best shown in FIG. 1, the upper strap  46  supports and seals the facepiece  22  against the face of the wearer by spreading the tension load in the strap  46  across the cam latch  16 , the yoke  14  and the facepiece  22 . Spreading the loads as described creates a tight, yet comfortable, fit and seal of facepiece  22  against the face of the wearer. 
     In one embodiment, the upper strap  46  comprises a material having an elongation sufficiently low such that the strap  46  does not overly stretch when the wearer tightens the strap ends on the headpiece  56 , thus allowing for maximum travel of the upper strap  46  through the strap guides  48 ,  50  when the cam latch  16  is moved to the disengaged, or parked, position. However, some elongation is necessary to allow the strap to flex, for example when the wearer makes facial movements. Accordingly, an exemplary strap elongation is above 0 percent maximum elongation to about 150 percent maximum elongation. In another exemplary embodiment, the maximum strap elongation is between about 10 to about 50 percent. In another exemplary embodiment, the maximum strap elongation is between about 25 to about 35 percent. In another exemplary embodiment, the maximum strap elongation is about 25 percent. The maximum elongation as herein defined allows that a 100 percent maximum elongation corresponds to a strap extension of double its initial length. 
     Turning now to FIG. 5, a side perspective view of an exemplary respirator  10  is shown illustrating a parked position. A preferred neck catch  112  may comprise a single support piece (not shown), or it may include two engageable/detachable portions  114 ,  116  (best seen in FIG.  1 ). The illustrated neck catch  112  advantageously provides a comfortable, rounded fit along the back of the wearer&#39;s neck. The engageable/detachable portions  114 ,  116  may include a mechanical attachment (not shown), such as is known in the art, including Velcro, buckles or hooks and eyes, among others, allowing facile and convenient donning and doffing of the neck catch  112 . Alternately, the lower straps  92 ,  94  may attach to a side buckle (not shown) positioned alongside the neck of the wearer. 
     Turning now to FIG. 6, a front perspective view of an exemplary respirator  10  illustrates a latched position  40 . The cam latch  16  includes a first and second concave regions  118 ,  120  configured to retain the upper strap  46  when the cam latch  16  is in a latched position. Thus, the upper strap  46  (not shown), which is angled from the first and second strap guides  48 ,  50  across the concave regions  118 ,  120 , around the exhalation valve housing  38  and through the first and second relief cuts  42  (not shown),  44  effectively holds the cam latch  16  in position by pressure of the upper strap  46  against the first and second concave regions  118 ,  120 . When the latch  16  is in the latched position under the chin of the wearer, the upper strap  46  further supports the facepiece  22  and biases it towards the face of the wearer. 
     The illustrated exhalation valve housing  38  further includes a ridge of material  122  (best seen in FIG. 2) disposed just interior to the relief cut  36  along a portion of the cam latch  16 . The ridge of material  122  is configured to engage the cam latch  16  in the latched position to further ensure that the cam latch  16  is secure. In one exemplary embodiment, the configurational fit between the ridge of material  122  and the cam latch  16  is such that latching of the cam latch  16  creates an audible click or snap. This farther ensures that the wearer is certain that the cam latch  16  is secure. 
     Turning now to FIG. 7, a rear perspective view of an exemplary respirator  10  illustrates the rear aspect of the facepiece  22 , the first and second strap guides  48 ,  50 , and the first and second strap cinchers  88 ,  90 . The rear aspect of the facepiece  22  includes readily deformable material around all points of contact with the face of the user to provide a comfortable and secure fit regardless of facial contouring. Accordingly, it is preferable that facepiece  22  comprise a resilient material, such as liquid silicone, rubber, or a thermoplastic elastomer, among others. The post  96 , around which a length of lower strap material is looped, and the tooth member  98  of the second strap cincher  90  are particularly evident in this aspect. 
     Turning now to FIG. 8, an exemplary headpiece  56 , including cinching relief cuts  52 ,  54 , is illustrated. The attachment of the upper strap  46  to the headpiece  56  may be accomplished in a variety of ways, including use of plastic rivets (not shown) swaged over by a known process, such as ultrasonic welding. However, the illustrated headpiece  56  includes first and second relief cuts  52 ,  54  comprising toothed, or uneven, incisions through the material of the headpiece  56  through which the upper strap  46  is passed. Thus, the user may tighten the upper strap  46  by simply pulling on ends  116 ,  118  (shown in FIGS. 9 and 10) of the strap  46 . Incising of headpiece material provides flaps  128 ,  130 , the toothed, or uneven, regions  132 ,  134  of which will hold the strap ends  116 ,  118  in place and maintain tension in the upper strap  46 . 
     Referring again to FIGS. 8,  9  and  10  the exemplary headpiece  56  shown includes cutouts  136 , which provide ventilation and flexibility to the headpiece  56 . 
     Turning now to FIG. 11, an exemplary sorbent cartridge shell  28  is shown. The sorbent cartridge shell  28  includes the preferable off-center opening  138  (the off-center aspect of which shifts the sorbent cartridge out of the wearer&#39;s view), including recessed portions  140  configured and arranged to receive the raised portions  86  of the first and second cartridge/filter retainers  80 ,  82 , a base portion  142 , including ridges  144 , and a sidewall portion  146 , including an upper edge  148 . The configuration of recessed portions  140  on the sorbent cartridge shell  28  and raised portions  86  on the first and second cartridge/filter retainers allows quick and facile installation or removal of the sorbent cartridge shell  28  via a simple twisting motion. The ridges  144  on the base portion  142  set the sorbent material (not shown) away from the base portion  142 , allowing an optimal amount of filter material surface area to be exposed. This reduces pressure loads and allows for easier breathing and more efficient filtering. Preferable material for this sorbent cartridge shell  28  includes carbon and absorbent filter materials. 
     Turning now to FIGS. 12 and 13, an exemplary sorbent cartridge cap  32  is illustrated. The sorbent cartridge cap  32  includes a plurality of openings  150 , an upper circumferential edge  152 , an outer rim  154  and an inner rim  156 . As preferred, the plurality of openings  150  are arranged as hexagonal openings defined by the material of the sorbent cartridge cap  32  to maximize the exposed surface area of the underlying filter material (not shown). An inner ring  158  of cap material may be provided, as illustrated, to decrease flex in the cap  32 , re-enforce the structure and set the filter disc (not shown) away from the cap material to increase the effective exposed filter disc surface area. The outer and inner rims  154 ,  156  of the sorbent cartridge cap  32  are sized and configured to guide the upper edge  148  of the sorbent cartridge shell  28  into place during sorbent cartridge assembly. In one exemplary embodiment, the outer and inner rims  146 ,  148  of the sorbent cartridge cap  32  are sized and configured to securely engage the upper edge of the sorbent cartridge shell  28 . The sorbent cartridge cap  32  may be connected to the sorbent cartridge shell  28  as is known in the art. In one exemplary embodiment, the filter cartridge cap is snapped or welded to the sorbent cartridge shell  28 . 
     Referring now to FIG. 14, an exemplary second cartridge shell  162  is illustrated. The second cartridge shell  162  may be sized and configured to receive a pleated, particulate filter (not shown). The second cartridge shell  162  includes a plurality of openings  164 , lower circumferential edge  166  and an extended rim  168 . In this embodiment, the plurality of openings  164  are arranged as circular openings defined by the material of the sorbent cartridge  162 , less preferred than hexagonal openings, but still providing a good amount of exposed surface area of the contained sorbent material (not shown). One advantageous embodiment provides that the extended rim  168  of the second cartridge shell  162  be sized and configured to receive a pleated filter (not shown), which filters particulate materials. The second cartridge shell  162  preferably is permanently attached, by welding, snapping or other known methods, to the top of the sorbent cartridge shell  30 . Alternately, the second cartridge shell  162  may be configured to engage threading  170  (shown in FIG. 1) (preferred where the second cartridge shell  162  is used) disposed on the sorbent cartridge cap  32 . 
     Turning now to FIG. 15, an exemplary standalone filter cartridge shell  172  component is illustrated. The standalone filter cartridge shell  172  is illustrated including an off-center opening  174  (the off-center aspect of which shifts the standalone filter out of the wearer&#39;s view), including recessed portions  176  configured and arranged to receive the raised portions  86  of the first and second cartridge/filter retainers  80 ,  82 , a base portion  178 , including ridges  180 , and a sidewall portion  182 , including an upper edge  184 . The configuration of recessed portions  176  on the standalone filter cartridge shell  172  and raised portions  86  on the first and second cartridge/filter retainers  80 ,  82  allows quick and facile installation or removal of the standalone filter cartridge shell  172  via a simple twisting motion. The ridges  180  on the base portion  178  set the filter material (not shown) away from the base portion  178 , allowing an optimal amount of filter material surface area to be exposed. This reduces pressure loads and allows for easier breathing and more efficient filtering. Suitable material for the standalone filter cartridge shell  172  includes, among others, filter materials capable of filtering particulates, and in particular, pleated particulate filters. 
     Turning now to FIG. 16, an exemplary filter cartridge cap  186  is illustrated. The filter cartridge cap  186  includes a plurality of openings  188  (as shown, hexagonal openings are preferred), an upper circumferential edge  190  and an inner ring  192 , connected to the upper circumferential edge  190  by spokes  194 . The upper circumferential edge  190  is sized and configured to securely engage the extended rim of either the second cartridge shell  162  or the standalone filter cartridge shell  172 . As shown, it is preferred that the inner ring  192  extend downward relative to the upper circumferential edge  190  to expose a maximal surface area of the second filter material (not shown). While the snap fit is illustrated, the second filter cartridge cap  172  may engage the second cartridge shell  162  or the standalone filter cartridge shell  172  by any known method, including gluing, threading, snap fits and welding, among others. 
     Referring now to FIG. 17, an exemplary disc filter base  196  component is illustrated. The disc filter base  196  includes the preferable off-center opening  198  (the off-center aspect of which shifts the disc filter out of the wearer&#39;s view), including recessed portions  200 , configured and arranged to receive the raised portions  86  of the first and second cartridge/filter retainers  80 ,  82 , a base portion  202 , including ridges  204 , and a sidewall portion  206 , including an upper edge  208 . The configuration of recessed portions  200  on the disc filter base  196  and raised portions  86  on the first and second cartridge/filter retainers  80 ,  82  allows quick and facile installation or removal of the disc filter base  196  via a simple twisting motion. The ridges  204  on the base portion  202  set the filter material (not shown) away from the base portion  202 , allowing an optimal amount of filter material surface area to be exposed. This reduces pressure loads and allows for easier breathing and more efficient filtering. As shown, the disc filter base  196  may also include external threads  210  to accommodate a threaded cover and an exemplary cover of which is described below. 
     Referring now to FIG. 18, an exemplary disc filter cover  212  is illustrated. The disc filter cover  212  includes a lower circumferential rim  214 , a sidewall portion  216 , a ceiling portion  218  and a plurality of openings  220  disposed through the ceiling portion  218 . The lower circumferential rim  214  and sidewall portions  216  are configured engage the upper circumferential edge  152  of the sorbent cartridge cap  32  or the upper edge  208  of the disc filter base  196  and receive a disc filter material (not shown). While the snap fit embodiment is illustrated, the disc filter cover  212  may engage the first sorbent cartridge cap  32  or the disc filter base  196  by any known method, including threading, snap fits and welding, among others. 
     The present respirator  10  is donned via manipulation of the cam latch  16  of quick release mechanism  12 . Donning is begun with the cam latch  16  in the up and unlatched position. A wearer grasps the headpiece  56  with one hand and the yoke  14  or exhalation valve housing  38  with the other hand. The two detachable portions  114 ,  116  of the neck catch  112  are positioned around the neck of the user and secured along with lower straps  92 ,  94 . The headpiece  56  is guided over the top of the head and the facepiece  22  is placed proximal to the face. The cam latch  16  is then lowered in the direction of the arrow  58  (in FIG. 1) into the latched position. 
     The respirator  10  is doffed by reverse (upward) motion of the cam latch  16 . The cam latch  16  rotates in the direction of the arrow  60  (in FIG. 1) about the pivot pins  18 ,  20  to the unlatched position. The quick release mechanism  12  is actuated in this fashion partially by manipulative force of the user, partially by the tension stored in the upper strap  46  and partially by the weight of the lower portion of the respirator  10 . Thus, the quick release mechanism  12  is actuated and the respirator parked simply by applying thumb pressure against cam latch  16 . In addition, respirator  10  in accordance with the present invention can be doffed without the removal of other safety headgear such as, for example, safety glasses (not shown). 
     Turning to FIG. 19, further illustration of exemplary respirator  10  parking is shown. As can be seen, the present respirator  10  provides for a convenient and comfortable parked position. Once the respirator  10  is doffed as described above, the yoke  16  rotates upwards, relative to the wearers face, and the effective length of the upper strap  46  between the headpiece  56  and the facepiece  22  is increased. The facepiece  22  drops away from the face of the wearer in the direction indicated by arrow  222 . In one embodiment, the upper strap  46  slides as much as four inches through the guide holes  48 ,  50  as the yoke  16  is moved from the latched position to the unlatched position. Thus, the respirator  10  is effectively parked without removal of neck catch  112  from the neck or removal of the headpiece  56  from the top of the head. Donning the respirator  10  from the parked position simply requires that the facepiece  22  be lifted into position on the face while the cam latch  16  is flipped downward in direction of the arrow  58 , preferably with the use of just one hand. 
     While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.