Simplex 900 Series Mechanical Pushbutton Lockset

We will install, change the combination, clear a lost combination, and troubleshoot some common problems on this workhorse of a pushbutton lock.


Pushbutton access control was one of the first alternatives to mechanical key control for entry doors. The ability to unlock a lock by pressing numbered buttons eliminated problems associated with the issuance, control, and collection of keys. The Simplex® 900 Series was one of the first mechanical pushbutton locks.

The Simplex 900 Series mechanical pushbutton locks are designed for light commercial and residential applications. They are equipped with a friction clutch that disconnects the outside thumbturn from the lock housing when excessive force is exerted. These field-reversible, rim type auxiliary locks are available having a spring latch with deadlocking trigger or one-inch throw deadbolt. The combination can be changed without having to remove the lock from the door or disassemble the lock.

The surface-mounted Simplex 900 Series mechanical pushbutton lock has five buttons through which the combination is entered. The combination can be any variation from one up to using all five buttons in sequence. Simplex was developed with the capability of pressing either one button or multiple buttons simultaneously. For example, the default combination is pressing "2" and "4" simultaneously, and then the "3".

There are approximately 500 combinations when each button is fully depressed and additional 500 theoretical combinations when buttons are only partially depressed.

Note: Before entering the combination, always turn the outside operating knob counterclockwise until it stops. This clears the combination chamber.

Once the combination has been entered in the correct sequence, turning the outside operating knob clockwise retracts the spring latch or deadbolt. The deadlocking spring latch models automatically relock when the door closes. The deadbolt models manually relock. Egress is attained using the interior thumbturn, which is free at all times.

For this article, we will install, change the combination, clear a lost combination, and troubleshoot some common problems. We will be working with Simplex Part # 9040000-26D-41, a deadbolt lock with no options.

Remember: For retrofit installations, the exterior faceplate can cover existing 2-1/8" diameter cross bore openings.

The Simplex 900 Series locks are surface-mounted. Follow these steps to install the lock.

Step 1. Determine the location for the lock. Kaba Access Control recommends the Simplex 900 Series be 8 to 10 inches above the existing lockset.

Step 2. Use the included template to locate the 5 cross bore openings. An additional hole is required if the lock has key override. The backset is determined by the handing of the door.

Step 3. Drill the two cross bore openings. When drilling a cross bore hole in a wood or hollow metal door, do not drill completely through the door. Stop drilling once the pilot bit or drill tip has exited the obverse side of the door. Remove the drill and begin to drill from the other side. This will ensure a more accurate cross bore opening and will stop the bit from causing damage to the face of a wood door.

Step 4. Drill the three mounting screw holes approximately 1/2"deep in a wood door, or through the skin of a hollow metal door. Remove any burrs prior to installation.

Step 5. From the rear of the door, slide the 900 Series lock assembly through the cross bore openings. Make certain the lock is flush against the face of the door. For doors that do not have an even mounting surface, use an adjustable riser plate, part number 74468.

Step 6. Install the three 1-1/2" long Phillips head mounting screws.

Step 7. On the front side of the door, place the holding bracket onto the keypad assembly with the slotted legs engaging the aligning pin. Make sure the bracket does not cover the thumbturn opening.

Step 8. Attach the holding bracket onto the door using the two 1/2" Phillips head screws.

Step 9. Remove the three screws securing the lock assembly to the door. Remove the lock assembly.

This content continues onto the next page...

We Recommend