Abstract:
A two point door latch device having a master latch assembly, an auxiliary latch assembly, a linkage operationally joining the master latch assembly and the auxiliary latch assembly, and a handle for operating the master latch assembly. Both the master latch assembly and the auxiliary latch assembly have bolts with beveled heads that extend from their respective housings or brackets when in a locked state, and both include springs which tend the bias the bolts to their unlocked states absent the handle being in the lock position. Furthermore, if the linkage becomes disconnected from the master latch assembly and/or the auxiliary latch assembly, or the linkage breaks, the springs will cause the bolts of the master latch assembly and the auxiliary latch assembly to be retracted to an opened state.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to the field of door latches, and particularly relates to a door latching mechanism with at least two latch assemblies that are operably connected by a linkage arm, the latch assemblies being operated by a single handle and including a safety automatic unlock feature to prevent locking of a door in case the linkage fails. Furthermore, each latch assembly has a tapered pin that applies a gradually changing closing force to a door as it is being closed. More particularly, the invention relatives to a two point door latch with tapered pins. 
       BACKGROUND OF THE INVENTION 
       [0002]    Door latching mechanisms with at least two latch assemblies are useful in certain applications where it is desirable to have multiple latch points. One such increasingly important application is in the area of walk-in bathtubs. Walk-in bathtubs feature a door with a gasket. The door opens either inwardly or outwardly. When the door is open, the user can basically walk into the bathtub without having to step over the otherwise relatively high wall of the bathtub. When the door is shut, its gasket will ride against a complementary opening is the tub, thereby forming a watertight seam. Walk-in bathtubs are growing in popularity with invalid patients, people with ambulatory problems, and those who simply prefer easy ingress and egress from a bathtub. 
         [0003]    When a walk-in bathtub is filled with water, a considerable amount of water pressure builds up from the 40-50 gallon capacity contained therein. If the door of a walk-in accidental pops open, or the gasket leaks, there is a potential for considerable water damage. Even a slight leak or any dripping whatsoever is unacceptable to manufacturers and consumers alike of walk-in bathtubs. Accordingly, many walk-in bathtubs are fitted with more than one latch to ensure good sealing along the entire door/door frame interface. For ease of operation, some prior art multi-latch door latching mechanisms had one latch assembly carry the door handle (master latch assembly) with the other latch assembly (slave latch assembly) being operably connected to the master latch assembly with a linkage. 
         [0004]    With prior art door latching mechanisms having at least two latch assemblies connected with a linkage, if the linkage breaks, gets out of alignment, or otherwise becomes disabled, it is possible that one or more of the latch assemblies can become stuck in a locked position, preventing the door from being opened. Another problem with prior art door latching mechanisms having at least two latch assemblies is that they are not generally designed to provide for even closing of the door along the location of each latch, and thus, leakage along the seal can sometimes occur. 
         [0005]    There accordingly remains a need for new designs of door latching mechanisms having at least two latch assemblies that prevent inadvertent locking of the door upon failure of the linkage, and also provide even sealing of a door with a door frame. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention relates generally to a two point door latch device, comprising: a master latch assembly having (a) an outer housing, (b) a handle adapter that rotatably extends into the outer housing, (c) a master bolt with proximal end and a distal end, the master bolt slidably passing into the outer housing, the proximal end having a guide pin, and (d) a cam plate with a rotation hole, an arch shaped slot with a first terminal end and a second terminal end, the first terminal end being further away from the rotation hole than is the second terminal end, and a master pivot, wherein the cam plate is rotatably retained within the outer housing and is rotationally connected to the handle adapter, and wherein the guide pin of the master bolt slides in the arch shaped slot of the cam plate between the first terminal end of the arch-shaped slot wherein the master bolt moves into the outer housing, and the second terminal end of the arch-shaped slot wherein the master bolt moves out of the outer housing; an auxiliary latch assembly having (a) a bracket assembly with a bottom wall and an upper end, and (b) an auxiliary bolt with a proximal end having an auxiliary pivot thereon, and a distal end, the auxiliary bolt being slidable in the bracket assembly with proximal end extendable above the upper end of the bracket and the distal end extending below the bottom wall of the bracket assembly; and a linkage that connects between the master pivot of the master latch assembly and the auxiliary pivot of the auxiliary latch assembly, wherein activation of the master latch assembly activates the auxiliary latch assembly. 
         [0007]    The invention further provides a two point door latch device, comprising: a master latch assembly having (a) a housing, (b) a handle adapter that passes into the housing, (c) a master bolt with proximal end and a distal end, the distal end having a beveled face, the master bolt slidably passing into the housing, and (d) a cam plate with a rotation hole, a guide with a first end and a second end, the first end being spaced further away from the rotation hole than is the second end, and a master guide follower, wherein the cam plate is rotatably retained within the housing and is connected to the handle adapter, and wherein the proximal end of the master bolt slides relative to the guide of the cam plate between the first end where the master bolt moves into the outer housing, and the second end where the master bolt moves out of the housing; an auxiliary latch assembly having (a) a bracket assembly with a bottom wall and an upper end, and (b) an auxiliary bolt with a proximal end having an auxiliary pivot thereon, and a distal end with a beveled face, the auxiliary bolt being slidable in the bracket assembly with proximal end extendable above the upper end of the bracket and the distal end extending below the bottom wall of the bracket assembly; and a linkage that connects between the master pivot of the master latch assembly and the auxiliary pivot of the auxiliary latch assembly, wherein activation of the master latch assembly activates the auxiliary latch assembly. 
         [0008]    In another embodiment the invention provides a two point door latch device, comprising: a master latch assembly having (a) an outer housing, (b) a handle adapter that rotatably extends into the outer housing, (c) a master bolt with proximal end and a distal end, the master bolt slidably passing into the outer housing, the proximal end having a guide pin, (d) a tension spring that connects between the master bolt and the housing, which tension spring tends to bias the master bolt into the housing and rotate the cam plate to exert a pulling force on the linkage connected to the cam plate and tends to pull the auxiliary bolt into the bracket assembly and into an unlocked position, and (e) a cam plate with a rotation hole, an arch shaped slot with a first terminal end and a second terminal end, the first terminal end being further away from the rotation hole than is the second terminal end, and a master pivot, wherein the cam plate is rotatably retained within the outer housing and is rotationally connected to the handle adapter, and wherein the guide pin of the master bolt slides in the arch shaped slot of the cam plate between the first terminal end of the arch-shaped slot wherein the master bolt moves into the outer housing, and the second terminal end of the arch-shaped slot wherein the master bolt moves out of the outer housing; an auxiliary latch assembly having (a) a bracket assembly with a bottom wall and an upper end, (b) an auxiliary bolt with a proximal end having an auxiliary pivot thereon, and a distal end, the auxiliary bolt being slidable in the bracket assembly with proximal end extendable above the upper end of the bracket and the distal end extending below the bottom wall of the bracket assembly, and (c) a tension spring that connects between the master bolt and the housing, which tension spring tends to bias the master bolt into the housing and rotate the cam plate to exert a pulling force on the linkage connected to the cam plate and tends to pull the auxiliary bolt into the bracket assembly and into an unlocked position; and a linkage that connects between the master pivot of the master latch assembly and the auxiliary pivot of the auxiliary latch assembly, wherein activation of the master latch assembly activates the auxiliary latch assembly. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1A  is a front right isometric view of an exemplary embodiment a two point door latch with tapered pins of the invention showing its master latch assembly and its auxiliary latch assembly in a locked state. 
           [0010]      FIG. 1B  is a front right isometric view of an exemplary embodiment a two point door latch with tapered pins of the invention showing its master latch assembly and its auxiliary latch assembly in an unlocked state. 
           [0011]      FIG. 2A  is a partially exposed inside a bathtub view showing the two point door latch with tapered pins of the invention showing its master latch assembly and its auxiliary latch assembly in a door of a walk-in bathtub, with the door closed against the bathtub and with the assemblies in their locked state. 
           [0012]      FIG. 2B  is an outside a bathtub view showing the two point door latch with tapered pins of the invention showing the door of the walk-in bathtub partially opened. 
           [0013]      FIG. 3  is a bottom front isometric view of an exemplary embodiment of the master latch assembly (with handle shown in phantom) of  FIG. 1A  in a locked state. 
           [0014]      FIG. 4  is a top front isometric view of an exemplary embodiment of the auxiliary latch assembly of  FIG. 1A  in a locked state. 
           [0015]      FIG. 5  is an exploded top right view of the master latch assembly of  FIG. 3 . 
           [0016]      FIG. 6  is an exploded top right view of the exemplary auxiliary latch assembly of  FIG. 4 . 
           [0017]      FIG. 7  is a partially exposed front plan view of the master latch assembly of  FIG. 3  in its locked position. 
           [0018]      FIG. 8  is a partially exposed rear plane view of the master latch assembly of  FIG. 3  in its locked position. 
           [0019]      FIG. 9  is a bottom plane view of the master latch assembly of  FIG. 3 . 
           [0020]      FIG. 10  is a right side view of the master latch assembly with handle of  FIG. 3 . 
           [0021]      FIG. 11  is a partially exposed front plan view of the master latch assembly of  FIG. 3  in its locked position, but in its unlocked state. 
           [0022]      FIG. 12  is a bottom plan view of the master latch assembly of  FIG. 11 . 
           [0023]      FIG. 13  is a right side view of the master latch assembly of  FIG. 11 . 
           [0024]      FIG. 14  is a front view of the auxiliary latch assembly of  FIG. 1A  with its auxiliary bolt fully extended. 
           [0025]      FIG. 15  is a right side view showing the auxiliary latch assembly of  FIG. 1A  with its auxiliary bolt extended fully. 
           [0026]      FIG. 16  is a front view of the auxiliary latch assembly of  FIG. 1B  with its auxiliary bolt fully retracted. 
           [0027]      FIG. 17  is a right side view showing the auxiliary latch assembly of  FIG. 16  with its auxiliary bolt fully retracted. 
           [0028]      FIG. 18  is a left front isometric view of the auxiliary latch assembly with its auxiliary bolt engaged with a strike plate. 
           [0029]      FIG. 19  is a partially exposed side view of the auxiliary latch assembly with its auxiliary bolt engaged with a strike plate. 
       
    
    
     DETAILED DESCRIPTION 
       [0030]    Turning first to  FIGS. 1A and 1B , there are shown front right isometric views of an exemplary embodiment a two point door latch with tapered pins  10  of the invention showing its master latch assembly  12  and its auxiliary latch assembly  14  joined by a linkage arm  16 , in a locked state ( FIG. 1A ) and an unlocked state ( FIG. 1B ). The linkage arm  16  can be made of rigid material such metal rod or strip, or can be made of other materials, such as strong plastic, composites, or the like. The linkage arm  16  could also comprise a cable retain in a cable housing, or any other arrangement that will reliably translate motion between the master latch assembly  12  and its auxiliary latch assembly  14 . The master latch assembly  12  has an outer housing  18  with a handle adapter  20  extending outside of the outer housing  18 . A cam plate  22  is rotatably connected to the handle adapter  20 , and includes an arched arm portion  24  with an arched slot  26  formed therein. The handle adapter  20  is rotatable relative to the outer housing  18 . As shown in  FIG. 3 , a handle  90  attaches to the handle adapter  20  with a pin  94 , which pin  94  passes through the handle  90  through a pin hole  96  formed in the handle adapter  20 . Extending from a left end wall  28  of the outer housing  18  is a pin tube  30 , through which pin tube  30  is extendable a master lock bolt  32 . At distal end  34  of the master lock bolt preferably there is included a beveled face  36 . Opposite the arched arm portion  24  of the cam plate  22  is an extension  38  with a master pivot  40 . A first end  42  of the linkage arm  16  is pivotally connected to the pivot  40 , such as with a nut  78 . A second end  44  of the linkage arm  16  is pivotally connected to the auxiliary pivot  46 , which auxiliary pivot  46  is connected to a proximal end  48  of an auxiliary bolt  50  of the auxiliary latch assembly  14 . The auxiliary bolt  50  has a distal end  52  and preferably includes a beveled face  54 . The auxiliary bolt  50  is slidably received in a bolt guide  56 , with the bolt guide  56  being located in a bracket assembly  58 . The bolt guide  56  can comprise a tube having a longitudinal slot  60  that extends at least partially along the length of the bolt guide  56  and preferably up to our near an upper end  62  of the bracket assembly  58 , which has an bolt aperture  64  formed therein. The upper end  62  of the bracket assembly  58  connects to a bottom wall  66  thereof through side walls  68 . A coil spring  70  is retained around the bolt guide  56 , and seats with a bottom end  72  of the coil spring  70  resting on the bottom wall  66  of the bracket assembly  58 . Attachment plates with holes  106  on the bracket assembly  58  can be provided to affix the auxiliary latch assembly  14  to a door. A top end  74  of the coil spring  70  impinges on a retention pin  76  or other stop device which is engaged with the auxiliary bolt  50 . The thusly compressed coil spring  70  will tend to bias the auxiliary bolt  50  upwardly absent the force of the linkage arm  16  pushing it downwardly, and will thus act as an emergency auxiliary latch assembly  14  release in case the linkage arm  16  breaks or disconnects from the auxiliary latch assembly  14 . As shown in the movement of the two point door latch with tapered pins  10  from the locked state of  FIG. 1A  to the unlocked state of  FIG. 1B , when the handle adapter  20  is turned, it will rotate the cam plate  22 , causing the master lock bolt  32  to withdraw into the master bolt tube  30 , pulling up on the linkage arm  16  and pulling up on auxiliary bolt  50  so that an upper end  80  will pull through the bolt aperture  64  and its distal end  52  with beveled face  54  will be pulled upwardly into the bolt guide  56 . 
         [0031]      FIG. 2A  is a partially exposed inside a bathtub view showing the two point door latch with tapered pins  10  of the invention showing its master latch assembly  12  and its auxiliary latch assembly  14  in a door D of a walk-in bathtub B, with the linkage arm  16  operationally joining the two assemblies, with the door D closed against the bathtub B and with the assemblies  12  and  14  in their locked state. The door D is attached to the bathtub B with a hinge H. The master bolt tube  30  can be seen as well as an exemplary handle  90  of the master latch assembly  12 . 
         [0032]      FIG. 2B  is an outside a bathtub view showing the two point door latch with tapered pins  10  of the invention showing the door D of the walk-in bathtub B partially opened. As can be seen the door D has a flange F around it perimeter, which flange F seats with a rim R around an opening O formed in the walk-in bathtub B. The master lock bolt  32  of the master latch assembly  12  and the auxiliary bolt  50  of the auxiliary latch assembly  14  are shown extending from the door D. A slam plate  130  is shown mounted on a sill  132  of the bathtub B. The slam plate  130  has a hole that receives the auxiliary bolt  50  of the auxiliary latch assembly  14  when the door D is closed on the bathtub B. Not shown but similarly situation is another slam plate that receives the master lock bolt  32  of the master latch assembly  12 . A seal S is preferably located adjacent to the flange F of the door D so that when the door D is closed against the recess R of the opening in the bathtub B, the door D will water tightly seal in place. 
         [0033]      FIG. 3  is a bottom front isometric view of an exemplary embodiment of the master latch assembly  12 , but without the exemplary handle  90 . The handle  90  has a head  92  that will be connected, e.g., via a pin  94  to the handle adapter  20 , which is shown as having a square end. The handle&#39;s head  92  has a pin hole and a complementary engagement (not shown) which is aligned with a pin hole  96  in the handle adapter  20  (shown in  FIG. 1A ). The outer housing  18  has a spring retainer  100 . Extending from the master lock bolt  32  is another spring retainer  102 . A tension spring  104  is connected between the two spring retainers  100  and  102  and exerts a biasing force that tends to pull the master lock bolt  32  from its extended position, where its distal end  34  extends from the master bolt tube  30 , inwardly back into the master bolt tube  30  absent any opposing force. A proximal end  110  of the master bolt tube  30  can preferably be forked and include a slot  112  formed therethrough, so that the slotted fork rides around the cam plate  22  in the vicinity of its arched slot  26 . A guide pin  114  (best shown in  FIGS. 5 ,  7  and  8 ) extends between the forked end bridging the slot  112  and being slidably retained in the arched slot  26  of the cam plate  22 . A gasket  116  can be placed around on the handle adapter  20  to enhance the sealing of the master latch assembly  12  when it is attached to a door. 
         [0034]    Turning to  FIG. 4 , there is shown a top front isometric view of an exemplary embodiment of the auxiliary latch assembly  14  of  FIG. 1A  in a locked state. The various features of the auxiliary latch assembly  14  are as described above with reference to  FIGS. 1A and 1B , and include an auxiliary pivot  46 , which auxiliary pivot  46  is connected to a proximal end  48  of an auxiliary bolt  50  of the auxiliary latch assembly  14 . The auxiliary bolt  50  has a distal end  52  and preferably includes a beveled face  54 . The auxiliary bolt  50  is slidably received in a bolt guide  56 , with the bolt guide  56  being located in a bracket assembly  58 . The bolt guide  56  can comprise a tube having a longitudinal slot  60  that extends at least partially along the length of the bolt guide  56  and preferably up to our near an upper end  62  of the bracket assembly  58 , which has an bolt aperture  64  formed therein. The upper end  62  of the bracket assembly  58  connects to a bottom wall  66  thereof through side walls  68 . A coil spring  70  is retained around the bolt guide  56 , and seats with a bottom end  72  of the coil spring  70  resting on the bottom wall  66  of the bracket assembly  58 . A top end  74  of the coil spring  70  impinges on a retention pin  76  which is engaged with the auxiliary bolt  50 . The thusly compressed coil spring  70  will tend to bias the auxiliary bolt  50  upwardly absent the force of the linkage arm  16  pushing it downwardly, and will thus act as an emergency auxiliary latch assembly  14  release in case the linkage arm  16  breaks or disconnects from the auxiliary latch assembly  14 . 
         [0035]      FIG. 5  is an exploded top right view of the master latch assembly  12  of  FIG. 3 . The handle adapter  20  is shown separated from the outer housing  18 . The handle adapter has a square head  140 , an enlarged collar  142  below the square head  140 , and a threaded shank  144 . The pin hole  96  is formed through the square head  140 . The gasket  116  fits around the collar  142  and provides a seal on the door to which the master latch assembly  12  is attached. A spacer  146  made of low friction material, such as nylon, can be provided below the collar  142  on the threaded shank  144 . A handle adapter shaft  148  slides into a hole (not shown) formed in the threaded shank  144  and is attached there with a shaft pin  150  that frictionally fits in a shank hole  152  and shaft hole  154  in the handle adapter shaft  148  to hold the handle adapter shaft  148  in place with the handle adapter  20  that that turning the handle adapter  20  turns the handle adapter shaft  148 . The handle adapter shaft  148  has a non-round cross-section. In lieu of this construction, the handle adapter shaft  148  can be press fit into the threaded shank  144  or can be formed together with the threaded shank  144 . A variety of spacers and washers  156  are provided for low friction operation of the handle adapter  20  relative to the outer housing  18 . The outer housing  18  has a shaft hole  158  formed therein though a top surface  160  which passes the shaft  148 . A threaded shaft nut  162  screws onto the threaded shank  144  and rotatably retains the handle adapter  20  in the shaft hole  158  of the outer housing  18 . An internal housing frame  170  fits inside the outer housing  18 . The outer housing  18  has an end wall  28  with the master bolt tube  30  passing therethrough. The internal housing frame  170  has a bottom wall  174  and a spaced apart top bracket  176 . A through hole  178  is formed therethrough. The cam plate  22  is shown with its arched arm portion  24  with arched slot  26  formed therein, and extension  38 . The master pivot  40 , for example a threaded pin, extends upwardly from the extension  38 . A spacer  180  and nut  182  are used to connect the cam plate  22  to the first end  42  of the linkage arm  16  as shown in  FIGS. 1A and 1B . The cam plate  22  has a rotation hole  184  formed therein with is adapted to non-rotatably receive the handle adapter shaft  148 , for example, by having a generally square shape to receive the generally square cross-section of the handle adapter shaft  148 . The arched slot  26  has a first end  26 A and a second end  26 B. The first end  26 A is closer to the rotation hole  184  than is the second end  26 B to the rotation hole  184 . Thus, when a camming action is set up when the cam plate  22  is rotated, as will be further described below. When fully assembled, the master lock bolt  32  will be positioned with its slot  112  around the arched arm portion  24  with arched slot  26  of the cam plate  22 , with the guide pin  114  passing through the slot  112  in the proximal end  110  of the master lock bolt  32  and through slot hole  186  to pivotally attach the master lock bolt  32  to the cam plate  22 . A washer  188  and nut  190  fix the guide pin  114  in place. When assembled, the cam plate  22  will be positioned in the internal housing frame  170  and the handle adapter shaft  148  will fit into the rotation hole  184  in the cam plate  22 . Thus, turning the handle adapter  20  will turn the cam plate  22 . The tension spring  104  will be connected at one end to the spring retainer  100  on the outer housing  18  and at its other end to the spring retainer  102 , which spring retainer  102  can comprise a bolt, washer and nut and fit into a hole  192  forward of the slot hole  186  of the proximal end  110  of the master lock bolt  32 . The spring  104  will thus tend to bias the master lock bolt  32  through the master bolt tube  30  and back into the master latch assembly  12 . A handle shaft nut  118  is provided which non-rotatably slips over a distal end  120  of the handle adapter shaft  148 . The handle shaft nut  118  will help retain the distal end  120  of the handle adapter shaft  148  in place when passed through the rotation hole  184  in the cam plate and rotatable fits within a base hole  122  formed in a bottom wall  124  of the outer housing  18 . While an arched slot  26  in the cam plate  22  is a convenient guide for receiving the guide pin  114 , instead of a slot, a raised guide or other arrangement can be used in lieu of a slot. 
         [0036]      FIG. 6  is an exploded top right view of the exemplary auxiliary latch assembly  14  of  FIG. 4 . The various features of the auxiliary latch assembly  14  are as described above with reference to  FIGS. 1A and 1B , and include an auxiliary pivot  46 , which auxiliary pivot  46  is connected to a proximal end  48  of an auxiliary bolt  50  of the auxiliary latch assembly  14 . The auxiliary bolt  50  has a distal end  52  and preferably includes a beveled face  54 . The auxiliary bolt  50  is slidably received in a bolt guide  56 , with the bolt guide  56  being located in a bracket assembly  58 . The bolt guide  56  can comprise a tube having a longitudinal slot  60  that extends at least partially along the length of the bolt guide  56  and preferably up to our near an upper end  62  of the bracket assembly  58 , which has an bolt aperture  64  formed therein. The upper end  62  of the bracket assembly  58  connects to a bottom wall  66  thereof through side walls  68 . A coil spring  70  is retained around the bolt guide  56 , and seats with a bottom end  72  of the coil spring  70  resting on the bottom wall  66  of the bracket assembly  58 . A top end  74  of the coil spring  70  impinges on a retention pin  76  which is engaged with the auxiliary bolt  50 . The thusly compressed coil spring  70  will tend to bias the auxiliary bolt  50  upwardly absent the force of the linkage arm  16  pushing it downwardly, and will thus act as an emergency auxiliary latch assembly  14  release in case the linkage arm  16  breaks or disconnects from the auxiliary latch assembly  14 . The auxiliary bolt  50  is at its upper end  200  generally rectangular so as to slide through the bolt aperture  64  formed in the upper end  62  of the auxiliary latch assembly  14 . An auxiliary bolt hole  82  is formed in the bottom wall  66  and receives the bolt guide  56  with its longitudinal slot  60 . The retention pin  76  slides through the retention pin hole  84  formed in the auxiliary bolt  50 . The auxiliary pivot  46  can comprise a bolt  86 , nut  88 , and spacer  98 . 
         [0037]      FIG. 7  is a partially exposed front plan view and  FIG. 8  is a partially exposed rear plane view of the master latch assembly  12  of  FIG. 3  in the locked position.  FIG. 9  is a bottom plane view and  FIG. 10  is a right side view of the master latch assembly  12  of  FIG. 3  in the locked position. In this locked state, the master lock bolt  32  fully extends from the master bolt tube  30  extending from the left end wall  28  of the outer housing  18 , and the cam plate  22  is rotated such that the guide pin  114  will abut against the second end  26 B of the arched slot  26  in the arched arm portion  24  of the cam plate  22 . As previously noted, the second end  26 B is further away from the hole in the cam plate  22  (not shown) which is aligned with the handle adapter  20  compared to the first end  26 A, and thus the master lock bolt  32  will allowed to extend from the master bolt tube  30 . The spring  104  extends between the spring retainers  100  on the housing  18  and the spring retainer  102  on the master lock bolt  32  and absent the handle adapter  20  being held in its rotational position, tends to bias the master lock bolt  32  back into the master bolt tube  30  as shown in  FIGS. 11-13 . 
         [0038]      FIG. 11  is a partially exposed front plan view,  FIG. 12  is a bottom plan view, and  FIG. 13  is a right side view of the master latch assembly  12  in an unlocked state. In this unlocked state, the master lock bolt  32  is withdrawn into the of the outer housing  18 , and the cam plate  22  is rotated such that the guide pin  114  will abut against the first end  26 A of the arched slot  26  in the arched arm portion  24  of the cam plate  22 . As previously noted, the first end  26 A is closer to the hole in the cam plate  22  (not shown) which is aligned with the handle adapter  20  compared to the second end  26 B, and thus the master lock bolt  32  will be drawn into the master bolt tube  30  so as not to extend from the master bolt tube  30 . The spring  104  extends between the spring retainers  100  on the housing  18  and the spring retainer  102  on the master lock bolt  32  and absent the handle adapter  20  being held in its rotational position, will tend to bias the master lock bolt  32  back into the master bolt tube  30  even if the handle adapter  20  is not turned to the open position. 
         [0039]      FIG. 14  is a front view and  FIG. 15  is a right side of the auxiliary latch assembly  14  of  FIG. 1A  with its auxiliary bolt  50  fully extended below the bottom wall  66  of the bracket assembly  58  and out of the bolt guide  56 . In this state, the auxiliary pivot  46  is close to the upper end  62  of the auxiliary latch assembly  14 . The coil spring  70  is compressed but tends to bias the auxiliary bolt  50  upwardly in the bolt guide  56  absent a force pushing it downwardly, viz., by the linkage arm  16  (not shown). The beveled face  54  of the auxiliary bolt  50  will be fully revealed in this state and available to engage with a slam plate  130  as shown in  FIG. 2B . Indeed, the beveled face  54  of the auxiliary bolt  50  functions to gradually pull in a door as the auxiliary bolt  50  engaged with a slam plate, and thus ensures a water tight seal of the door with its bathtub opening. 
         [0040]      FIG. 15  is a right side view and  FIG. 16  is a front view showing the auxiliary latch assembly  14  of  FIG. 1A  with its auxiliary bolt  50  retracted back into the bolt guide  56 . In this state, the spring  70  is expanded between the bottom wall  66  and the retention pin  76 . This is the state of the auxiliary latch assembly  14  when the handle on the master latch assemble is moved to its opened position or, if the linkage arm  16  (not shown) breaks or becomes disconnects, thereby ensuring that a sure can open the door. 
         [0041]      FIG. 16  is a front view and  FIG. 17  is a right side view of the auxiliary latch assembly of  FIG. 1B  with its auxiliary bolt  50  retracted above the bottom wall  66  into the bracket assembly  58 . When so withdrawn, its upper end  200  carrying the auxiliary pivot  46  will extend upwardly above the upper end  62 , and its beveled face  54  no longer being able to engage a strike plate. 
         [0042]      FIG. 18  is a left front isometric view and  FIG. 19  is a partially exposed side view of the auxiliary latch assembly  14  with its auxiliary bolt  50  extended into a cavity  202  of the slam plate  130 . Indeed, as the auxiliary bolt  50  is moved into the cavity  202  from its upper surface  204  down towards the bottom  206 , its beveled face  54  will act to move the auxiliary latch assembly  14  and its attached door D (a portion of which is shown in phantom lines) in the direction of the force arrow F towards the bathtub B (a portion of which is shown in phantom lines) to thereby ease the door D into place with the bathtub B. 
         [0043]    Although the invention has been described with reference to a master latch assembly  12  and one auxiliary latch assembly  14 , additional linkages can be connected to the master latch assembly  12  so that more than one auxiliary latch assembly  14  can be operated by the same master latch assembly  12 . For example, if a design calls for three interoperated latches instead of two, simply adding one more auxiliary latch assembly  14  and a one more linkage  16  could easily be accommodated by the invention. 
         [0044]    The preferred embodiments of this invention have been disclosed, however, so that one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.