Pocket Knife Lock Types – A Rundown

Every pocket knife is different, from the blade shape to the metal composition to how the handle feels in your hand, but of all the attributes a pocket knife can have, there’s nothing more important than a good locking mechanism.

If a knife’s lock isn’t up to par, it can be difficult to open and easy to break (plus, it’s just a death sentence for your fingers). Luckily, most pocket knives have well-built locks that you can count on to last for years, so the question really becomes what lock works best for you?

To ensure you get a knife lock that suits your needs, you need to keep in mind how easily you want to open it, how safe you want it to be, and how much maintenance it will require to keep working smoothly. Some other things that could affect your decision would be any laws restricting the use of certain locks and whether you’re right- or left-handed.

That all said, let’s take a look at some of the more common pocket knife lock types and how they work.

All Locks Are Different - Or Are They?

There are a lot of locks in existence and the list below is definitely not exhaustive. The sheer number of locks out there could give any knife newbie a headache. But the thing is, most lock types are just based off other locks, which means not every lock is completely unique.

For example, one knife company may look at a lock, give it a twist, and rebrand it with a new name, such as when Spyderco took the popular Liner Lock and turned it into the Compression Lock. But when you dive into the lock’s fundamentals, you’ll find it behaves very similarly to the lock it was based off of.

 

Liner Lock

This is definitely one of the most common locking mechanisms because it’s simple, strong, and cheap. It involves the knife’s lining moving in behind the blade and keeping it from closing. 

This mechanism works because part of the lining inside the handle wants to move into the middle where the blade is. And the only instance where the blade doesn’t block the lining is when the blade is in the open position.

Once the liner jumps into the space behind the blade and locks it in place, you’ll have to push the liner back into its original place before the blade can close again. Also, you’ll often find a small metal detent (bump) on the lining which helps hold the blade in the closed position.

The biggest problem with this mechanism is that, when you release the blade, your finger will be in its path by default, which makes it a little more dangerous.

Frame Lock

This is basically the same thing as the liner lock except instead of some lining inside the knife doing the work, it’s the frame itself.

The part of the frame that’s cut off tends towards the middle of the handle and will fall into place as soon as the blade gets out of the way, which happens to be when it’s completely open. Very similar to liner locks, you’ll find a small detent on the frame that keeps the blade closed.

Once again, the frame lock presents some danger when it closes because your fingers will be in the path of the blade.

Compression Lock

Leave it to Spyderco to give mechanisms their own twist. The compression lock is essentially a stronger and safer version of the liner lock.

It works by having the liner fall into place between the blade and a stop pin, so instead of the liner taking all the force, it simply passes it on to the pin. The liner can also be accessed from the spine of the blade, so that means your fingers won’t be in danger of getting cut every time you close the knife.

Back Lock

A back lock is almost like if the blade and the handle were two pieces of a jigsaw puzzle that can only fall into place when the blade is opened. It’s also similar to a ratchet mechanism, which allows movement in only one direction (like with a socket wrench or handcuffs).

On the spine of the blade you’ll find a lever with the pivot right in the middle. An upward force is applied to the side of the lever nearest the butt which causes the other side to go down, almost like a tenth grader hogging the seesaw at a preschool playground.

The side of the lever that goes down has a tooth that would fit nicely into a hole at the base of the blade, which lines up with the tooth when the blade is fully opened. And with the force that’s being exerted on the lever, the tooth falls into place with a snap.

To close the blade, you simply push down on the far end of the lever, which will raise the tooth up.

Tri-Ad Lock

This is sort of an upgrade to the back lock, which was designed for Cold Steel knives. Really the only difference is the inclusion of a stop pin between the blade and the lever on the spine.

The stop pin helps take most of the wear and tear that would normally be directed at the lever. This means the knife will be able to take bigger hits without the locking mechanism getting destroyed. For example, if you wanted to throw your pocket knife, this lock would keep the insides from breaking into a thousand pieces.

And just like with the back lock, after the tooth on the lever catches the blade to keep it open, you simply push down on the far end of the lever to release the blade.

Slip Joint

This isn’t actually a lock, but the lock back mechanism was based off of this design. You’ll find the slip joint on any Swiss Army knife and any older pocket knife, which you probably know don’t really lock.

Instead of a tooth that holds the blade in place, there’s simply a flat piece of metal that applies pressure to the base of the blade and holds it in place. All you need to do is push down on the spine of the blade and it will close.

The slip joint is a lot less threatening than other locking systems and is also legal in a lot more places.

Axis Lock

A locking mechanism by Benchmade, the axis lock is safe and easy to use. It involves a small bar that’s pushed into a notch at the base of the blade. This is accomplished by the force of an omega spring (it looks like the Greek letter omega).

When you pull the bar back, the blade is allowed to close. And when you open the blade again, the bar will snap back into the notch.

The biggest problem with the AXIS lock is that is involves lots of moving parts and is more susceptible to failure. So it’s important to keep this one clean and greased.

Ball Bearing Lock

If you take the AXIS lock and replace the bar with a ball bearing, you have yourself a Spyderco ball bearing lock. 

Inside this system, you’ll find a spring that would just love to shove a ball bearing into a small hole. Fortunately for the spring, the base of the blade has a notch that fits the ball bearing perfectly.

When the blade is opened, the notch lines up with the spring and the ball bearing is shoved into the crevice. The only way to get the blade closed again is to pull the spring back with a slide on the outside of the handle, which will let the ball bearing move out of the notch.

Button Lock

A button lock is what you’d find on an automatic knife where you press the button and watch the blade flip open. It’s been recently used in manual knives, but it’s still mostly for automatics.

It functions very similarly to the axis lock except that the bar moves from side to side instead of forwards and backwards. This allows a gap in the bar to line up with the blade, letting it pass through.

The bar will fill a hole at the base of the blade when the blade is open or closed to keep it from moving. When you push the button and move the bar, you let the blade slip through a gap in the bar.

Collar Lock

This is a special type of locking mechanism where the blade doesn’t lock in place automatically.

When the blade is deployed, the user must twist a ring that’s found at the bolster of the knife (which looks like a turtleneck collar).

The ring has a small slit that allows the blade to pass through, but only when the slit is facing a certain direction. If it’s turned it’ll block the blade. 

What’s cool about this one is that it can lock the blade in place even if the knife is closed (which can make it a little safer). The only problem is that the ring has to be properly oiled and maintained for it to work smoothly.

Friction Folder

The only thing that keeps the blade locked in this mechanism is your hand. Basically, the tang of the blade (the part that extends into the handle) has to be held in place when the blade is deployed.

It’s super simple and only involves one moving part, but it can take up a bit of space when it’s closed because the tang sticks out from the handle.

You should now be well-versed in all things pocket knife locking. It can all seem very confusing at first, but most locks share the same fundamentals. Then you have locks that are based on other locks and brand-specific locks and locks that are almost one type of lock but are maybe another type and, well, it all kind of goes downhill from there. If you can just remember some fundamentals about knife locks, though, you should be fine the next time you’re looking for a good folder.

Hopefully you found this article helpful. If I missed anything or have anything to add (or just want to type something), be sure to leave a comment below and I’ll get back to you as soon as possible.

6 thoughts on “Pocket Knife Lock Types – A Rundown

  1. It’s amazing for something as simple as a knife how many different locking systems they have invented. With such types of knives the less parts involved the better because as you point out these can lead to failure and need proper maintenance. I had use a few these different mechanisms in the past and I found the slip joint to be less dangerous and easy to use.

    1. Hi Stratos,

      You are right that the more complicated a mechanism is, the easier it is to break. It’s also harder to take care of (which is one reason some people like fixed-blade knives).

      The slip joint is very simple and non-threatening and it’s easy to use. It’s also one of the most legal locks (that is, it’s legal in the most places) and it’s a good first knife for newbies.

      Isaac

  2. Another great article with some amazingly clear illustrations! I find it easy to get lost on your site, it has such great content. I’m just curious with this one though if there are any of these locks that are actually illegal in some countries. I’ve been told that having a locking knife in the UK is illegal and that if caught with one, you would get into serious trouble. Do you know anything about this?

    1. Hi Kit,

      In the UK, it’s illegal to carry a folding knife with a blade longer than three inches if you don’t have a “good reason.” It’s also illegal to carry knife that can be locked in the open position. So if you have a Swiss Army knife, you’ll be fine.

      “Good reasons” can include taking a knife to use at work or a hobby, but does not include self defense. Basically, you need to be planning on using it.

      Anyways, I’m glad you enjoyed this article! I try to make things as clear as possible (or at least put ideas in a new light). It’s an interesting challenge trying to take a confusing topic and reducing it to a very simple idea.

      Isaac

  3. Interesting aritcle. I hadn’t realised that so many different mechanisms kept the blade locked This is obviously very important since we don’t want to lose fingers as you mention.

    I have a Swiss army knife that was given to me by my Grandfather but it remains in a drawer and is used rarely. I’m not too sure if it has a locking feature for the blade. I will check.

    Some appear to work by themslves others maybe you have to remember to activate the lock once the blade is active. Be interested to hear your response.

    Thanks for the information and great pictures.

    1. Hi Mike,

      Pocket knifes can be confusing since there are so many components. And locking mechanisms are no exception.

      I don’t think there exists a Swiss Army knife without a slip joint mechanism keeping the knife in place. Any other lock would probably be too difficult to implement effectively.

      Most locks activate automatically, but there are a few that need to be locked manually (like the collar lock).

      I’m glad you were able to learn a thing or two!

      Isaac

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