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How Combination Padlocks Work -

Combination padlocks are relied upon to safeguard and protect the valuables of students and homeowners everywhere. These inexpensive locks are very functional and are largely marketed to teenagers as is evident by the wide variety of vivid colors and designs available. Many people prefer a combination padlock over a padlock that locks with a key because they don’t need to worry about another key potentially getting lost. If you use a combination padlock to secure your gym locker there’s no need to worry about the key falling out of your pocket during a workout. I have one on the storage shed door out in the yard like so many other people do. They are often used for self-storage units too. Simplicity and ease of use are the reasons tens of thousands of combination padlocks are sold every day.

We’ve had customers and locksmith students contact us to inquire about how combination padlocks locks are made, what makes them “tick”. There isn’t a lot of information available in print which is why there isn’t a book available on the Lockpickshop.com website. We do have a cutaway combination lock on the site which is great because you can see inside of the lock and see exactly how these locks are put together. We also have a book on the site Opening Combination Padlocks which is really something else! The author claims to show the reader a simple method and determine the combination of any padlock in minutes.

Recently I ran across a show on TV a few months ago that was filmed in a factory that fabricates combo locks here in the US. The TV show brought the viewer through the entire process of how these locks are made and I found the production process really fascinating.

The combo locks main locking mechanism is called the base plate. The base plate is made up of 7 different components. First there is the lock bolt, made of very dense rubber or hard plastic, that slides over to free the shackle each time the correct combination is dialed. All of the base plate components are riveted in place so the lock will withstand repeated use. Once assembled with all 7 components the base plate is secured to the lock housing.
Next, the trip lever spring is installed. The trip lever spring is the part of the combination lock that automatically scrambles the lock mechanism every time the lock is closed.
Next the shackle is fit through holes in the housing, positioning one end against the trip lever. The other side of the shackle is fastened with a tiny steel bar called the yoke. The shackle is greased so it slides up and down easily.

The locks combination function is made up of 3 stacked discs, called tumblers. The lock dials are stamped and colored with paint. The dials can be customized with a school logo or company name in up to 4 colors. Each color is separately applied by a printing machine. Then, each painted dial is treated with 2 coats of varnish to harden and protect the paint. The dial components are assembled. First, the indicator button is fastened to the dial. Then the third tumbler is riveted to the back of the dial. This tumbler controls the movement of the other two tumblers inside the locks housing. All three tumblers have “V” shaped indentations. When the correct combination is dialed these “V” indentations align allowing the lock bolt to slide over which frees the shackle so the lock opens. Each of the three tumblers have a code number stamped on the back. This code number corresponds to the number of it’s indentations.
Each locks three tumbler code is programmed into a computer which randomally creates each locks combination.
There are over fity THOUSAND possible three-digit combinations. The system then prints out the combination along with a bar code. The bar code is programmed into a central computer where it is recorded along with the locks serial number. The “guts” of the combination lock are now complete.

Final assembly starts with putting the dial on tool on top of the lock casing. Then a forming tool presses down on the casings rim forming it tightly over the dial. Finally, a computer guided machine engraves a serial number on each lock before it is sent to an area where it will be inspected and tested. Each combination lock is tested by hand. The combination is dialed on every lock to ensure that it opens before it passes inspection.