Patent Abstract:
A reversible mortise lock comprises a latch bolt which is removable from the housing for ease of reversal. A securing member is disposed inside the lock housing for releasbly holding the latch bolt in the housing. The securing member includes a securing element having a blocking surface biased into engagement with the latch bolt for securing the latch bolt to the securing member. The securing element has a surface accessible from outside the lock housing which when pressed releases the latch bolt from the securing member. Once the latch bolt is freed, the latch bolt can be completely removed from the lock housing, reversed and reinstalled. This releasing surface is only accessible through the side walls of the lock housing. Therefore, latch bolt reversal must be performed before the lock is installed in a door. Once the lock is installed, the latch bolt cannot be reversed because the latch bolt cannot be removed from the lock. A locking mechanism for use in the lock comprises a blocking element in the housing and a toggle for manually moving the blocking element between a locked position and an unlocked position relative to a latch operator. A stop is removably attached to the blocking element and adapted in the locked position to prevent operation of the outside latch operator. The stop is also accessible through the side walls of the lock housing and positioning of the stop in the blocking element is accomplished before installation. Preferably, the stop is a threaded plug which is received in a threaded opening in the blocking element. Thus, a screw driver is the only tool needed to release the latch bolt from the lock housing for reversal of the latch bolt and locking mechanism.

Full Description:
BACKGROUND 
     This invention relates generally to mortise locks, and more particularly to latch assemblies and locking mechanisms for use in reversible mortise locks. 
     A mortise lock is designed to fit into a mortised recess formed in the edge of a door which is opposite to the edge of the door that is hinged to the door frame. The mortise lock generally includes a rectangular housing, or case, which encloses the lock components. The principal lock component is a beveled latch bolt which projects beyond the edge of the door and into an opening in the door frame to latch the door in a closed position. The latch bolt is moveable to a retracted position inside the case to permit opening of the door by operation of a latch operator, such as a door knob or lever handle. 
     Mortise locks are typically configured so that the latch operators mounted on the inside and outside surfaces of the door can operate independently. The outside latch operator can either be rotated to retract the latch bolt, or locked against rotation to prevent retraction of the latch bolt. Preferably, the inside latch operator can always be rotated to retract the latch bolt. The locking of the outside latch operator is usually controlled by a manual actuator, such as, for example, push buttons or a pivoted toggle, which is exposed at the edge of the mortise lock near the latch. The manual actuator has an associated link within the mortise lock case which, in one position of the manual actuator, engages a moveable portion of the outside latch operator inside the lock case so as to prevent rotation of the latch operator. In a second position, the link disengages from the moveable portion thus permitting rotation of the outside latch operator. The inside latch operator is usually unaffected by the manipulation of the manual actuator and remains rotatable at all times. 
     Adjustments must be made to the mortise lock depending on whether the lock is mounted in a left-hand or right-hand door. A mortise lock mounted in a left-hand door must be rotated 180° about a vertical axis for mounting in a right-hand door. Consequently, the latch bolt must also be rotated 180° about a horizontal axis so that the beveled face of the latch faces the door-closing direction. In addition, the inside and outside latch operators of the left-hand door mounted lock become the outside and inside latch operators, respectively, of the right-hand door mounted lock. Therefore, a change must be made if the latch operator controlled by the locking mechanism happens to be the inside latch operator when the lock is installed. 
     The necessary adjustments to the mortise lock can be accomplished without opening the case. Typically, the latch bolt can be pulled partially out of the housing, usually against the force of a spring, rotated 180° and then allowed to be pulled back into the housing by the spring. However, this arrangement can lead to tampering after the lock is installed since the latch bolt can be reversed even when the mortise lock is in the door, which would prevent the door from closing. Moreover, the conventional mechanisms for reversing the operation of the locking mechanism are complicated and difficult to manipulate. 
     For the foregoing reasons, there is a need for a latch assembly for use in a reversible mortise lock which includes a latch bolt that cannot be reversed after the lock is installed in a door. Reversal of the latch bolt for use with a door of the opposite hand should be easily accomplished in the field. Further, any corresponding changes in the locking mechanism to effect locking of the outside latch operator should also be uncomplicated. The new latch assembly and locking mechanism should be straightforward in manufacture and use. 
     SUMMARY 
     Therefore, it is an object of the present invention to provide a reversible mortise lock wherein the latch assembly cannot be reversed when the lock is installed on the door. 
     A further object of the present invention is to provide a new latch assembly and locking mechanism for a mortise lock which are simple to reverse in the field prior to installation in the door. 
     According to the present invention, a mortise lock includes a latch assembly comprising a latch bolt having a first portion adapted to project from an opening in the lock housing in an extended position of the latch bolt while a second portion of the latch bolt remains within the lock housing. The latch bolt is removable from the lock housing through the opening. A securing member inside the housing is releasably attached to the second portion of the latch bolt. 
     The securing member comprises a securing element having a blocking surface and means for biasing the securing element and blocking surface into engagement with the second portion of the latch bolt for releasably securing the latch bolt to the moving member. The securing element further comprises a disengaging surface which when moved against the force of the biasing means releases the second portion of the latch bolt from the securing member so that the latch bolt may be removed from the lock housing. 
     In further accord with the present invention, a mortise lock of the type having a latch bolt normally projecting from the lock housing and means including a moveable member in the lock housing connected to a door knob or lever handle for moving the latch bolt to a retracted position in the housing, has a locking mechanism comprising a blocking element in the housing and means for moving the blocking element between a locked position and an unlocked position relative the moveable member. The blocking element has an opening adapted to receive a portion of the moveable member when the blocking element is in the locked position for allowing the moveable member to move and the door knob or lever handle to rotate. A stop is removably positioned in the opening of the blocking element for preventing movement of the moveable member when the blocking element is in the locked position. 
     Also in accord with the present invention, a mortise lock comprises a housing and a latch bolt removably mounted in the housing through an opening in the housing. A securing member is disposed inside the housing for movement relative to the housing. The securing member comprises a securing element having a blocking surface and means for biasing the blocking surface into engagement with the latch bolt for releasably securing the latch bolt to the securing member. The securing element further comprises a surface which when pressed moves the securing element against the force of the biasing means for releasing the latch bolt from the securing member so that the latch bolt may be removed from the housing. The securing member is moveable between a first position where the latch bolt is inside the housing and a second position where a portion of the latch bolt projects through the opening in the housing. Means for moving the securing member to the first position are provided, including a moveable member in the housing. A blocking element is disposed in the housing and means are provided for moving the blocking element between a locked position and an unlocked position relative to the moveable member. A stop is removably attached to the blocking element and adapted in the locked position to prevent operation of the moveable member. 
     An important feature of the present invention is that the releasing surface of the securing member is only accessible through the side walls of the mortise lock case. Therefore, latch bolt reversal must be performed before the lock is installed. Moreover, once the latch bolt is freed from the moveable member, the latch bolt can be completely removed from the lock housing, reversed and reinstalled. The blocking element and removable stop for locking the lock are also accessible through the side walls of the lock housing. Thus, repositioning of the stop in the blocking element is also accomplished before installation. Preferably, the stop is a threaded plug which is received in a threaded opening in the blocking element. 
     Reversal of the latch bolt and locking mechanism is simple to perform prior to installation of the lock. A screw driver is the only tool needed to release the latch bolt from the lock housing for reversal of the latch bolt and locking mechanism. Once the lock is installed in a door, the latch bolt cannot be reversed because the latch bolt cannot be removed from the lock. 
     Additional objects, features and advantages of the present invention will be apparent from the following description in which references are made to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more complete understanding of the present invention, reference should now be had to the embodiments shown in the accompanying drawings and described below. 
     FIG. 1 is a perspective view of an embodiment of a mortise lock assembly according to the present invention; 
     FIG. 2 is a elevation view of the mortise lock assembly taken along line  2 — 2  of FIG. 
     FIG. 3 is a perspective exploded view of an embodiment of a latch assembly used in the mortise lock assembly FIG. 1; 
     FIGS. 4 and 5 are opposite side elevational views of an anti-friction latch used in the latch assembly of 
     FIGS. 6 and 7 are front and rear elevational views, respectively, of the latch tail and spring clip of FIG  3 ; 
     FIGS. 8,  9 ,  10  and  11  are side elevational views of the tail plate of FIG. 3; 
     FIG. 12 is an exploded perspective view of an alternative embodiment of a tail plate and spring clip f use in the latch assembly of FIG. 3; 
     FIGS. 13 and 14 are front and rear elevational views, respectively, of the tail plate and spring clip embodiment of FIG. 12 similar to FIGS. 6 and 7; 
     FIG. 15 is a side elevational view of the tail plate embodiment of FIG. 12 similar to FIG. 8; 
     FIGS. 16 and 17 are side sectional views of the tail plate and spring clip embodiment of FIG. 12 showing the latch tail entering the tail plate taken along line  16 — 16  of FIG. 13; 
     FIG.  18 . is a side sectional view of the tail plate and spring clip embodiment of FIGS. 16 and 17 in combination with a screw driver blade illustrating the removal of the latch tail from the tail plate; 
     FIG. 19 is a perspective view of a hub used in the mortise lock assembly of FIG. 1; 
     FIG. 20 is a sectional view of the mortise lock assembly of FIG. 2 taken along line  20 — 20  of FIG. 2 showing an embodiment of a locking mechanism used in the mortise lock assembly of FIG. 1 in an unlocked position; 
     FIG. 21 is side elevational view of the locking mechanism embodiment of FIG. 20 with other lock components removed; 
     FIGS. 22 and 23 are the same views as FIGS. 20 and 21, respectively, but showing the locking mechanism embodiment in a locked position; and 
     FIG. 24, the same view of the mortise lock assembly of FIG. 2 but showing the latch bolt and deadbolt retracted into the case by actuation of a latch operator. 
    
    
     DESCRIPTION 
     The latch bolt and locking mechanism according to the present invention are for use in a mortise lock and may be used with any conventional mortise lock assembly such as, for example, the mortise lock assembly described by U.S. Pat. No. 4,118,056, the contents of which are hereby incorporated by reference. Accordingly, detailed explanations of the functioning of all of the mortise lock components are deemed unnecessary for understanding of the present invention by one of ordinary skill in the art. 
     Referring now to FIG. 1, a mortise lock assembly according to the present invention is shown and is generally designated by reference numeral  30 . The lock  30  comprises a generally rectangular box, or case  32 , for housing the lock components and is adapted to be received in a mortise in the free, or unhinged, edge of a door. One of the side walls of the case  32  comprises a cap  34  which is secured to and forms a closure for the case  32 . 
     FIG. 2 shows the lock with the cap side wall  34  removed. The case  32  includes a side wall  36  and, as seen in FIG. 2, integral top  38 , bottom  40 , front  42  and rear  44  walls. The front wall  42  has openings for a latch bolt  46 , a deadbolt  48 , an auxiliary bolt  50  and a flush-mounted toggle  52 . A face plate  54  is secured to the front wall of the case  32  and has openings which correspond to the openings in the front wall  42 . The latch bolt  46 , deadbolt  48  and auxiliary bolt  50  are shown projecting from their respective openings in the front wall  42  and face plate  54 . 
     An embodiment of the latch assembly for use in the mortise lock assembly of FIG. 2 is shown in FIG.  3  and designated generally at  56 . The latch assembly  56  comprises the latch bolt  46  including a bolt head  58  and an integral latch tail  60 , an anti-friction latch  62 , a coil spring  64 , a spring flange  66 , a tail plate  68  and spring clip  70 . The bolt head  58  includes a beveled face  72  and a slot  74 . A short pin  76  extends from one side of the bolt head  58  and into the slot  74  for pivotally mounting the anti-friction latch  62 . 
     The anti-friction latch  62  is shown in more detail in FIGS. 4 and 5. As seen in FIG. 5, one side of the anti-friction latch  62  has a groove  78  for receiving the pin  76  when the anti-friction latch  62  is slipped into the slot  74  during manufacture. The groove  78  is closed near its open end in a press operation to keep the anti-friction latch  62  in the bolt head  58 . A lever  77  extends from one side of the anti-friction latch and a stub  79  extends from the opposite side. When the latch assembly  56  is in the case (FIG.  2 ), the anti-friction latch  62  and the opening for the latch bolt  46  in the front wall  42  of the case  32  are configured so that the lever  77  engages behind the front wall  42  while the stub  79  engages behind the face plate  54 . 
     Returning to FIG. 3, the latch tail  60  extends from the rear of the bolt head  58 . The portion  61  of the latch tail  60  adjacent the bolt head  58  is thicker than the free end so that the coil spring  64  must be forced onto that portion of the latch tail thereby holding the coil spring  64  on the latch tail  60 . The free end of the latch tail  60  is rounded and includes a notch  80  longitudinally spaced from the free end. The tail plate  68  is generally cube-shaped and has a pass-through opening  82  for receiving the free end of the latch tail  60 . The spring clip  70  is a flat rectangular piece defining an irregular opening  84  and having an angled tab  86  extending from one edge of the clip  84 . The tail plate  68  has a slot  88  which intersects the tail plate opening  82  for receiving the spring clip  70 . The spring clip tab  86  fits in a groove  90  in the side of the tail plate  68 . 
     Each side of the tail plate  68  is shown in FIGS. 6 through 11. The tail plate  68  has a support boss  91  which sits against the case side wall  34  when the tail plate  68  is in the case  32 . The support boss  91  has a retraction surface  92 . An opposed boss  94  fits in a linear guide slot  96  in the cap side wall  14  (FIG. 1) for guiding and supporting linear movement of the tail plate  68 . Referring particularly to FIGS. 6 and 7, the tail plate  68  is shown from the front and rear, respectively, with the spring clip  70  in the slot  88  in the tail plate  68 . The irregular opening  84  in the spring clip  70  aligns with the opening  82  in the tail plate  68 . The dimensions of the spring clip  70  and the position of the slot  88  are such that the spring clip  70  partially blocks the opening  82  through the tail plate  68 . The tab  86  is braced against the surface of the groove  90  in the tail plate  68  to bias the spring clip  70  upward to this position as seen in FIGS. 6 and 7. 
     An alternative embodiment of the tail plate  68   a  and spring clip  70   a  for use in the latch assembly  56  of the present invention is shown in FIGS. 12 through 15. In this embodiment, the spring clip  70   a  is L-shaped and has an irregular opening  84   a . Two coil springs  98  are disposed in depressions  100  (FIG. 15) in the tail plate surface on either side of the groove  90   a  for biasing the spring clip  70   a  upward to the position shown in FIGS. 13 and 14 partially blocking the opening  82   a  in the tail plate  68   a . The other sides of the tail plate  68   a  are configured the same as seen in FIGS. 9-11. 
     Connection of the latch bolt  46  to the tail plate  68   a  and spring clip  70 a is shown in FIGS. 16 and 17. In FIG. 16, the free end of the latch tail  60  is shown entering the opening  82   a  in the tail plate  68   a . As the latch tail  60  initially enters the tail plate  68   a , the rounded end engages the edge of the opening  84   a  in the spring clip  70   a  forcing the clip down and compressing the springs  98 . When the latch tail notch  80  passes the spring clip  70   a , the springs  98  push the clip upward so that the edge of the opening  84   a  in the clip engages behind the notch  80  in the latch tail  60  securing the latch tail in the tail plate  68   a . It is understood that the embodiments of the tail plate and spring clip in FIGS. 6 through 15 are exemplary and other structures are possible, as long as the function of the overall structure for releasably holding the latch tail in the tail plate is maintained. 
     As seen in FIG. 2, when the latch assembly  56  is in position in the mortise lock assembly  30 , a substantial portion of the latch bolt  46  is inside the case  32  even when the latch bolt  46  is in the extended position with a predetermined portion projecting beyond the front of the case  32 . The latch tail  60  extends rearwardly from the bolt head  58  through a guide slot formed in a boss  102  fixedly mounted between the side walls  34 ,  36  for guiding and supporting the linear reciprocal movement of the latch bolt  46 . The coil spring  64  is held in compression between the bolt head  58  and the spring flange  66 , which is urged against the boss  102 , for normally biasing the latch bolt  46  outwardly to the extended position. A boss  103  on the spring flange  66  fits in a hole  104  (FIG. 1) in the cap side wall  34  for holding the flange  66  in position. 
     The latch bolt  46  is moveable in the openings in the front wall  42  of the case  32  and face plate  54  to the retracted position inside the case by operation of a latch operator comprising either an inside or outside knob or lever handle (not shown). In addition, the latch bolt  46  automatically retracts when the anti-friction latch  62  and the beveled face  70  of the bolt head  58  engage the door frame upon closing of the door. Initially, the anti-friction latch  62  engages the door frame pivoting the anti-friction latch on the pin  76  in the bolt head  58 . As the anti-friction latch  62  pivots, the lever  77  works against the front wall  42  of the case  32  driving the latch bolt  46  rearward into the case  32 . When the latch operator is released, or the door is in the door  20 B frame, the coil spring  64  returns the latch bolt  46  to the extended position. 
     According to the present invention, the latch bolt  46  is reversible for use with a door of the opposite hand. In order to reverse the latch bolt  46 , it is necessary to disconnect the latch bolt from the tail plate  68  and remove the latch bolt  46  from the lock assembly  10 . This is accomplished by first removing the face plate  54  and then manually pushing the latch bolt  46  into the case  32 . Next, the user manually depresses the spring clip  70 , which is accessible through the guide slot  96  in the cap side wall  34 . As seen in FIG. 18, by pressing on the spring clip  70   a  with a screw driver  106  or other tool, the spring clip  70   a  is pushed down against the force of the springs  98  thereby releasing the latch tail  60  from the spring clip  70   a  and tail plate  68   a . When the latch bolt  46  is free of the tail plate  68   a , the latch bolt  46  may be pulled through the opening in the front wall  42  of the case  32  (FIG.  1 ), rotated 180° , inserted into the case  32  and reattached to the tail plate  68   a , as described above. The slot  96  and hole  104  in the cap side wall  34  are used for viewing to guide the latch tail  60  through the flange  66  and boss  102  and into the opening  82   a  in the tail plate  68   a . Because the anti-friction latch  62  can pivot and move linearly with respect to the bolt head  58  on the pin  76 , at least to the extent of the groove  78  which has not been pressed in, the latch bolt  42  is easily manipulated during removal and reinsertion. 
     It is understood that other means for biasing the spring clip to the position where the spring clip partially blocks the tail plate opening are possible. For example, the spring clip embodiment shown in FIGS. 12 through 15 would work without the coil springs if the clip material was flexible enough to allow the clip to be pushed down to clear the tail plate opening. Thus, we do not intend ourselves to limit to the specific embodiments of the spring clip biasing means shown herein. 
     As noted above, the latch operator comprises means for retracting the latch bolt  46  including an inside or outside knob or lever handle. The retracting means comprises two independent, coaxial rollback hubs  108  which are mirror images of one another. The hubs  108  are rotatably mounted in opposed holes in the walls  34 ,  36  of the case  32  below the latch assembly  56  (FIG.  2 ). The hub  108  which fits in the case side wall  36  is shown in FIG.  19 . The hubs include a star-shaped aperture  110  for non-rotatable connection to inside and outside spindle drives (not shown) connected to the knobs or lever handles for rotating the hubs  108 . Each hub  108  has an upper rollback surface  112  which faces the rear wall  44  of the case  32 , a forwardly extending boss  114  and downwardly depending legs  116 . As seen in FIG. 2, the legs  116  engage an L-shaped bracket  118  attached to the bottom of the case  32  for preventing clockwise rotation (as seen in FIG. 2) of the hubs  108 . Two torsion springs  120  are mounted on a transverse pin  122  adjacent to the front of each hub  108 . An end of each spring  120  fits in a notch  124  (FIG. 18) in the hubs  108  for restoring the hubs to the neutral or home position when the knob or handle is released. It is understood that, as an alternative, the mortise lock assembly may have a single hub to which both the inside and outside spindle drives are connected. 
     The retracting means also includes a retractor shoe  126  and a hub lever  128 . The shoe  126  is mounted for linear movement within the case  32  and has a forwardly facing bearing surface  130  for engaging the rollback surfaces  112  of the hubs  108  and a rearwardly facing bearing surface  132 . In this arrangement, the shoe  126  moves linearly rearward in response to counterclockwise rotation, as seen in FIGS. 2 and 24, of either of the rollback hubs  108 . A torsion spring  134  acts between the rear wall  44  and the retractor shoe  126  to urge the shoe toward engagement with the roll back hubs  108 . 
     The hub lever  128  comprises a generally flat, L-shaped lever disposed within the case  32  against the case side wall  36 . The hub lever  128  is pivotally supported on a pin  129  at its lower forward leg  136  below and in front of the hubs  108 . The upper leg  138  of the hub lever  128  extends upwardly to the rear of the hubs  108  and has a first laterally projecting tab  139  adjacent the rearward bearing surface  132  of the shoe  126 . A portion of the upper leg of  138  of the hub lever  128  is adjacent to the retraction surface  92  of the tail plate  68 . A torsion spring  143  acts between the rear wall  44  and the first tab  139  to bias the hub lever  128  into operative engagement with the retractor shoe  126 . 
     As seen in FIG. 24, the latch bolt  46  is retracted by rotating one of the rollback hubs  108 . Rotation of the rollback hub  108  causes the rollback surface  112  to engage the bearing surface  130  of the retractor shoe  126  moving the shoe linearly rearward. The shoe&#39;s rearward bearing surface  132  engages the first hub lever tab  139  to pivot the hub lever  128  in a counterclockwise direction as seen in FIG.  24 . The portion of the upper leg of  138  of the hub lever  128  acts against the retraction surface  92  of the tail plate  68  to move the tail plate and connected latch bolt  46  to the retracted position. 
     The present invention is also concerned with the locking mechanism (FIG. 2) for selectively securing one or both of the retractor hubs  108  from rotation. The locking mechanism comprises an elongated slide plate  142  and the toggle  52 . Referring to FIG. 20, the rearward end  144  of the slide plate  142  has two slots  146  for receiving a portion of the hubs  108  adjacent the respective bosses  114 . Both ends  144 ,  145  of the slide plate  142  have opposed lateral tabs  148 ,  149  which ride in corresponding slots  150  in the side walls  34 ,  36  of the case for guiding and supporting linear movement of the slide plate  142  relative to the hubs  108 . Each rear plate tab  148  has a transverse hole  152  which opens into the slots  146 . The holes  152  are preferably threaded for receiving a blocking screw  154 . The screw  154  is sufficiently long so that when the screw  154  is threaded into the tab  148  the screw extends into the slot  146 . 
     The slide plate  142  is cooperatively linked to the toggle  52  which is accessible through the opening in the front wall  42  and face plate  54 . Manipulation of the toggle  52  linearly reciprocates the slide plate  142  relative to the hubs  108  between an unlocked position (FIGS. 20 and 21) and a locked position (FIGS.  22  and  23 ). The locking mechanism is moved to the locked position by depressing the upper end of the toggle  52  thereby moving the slide plate  142  so that the rearward end  144  is positioned adjacent the hubs  108 . When the locking mechanism is in the locked position, the screw  154  is in the path of the boss  114  on one of the retractor hubs  108  thereby preventing rotation of the hub  108 . As noted above, the hub  108  preferably affected by the locking mechanism is on the outside of the door. Therefore, the screw  154  is preferably placed in the rear slide plate tab  148  corresponding to the outside hub  108  so as to prevent rotation of the outside hub and retraction of the latch bolt  46  from the outside when the lock is locked. The inside hub  108  can still turn to permit retraction of the latch bolt  46  since the hub boss  114  passes freely through the open slot  146  in the slide plate  142 . If the mortise lock is reversed for installation in a door of the opposite hand, the screw  154  is simply moved to the opposite rear tab  148 . Of course, in mortise locks using a single hub, the screw prevents rotation of both operators. Similarly, in the illustrated embodiment, a second stop screw can be used with the same effect. The locking mechanism is unlocked by depressing the lower end of the toggle  52  thereby moving the slide toward the front wall  42  of the case  32  and away from the hubs  108  (FIGS.  20  and  21 ). 
     Preferably, the mortise lock assembly includes the deadbolt  48  and the auxiliary bolt  50 . The deadbolt  48  is selectively moved between an extended position and retracted position by operation of a key cylinder or thumb turn (not shown) in a conventional manner. The cylinder and thumb turn rotate a deadbolt lever  156  which engages the sides of a slot  158  in the rearward end  160  of the deadbolt  48  for extending or retracting the deadbolt. The upper leg  138  of the hub lever  128  has a second laterally projecting tab  162  for engaging the deadbolt lever  156  when the deadbolt  48  is in the extended position for retracting the deadbolt along with the latch bolt  46  in response to rotation of either hub  108  (FIG.  24 ). 
     A rotating stop lever  164  is provided for functionally connecting the deadbolt lever  156  and locking mechanism (FIG.  2 ). The lower end  166  of the stop lever  164  is positioned in a slot  168  in the slide plate  142  and the upper end  170  is arranged in the path of the deadbolt lever  156 . When the deadbolt  48  is moved from the retracted position to the extended position the deadbolt lever  156  engages the upper end portion  170  of the stop lever  164  to rotate the lever in a clockwise direction (as seen in FIG. 2) and move the locking mechanism, including the side plate  142  and toggle  52 , to the locked position. Thus, the locking mechanism automatically moves to the locked position when the deadbolt  48  is moved to the extended position. The locking mechanism remains in this position, even when the deadbolt  48  is retracted by operation of one of the hubs  108  (FIG.  24 ), until the toggle  52  is actuated to move the slide plate  142  away-from the hubs  108 . When the deadbolt  48  is moved from the retracted position to the extended position the deadbolt lever  156  engages the upper end portion  170  of the stop lever  164  to rotate the lever in a clockwise direction (as seen in FIG. 2) and move the locking mechanism, including the side plate  142  and toggle  52 , to the locked position. Thus, the locking mechanism automatically moves to the locked position when the deadbolt  48  is moved to the extended position. The locking mechanism remains in this position, even when the deadbolt  48  is retracted by operation of one of the hubs  108  (FIG.  24 ), until the toggle  52  is actuated to move the slide plate  142  away from the hubs  108 . 
     Means for deadlocking the latch bolt  46  in the extended position is also provided (FIG.  2 ). The deadlocking means  172  comprises the auxiliary bolt  50 , a deadlocking lever  174  and an auxiliary latch lever  176 . When the door is closed, the auxiliary bolt  50  is depressed by the door frame which allows the deadlocking lever  174  to pivot in a counterclockwise direction under the biasing force of a compression spring  178  to a position where the deadlocking lever prevents manual depression of the latch bolt  46 . The deadbolt  48  also has a shoulder  180  which is adjacent the rear surface of the bolt head  58  when the deadbolt is extended also for preventing depression of the latch bolt  46 . 
     The previously described embodiments of the present invention have many advantages, including the provision of a reversible mortise lock which cannot be tampered with after installation. Moreover, because the latch bolt reversal relies on removal of the entire latch bolt from the case rather than partial removal, the bolt head can be as long as is practical thereby providing greater strength and security for the lock. The mortise lock incorporating the new latch assembly and locking mechanism is easily modified from outside of the lock casing with a screw driver for use with either a right-hand door or a left-hand door. In either arrangement, the latch operators are operable to open the door when the lock is unlocked. When the lock is locked, rotation of the outside latch operator is prevented, whereas the inside latch operator is still operable to open the door. With the addition of another blocking screw, the inside latch operator can also be locked against rotation. 
     Although the present invention has been shown and described in considerable detail with respect to only a few exemplary embodiments thereof, it should be understood by those skilled in the art that we do not intend to limit the invention to the embodiments since various modifications, omissions and additions may be made to the disclosed embodiments without materially departing from the novel teachings and advantages of the invention, particularly in light of the foregoing teachings. For example, a single rollback hub can replace the two, independent hubs so that the locking mechanism affects both the inside and outside latch operators. Accordingly, we intend to cover all such modifications, omission, additions and equivalents as may be included within the spirit and scope of the invention as defined by the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures.

Technology Classification (CPC): 4