Securitron UNL-24 UNLATCH - Manual (Page 4)

PN# 500-18300
Page 4 Rev. D, 08/11
If the amount of slack or rattling is less than 1/16-1/8”, you have a “tight” door and the
ability of the door to close and latch reliably is in question. To adjust for this, first check to see if
the stop has “silencers” on it. These are cylindrical rubber bumpers which quiet the noise of a
closing door but also have the effect of making the door close earlier. Remove the silencers
(they pull out) and this will add slack to the closed position of the door. Be sure to check the
entire length of the door for the silencers. If the door has no silencers and is still tight in
latching, a locksmith should be engaged to readjust the door so that it closes properly or the
installation will not be reliable.
Note that Figure 4 illustrates the points made in this Section.
FIG. 4: FINAL ADJUSTMENT OF DOOR CLOSING TOLERANCE
VIEW OF UNLATCH LOOKING STRAIGHT INTO DOOR FRAME
STOP
SILENCER TWO SPACERS
OPEN
CAVITY
DEADLATCH
PLUNGER
SPRINGLATCH
PLUNGER
3. OPERATION
While you can make a successful installation without knowing how the UnLatch functions, it’s
best if you understand its operation in the event you run into any difficulties or questions. The
operation of the UnLatch is, of course, intimately connected with the way latches and specifically
deadlatches work on a door so we’ll cover this first.
An ordinary latch is called a springlatch and it’s used on low security interior doors. One of the
reasons that this latch’s security is low is that an intruder can retract the latch and open the
door from the outside by slipping something flexible like a credit card in between the door and
frame. To forestall this, the deadlatch was created. The deadlatch includes a deadlatch pin
which is depressed against the flat part of the strike when the door is closed. When the
deadlatch pin is depressed, the latch cannot be pushed in (by a credit card for instance); it is
mechanically blocked. Deadlatches therefore offer a considerably higher level of security and
this level of security is usually desired on doors subject to electric control from the installation of
the UnLatch or other electric strike. The UnLatch makes full use of the deadlatch pin and
preserves its security function. Springlatches however can also be employed with the UnLatch.
Note that the UnLatch has two rectangular plungers which move under the control of a motor.
We call these the springlatch plunger and deadlatch plunger. When the door is in the
closed and secure position, the springlatch pushes in the springlatch plunger and the deadlatch
pin rests on the deadlatch plunger which pushes in the deadlatch pin. This maintains the latch
in the secure position and makes full use of the deadlatching function.
When the UnLatch operates (the trigger wire connects to the +V wire), the deadlatch plunger
retracts into the body of the UnLatch which allows the deadlatch pin to move out. Then both
plungers simultaneously push the latch and deadlatch pin back into the latch body and the door
may be opened from the outside. This operation takes about 1/3 of a second. When the trigger
wire is removed from the +V wire, the UnLatch will return to its initial condition: the springlatch
plunger will retract into the UnLatch body which allows the latch to resecure the door and the
deadlatch plunger will push out depressing the deadlatch pin and freezing the latch for best
security.