Common Lock Functions

A lockset’s function determines what steps must be taken to secure, unlock and open a door secured by that lockset.  This may necessitate the use of a key to retract a latch each time one wishes to gain access, or it may only necessitate the rotation of a lever or knob.  This article will cover the most common lockset functions found on cylindrical lever and knob locksets on the market today.

            Converting a lockset’s function requires replacing internal parts, which can be expensive.  Some manufacturers may not have replacement parts readily available so replacement of the entire lockset can sometimes actually be more affordable.  Therefore, it is important that you select the proper lockset when you develop your initial security plan.  For this reason, I will also be providing examples of where you will most likely encounter these locksets.  Below I have compiled a list of the five most common types of cylindrical lock you will likely encounter.  Next to the name of each function is the corresponding code developed by the American National Standards Institute (ANSI):

Passage Latch (F75):  Rotation of either the inside or outside handle retracts the latch bolt.  No key is required.  This type of a lockset is only used to keep a door closed and not intended in any way to secure an area.  It is generally used in conjunction with a latch bolt that does not deadlock, as loiding would not be a concern

Privacy Latch (F76):  In the center of the inside handle is a button.  When pushed in, the outside handle becomes locked.  The outside handle may be unlocked either by rotating the inside handle or by inserting a small screwdriver or emergency key universal to that lock’s model (e.g. all Schlage AL40S levers can be opened using the 35-250 privacy key).  This lock is commonly found on restrooms and areas where one is protecting themselves against someone inadvertently walking in.  It should not be used to secure property against theft.  Closing the door will typically cause the inside button to pop out, preventing a lockout.  This type of lock is commonly sold with a latch bolt that does not deadlock

Classroom Lock (F84):  Rotation of the inside handle will always retract the latch bolt, allowing for egress at all times.  On the outside handle is a keyed cylinder.  Rotation of the key 360 degrees clockwise will unlock the outside handle and allow for the removal of the key.  Rotation of the key 360 degrees counterclockwise will lock the outside handle and also allow for the removal of the key.  This type of lock is sold with a deadlatch to keep the lock from being loided.  There is no button or thumb turn on the inside handle.  Therefore, if the door is unlocked one must have the key in order to secure it.  This lock is commonly found in schools and universities where students may try to lock their instructor out of the classroom, hence the name for this function

Storeroom Lock (F86):  Rotation of the inside handle will always retract the latch bolt, allowing for egress at all times.  On the outside handle is a keyed cylinder.  Rotating the key will retract the latch bolt temporarily, allowing the door to be pulled open.  The outside handle cannot be used to retract the latch bolt at any time and only exists to pull the door open or closed.  This type of lock is sold with a deadlatch to keep the lock from being loided.  This lock is commonly found paired with an electric strike on access controlled doors.  Users would gain entry through the use of an access credential, such as a keycard, and then the door locks behind them after they enter.  The keyed cylinder mostly acts as an emergency override in the event of panel or strike failure.  This type of lockset alleviates any concern a client may have about their door being left unlocked

Entrance lock, inside view.  Notice the button/thumbturn

Entrance Lock (F109):  On the inside handle is a button/thumbturn.  Pushing the button in will lock the outside handle.  On the outside handle is a keyed cylinder.  When the lock is in this condition, rotating either the key or inside handle will retract the latch bolt and cause the inside button to pop out, unlocking the outside handle.  If the button thumbturn is pushed in, then rotated 90 degrees clockwise, rotating the key or inside handle will retract the latch bolt, but it will not unlock the outside handle.  To unlock the outside handle, turn the thumbturn 90 degrees counterclockwise, then rotate the inside handle.  This type of lock is sold with a deadlatch to keep the lock from being loided.  You will find this lock on individual working or living areas such as offices or apartments where there is little concern about someone maliciously locking others out and where a user may wish to leave their area unlocked temporarily

Not all locks on the market conform to the ANSI standards, but many do.  Knowing what the common lock functions are will allow you to be better prepared as a consumer and know what options you may have.