Escape: Handcuffs and Double-locks.

Version 1.1

Today’s blog is the second part of our look at handcuffs. Once I have this out the way I can move on to the product reviews and suggestions.
I have seen suggestions that the handles of some lock picks can be used as shims. Most lock pick handles are way too wide for such use. Even types like the Bogotas that have handles designed to serve as turning tools are likely to be a millimetre or so too wide for many handcuffs. What can be done, however, is to use the head of a pick. Obviously some designs of head are too wide. Picks I have successfully shimmed with include my half-snowman, the Dangerfield one-hump Bogota and the jag from the “James Bond Credit Card” set. Some of the snakes and hooks should also be suitable.

Another experiment I conducted was to use a handcuff shim on a cable tie. As I suggest in the previous post, I have further slimmed down the single end of the shim I made. With it I have successfully disengaged the locking mechanism of a cable tie. Admittedly the tie I had handy was larger than average but I believe the tool should be effective on standard sized zip ties too.

In the last post on handcuffs I dealt with how to deal with single-locked cuffs. If you are in cuffs for any length of time a trained captor is likely to double-lock them. This is why I am rather dubious about E&E sets that contain a multitude of different shims.

In the diagram above the double-lock mechanism is in red. Whilst the green single-lock pawl moves up and down, the double-lock mechanism slides back and forth (or up and down, with respect to the diagram above). The single-locking pawl is under constant pressure from a spring. The double-lock mechanism, however, clicks from one position to another and back again. When the double-lock is applied the red piece will physically prevent the green part from raising. Hence when a double-lock is applied the cuff cannot be further tightened and cannot be shimmed.
In the diagram above, you can see a channel above the double-lock mechanism. The handcuff key has a post that can be inserted into this hole to push the double-lock into the locked position. A paper clip, pen refill or any object of similar dimensions can be used to apply this lock if a key is not handy. Incidentally, looking for a post on the key is a good way to determining if the handcuffs you are considering buying a “real” or a novelty item. On some designs of handcuff there is a slot cut in the side and the lock is applied by using the post to flick across a “trigger”. A handcuff of this type can be seen in the “Secrets of shimming” video in the previous post.

To disengage the double-lock you normally need a key. The key is turned in the opposite direction to that you would use to open single-locked cuffs. First the double-lock must be released, then the key turned in the opposite direction to release the single-lock. In the diagram above the key would first be turned anti-clockwise, and then clockwise.
The primary means of dealing with double-locked cuffs is a key. You are advised to spend your money on acquiring a few keys before you invest in commercial shims. Later articles will look at some of the E&E keys available. But a word of caution:
Many years ago I watched a movie about undercover cops at a high school. In one scene a youth spots the handcuff key on a policewoman’s key ring. He says something like “I’ve been busted enough times to know a handcuff key when I see one!” The supposed schoolgirl manages to talk her way out of it, making some comment about being kinky or similar. Having a handcuff key in plain sight on your key ring may get you identified or mistaken for a cop, and the results of this may be more serious than in the movie. Some cops will take a dim view of non-police having handcuff keys, regardless of what the actual local laws permit. Likewise, in some localities carrying of a handcuff key(s) may be illegal. Escaping from legitimate custody is certainly illegal. The techniques on this blog are intended for protection against illegal restraint.
If you do not have a key there are a few things you can try to release a double-lock. Some lock picks can be used to push the bolt back to its unlocked position. Probably these will be hooks, but I have done it with the Dangerfield single-hump Bogota too. I’ve used the same tool to then lift the single-lock. The bulldog clip handle and some other improvised means work better for the latter, however.
A better way to disengage a double-lock is to use a hairpin aka bobby pin. Strip the protective bulb from the end and bend the straight part. Contrary to what you may see in many youtube videos I have found that a gentle curve with a radius of about 18mm works best on the cuffs I have tried. If the slot at the bottom of the keyway is “6 o’clock” then you want to insert your piece of pin at about “2 o’clock”. Give it a vertical angle of about 30-45 degrees. The idea is that it curves around the post and the wall of the keyway to push on the bolt until it clicks across. Bend the pin more as necessary. You can use this slightly curved pin to shim the cuffs once the double-lock has released.
Transparent training cuffs, such as those supplied by Shomer-tech are useful in learning this technique, but be aware doing this repeatedly can damage the plastic around the keyhole. Once you have the basics practice on all metal cuffs.

No discussion of the double-lock would be complete without some mention of kinetic unlocking techniques. The idea is to strike the cuff against a hard surface so that conservation of momentum causes the double-lock bolt to bounce up to the unlocked position. I’m told that this trick is more likely to work with older models of modern handcuffs. A related technique is pull on the shackle of the cuff as the body is struck. The theory is that if the double-lock does not fully disengage it will still move enough to allow the pawl to temporarily lift. Pulling on the shackle while striking the cuff seems a rather complicated operation if you are on your own.
The Darby-style handcuffs that Houdini was familiar with were vulnerable to being opened by striking. Strike near the hinge and keyhole. Darby-style cuffs are still in use in some parts of the world.