Chapter 9 Set 05: Door Locks and Security Devices

What is the purpose of a door latch?

To hold the door closed using a spring-loaded bar that enters a receiver in the frame.

Does every door latch include a lock?

No; a latch may or may not incorporate a lock.

What four basic lock categories are described in the chapter?

Mortise, cylindrical, rim, and high-security locks.

Where is a mortise lock installed?

In a cavity cut into the edge of the door.

How do older and newer mortise assemblies differ?

Older assemblies may have only a latch; newer ones commonly have a latch and key-operated deadbolt.

How does a mortise lock secure the door?

Its bolt extends into a receiver in the jamb.

Where are mortise locks commonly found?

Exterior wood and metal doors of residences, commercial buildings, and industrial buildings.

What is the most common residential lockset type identified in the chapter?

The cylindrical lock.

How is a cylindrical lock installed?

Through two holes at right angles: one through the door face and one through the door edge.

What are the two cylindrical-lock types described?

Key-in-knob locks and tubular deadbolt locks.

Where are the operating features on a key-in-knob lock?

A keyway in the exterior knob and a keyway or locking button in the interior knob.

What kinds of interior buttons may key-in-knob locks have?

Push buttons or push-and-turn buttons.

How does an unlocked key-in-knob latch operate?

Turning either knob retracts the spring-loaded, beveled latch bolt.

How long is a typical key-in-knob latch bolt in the chapter?

Usually no more than 3/4 inch.

What makes key-in-knob locks relatively easy to pry open?

The short latch can clear the strike when the door and frame are spread apart.

Where is a tubular deadbolt usually mounted?

Above the doorknob.

How does a single-cylinder deadbolt operate?

An exterior keyway and an interior thumb turn.

How does a double-cylinder deadbolt operate?

It has a keyway on both sides of the door.

What approach does the chapter identify as easiest for a modern deadbolt in a wooden residential door?

Forcing the door itself.

What is a rim lock?

A supplemental lock mounted on the interior surface of a door.

Where may rim locks be found?

Houses, apartments, and some commercial buildings.

Why can a rim lock be difficult to identify from outside?

Some rim locks have no exterior keyway.

What are the three rim-lock types described?

Night latch, deadbolt, and vertical deadbolt.

How does a night-latch rim lock work?

Its spring-loaded, beveled bolt allows the door to lock when closed.

How does a rim deadbolt differ from a night latch?

Its rectangular bolt must be retracted before the door can close, then extended into the receiver.

How does a vertical rim deadbolt resist spreading?

Its bolt moves vertically into a receiver rather than across the door-to-jamb gap.

What is a multiple-bolt or multilock system?

A high-security lock that extends bolts about 1 inch into two or more points; some secure all four door edges.

How may electronic keyless locks be operated?

By keypad, card reader, or fingerprint reader; some also have a keyway.

What is the usual power source and purpose of the electronic keyless locks described?

Batteries; they provide continuous security and controlled access.

How does an electromagnetic lock hold a door closed?

An energized electromagnet on the frame attracts an armature plate on the door.

What releases the electromagnetic lock described in the chapter?

Shutting off its electrical power.

What is a padlock?

A portable or detachable lock, operated by a key or combination.

How does a standard padlock differ from a heavy-duty padlock?

A standard shackle is 1/4 inch or less and not case-hardened; a heavy-duty shackle is over 1/4 inch and case-hardened.

What is heel-and-toe locking in a padlock?

Both ends of the shackle lock into the body.

Why must both sides of a heel-and-toe padlock shackle be cut?

The shackle will not pivot when only one side is cut.

What is a drop bar?

A wood or metal bar resting in door-mounted brackets and extending across the doorframe.

What is a door chain?

A supplemental residential device that allows limited opening while restricting entry.

What is a door limiter?

A device with a frame-mounted shaft and knob and a hinged U-shaped shackle on the door that limits opening.

What is a surface bolt?

A manually operated supplemental bolt mounted on a door or some windows.

What is an internal-mounted or flush bolt?

A bolt in the edge of one leaf of a double door, allowing that leaf to remain secured while the other operates.

What difficulty do supplemental locking devices create during size-up?

Their presence and engagement may not be visible from outside.