Abstract:
A backpack assembly for a self contained breathing apparatus comprises a plurality of components positioned in housings that define a body for the backpack assembly. The body is assembled to a back frame. A pivoting and swiveling hip plate is connected to the back frame in multiple distinct positions to provide a customizable and comfortable fit for the wearer.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the priority benefit of U.S. Provisional Patent Application No. 60/925,036, filed Apr. 18, 2007, which is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention generally relates to a backpack assembly for a self contained breathing apparatus. 
         [0004]    2. Description of the Related Art 
         [0005]    Self contained breathing apparatuses (“SCBA”) are used by firefighters, for instance, while fighting fires. The SCBA generally include backpack assemblies that support many of the components of the SCBA. Because many of the components are modular in nature, many of the components dangle from the backpack assembly and can form potential snag points during movement within a structure. Firefighters have grown accustomed to this but improvement over the prior constructions is possible. 
         [0006]    In addition, the backpack assemblies are strapped to the hip/waist region of the firefighters using hip pads. To improve comfort, the pads can be configured to move relative to the balance of the backpack assembly. Such movement, however, can cause some psychological discomfort if the firefighter does not believe that the backpack assembly is tightly secured in position. 
       SUMMARY OF THE INVENTION 
       [0007]    Accordingly, an improved backpack assembly features several components that are integrated into a streamlined body such that potential snag points are greatly reduced. The integrated body also results in a sleek design that greatly reduces or eliminates bulky protrusions that restrict movement. 
         [0008]    In addition, a swiveling and pivoting hip plate is provided to attach the hip pad to the balance of the backpack assembly. The configuration disclosed limits movement in manners that improve the fit while improving the feedback from the backpack assembly to the firefighter. 
         [0009]    Other improvements also include: an improved tank band assembly that can facilitate rapid exchanges of air cylinders including air cylinders having varied diameters and valve stem configurations; colorized straps to quickly identify twists in the straps when the backpack assembly is being put on; a low air warning (audible and/or visual) on a back surface of the backpack assembly so others following the firefighter will be able to identify a low air supply condition if the firefighter does not identify it himself; handles and carabineer attachment points on the backpack assembly that have a pull strength of 1000 pounds or more; enlarged grabs to help tighten the backpack assembly straps while wearing gloves; and an adjustable hip plate assembly that enables the backpack assembly to be customized for various body sizes and shapes. 
         [0010]    Some aspects of some embodiments of the present invention involve a backpack assembly for a self contained breathing apparatus. The backpack assembly comprises a back frame that has a forward surface and a rearward surface. The forward surface has a lower portion. A hip plate is positioned along the lower portion of the forward surface. A bushing is positioned between the hip plate and the forward surface of the back frame. A plate covers at least a portion of the bushing. A pin connects the hip plate to the back frame and the pin is positioned between at least a portion of the bushing and at least a portion of the plate. In some embodiments, the bushing comprises fingers that contact the pin. In some embodiments, the pin is adapted for rotational movement in a radial direction of the pin such that the hip plate can swivel relative to the back plate about a first axis while pivoting relative to the pin about a second axis. The first axis preferably is generally normal to said second axis. In some embodiments, the bushing can be mounted to the back frame in multiple locations such that the height of the hip plate relative to the back frame can be adjusted. 
         [0011]    Some aspects of some embodiments of the present invention relates to a self contained breathing apparatus comprising a backpack assembly. The backpack assembly comprises a back frame. A body is mounted to the back frame. The body has an outer periphery defined by an outer periphery of the back frame. The body houses one or more accessories for the backpack assembly and is disposed on an opposite side of the back frame relative to a body of a user of the self contained breathing apparatus. One of the accessories comprises a low air visual alert. In some embodiments, the accessories further comprise a first stage regulator and a power source. In some embodiments, the accessories further comprise a PASS unit, the PASS unit comprising at least one audible alert device and at least one visual alert device. In some embodiments, the accessories further comprise a low air alert device and a low battery alert device. Preferably, at least one audible alert device is located on a first side of the backpack assembly and at least one audible alert device is located on a second side of the backpack assembly where the first side of the backpack assembly being opposite of the second side of the backpack assembly. More preferably, two audible alert devices are located on the first side of the backpack assembly and two audible alert devices are located on the second side of the backpack assembly. The audible alert on the first side of the backpack assembly can be positioned on an upper half of the backpack assembly. The audible alert on the second side of the backpack assembly also can be positioned on an upper half of the backpack assembly. Preferably, at least one of the audible alert devices comprises a bell, a whistle device or a warble whistle. 
         [0012]    Some aspects of some embodiments of the present invention involve a backpack assembly for a self contained breathing apparatus. The backpack assembly comprises a back frame that comprises at least one opening formed just inside of a peripheral surface of the back frame. The at least one opening defines a handle that supports about 1000 pounds of load. Preferably, a carabineer attachment point is positioned proximate the handle and the carabineer attachment point is capable of supporting 1000 pounds of load. In some embodiments, the carabineer attachment point is positioned between the at least one opening and the peripheral surface of the back frame. 
         [0013]    Some aspects of some embodiments of the present invention also involve a backpack assembly for a self contained breathing apparatus where the backpack assembly comprises a back frame. A tank band assembly is secured to the back frame and the tank band assembly comprises a tank band, a first handle and a second handle. The first handle is coupled to an adjustment mechanism that adjusts a circumference of the tank band and the second handle is connected to the tank band such that the tank band can be opened and closed. In some embodiments, the first handle and the second handle are on opposite sides of a tank. In some embodiments, the second handle comprises a spring loaded cam locking mechanism. 
         [0014]    Some other aspects of the present invention relate to a backpack assembly for a self contained breathing apparatus. The backpack assembly comprises a back frame that comprises a rearward surface and a forward surface. The rearward surface and the forward surface are connected by at least one peripheral surface. At least one handle is defined by an opening that is positioned along the peripheral surface. A waist pad is connected to the back frame with a hip plate and the hip plate is connected to a forward surface of the back frame. A shoulder strap is connected to the back frame and a front PASS device is supported by the shoulder strap. The front PASS device is connected by a conduit to an upper housing. The upper housing is mounted to the rearward surface of the back frame. The upper housing comprises a low air audible alarm, a low air visual alarm, a low battery visual alarm and a transducer for a heads-up display. A middle housing is mounted on the rearward surface of the back frame generally below the upper housing. The middle housing comprises a back PASS device. The back PASS device comprises at least one audible alarm device, at least one visual alarm device and at least one firefighter locating beacon. The front and back PASS devices preferably provide two alarms on the front and two alarms on the back such that the PASS devices are not muffled regardless of the positioning of a downed firefighter. A tank band assembly is mounted on the rearward surface of the back frame. The tank band assembly is positioned generally below the middle housing and a tank being mounted within the tank band assembly. A lower housing is mounted on the rearward surface of the back frame. The tank is supported by the lower housing. The lower housing comprises a central power supply and a first stage regulator. A CGA wheel is connected an offset swivel assembly, the offset swivel assembly is connected to a hose and the hose is connected the first stage regulator. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0015]    These and other features, aspects and advantages of certain embodiments of the present invention will become apparent from consideration of the description below, which makes reference to the appended drawings. 
           [0016]      FIG. 1  is a front perspective view of a backpack assembly that is arranged and configured in accordance with certain features, aspects and advantages of the present invention. 
           [0017]      FIG. 2  is a rear perspective view of the backpack assembly of  FIG. 1 . 
           [0018]      FIG. 3  is a front elevation view of a back frame assembly for the backpack assembly of  FIG. 1 . 
           [0019]      FIG. 4  is a perspective view of a portion of the back frame assembly of  FIG. 3 . 
           [0020]      FIG. 5  is an enlarged perspective view of a portion of the back frame assembly of  FIG. 3 . 
           [0021]      FIG. 6  is sectioned perspective view of a bushing used in the back frame assembly of  FIG. 3 . 
           [0022]      FIG. 7  is a perspective view of the bushing and a pin used in the back frame assembly of  FIG. 3 . 
           [0023]      FIG. 8  is a perspective view of a portion of the back frame assembly of  FIG. 3 . 
           [0024]      FIG. 9  is an exploded perspective view of the back frame assembly of  FIG. 3 . 
           [0025]      FIG. 10  is an enlarged perspective view of a portion of the back frame assembly of  FIG. 3  in which an ordinate system is introduced. 
           [0026]      FIGS. 11 and 12  show a hip plate of the back frame assembly of  FIG. 3  in two different modes of movement. 
           [0027]      FIG. 13  is a view of the hip plate being connected to a hip/waist pad assembly. 
           [0028]      FIG. 14  is a top down perspective view of the backpack assembly of  FIG. 1 . 
           [0029]      FIGS. 15 and 16  are perspective views of a heads up display transducer housing that is used in the backpack assembly of  FIG. 1 . 
           [0030]      FIG. 17  is a perspective view of a lower portion of the backpack assembly of  FIG. 1 . 
           [0031]      FIGS. 18 and 19  are perspective views of a hose and swivel attachment to a CGA wheel used in the backpack assembly of  FIG. 1 . 
           [0032]      FIGS. 20 and 21  are views of grabs used in the backpack assembly of  FIG. 1 . 
           [0033]      FIG. 22  is a perspective view of a portion of a unified electrical and pneumatic coupler used in the backpack assembly of  FIG. 1 . 
           [0034]      FIGS. 23 and 24  are perspective views of a front PASS unit used in the backpack assembly of  FIG. 1 . 
           [0035]      FIGS. 25-31  are views of a tank band assembly used in the backpack of  FIG. 1 . 
           [0036]      FIG. 32  is a perspective view of a housing containing a back PASS device and ultrasonic beacons used in the backpack of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0037]    With reference initially to  FIG. 1  and  FIG. 2 , a backpack assembly  30  is illustrated therein. The backpack assembly  30  has particular utility with self contained breathing apparatuses but certain features, aspects and advantages of the backpack assembly  30  can be used in other applications. The backpack assembly  30  is shown with an air cylinder or tank  32  supported thereon. While not shown, the backpack assembly  30  can be used with a face piece that, in some embodiments, is provided with a heads up display (“HUD”) and a communication system. Any other suitable accessories also can be used. 
         [0038]    The illustrated backpack assembly  30  advantageously features several components that have been integrated together to result in a greatly streamlined backpack assembly  30  when compared to prior backpack assemblies that had many components attached along peripheral portions of the backpack assemblies. The components are connected to or disposed in a body formed by several housing assemblies. The streamlined backpack assembly results in reduced snag points. The integrated construction also has been configured to achieve a desirable aesthetic appearance for the backpack assembly  30  and for many of the components of the assembly  30 . 
         [0039]    Prior to describing the components of the illustrated backpack assembly  30  in detail, the overall construction will be introduced. With reference to  FIG. 1 , the backpack assembly  30  comprises a back frame  34 . The back frame  34  defines a chassis to which the remaining components are assembled. In the illustrated configuration, upper padding  36  is secured to an upper forward portion of the back frame  34 . A waist pad  40  is connected to the back frame  34  with a swivel and pivot hip plate  42  (see  FIG. 3 ). The waist pad  40  is positioned generally below the upper padding  36  and also is positioned on a forward surface of the back frame  34 . The swivel and pivot hip plate connection provides comfort and ergonomic weight placement in any body position. The connection leads to 35% greater mobility when side bending, up to 30% greater trunk mobility when forward bending and 20% more hip flexion. 
         [0040]    A harness  44  also connects to the back frame  34 . The harness  44  preferably comprises two shoulder straps  46 . Ends of the illustrated shoulder straps  46  are connected to back straps  50  preferably using parachute-style buckles  52 . The buckles  52  allow easy release but other types of connections can be used. Lower ends of the back straps  50  can be connected to the hip plate  42 . The harness  44  also comprises a waist belt  54 , which can comprise two portions that are connected by a buckle  56 . The two portions of the waist belt  54  preferably are connected to the waist pad  40  in a manner that will be described below. The shoulder straps  46  and the waist belt  54  can be adjusted using portions that are connected to large hand grabs  60 . Preferably, the straps  46 ,  50 , the belts  54 , and the pads  36 ,  40  are easily replaced in the field. 
         [0041]    With continued reference to  FIG. 1 , a front PASS device  62  is supported by the right (as viewed by the user) shoulder strap  46 . The PASS device  62  is a personal alert safety system, which is a one-way communications device used by firefighters entering a building to alert others that the wearer of the PASS device  62  is in trouble and in need of rescue. The illustrated PASS device  62  also includes a beacon  64  for a firefighter locating system. The beacon  64  can comprise an omnidirectional ultrasonic transmitter, as will be described in greater detail below. 
         [0042]    A pneumatic hose  70  and an electrical cable  72  connect the PASS device to an upper housing  74 , which is connected to the upper portion of the back surface of the back frame  34 . With reference now to  FIG. 2 , a second pneumatic hose  76  also is connected to the upper housing  74 . With reference again to  FIG. 1 , the second pneumatic hose  76  extends along a portion of the left shoulder strap  46 . A second electrical cable  80  also extends along a portion of the left shoulder strap  46 . The second pneumatic hose  76  and the second electrical cable  80  are connected to a third pneumatic hose  82  and a third electrical cable  84 , respectively. In the illustrated configuration, a single coupler  86  is used to connect the pneumatic hoses  76 ,  82  and the electrical cables  80 ,  84 . 
         [0043]    The third pneumatic hose  82  extends to a second stage regulator (not shown), which can be positioned along the lower left side of the back frame  34 . The second stage regulator (not shown) can be connected to a face mask or the like. 
         [0044]    With reference again to  FIG. 2 , the upper housing  74  in the illustrated configuration contains a low air audible alarm  92 , which is positioned to the left side of the upper housing  74 . The right side of the upper housing  74  comprises a low air light  94 , a low battery light  96  and a HUD transducer  100 . The upper housing  74  and the components housed therein will be described in greater detail below. 
         [0045]    A middle housing  102  is mounted to the back frame  34  just below the upper housing  74 . The middle housing  102  contains one or more back PASS devices  104 . Accordingly, the middle housing  102  includes two audible alert devices  106  and two visual alert devices  110 . The illustrated middle housing  102  also houses two beacons  112  for the firefighter locating system. 
         [0046]    A tank band assembly  114  is mounted to the back frame  34  just below the middle housing  102 . The tank band assembly  114  is used to secure the cylinder  32  to the back frame  34 . Advantageously, the tank or cylinder  32  is secured in a lower position (e.g., the top end of the tank is below the top end of the back frame). The lower position of the tank helps the tank to rotate away from the leg and hip region of the user, which provides space for less restricted mobility. In addition, the lower position allows that tank to slide over the buttocks during trunk extension. The tank band assembly will be described in greater detail below. 
         [0047]    A lower housing  116  is mounted to the back frame  34  just below the tank band assembly  114 . The lower housing  116  preferably contains a central power supply  118 , which can comprise 4 C-cell batteries in series. The central power supply  118  supplies power to the backpack assembly  30 . The lower housing  116  also houses a first stage regulator  120 . The first stage regulator  120  can be connected to a removable buddy breather (not shown) by a hose (not shown). A removably coupling can be provided at the end of the hose (not shown) that connects to the lower house  116  such that the buddy breather (not shown) can be removed if desired. In some configurations, the hose (not shown) can be about 36 inches long. Other lengths can be used. The hose (not shown) can be connected to the first stage regulator  120  with a swivel coupling (not shown) that swivels about an axis of the hose (not shown) such that the likelihood of kinking of the hose (not shown) is greatly reduced. The buddy breather (not shown) can be positioned within a pouch (not shown) that can be connected to a left side of the back frame  34 . 
         [0048]    A CGA wheel  132  can be connected to the first stage regulator  120  with a hose  134 . The hose preferably is connected to the CGA wheel  132  with an offset swivel assembly  136 , which provides flexibility in locating the CGA wheel  132  such that various valve stem configurations can be accommodated by the backpack assembly  30 . 
         [0049]    Having introduced a basic construction of the illustrated backpack assembly  30 , several of the components will be discussed in greater detail with reference to the drawings of one example of the backpack assembly  30 . 
       Back Frame 
       [0050]    As discussed above, the back frame  34  preferably defines the chassis around which the harness  44  and the balance of the backpack assembly  30  are constructed. With reference now to  FIG. 3 , the back frame  34  and the articulating hip plate  42  are illustrated. 
         [0051]    The illustrated back frame  34  can be formed in any suitable manner. The illustrated back frame comprises a plate member  140 . The plate member  140  of the back frame  34  can be formed of any suitable material. In one configuration, the plate member  140  is formed of aluminum. The aluminum back frame  34  provides a lightweight construction with high strength and rigidity. In some embodiments, the back frame  34  can be constructed of suitable tubular components. In either configuration, the back frame  34  defines a suitable platform upon which the balance of the backpack assembly  30  can be mounted or to which the balance of the backpack assembly  30  can be attached. 
         [0052]    With reference to  FIG. 3  and  FIG. 4 , the plate member  140  of the back frame  34  comprises one or more handle openings  142 . The handle openings  142  help to define handles  144  along the periphery of the plate member  140 . In the illustrated configuration, the plate member  140  comprises three openings  142  and three handles  144 . The openings  142  and handles  144  in the illustrated configuration are positioned at a top of the plate member  140  and at each lateral side of the plate member  140 . The openings  142  and the handles  144  preferably are sized and configured to allow the backpack assembly  30  to be lifted or pulled as desired. In one preferred configuration, the handles  144  are sized and configured to withstand a 1000 pound load (i.e., a 1000 pound drag load). The handles, as shown in  FIGS. 1 and 2 , preferably also comprise a reinforcing plate  146  that can be secured to the plate member  140  using fasteners or any other suitable technique. 
         [0053]    Moreover, in the illustrated configuration, the handles  144  include carabineer attachment points  148 . Preferably, each of the handles  144  includes one or more attachment point  148 . In some configurations, however, less than all of the handles  144  may include an attachment point  148 . The attachment points  148  can be formed in any suitable manner. In the illustrated configuration, each of the attachment points  148  is defined by a hole that extends through the handle  144  and preferably through the associated reinforcing plate  146 . 
         [0054]    With continued reference to  FIG. 3  and  FIG. 4 , the plate member  140  preferably comprises one or more channel  150 . In the illustrated configuration, two channels  150  extend along a substantial portion of the length of the plate member  140 . The channels  150  protrude from the front surface of the plate member  140 . A lower portion of each of the illustrated channels  150  forms a crossing pattern. In some configurations, a separate channel can be used to connect the two channels  150  that extend in a generally vertical direction. The channels  150  reinforce the plate member  140  and can be used as a conduit of internal wires, cables, hoses or the like. 
       Hip Plate 
       [0055]    With reference now to  FIGS. 4 through 12 , the hip plate  42  (see  FIG. 3 ) has been removed from the back frame  34  so that a hip plate mounting assembly  152  can be better shown. The mounting assembly  152  advantageously enables the hip plate  42  to articulate relative to the back frame  34 . The articulation allows motion between the back frame  34 , which is secured to the shoulders when worn, and the hip plate  42 , which is secured to the hips and shoulders when worn. In one configuration, the mounting assembly  152  provides some level of movement between back frame  34  and the hip plate  42  while limiting that movement to provide a suitably stiff configuration. Preferably, the hip plate  42  is not capable of substantial lateral movement relative to the back frame  34 . More preferably, such lateral motion is significantly restricted with a goal of eliminating lateral motion of a mass associated with the cylinder  32  that is attached to the back frame  34 . 
         [0056]    The illustrated mounting assembly  152  comprises a bushing  154 . The bushing  154  can be formed of any suitable material. In one preferred configuration, the bushing  154  defines means for dampening and limiting rotation within a desired range. Preferably, the bushing  154  is formed of an elastomeric material. More preferably, the bushing  154  is formed of an elastomeric material that can sustain a 500 degrees Fahrenheit flash temperature, a 200 degrees Fahrenheit soak temperature and a temperature of 500 degrees Fahrenheit for 5 minutes. Even more preferably, the bushing  154  is formed of butyl rubber. 
         [0057]    The illustrated bushing  154  preferably comprises a generally cylindrical outer surface  156  (see  FIG. 5 ). The illustrated bushing  154  also preferably comprises a pair of inner contoured surfaces  158 , one of which is shown in the cross-section of  FIG. 6 . Each of the contoured surfaces  158  in the illustrated configuration defines two fingers  160 , which will be discussed in greater detail below. The contoured surfaces  158  also advantageously define a lower stepped region  162 . A ridge  164  also can be defined along a portion of each of the stepped regions  162 . The fingers  160  preferably extend over a portion of the thickness of the bushing  154  while the stepped regions  162  extend over a balance of the thickness of the bushing  154 . In other words, in the illustrated embodiment, the stepped regions  162  and the fingers  160  together extend over substantially the entire thickness of the bushing  154 . 
         [0058]    The bushing  154  also preferably comprises a pair of mounting holes  166 . The mounting holes  166  in the illustrated configuration extend through the entire thickness of the bushing  154 . Other configurations are possible. 
         [0059]    With reference to  FIG. 5 , a pin  168  preferably extends through a recess defined by the stepped regions  162 . The pin  168  comprises a centerline CL. The centerline CL preferably is able to sweep through an included angle α of about 30 degrees in each direction relative to a centered position. In other words, a total sweep of about 60 degrees is possible by the pin  168 . 
         [0060]    As shown, the fingers  160  extend toward the pin  168 . The pin  168  preferably is contacted by the fingers  160  in four places. Other configurations are possible. The illustrated configuration, however, provides an unbiased yet stable hold on the pin  168  by the bushing  154 . Advantageously, the fingers  160  are able to flex (see  FIG. 7 ) when the pin  168  sweeps through all or at least a portion of the full sweep. By flexing, the fingers  160  dampen the movement of the pin  168 , and thereby dampen the movement of the hip plate  42  relative to the back frame  34 . The flex of the fingers  160  also helps to return the pin  168  to a neutral position, which is generally horizontal in the illustrated configuration. 
         [0061]    The full sweep angle preferably is defined, at least in part, by an outer portion of the contoured surfaces  158 . In other words, portions of the contoured surfaces  158  define stops  170 . The stops  144  preferably come into contact with the pin  168  at the limit of the sweep. Other configurations to limit the sweep of the pin  168  also are possible. 
         [0062]    With reference now to  FIGS. 4 and 5 , the bushing  154  preferably is sandwiched between the plate member  140  and a bushing plate  172 . The bushing plate  172  preferably is formed of a suitably rigid material. In one embodiment, the bushing plate  172  is formed of aluminum. Other materials also can be used. The bushing plate  172  preferably has a diameter that is slightly less than a diameter of the bushing  154 . 
         [0063]    The bushing plate  172  can be secured to the plate member  140  by suitable fasteners. In one configuration, two standoffs  174  are secured to the plate member  140 . The standoffs  174  can be formed of any suitable material. In the illustrated configuration, the standoffs  174  are formed of stainless steel. The standoffs  174  extend at least partially through the mounting holes  140  of the bushing  154 . In one embodiment, the standoffs  174  extend fully through the bushing  154 . The bushing plate  172  can be secured to the standoffs  174  by screws  176  or other suitable fasteners. Preferably, the bushing plate  172  moderately squeezes the bushing  154  when mounted to the plate member  140 . 
         [0064]    In the illustrated embodiment, one or more bosses  175  extend from the surface of the bushing  154 . The bosses  175  can be integrally formed with the bushing  154 . The bosses  175  are used in conjunction with corresponding slots or recesses  177  formed in the bushing plate  172  as alignment aids during manufacturing. Other techniques also can be used. 
         [0065]    The pin  168  also preferably is compressed between the bushing  154  and the bushing plate  172 . The compression of the pin  168  advantageously provides a small degree of resistance in the mounting assembly  152  such that the mounting assembly  152  is less likely to rattle significantly. 
         [0066]    With reference to  FIG. 8 , the hip plate  42  comprises two mounting ears  178 . The mounting ears  178  can be integrally formed with the hip plate  42  or can be separately formed from the hip plate  42  and secured to the hip plate  42  in any suitable manner. The pin  168  extends through the ears  178  such that the pin  168  pivotally secures the ears  178 , and therefore, the hip plate  42 , to the mounting assembly  152 . In one embodiment, the pin  168  is a rivet. Other types of pins also can be used. 
         [0067]    The ears  178  extend alongside a portion of the bushing  154 . Preferably, the ears  178  do not extend so far alongside the bushing  154  that they come into contact with the plate member  140 . Because the bushing plate  172  is slightly undersized relative to the bushing  154 , slight movement of the hip plate  42  in a manner that causes either the left ear or the right ear of the ears  178  to move toward the plate member  140  relative to the other of the ears  178  will cause one or both of the ears  178  to rub against the bushing  154  rather than the bushing plate  172 , which reduces premature wear of the metal members (i.e., the bushing plate  172  and the ears  178 ) and reduces rattling. 
         [0068]    With reference again to  FIG. 3 , the hip plate  42  comprises an enlarged central opening  180 . The enlarged central opening  180  in the illustrated configuration comprises two opposing rolled edges  182 , which reinforce the hip plate  42 . The mounting ears  178  can be integrally formed with the rolled edges  182  in some configurations. The enlarged central opening  180  also comprises a header  184 , which extends across the top of the opening  180 . Preferably, the enlarged central opening  180  generally surrounds the mounting assembly  152 . 
         [0069]    With reference to  FIG. 10 , the bushing  154 , through resistance to compression loads, allows very limited rotation of the hip plate  42  about a Y-axis. This rotation about the Y axis also is greatly limited by the ears  178  that contact the sides of the bushing  154 . By reducing and/or eliminating the movement about the Y axis, a sensation of stability is provided to the user. 
         [0070]    The hip plate  42  can move relative to the plate member  140  about the X-axis (see  FIG. 11 ). The movement of the hip plate  42  about the X axis generally is limited by the header  184  of the hip plate  42 . The header  184 , or another upper portion of the hip plate  42 , can contact either the bushing  154  or the plate member  140  in the illustrated configuration. Thus, the hip plate  42  can move relative to the plate member  140  in a limited range about the X axis. 
         [0071]    The hip plate  42  is able to rotate about the Z-axis in the manners described above (see  FIG. 12 ). The movement of the hip plate  42  is limited by the interplay between the pin  168 , the fingers  160  and the stops  170 . As described above, the fingers  160  are designed to easily collapse when the pin  168  rotates off center about the Z axis. When the fingers  160  collapse, the fingers  160  allow a natural and minimally restrictive movement of the pin  168 . When not being worn, the fingers  160  generally return the hip plate  42  to a neutral position, which assists the user when putting on the backpack assembly  30 . In addition, as discussed above, the stops  170  limit the range of rotation about the Z axis. 
         [0072]    With reference again to  FIG. 3 , the plate member  140  preferably comprises a plurality of mount holes  186 . The plurality of mount holes  186  allows the position of the mounting assembly  152  to be moved upward or downward along the plate member  140 . In the illustrated configuration, the middle two of six mount holes  186  have been used to mount the mounting assembly  152 . Providing the plurality of mount holes  186  allows a single plate member  140  to be used while allowing some customization of sizing to accommodate various body structures of the end users. For instance, at least three different hip plate mounting locations are provided in the illustrated configuration. Thus, some configurations provide customization among a small, a standard and a large configuration to accommodate varied body sizes for the end users. 
         [0073]    With continued reference to  FIG. 3 , the illustrated hip plate  42  comprises an inverted generally T-shaped configuration. The mounting assembly  152  advantageously is located proximate an upper portion  188  of the hip plate  42 , while the base  190  of the hip plate  42 , which is adapted to rest in the hip region of an ultimate user, is positioned lower than the mounting assembly  152 . In some configurations, a hip plate  42  with an elongated upper portion  188  can be used in addition to, or as an alternative to, the plurality of mount holes  186 . In other words, an elongated upper portion  188  can be used to accommodate a user with a longer torso. 
         [0074]    With reference to  FIG. 13 , the pivot point (i.e., the pin  168 ) preferably is spaced apart from a center WB of the waist belt  54  by a suitable distance DY. Locating the pin  168  above the center WB of the waist belt  54  creates a small concave pocket in the user&#39;s back when the user bends over, which provides increased comfort for the user. The pocket also reduces the amount of shoulder strap restriction experienced by the user. Moreover, by lengthening the distance DY between the waist belt center WB and the pivot point  168 , the top of the air cylinder  32  can lie generally flat against the top of the back, which provides the lowest possible profile when a user is crawling. 
       Harness 
       [0075]    With continued reference to  FIG. 13 , the base  190  of the hip plate  42  preferably comprises a plurality of belt apertures  192 . The belt apertures  192  are sized and configured to accept suitable webbing or the like. In the illustrated configuration, the hip plate  42  also comprises two enlarged windows  194 . The windows  194  provide access to loops  196  formed on the waist pad  40 , as will be explained below. As will be appreciated, a coupler belt  198  extends through the lower belt apertures  192  and through the loops  196 , which will be positioned in the region of the windows  194 . The coupler belt  198  can be joined to the waist belt  54  with D rings or the like. 
         [0076]    The waist pad  40  also comprises an upper loop  200 . The upper portion  188  of the hip plate  42  is inserted into the upper loop  200 . With the upper portion  188  inserted in the upper loop  200 , the coupler belt  198  is passed through the outer belt aperture  192  at one side of the hip plate  42 . The coupler belt  198  then is passed through the first waist strap loop  196 , which generally is positioned in the region of the window  194 . The coupler belt  198  then is passed through the central belt apertures  192  prior to being passed through the second loop  196 , which also generally is positioned in the region of the other window  194 . Finally, the coupler belt  198  is passed through the other outer belt aperture  192 . In this manner, the waist pad  40  can be mounted to the hip plate  42 . 
         [0077]    The coupler belt also passes through outer loops  202  prior to being passed through the D-ring or other suitable coupler plate  204  (see  FIG. 1 ) and being doubled back on itself. Each lateral end of the coupler belt  198  can extend through the coupler plate  204 . The coupler plates  204  can be used to connect the waist belt  54  to the coupler belt  198 . In one preferred configuration, each end of the coupler belt  198  folds back upon itself and is secured thereto with a belt button  206 . The belt button  206  preferably comprises two portions that can be threaded together such that the coupler belt  198  is removably secured in position. Such a configuration enhances the ability to service the backpack assembly  30  in the field. For example, the waist pad  40  can be readily removed and replaced with a coin or screwdriver. 
         [0078]    The hip plate  42  also preferably comprises back strap apertures  208 . The back straps  50  can be secured to the hip plate  42  through the back strap apertures  208  in any suitable manner. 
         [0079]    Preferably, at least the webbing used for the back straps  50  and the webbing used for the waist belt  54  is color coated on one side. In other words, the two sides of the strap have different appearances from each other. The color coating enables twists in the belts and straps to be quickly identified. The color coating can be provided by using a spray on coating or the like. Preferably, the coating is fire retardant. More preferably, the coating stiffens the webbing. In some configurations, the color coating can be woven or silk screened. Other manners of providing webbing that has a color marking on only one side or different color marking on opposing sides also can be used. 
       Hand Grabs 
       [0080]    At the end of the back straps  50  and at the ends of the waist belt  54  are the oversized hand grabs  60 . The hand grabs  60  provide a tactile confirmation as well as a visual confirmation that the backpack assembly  30  has been properly put on. Moreover, the oversized hand grabs  60  improve the grip of a gloved hand while putting on the backpack assembly  30 . 
         [0081]    With reference now to  FIG. 20  and  FIG. 21 , the hand grabs  60  preferably comprise a two-piece construction. The illustrated hand grabs  60  comprise a sleeve  240  and an insert  242 . The sleeve  240  preferably comprises a passage through which an end of a belt or strap can be threaded. The insert  242  preferably comprises a pseudo-D-ring construction with a passageway  244  defined through a tab  246 . The tab  246  preferably comprises studs  250  on each side with serrated teeth  252  positioned within the passageway  244 . Other grabbing structures can be used. 
         [0082]    The end of the belt or strap can be threaded trough the passageway  244  and folded back over the tab  246 . With the end of the belt or strap folded over the tab  246 , the insert  242  is pulled back into the sleeve  240  such that the belt or strap is locked in position relative to the insert  242  and the sleeve  240 . 
         [0083]    With continued reference to  FIG. 20  and  FIG. 21 , the sleeve  240  preferably comprises two lateral slots  254  and the insert  242  preferably comprises two posts  256  that, when the insert  242  is positioned in the sleeve  240 , extend laterally outward through the slots  254 . These posts  256  reinforce the hand grabs  60  and provide structure that can be used to guide the insert  242  fully into the sleeve  240 . 
         [0084]    In one configuration, the insert  242  can be snap fit into the sleeve  240 . In the illustrated construction, a hole  260  in the sleeve  240  can align with a hole in the insert  242  such that a threaded fastener of the like can be passed into the hole in the insert through the hole  260  and can be used to secure the insert  242  within the sleeve  240 . Other configurations also can be used. 
         [0085]    The hand grabs  60  can have any suitable external appearance. In one configuration, a plurality of ribs  264  is provided to enhance the ability of a user to grip the hand grabs  60  with a gloved hand. Other configurations also can be used. 
       Upper Housing 
       [0086]    With reference now to  FIG. 14 , a rear perspective view of the backpack assembly  30  is presented with the tank removed for improved clarity. As shown in  FIG. 14 , the upper housing  74  is provided proximate a top portion of the plate member  140 . The upper housing  74  in the illustrated configuration houses a heads up display transducer  100 , alert lights  94 ,  96  and an audible alarm  92 . 
         [0087]    With reference to  FIGS. 14-16 , the HUD transducer  100  preferably is positioned within a HUD transducer housing  210 . The HUD transducer housing  210  preferably comprises a manifold  212 . The HUD transducer  100  is in fluid communication with the manifold and is in electrical communication with a printed circuit board (not shown) or the like. The HUD transducer housing  210  also comprises a low air LED (not shown) and a low air LED cover  214 . The HUD transducer housing  210  also comprises a low battery LED (not shown) and a low battery LED cover  216 . Thus, the HUD transducer housing  210  contains visual alarms for both a low battery condition and a low air condition. For low air supply conditions (e.g., less than about ¼ tank), the audible alarm  92  can emit an audible alert. For instance, a bell, a whistle, a warble whistle or the like can be emitted. In addition, the low air LED, which is positioned below the low air LED cover  214 , preferably flashes at a first rate when a first level of air (e.g., ¼ tank) is detected and preferably flashes faster when a second level of air, which is lower than the first level or air, is detected (e.g., 1/10 tank). 
         [0088]    The circuitry contained with the upper housing  74 , and more specifically the HUD transducer housing  210 , monitors battery power. The battery power is supplied from the central power supply  118 , through the HUD transducer circuitry and then to the back PASS  104  and finally to the front PASS  62 . The circuitry in the HUD transducer housing  210  also preferably tracks the air supply using the HUD transducer  100  in combination with the manifold  212 . When air pressure is sensed, the circuitry turns on the front PASS  62 , the back PASS  104  and any display associated with the HUD transducer. In one particular configuration, the circuitry wakes up the HUD and back PASS  104  and the back PASS  104  wakes up the front PASS  62 . 
         [0089]    The circuitry also preferably calculates and tracks the airtime remaining based upon the air supply remaining in the tank  32 . This information, together with information from the PASS devices, is logged and the information regarding remaining air time can be presented to the user through a HUD or other display, such as in the mask, for instance. In one configuration, a data log is created for each time the PASS devices  62 ,  104  are turned on, turned off or enter an alarm mode. In another configuration, the data log records the intervals of air remaining while the air is being used. In one preferred configuration, the data log captures the most recent 2,000 events. Other numbers of events also can be captured and retained for downloading. Further, the data logged can be downloaded to a personal computer or the like for analysis. For this reason, a data port can be provided. The data port can be housed in a water-resistant portion of the backpack assembly  30 . In the presently preferred configuration, the data port is positioned behind the upper back support padding  36  in a water tight compartment. Other configurations are possible. 
         [0090]    The circuitry can be connected to circuitry contained in the middle housing  102  using a pin sleeved cable  216 . The cable can be hardwired to the circuitry contained in the HUD transducer housing  210  and can use spring pins  218  to connect to the circuitry in the middle housing  102 . Other configurations also are possible. 
         [0091]    The upper housing  74  also comprises the low air audible alarm  92 . The audible alarm  92  can comprise speakers, bells or the like. The audible alarm  92  advantageously is positioned proximate an ear of a user and to a lateral side of any tank that may be carried by the backpack assembly  30 . 
       Middle Housing 
       [0092]    The middle housing  102  can contain one or more PASS devices  104 . In the illustrated configuration, the middle housing  102  contains the left PASS device  104  and the right PASS device  104 . As described above, the PASS device  104  is a personal alert safety system, which is a one-way communications device used by firefighters entering a building to alert others that the wearer of the PASS device is in trouble and in need of rescue. In the illustrated configuration, each PASS device  104  comprises the transducer or speaker  106  and the visual alert, such as the LED  110 . Advantageously, each speaker  106  is angled outward such that the speaker  106  is angled away from the air cylinder  32  that is secured to the back frame  34  during use. In this manner, the sound emitted from the speaker  106  is less likely to be obstructed by the tank. The speakers preferably emit a sound pressure level of at least 95 dBA and preferably are tested to temperatures of at least 900° F. 
         [0093]    The PASS device  104  can comprise a sensor configuration. For example, the sensor configuration can comprise a three-axis accelerometer or the like. In a preferred configuration, however, the signals regarding movement are provided to the back PASS device  104  from a sensor associated with the front PASS device  62 , which experiences significantly more movement than the back PASS device  104  because the front PASS device  62  is dangling from the shoulder strap  46 . Nevertheless, any suitable sensor configuration can be used. When the sensor configuration senses that no movement has occurred for a predetermined period (e.g., approximately 20 seconds), an alarm sequence is activated, which causes a sound to be emitted from the speaker  106  and causes the LED  110  to flash. The LED  110  also can flash to indicate that the PASS device  104  is operational and/or to indicate whether the PASS device  104  is in a sensing or alarm mode. The back PASS device  104  preferably powers the alert devices  106 ,  110 . 
         [0094]    Power is supplied to the back PASS devices  104  from the central power supply  118 . The power is supplied separately to the HUD transducer  100  and the back PASS devices  104 , which therefore can be separately powered. The separate power supplies also enable the back PASS devices  104  to be powered down without powering down the HUD transducer  100  and its associated circuitry. In addition, the back PASS devices  104  can be provided as separate modules and, therefore, the separate supply of power to the two devices enables simplified manufacture regardless of whether the optional back PASS devices  104  are included or not. 
         [0095]    The back PASS device  104  also can provide power to the beacons  112 . In a preferred configuration, the beacons  112  are not powered unless the PASS devices  104  enter an alarm mode. The beacons  112  can be positioned to the lateral sides of the middle housing  102 . Preferably, the beacons  112  are somewhat protected by cages  113  that are positioned over the beacons  112 . By positioning the beacons  112  to each lateral side, the beacons  112  are much more likely to be detected during a rescue operation. 
       Lower Housing 
       [0096]    The lower housing  116  preferably comprises a central power source housing portion  222  positioned to one side of the lower housing  116 . The housing portion  222  preferably is sized and configured to contain the four C-cell batteries in series described above. Other configurations also are possible. Preferably the power source housing portion  222  comprises a lower closure  224  that substantially seals an opening into a power source chamber defined within the central power source housing portion  222 . The closure  224  preferably comprises a recessed portion that allows the closure to be removed with the use of a coin or a flathead screwdriver. Thus, the closure  224  protects the central power source while facilitating a rapid replacement of the central power source while in the field. 
         [0097]    With reference again to  FIG. 1 , a bumper  226  preferably protects a lower portion of the back frame  34 . In the illustrated configuration, the bumper  226  covers a lower portion of the back frame  34 . The bumper  226  reduces the likelihood that the backpack assembly  30  will slip on a floor surface when not being worn and also reduces the likelihood that the backpack assembly will scratch a floor surface due to sliding on the floor surface when not being worn. 
         [0098]    With reference to  FIG. 17 , a lower portion of the lower housing  116  preferably comprises at least one tank support  228  and a central tank recess  230 . In the illustrated configuration, two tank supports  228  are positioned to support the tank, which is partially received within the central tank recess  230 . In particular, the illustrated tank supports  228  are positioned on each side of the tank  32  and limit the downward movement of the tank  32  relative to the tank band assembly  114 . The tank supports preferably  228  have a rubberized surface although other constructions are possible. 
         [0099]    As shown in  FIG. 2 , a rapid intervention crew/company universal air connection system (RIC UAC)  232  is positioned at the bottom of the illustrated lower housing  116  proximate to the CGA wheel  132 . The RIC/UAC  232  allows emergency replenishment of breathing air to the tank  32  in manners known to those of skill in the art. 
       Offset Swivel Assembly 
       [0100]    The offset swivel assembly  136  connects the hose  134  to the CGA wheel  132 . With reference to  FIG. 18  and  FIG. 19 , the swivel assembly  136  will be described in greater detail. As illustrated in  FIG. 19 , the illustrated swivel assembly  136  facilitates rotation about three axes: A 1 , A 2  and B 1 . The first two axes A 1 , A 2  are generally parallel to each other and the third axis B 1  is generally perpendicular to the first two axes A 1 , A 2 . An offset link  234  connects the wheel  132  to a fitting  236  at the end of the hose  134 . Preferably, a fluid passage is defined through a first pivot shaft that connects the fitting  236  and the offset link  234  and a fluid passage is defined through a second pivot shaft that connects the offset link  234  and the wheel  132 . The offset link  234  also comprises a fluid passage. Accordingly, while the offset link  234  can rotate about the axis A 1  and the axis A 2 , a fluid passage extends through the coupling between the hose  134  and the CGA wheel  132 . 
       Quick Disconnect 
       [0101]    With reference to  FIG. 1  and  FIG. 22 , the coupler  86  provides a simultaneous quick disconnect between two pneumatic hoses and two electrical cables. With reference to  FIG. 22 , a first portion  266  and a second portion  282  of the coupler  86  are shown. As illustrated, the coupler  86  features an electrical portion  270  and an air portion  272  that are integrated into a single component. The electrical portion of the first portion  266  can comprise a gasket  273 . A raised wall  268  of the second portion  282  can be positioned within a recess  269  formed within the first portion  266 . The raised wall  268  can be received within the recess  269 , or other slot or opening, formed within the second portion  282 , which mates with the first portion  266 . The mating wall and slot align in only one angular orientation, which results in the pins of the electrical portion being properly aligned with respective sockets during coupling. Accordingly, the coupler  86  enables a connection between the air portions only when the electrical portions are properly aligned. 
         [0102]    The coupler operates similar to most quick disconnects. To separate the two portions  266 ,  282  of the coupler  86 , a push ring on the second portion  282  is urged toward the first portion  266 . When the push ring moves, the two portions can be disconnected. 
       Front PASS Device 
       [0103]    The front PASS device  62  is illustrated in  FIG. 23  and  FIG. 24 . In some configurations, the front PASS device  62  may not be included with the backpack assembly  30 . When included, however, it preferably is positioned along the right shoulder strap  46 . The front PASS device  62  contains various circuitry, sensors and other components. 
         [0104]    In one configuration, the front PASS device  62  comprises an outer housing  290 . The outer housing  290  preferably is rugged and substantially liquid resistant. A motion detection apparatus can be positioned within the outer housing  290 . The motion detection apparatus can comprise a three axis accelerometer. Other types of motion detection apparatuses can be used, including but not limited to, mercury switches and laser beams targeting a mirror on a spring. 
         [0105]    The motion detection apparatus preferably is connected to circuitry that can be used to detect when the front PASS device  62  has been stationary for a preset period. In one configuration, the preset period is about twenty seconds. If the front PASS has been stationary for the preset period, then an alarm mode is entered. During the alarm mode, the front PASS drives a speaker  292  that is mounted in the outer housing  290 . The front PASS  62  also drives the back PASS  104 . 
         [0106]    With reference still to  FIG. 23 , an LED lens  294  is mounted in the outer housing  290  or boot. The LED lens  294  overlies two or more status lights. The multiple LED lights positioned under the lens  294  provide improved visibility and provide redundant backup in case of LED failure. The multiple LED lights preferably flash periodically to indicate that the front PASS is operational and the multiple LED lights preferably flash more rapidly or in a different pattern to indicate that the power supply is running low. The multiple LED lights also enable green lights to be used with the front PASS  62  is in the sensing mode, while red lights are used with the front PASS  62  is in alarm mode and yellow (amber) lights are used to give a user battery status information, even when the backpack assembly  30  is not being used. 
         [0107]    An analog gauge (see  FIG. 24 ) is positioned under a gauge cover  300 . The analog gauge is a redundant feature that advantageously works independent of the electronic sensing systems using data from the HUD transducer  100 . The gauge preferably comprises a photoluminescent face  302 , which improves the visibility of a needle  304 . If power is needed for the analog gauge, an external power source can be provided. 
         [0108]    As illustrated, an alarm button  306  can be provided. The alarm button  306  can be mounted in any orientation on the front PASS  62 . Preferably, the alarm button  306  is large enough for easy manipulation by a gloved hand. The alarm button  306  allows a user to put the front PASS into alarm mode at any time simply by pressing the button  306 . Thus, in the event of an emergency experienced by the user, the alarm button  306  can be depressed such that the front PASS, back PASS and any beacons enter the alarm mode. To reset the alarm, the alarm button  306  can be depressed two consecutive times. 
         [0109]    To connect the front PASS  62  to the back PASS  104 , a power cable  310  can be provided. Within the power cable  310  can be 2 power wires and three signal wires. The signal wires can comprise the following wires: low battery, signal, and ground. The power cable  310  can be hard wired to the front PASS  62  and can be connected to the back PASS  104  with spring pin couplers. In the illustrated configuration, a five spring pin coupler can be used. In some embodiments, more data can be transmitted with a power cable  310  having additional wires and a corresponding number of spring pins can be found on the associated spring pin coupler. 
         [0110]    The illustrated front PASS  62  also has the beacon  64  built in to the front PASS housing  290 . Because the beacon  64  can be an optional element, the beacon  64  is secured to the housing  290  with threaded fasteners and is positioned within its own protective housing  312 . Other configurations are possible. 
       Tank Band Assembly 
       [0111]    The tank band assembly  114  advantageously allows loosening with a single hand and facilitates rapid tank exchanges. As will be described with reference to  FIG. 25 , the tank band assembly  114  preferably comprises a locking mechanism  320  that can be released with a thumb and a cam latch mechanism  322  can be operated with a hand to loosen a tank band  324 . 
         [0112]    In one preferred configuration, the tank band  324  can be lengthened to expand a diameter of the tank band  324  or shortened to shrink a diameter of the tank band  324  by operating the cam latch mechanism  322 , which is positioned to one side of the cylinder  32  in the illustrated configuration. Thus, the illustrated tank band assembly  114  facilitates the rapid exchange of cylinders having different diameters. In a preferred configuration, the tank band assembly  114  enables the backpack assembly  30  to accommodate tanks with diameters ranging from at least about 5 inches to at least about 7.3 inches. Once a cylinder is positioned within the tank band assembly  114 , the slack of the tank band  324  can be slid into the cam latch mechanism  304 , which can be snapped to a locked position prior to the tank band locking mechanism  320  tightening the tank band  324  around the cylinder  32 . 
         [0113]    With reference to  FIG. 25 , the illustrated tank band assembly  114  comprises a base  330 . The base  330  can be used to secure the tank band assembly to the back frame  34 . In the illustrated configuration, the base  330  comprises four mounting holes  332 . The mounting holes can receive mechanical fasteners, which secure the base  330  to the back frame  34 . In some configurations, the base  330  can be secured in other manners, including but not limited to, interlocking mechanical structures, adhesives and the like. 
         [0114]    The illustrated base  330  comprises two pairs of ears  334 . One set of the ears  334  pivotally connects the tank band locking mechanism  320  to the base  330  and the other set of ears  334  pivotally connects the cam latch mechanism  322  to the base  330 . Other mounting configurations also can be used to secure the tank band locking mechanism  320  and the cam latch mechanism  322  to the base  330 . A central portion of the base  330  also comprises a recess  336  that is generally cylindrical in shape. The recess  336  accommodates a portion of the tank band  324  that is not being used to secure the cylinder  32 . 
         [0115]    The cam latch mechanism  322  allows excess tank band to be removed from between the cam latch mechanism  322  and the tank band locking mechanism  320 . The cam latch mechanism comprises a main pivot arm  340 . The main pivot arm  340  preferably is pivotally connected to the base  330 . In the illustrated configuration, a pivot shaft  342  connects the main pivot arm  340  to the respective ears  334 . The shaft  342  can be secured in position in any suitable manner, such as through the use of snap rings  344 , for instance but without limitiaton. In one configuration, the main pivot arm  340  can include ribs  345  (see  FIG. 27 ) that abut upon the base  330  such that the range of pivotal movement of the main pivot arm  340  relative to the base  330  can be limited. The limited range advantageously reduces or eliminates the ability of the main pivot arm to flop from side to side when a tank is not mounted to the backpack assembly  30 . 
         [0116]    The main pivot arm  340  preferably defines a slot  346 . The slot is sized and configured to receive the width and thickness of the tank band  324 . In the illustrated configuration, the slot  346  is formed at least in part by an inner surface  350 . Preferably, the inner surface is generally cylindrical in shape and defines a portion of a cylindrical surface in which the tank  32  will be positioned. 
         [0117]    An upper portion of the main pivot arm  340  defines a through bore that contains a shaft  352 . The shaft  352  supports two torsion springs  354  at each end of the shaft  352 . The torsion springs preferably are housed within the portion of the main pivot arm  340  through which the shaft extends. The main pivot arm  340  also comprises slots  356  that receive one end of the torsions springs  354 . The other end of the torsion springs  354  preferably connect to a locking bracket  360 . Thus, the locking bracket  360  can be biased into an open position when no tank  32  is mounted to the backpack assembly  30 . 
         [0118]    The locking bracket  360  is pivotally connected to the main pivot arm  340  by the shaft  352 . In the illustrated configuration, the locking bracket  360  comprises a tab  362  that ends in at least one tooth  364 , but preferably two teeth  364  are provided. The two teeth  364  extend into the slot  346  when the locking bracket  360  is in a closed position, which is shown in  FIGS. 26 and 27 . When the teeth are engaged with the tank band  324 , the ends of the teeth maintain the locking bracket  60  in the closed position. Preferably, the inner surface  350  of the main pivot arm  340  also comprises corresponding apertures  366 . The apertures, in one configuration, accommodate the teeth  364  when the locking bracket  360  is pivoted to the closed position. 
         [0119]    For aesthetic reasons and for improving the grip one can get on the locking bracket  360 , a handle  370  (omitted from  FIG. 27  to clearly show the locking bracket  360 ) can be secured over the outer portion of the locking bracket  360 . The handle  370  can be sized and configured as desired. In the illustrated configuration, the handle  370  is secured to the locking bracket  360  with rivets  372  or other mechanical fasteners. Other suitable fastening techniques also can be used. 
         [0120]    As explained above, the torsion springs  354  urge the locking bracket  360  toward the opened position. Thus, to limit the movement of the locking bracket  360  and the handle  370  in the opened direction, a rib  374  is positioned on the main pivot arm  340 . When the handle  370  is moved toward the opened position, an upper surface of the illustrated handle  370  comes into abutment with the rib  374  such that the range of handle movement can be limited. Other constructions can be used. 
         [0121]    With reference now to  FIG. 28 , the tank band locking mechanism  320  will be described in further detail. The mechanism  320  also comprises a main pivot arm  380 . A pivot shaft  382  pivotally couples the main pivot arm  380  to the ears  334  of the base  330 . The pivot shaft  382  can be secured in position in any suitable manner, such as through the use of snap rings  384  or the like. 
         [0122]    The main pivot arm  380  preferably comprises structure that works together with structure on the base  330  to limit the pivot range of the main pivot arm  380  relative to the base  330 . In the illustrated arrangement, the main pivot arm  380  comprises ribs  386  ( FIG. 29 ) that abut on the base  330  to limit the movement of the main pivot arm  380  toward the other main pivot arm  340 . Because the tank band  324  connects the two pivot arms  340 ,  380  and because the main pivot arms  340 ,  380  each limit the range of movement in opposing directions, the overall movement of the three components can be limited in each direction when no tank  32  is enclosed by the assembly  114 . 
         [0123]    A support bracket  390  (see  FIG. 30 ) has a tab that extends downward into a pocket formed in the main pivot arm  380 . Helical springs  392  are mounted to shafts  394  at their upper ends and are mounted to rivets  396  or other mechanical fasteners or structures formed in the main pivot arm  380 . The springs  392  allow some relative movement between the support bracket  390  and the main pivot arm  380 . 
         [0124]    With reference to  FIG. 31 , a cam bracket  400  is pivotally coupled to the support bracket  390  with the shafts  394 . The cam bracket  400  therefore can pivot about the shafts  394  relative to the support bracket  390 . An end portion  402  of the tank band  324  preferably is rolled or otherwise connected to a member forming a passage. The passage receives a shaft  404  ( FIG. 30 ). The shaft  404  is supported by the cam bracket  400 . Advantageously, the shaft  404  is positioned lower (in the figures) than the shafts  394 . Thus, when the cam bracket  400  pivots downward relative to the support bracket  390 , the end portion  402  of the tank band  324  is moved such that the band tightens around the cylinder  32 . In addition, by virtue of the forces loaded on the locking mechanism  320  when the cylinder  32  is captured by the band  324 , the cam bracket  400  tends to stay in the closed position without any retaining feature. 
         [0125]    A handle  406  ( FIG. 29 ) can be secured to the cam bracket  400  in any suitable manner. In the illustrated configuration, the handle  406  is secured with rivets  410  or other mechanical fasteners. The handle  406  can comprise a first portion or strike  412  of a latch lock assembly  414 . The strike  412  can be positioned within a generally enclosed passage at one side of the handle  406 . A finger  416  preferably is joined to the support bracket  390  by a mechanical fastener  420  of the like. The finger  416  engages the strike  412  of the latch lock assembly  414  when the handle  406  is pivoted to the closed position. In this manner, the latch lock assembly  414  assists in maintain the tank band locking mechanism  320  in a closed position. Of course, to unlock or open the tank band locking mechanism  320 , a user can push the finger  416  over the strike  412  and raise the handle  406  to release the tension on the band  324 . 
         [0126]    The tank band  324  preferably comprises a plurality of apertures  420 . In the illustrated configuration, the apertures  420  correspond in size, shape and position to the teeth  364  of the cam latch mechanism  322 . Preferably, the teeth are punched from the inside surface of the tank band  324  to reduce the likelihood of damage to the tank by the minimal burring that could result. A portion of the tank band  324  also comprises a central slot  422 . While the illustrated slot  422  is positioned centrally, other locations also can be used. The slot  422  preferably also is formed from the inside surface of the tank band  324 . Moreover, in some configurations, the tank band  324  features rolled outer surfaces to further protect the tank  32 . 
         [0127]    The slot  422  advantageously does not extend fully to either end of the tank band  324 . A protrusion formed in the cam latch mechanism rides in the slot  422 . In one configuration, the protrusion is formed on a back side of the inner surface  350 . The protrusion and the slot cooperate to limit the amount of outfeed or infeed of the tank band  324  relative to the cam latch mechanism  322 . 
         [0128]    With continued reference to  FIG. 28 , the base  330  preferably also comprises sloping bosses  424  or other such surfaces to reduce the likelihood that the tank band  324  will feed between the base  330  and the main pivot arm  380 . Other suitable configurations also can be used. 
         [0129]    In accordance with the description above, the distance of the tank to the lumbar spine can be minimized. In addition, the center of the tank can better align with the lower thoracic region, which allows a more upright trunk posture. Moreover, pressures measured at the scapular and sacral regions are negligible (equal or less than about 5 pounds) while traditional SCBAs measure up to 15 pounds of pressure at the scapular region and 22 pounds at the sacral region. 
         [0130]    Although these inventions have been disclosed in the context of a certain preferred embodiments and examples, it will be understood by those skilled in the art that the present inventions extend beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the inventions and obvious modifications and equivalents thereof. In addition, while a number of variations of the inventions have been shown and described in detail, other modifications, which are within the scope of the inventions, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combinations or subcombinations of the specific features and aspects of the embodiments may be made and still fall within one or more of the inventions. Accordingly, it should be understood that various features and aspects of the disclosed embodiments can be combine with or substituted for one another in order to form varying modes of the disclosed inventions. Thus, it is intended that the scope of the present inventions herein disclosed should not be limited by the particular disclosed embodiments described above.