Lockable door latch

Claim 1

A DOOR LATCH INCLUDING, A CASING ADAPTED TO BE MOUNTED IN A DOOR, A KEEPER FORMING STRIKER PLATE ADAPTED FOR FIXING IN A DOOR FRAME MEMBER IN WHICH THE SWINGING EDGE OF THE DOOR IS RECEIVED, A LATCH BOLT SLIDABLY MOVABLE IN ITS LONGITUDINAL DIRECTION AND SWINGABLE IN A TRANSVERSE DIRECTION BETWEEN STOPS WITHIN SAID CASING AND CONSISTING OF A CATCH RIGIDLY ASSOCIATED WITH AND PROJECTING FROM ONE END OF A MOUNTING MEMBER, A PAIR OF CONVEX FACES ARRANGED CONVERGINGLY ON OPPOSITE SIDES OF THE CATCH OF WHICH THE WIDEST REGION IS SLIDABLY AND ROLLINGLY ENGAGEABLE ON A PAIR OF INWARDLY DIRECTED AND PARALLEL SPACED FACE REGIONS PRESENTED BY OPPOSITE SIDES OF THE CASING, SPRING MEANS BIASSING THE LATCH BOLT IN ONE DIRECTION WITH THE CATCH EXTENDING THROUGH ONE END OF THE CASING STOP MEANS ON THE LATCH BOLT LIMITING THE EXTENT OF PROJECTION OF THE CATCH FROM THE CASING, A MANUALLY OPERATED BAR AXIALLY SLIDABLY AND NON-ROTATABLY LOCATED TRANSVERSELY THROUGH THE CASING AND THE DOOR AND HAVING KNOB-LIKE MEMBERS ON THE ENDS, ESCTUCHEON PLATES FOR FIXING ONTO THE DOOR FACES AND PRESENTING MEANS FOR SLIDABLE AND NONROTATABLE LOCATION OF THE BAR, STOP MEANS LIMITING THE SLIDING MOVEMENT OF THE BAR TO TWO ALTERNATIVE POSITIONS, SPRING MEANS ENGAGING AN ESCUTCHEON PLATE AND A PROJECTION ON THE BAR FOR BIASSING THE BAR AND ASSOCIATED PARTS TO ONE OF TWO ALTERNATIVE POSITIONS OF THE BAR, A PASSAGE ACROSS A PORTION OF THE BAR, A FORMATION ON THE MOUNTING ANY POSITION OF THE BAR, A FORMATION ON THE MOUNTING MEMBER SLIDABLY ENGAGEABLE ALONG THE PASSGE WHEN IN ALIGNMENT THEREWITH FOR LONGITUDINAL CATCH RETRACTING MOVEMENT OF THE LATCH BOLT, A PAIR OF CONVERGINGLY ARRANGED FACES ON OPPOSITE SIDES OF THE STRIKER PLATE ADAPTED FOR SWINGING THE LATCH BOLT IN TRANSVERSE DIRECTIONS WHEN THE CATCH IS THRUST ONTO THE STRIKER PLATE AND FOR EFFECTING CATCH RETRACTION BY A WEDGING ACTION ON OPENING AND CLOS-/ ING OF THE DOOR, AND SHOULDER MEANS ON THE MOUNTING MEMBER ENGAGEABLE ACROSS THE BAR WHEN THE MOUNTING MEMBER IS NOT IN ALIGNMENT WITH THE PASSAGE FOR BLOCKING THE LONGITUDINAL MOVEMENT OF THE LATCH BOLT, SAID ALIGNMENT BEING ATTAINED, ON OPENING OF THE DOOR, BY DISPLACING THE BAR TO AN ALTERNATIVE POSITION AGAINST THE ACTION OF ITS BIASSING SPRING MEANS WHILE THE LATCH BOLT IS SWUNG IN ONE DIRECTION BY TRANSVERSELY DIRECTED PRESSURE BETWEEN THE CATCH AND ONE OBLIQUE FACE OF THE STRIKER PLATE, WHEREAS ON CLOSING THE DOOR THE MOUNTING MEMBER IS ALIGNED WITH THE PASSAGE WHEN THE LATTER IS IN THE POSITION RESILIENTLY MAINTAINED BY THE BIASSING SPRING MEANS OF THE BAR, BY SWINGING OF THE LATCH BOLT IN THE OPPOSITE DIRECTION WHEN STRIKING THE OTHER SIDE OF THE STRIKER PLATE.