Abstract: The locking mechanism includes a lever handle having a fluted passageway for fitting to an adjacent end of a latch spindle. The passageway allows the handle to turn relatively to the latch spindle in opposite directions through a predetermined angle of movement. At one end of this angle of movement, the handle is in a horizontal rest position and is engageable with the latch spindle for turning the spindle in a direction to withdraw the latch bolt from its latching position, and at the opposite end, the handle is in a lifted locking position and is engageable with the spindle to prohibit turning thereof in the opening direction. At the locking position, a locking member slidably mounted in the handle and controlled by a trigger part, extending behind the lever part of the handle is engageable in one of a pair of retainer holes depending on the handing of the lever handle.

Abstract: A locking device (1) is provided for a door latch in which a latch bar of the door latch mechanism is turnable to retract a latch bolt of the latch mechanism. A locking means is adapted to be actuated in response to turning of a door handle (3) for the latch mechanism in anti-clockwise direction so as to lock the latch bolt in its extended latching position. It is released by turning the handle in the clockwise direction.