Glossary Terms - T

Tail Piece

The connecting link attached to the end of a rim cylinder which transmits the rotary motion of the key through the door, into the locking mechanism.


A pattern or layout schedule of the exact positions and sizes that provides a door and/or frame manufacturer the necessary information with which to prepare for finish hardware, door lites and louvers.


A strip fastened to the floor beneath a door. It serves as a stop, prevents heat loss, and provides a strike location for latching the bottom rod of a vertical rod exit device.

Throw (of a Deadbolt or Latchbolt)

The measurement from the tip of the bolt to the latch faceplate when the bolt is extended to its maximum projection.

Throw-Off Latchbolt

A cylindrical lock latchbolt which automatically unlocks the outside trim as the door closes, to prevent accidental lockout.


A small pivoted lever type actuator projecting outward from the door face which operates the exit device or lock.


Device mounted on the inside of a door to throw the deadbolt.


Mechanism designed to allow the user to lock or unlock the outside trim without a key.


Converts one AC (Alternating current) voltage to another AC voltage.

Transient Suppression

Circuitry inside a solenoid or electro magnet to prevent large electrical spikes being generated back into power supplies, card readers, and other equipment when the device is turned off. Transients can damage or destroy these items.

Transom Frame

A door frame prepared for a panel or glazing material above the door opening that has a horizontal member also called a transom bar which separates the transom opening from the door. Can also be provided without a transom bar when a matching panel above the door is desired.


A knob, lever, pull or thumbpiece used on the outside of an exit device door to control access to an area.

Trim Locking

Trim Locking – Refers to the control of the lockable side of the door (usually the outside).

Tubular Lock

A type of bored lock or latch.

Turn Piece

A small lever or “T” shaped lock trim with a spindle attached which is used to operate the deadbolt on a mortise lock.

Two Step Progression

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