SIMPLEX 900 Series Auxiliary Locks

The SIMPLEX® 900 Series auxiliary pushbutton locks are designed for easy installation. These rugged, weather-resistant locksets can be mounted above existing locksets or used alone. The standard model is equipped with a deadbolt. A spring latch model with automatic relock and a dead latch trigger is also available.

Model 929 complies with paragraph 36a of the Industrial Security Manual published by the U.S. Department of Defense (DOD), and is approved as a substitute for expensive guard forces in the protection of Closed and Restricted Areas in DOD contractor’s plants.


  • Rugged weather-resistant all-metal construction
  • Fully mechanical – not affected by power failures
  • Clutch-protected turn knob cannot be forced
  • No keyway to be picked
  • Large easy-to-depress pushbuttons
  • One-hand operation
  • Deadbolt models available with 2 3/8″ (60 mm) and 2 3/4″ (70 mm) backsets
  • Exterior trim plate covers 2 1/8″ (54 mm) bores
  • 1″ (25 mm) deadbolt models have a saw resistant hardened steel insert
  • Mounts above existing lockset or can be used alone
  • For interior or exterior use
Operating Instructions
  • Turn control knob LEFT (counter-clockwise) to activate buttons. (control knob is located on outside below buttons and should read “SIMPLEX”).
  • Press and release the correct buttons in the proper order.
  • Turn the control knob to the RIGHT (clockwise) to open.
  • To lock deadbolt models (DL), turn control knob back to LEFT (counter-clockwise). Latch models (NL) lock automatically.
Changing the Combination


  • Door to be in open position
  • Tools – Allen (hex) Key supplied
  • Choose a new combination and write it down. You can use one button or all five for a combination, but each button can only be used once. You can use two or more buttons simultaneously.


WARNING: Once procedure has been started, it must be completed, correctly, or “Lost Combination” may occur. Finding a lost combination requires complete disassembly of lock and combination chamber. This should only be done by an authorized professional service company.

  • With door in open position, lock the Simplex lock. (latch or deadbolt should be in extended position)
  • Remove the Allen screw from the interior lock housing. (depending on the hand of the lock, this screw will be found either on the top or bottom of inner housing)
  • Fully turn the outside control knob ONCE to the LEFT.
  • Enter the existing combination (factory combination for newly installed locks is; press 2 and 4 simultaneously, release, then press 3) you should feel a click as each button is pressed. DO NOT TURN CONTROL KNOB
  • Insert the Allen wrench into hole from where screw was removed, and depress the change button. Gently push to the stop position (a slight click should be felt).
  • Remove wrench from hole.
  • Fully turn outside control knob ONLY ONCE to the LEFT all the way to stop position. Then release knob. This clears existing combination.
  • Enter you new combination, press buttons carefully – a slight click should be felt as each button is depressed. (see requirements above for picking new combination)
  • Fully turn control knob all the way to the RIGHT, to stop position. Latch or Deadbolt (depending on model) should retract. Then release knob.
  • HOLDING DOOR OPEN, Test lock SEVERAL TIMES. Enter new combination and turn control knob to Right – latch or deadbolt should retract. To lock deadbolt models turn control knob back to left (Latch models lock automatically when control knob is released). DO NOT CLOSE DOOR IF UNIT DOES NOT SEEM TO BE WORKING PROPERLY
  • If lock opens every time control knob is turned right WITHOUT entering any buttons, re-start procedure from STEP 5.
  • Replace Allen screw in lock housing