Glossary Terms - S


The ability to lock or unlock doors automatically at pre-determined times, or to restrict cardholder access to specific time periods.

Seated (Amps)

The current that a device consumes during normal operation. See in-rush.

Secondary Arm

That part of a double lever arm that connects to the shoe of the arm.

Sectional Trim

Lock trim with two sections; a lever or knob with a rose which is not joined by an external plate to the cylinder above.

Secure Position

Monitoring signal switch shown in the secure position in drawings and schematics. This not only will allow the installer to determine the correct terminals to connect, but will also allow Engineers to follow the diagrams for an understanding of operation.

Secure Side

Refers to the area or side of an opening that is locked; requires a key, card, etc. to enter.

Self-Latching Flush Bolt

A mortise bolt installed near the top and bottom of the inactive leaf of a pair of doors which automatically projects into the header and sill when the active leaf is closed but must be manually released from the header and sill when the active leaf is open.


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Sex Nuts and Bolts (SNBs)

Through bolts required for all non-steel reinforced fire doors, and recommended for non-reinforced wood and mineral core doors.

Shear Line

The line in a cylinder at which the tumblers will position themselves when the correct key is inserted allowing the cylinder plug to rotate within the shell.

Shim Kit

Pieces of metal that permit mounting of an exit device on a door that has a surface projecting vision light (glass bead) moulding.


The part of the secondary arm which attaches to the frame face, soffit or door.

Side Bar

(BLOCKING BAR) – A spring loaded bar located within the cylinder shell extending parallel to the keyway that when activated by a key with the proper machining, allows for a shear line between the cylinder shell and plug. When the wrong blank is inserted into the cylinder the blocking bar inhibits the rotation of the cylinder plug even if the combination of the key biting is correct to operate the lock.

Sidelight Frame

A door frame prepared for the application of glazing material alongside the door opening.

Signaling Switch

Used to actuate monitoring horns or lights in an alarm circuit.

Silent Operation

Use of components which eliminates the “buzz” normally associated with AC operation. See Rectifier.

Simplex Key Section

A single independent key section which cannot be expanded into a multiple key section system.

Single Acting Door

A door prepared for a spring hinge or pivot type hardware and is only capable of swinging in one direction.

Single Step Progression

A progression using a one increment difference between bittings of a given position when pinning cylinders.

Sized Closer

A closer whose spring design allows for a fixed spring power size 1 through 6.

Smart Card

High frequency, 13.56 MHz contactless / contact cards (current standard) that provide a higher level of security than proximity cards by using a more secure method of authentication.

Smoke Detector

A device that detects visible or invisible particles of combustion.


The portion of a frame located between the stops on a double rabbeted frame and between the stop and the larger face on a single rabbeted frame. It is the only part of a door frame that varies according to jamb depth.


An electromechanical device that operates the lock bolt when electricity is applied, a mechanical motion is obtained that moves the bolt.


The bar or tube that connects the lever or knob on one side of the door through and actuating the hub(s) of the lock or latch to the trim on the other side of the door.

Split Astragal

An astragal that is split through the middle on a pair of doors, allowing both doors to operate independently.

Spring Hinge

A closing device in the form of a hinge with a built-in spring used to hang and close the door.

Spring Power

A measurement for closing force or the ability to overcome draft, air pressure, weight or other resistance to door closing.

Star Punch

An eight-sided socket hole in the closer arm, permitting spindle pre-loading. Provides full functioning of backcheck and delayed action valves, and additional closing force, on parallel arm mountings.

Stile and Rail Door

A method of building doors that precedes the modern Full-Flush door type. In this door type the rails and stiles are tubular in shape with the corners mitered and welded to form the doors perimeter.


A metal plate that is prepared to receive a bolt or latch when the bolt or latch is projected and the door is in a closed position. Sometimes called the Keeper in older terminology.

Surety Key Sections

(MULTIPLEX KEY SYSTEM) – Used to expand a master key system by repeating the same or similar key bittings on different key sections. Keys of one section will not enter locks with a different section, yet there is a Master Key section which is milled so that it will enter some or all of the different keyways in the system.


A supplemental word used in conjunction with the hand of a door.


Device that makes or breaks connections in an electrical circuit.