Mortise lock having secured stops

摘要

A mortise lock has two relatively-rotatable knob or lever-controlled spindles for independent operation from opposite sides of a door of a resiliently extending latchbolt and positively extending deadbolt, and stop buttons accessible at an edge of the door for blocking operation of the bolts from one side in a higher security state. The lock also has a safeguard effective to block a change in the state of the stop buttons to a lower-security state unless the deadbolt is first positioned at a pre-determined point between full retraction and full extension using a key. The lock is a double cylinder lock such that operation of the deadbolt from either side requires a key. The lock may be mastered such that operation of the deadbolt requires a master key while operation of the latch requires a common key. Therefore the ability to change the stop buttons is restricted.