Servicing Kaba Simplex Pushbutton Locks

Feb. 26, 2019
In case of a forgotten combination, 66 potential combinations can be tried as a way of possibly opening a Simplex lock quickly.

One of the most popular locks sold during the last 40 years has been the Kaba Simplex mechanical pushbutton lock. Simplex locks began the revolution towards keyless single-door access control systems. Once sold under the Ilco Unican name, Kaba now owns the company. The Kaba Simplex mechanical push button lock product line has been extended to include deadbolt locks, dead latch locks, cabinet locks, control for electronic security, and specialty products for operating aluminum door or exit device applications.

Product categories include the 1000 series cylindrical locksets, the 8100 series mortise locksets, 2015 series used for outer trim on exit devices, 3000 series for narrow stile aluminum door locks, 6200 series auxiliary deadbolt locks, 7100 auxiliary latch lock, 900 series deadbolt or spring latch locks, 9600 series deadbolt or deadlatch locks, locks for cabinets and File Guard for 2-5 drawer file cabinets.

All of the locks mentioned above use the same basic locking system called a chamber. The chamber contains five wheels and each wheel contains a slot. If the correct combination of numbers is pressed, the slots of each wheel are aligned in the same plane. Depending on the lock design, when a thumbturn, lever or knob is then turned, a secondary lock part can enter the aligned slots and the lock can be unlocked.

Some restrictions must be observed. One rule is that each button can only be used once in a combination. Once a button is pressed, it is disconnected from any further use during the unlocking process. Another rule is that two or more buttons can be pressed simultaneously. Finally, all buttons do not have to be used. As example, a combination of only "1" or "4" could be used. It is also possible to press each button only half-way in. This effectively doubles the amount of available code combinations, but pressing half-way is not very practical in everyday use.

It is an interesting mathematical challenge to determine the amount of possible combinations but people with time on their hands have determined that there are approximately 1000+ full-press combinations and approximately 2000+ combinations if half-press combinations are added.             

In case of a forgotten combination, the following numbers can be tried as a way of possibly opening a Simplex lock quickly. This list contains only 66 combinations. There are more than 900 other common combinations, but they require dexterity and time in order to configure users’ fingers when pressing several buttons at once. It is more likely that users will only choose an easy combination with up to three numbers and individual numbers for the combination.

Depending on the type of Simplex lock, the lever, knob or thumbturn is rotated in one direction during an unlocking procedure and turned in the opposite direction to 'clear' the combination if numbers were incorrectly pressed. When trying each tryout combination, be sure to 'clear' the prior combination before trying the next tryout combination on the list.

Before trying any of these combinations, always try pressing 2 and 4 together, then press 3. This is the code that all Kaba Simplex locks are set to at the factory. Amazingly sometimes the user will never change the combination and continue using the factory default combination. 


  1. Perform all operations with the door or cabinet open so you have accessibility to the lock case if necessary.
  2. Turn the thumb turn, knob or lever in the direction which 'clears' the chamber unit. 
  3. Enter the existing combination. A lockout slide is located at one end of the chamber. Depending on the Simplex product, you must remove a set screw, unscrew a wafer lock plug or search the back of the Simplex lock to find the slide (photo 2).   
  4. Depress the slide to set the chamber to a neutral position.
  5. Turn the thumb turn, knob or lever to the 'clear' position.
  6. First, write down the new combination for future reference. Next, carefully depress the buttons of the new combination. 
  7. Turn the thumb turn, knob or lever fully to the unlock position.

The new combination is now set. Try the combination several times with the door ajar to be sure the combination is operating correctly.

As an antidote for the tryout list, when changing a Kaba Simplex combination, always include at least one set of numbers which must be pressed in unison.