Different Types of Locks and Keys

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There are many different types of locks and keys.
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Ask an average person to name all the kinds of locks they can, and they might be able to list off padlocks, deadbolts, door handle locks, and maybe furniture locks. But if you ask a locksmith, they'll easily be able to rattle off at least 10 locks, and if they really put their mind to it, maybe 20 or more. When you get into the different types of keys, the disparity will be even more obvious as there are easily dozens of key types used by Americans every day.


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Common Types of Locks

Given that locks have been around for more than 6,000 years, it's no surprise that many lock designs are either antiquated or just not widely used. That being said, there are some very popular lock types out there that most people have used in their day-to-day lives. Some of the most popular locks include padlocks, deadbolts, door handle locks, furniture locks, digital locks, and other cylinder locks.


Common Types of Keys

The many types of keys are often divided up by their use. Examples include car keys, hotel keys, padlock keys, house keys, diary keys, and furniture keys. The keys may also be grouped according to how they're made; for example, laser keys are cut with a laser and are more precise and secure than traditional mechanically cut keys, which are what most people use on locks in their homes. Keys can also be defined by how they're shaped; for example, most keys people use on a regular basis are double-sided keys, but home locks can also be fitted with four-sided keys shaped like a cross, and padlocks can be fitted with tubular keys with circle shapes.


Other keys are defined by their technological features, such as chip keys, magnetic keys, key cards, keyless entry remotes, and smart keys. Many cars built since the 2000s use chip keys, also called transponder keys, and can't be started with only a properly shaped key. They instead require a key with a chip built in that's programmed to work with the specific vehicle.


Smart keys are similar to keyless entry remotes used to open cars, only they allow a vehicle owner to open the car from anywhere rather than just nearby locations, and some even allow the owner to start the car remotely. Keyless entry remotes, smart keys, and magnetic keys are examples of technologically advanced keys that can open a lock without touching it.



Some of the types of keys may overlap. For example, a car key may be a laser key, a double-sided key, and a chip key all in one.

Types of Padlocks

Padlocks have been around since ancient Egypt and are still celebrated for their portability and simplicity. Master Lock was founded in 1921 and is one of the most popular brands of padlocks in the world. There are two main types of padlocks: combination locks and key locks. Combination locks can be opened with a rotating combination dial, while key locks require a key.


Padlocks that use keys can be key-retaining, meaning the key can't be removed while the lock is open, or non-key-retaining, meaning the lock can be removed while the lock is open. Padlocks using keys can also be either re-keyable or not, meaning the key cylinder can or can't be replaced.


There are only a few different types of padlock keys, usually different sizes of mechanically cut keys, which are the most commonly used type of keys. That being said, sometimes padlocks have tubular keys, dimple keys, smart keys, or other designs.

Types of Deadbolts

Most homes feature a deadbolt, which is a commonly used external lock. There are four types of deadbolt locks: single cylinder, double cylinder, lockable thumb turn, and jimmy proof. The majority of deadbolts used on homes are single cylinder deadbolts, which use a key cylinder on the outside and a thumb turn on the inside to close and open the lock. Double deadbolts use a key cylinder on both the inside and outside, but these are illegal under many housing codes because it may take too long to exit during an emergency.


Single cylinder deadbolts can be problematic as they can easily be opened if accessed from the inside — for example, from a nearby window — but double cylinder deadbolts can be frustrating since a key is always required for use even while you're inside. The lockable thumb turn is a perfect hybrid of the two as it still has a thumb turn that can be used on the inside; however, this can be locked with a key so it can't be used when no one is authorized to be in the home. This means anyone attempting to use the locking mechanism will need a key.

Jimmy-proof locks are a particularly secure form of deadbolt as they're resistant to the use of force (such as a crowbar) to open the door. They're installed on the exterior of the door and the jamb bracket, preventing the door from being pulled away from the doorjamb. These were originally invented by former police officer Samuel Segal, who founded his own lock company in 1912. Like all deadbolts, these can be rekeyed if necessary.

Door Handle Locks

The two most common door handle locks are knob locks and lever handle locks. That's because most door handles are either knobs or levers. Most homes have knob locks, although they may sometimes have lever handles on double doors.

Knob locks use a simple spring lock with a key cylinder on one side and a rotatable knob on the other. The knobs can easily be broken off with a hammer or similar tool, meaning they're easy to pick or break. Experts recommend using a knob lock only in combination with another more secure lock, such as a deadbolt.

Lever handle locks are pretty much the same as knob locks, only they're installed in handles that use levers rather than knobs. Lever handles move up and down rather than turn like a rotatable knob. These are often used in office buildings due to the Americans With Disabilities Act regulations since they're easier to open. Because levers already give way to pressure naturally, these handles are even easier to break than knob locks. All lever and knob locks can both be rekeyed.

Types of Door Keys

Both deadbolts and door handle locks use similar keys and, in fact, an office or home can rekey all of its door locks so they use the same key. Most office and home door keys are mechanically cut and can be easily duplicated. While keys can be stamped to say "do not copy," which will ensure most locksmiths won't make copies of the key, it's still possible to get copies of these keys by finding a locksmith who's willing to look the other way.

Hotels historically used mechanically cut keys, but since these were easily lost, many hotels turned to electronically coded locks that use key cards. Many businesses now use electronic locks to restrict access to employees by using a keypad or a key card. Some homeowners are also adding smart locks to their home that can be opened with smartphones.

Types of Furniture Locks

There's not actually a specific type of lock called a "furniture lock," but there are a number of similar locks that can be used to secure furniture such as desks, filing cabinets, or sliding doors. Most locks used for furniture are push button, cam lock, or bolt style. Push-button locks have a rod that extends out the back of the lock when locked; when unlocked, the lock will pop out, retracting the rod into the body. These can be secured again by just pushing the lock back into its shell.

A cam lock has a very simple design that offers little security. These are largely used for filing cabinets and mailboxes and consist of nothing more than the base and the cam. The base is the front part where the key is inserted and the cam is the rear part that spins to lock the latch when the key is inserted.

Bolt-style locks are often found on desks, drawers, and cabinets. These use a simple flat piece of metal that extends out the side or top of the lock into a lock slot when the key is turned. Bolt-style locks, cam locks, and push-button locks can use multiple types of keys, including tubular keys, smartphone keys, or dimple keys, but they most often use basic mechanically cut keys or simple skeleton or master keys.

New Lock Technology

Locks haven't been left behind in the digital age, and many new locks take advantage of technology. Vehicle ignition locks programmed to work only with the correct chip key are one example. Locks that rely on key cards or digital pin codes involve newer technology as well. Perhaps the biggest advance in recent lock technology is smartphone-enabled locks that can be opened remotely from anywhere with a cell phone or Wi-Fi signal.

These digitally enhanced locks offer many benefits. Those that rely on key cards or pin codes can be rekeyed easily and inexpensively in nearly an instant (which is why most hotels now use key cards). Cars with chip keys are more difficult to steal as thieves need a properly coded chip. Finally, smart locks can allow for remote unlocking, which can be convenient for those expecting visitors while they're away from home.

On the downside, these digital locks can fall victim to bugs, power outages, or hacking. Hackers are a particular problem as they can easily reprogram locks that rely on key cards or pin codes as well as hack smart locks to open locks on cars or homes and even remotely start vehicles. Of course, most traditional locks can be opened without a key through shimmying, jimmying, smashing, or picking, so it's important to remember that while technological locks may have their problems, so do traditional locks.