Everything You Need to Know About the 23 Most Common Types of Locks
Locks were born out of necessity as people sought ways to protect their possessions. Though the first locks were made from a series of rope knots and bore no resemblance to the locks used today, they served the same purpose and were the inspiration for a new technology that would forever change the face of history.
Lock History: Locks Through the Ages
The oldest known locking mechanism dates back more than 6,000 years, discovered in the ancient Mesopotamian kingdom of Assyria. The ancient Egyptians developed a similar technology and are generally credited with creating the first mechanical lock, which was a basic pin tumbler lock made entirely from wood. They were also the first to incorporate this feature into their architecture as a means of security.
This lock was made up of a wooden post attached to the door and a bolt that could slide horizontally into the post. The bolt was outfitted with a set of openings that were filled with pins, and a large wooden key was created with pegs that matched the holes and pins. If the key was placed into the opening and lifted up, then the pins would move and allow the security bolt to be moved as well.
The Greeks and Romans made many innovations to lock technology during their respective eras. Greek locks were not considered to be overly secure, but their ideas served as an inspiration for later technologies developed by the Romans. The most significant change made by the Romans was switching the predominate material from which locks were made from wood to metal. Iron locks also allowed for keys to be reduced down to a more modern-day size.
People would often wear their keys as pendants or even have them infused into rings, both for safe-keeping and as an indicator of wealth. If you had a key, you were bound to have something valuable enough to need protecting.
After a period of advancement in the Roman age, locks went through a dark age in which no major innovations were made again until the 18th century. When Robert Barron made “a lock far more secure than any hitherto made” in 1778, his double-acting tumbler lock, it marked the emergence of a new era of lock technology that has led all the way to the modern age of locksmithing.
Today the broad spectrum of different locks is innumerable, and each design has its pros and cons depending on the desired function and setting in which the lock will be utilized. You use locks every day, so it is important to understand the different options available to you when considering both functionality and security. This list of 23 types of locks includes the most common locks seen in the United States, as well as useful information about their form and function to better inform you about the locks in your life.
Padlocks are the most common type of freestanding lock and easy to identify in a lock line-up. The very first padlocks were used in ancient Egypt and Babylon, favored for their portability, which is still the main draw of this style of lock today. Harry Soref patented the first laminated padlock in 1924 after founding the Master Lock company in 1921, and his design is still utilized today. There are now two main types of padlocks with many other minor variations.
1. Combination Padlocks
Combination locks are padlocks that require a specific number sequence in order to unlatch the locking mechanism. These can have either a single dial or multiple dials, though the single dial locks most commonly seen on school lockers and safes are actually considered more secure than the multi-dial locks often used in bike locks and on briefcases.
The first combination lock was invented by James Sargent in 1857, and the modern-day combination lock was developed by Linus Yale, Jr. using his father’s pin tumbler lock technology in conjunction with Sargent’s invention. Unfortunately, these locks are relatively easy to pick or crack.
2. Key-Based Padlocks
Key-based padlocks require a key to be opened. Some varieties of these padlocks can be rekeyed, and others cannot. Keep in mind that if it cannot be rekeyed and you lose the key, your lock will be permanently locked unless you are able to pick it or cut the shackle.
Key-based padlocks can also be key-retaining, which means the lock will not allow the key to be removed while it’s open.
3. TSA-Approved Locks
When you are flying within the United States, the Transportation Security Administration has designated a series of approved padlocks that can be used to secure your luggage. They are generally combination locks that can also be accessed with a master key only TSA employees are supposed to have.
These locks have become somewhat of a joke in recent years, however, because they are seen as easy to pick and ineffective in protecting people’s belongings. There have also been stories reported about locks missing entirely when people receive their luggage after traveling.
Deadbolts are generally thought of as being more secure than the standard spring lock because they cannot be opened unless a key is used to rotate the lock cylinder to the open position. You often see these used on homes and other exterior doors as an additional layer of security in combination with a less-secure lock.
The first deadbolt, or “jimmy-proof lock” was invented by former cop Samuel Segal, who founded Segal Lock & Hardware Company in 1912. His design was intended to keep out burglars as the practice of jimmying locks became more widespread. Today, there are three main variations of the basic deadbolt, as well as the jimmy proof deadbolt fashioned after Segal’s invention.
4. Single Cylinder
Most American homes use single cylinder deadbolts, which operate with a key on the outside and a thumbturn on the inside.
For an additional security, a flip guard can be installed around the thumbturn to prevent it from rotating, meaning that the deadbolt cannot be picked, bumped, or even unlocked using the key when the guard is in place.
5. Double Cylinder
Double cylinder deadbolts are considered more secure because they require a key on both the inside and outside but also pose a safety hazard in the event of an emergency. Some housing codes in the United States do not allow for this form of deadbolt, specifically on rental housing.
6. Lockable Thumbturn Style
For maximum security, a lockable thumbturn style deadbolt is recommended because the door can be locked from both the inside and outside.
It is a hybrid of the single and double cylinder locks, with a key cylinder on one side and a thumbturn that can be locked with a key on the other. When people are home, the inner thumbturn can be left in the unlocked position, and the door will operate like a standard single cylinder deadbolt. If the thumbturn is locked, no one on the outside or inside can operate the lock.
7. Jimmy Proof Deadbolts
The jimmy proof deadbolt is a variation on the standard deadbolt that is mounted on the surface of the door and usually found in apartments and on double doors. This form of deadbolt is often preferred in these settings because the surface mount calls for little modification to the door during installation, and they are unique because the deadbolt actually interlocks with the jamb bracket, making them more resistant to excessive force than the standard deadbolt.
Locks in Handles
8. Knob Locks
Knob locks are commonly used on the exterior doors of homes in combination with a deadbolt lock. They are a simple form of spring lock and not very secure because the cylinder is in the knob and not in the door.
Unfortunately, the knob can be knocked off the door with a hammer, pliers, or the application of enough force, making the fact that these locks are relatively easy to pick almost irrelevant. A knob lock should never be used as the only lock on an exterior door, and though they were once popular in a variety of applications, knob locks are best used as interior locks in a residential setting.
9. Lever Handle Locks
Locks with lever handles are most commonly seen in a commercial setting due to their compliance with the Americans with Disabilities Act and are generally only used on interior doors. They have a lever that serves as the rotatable turn knob on one side and a key cylinder on the other, much like a knob lock, but are even less secure than knob locks because they can often be opened by brute force.
10. Vending/T-Handle Locks
T-handle locks are often called vending locks because they are most often used on vending machines and ATMs. When you open one of these locks, you are actually removing the lock from the device, meaning it is extremely easy to replace.
These locks come with either a spring latch or a dead latch. The spring latch automatically relocks when the t-handle is snapped back into place, and the dead latch requires the lock be resecured with a key.
11. Mortise/Rim Cylinder Locks
Though listed together, mortise cylinders and rim cylinders are actually two different types of locks that share many similarities. These hybrid locks are considered to be more secure than deadbolts, and you are most likely to see one of them on commercial doors, glass entry doors, or in an apartment setting.
The main difference between the mortise cylinder and the rim cylinder is that the rim cylinder has a long tailpiece that extends from its backside that goes through the door and into the locking mechanism on the other side when installed. Mortise cylinders are threaded on the side and actually screw into the mortise hardware installed in the door. They have a cam where the rim cylinder has its extended tailpiece, which is used to operate the lock.
12. Interchangeable Core Cylinders
If you have ever wondered what types of locks big businesses, universities, and other institutions use, locks with interchangeable core cylinders are likely the answer. These locks are beneficial because their design makes them easy to change, as the core can be replaced without having to disassemble the lock.
Two different types of keys are used to operate interchangeable locks. The standard operator key is used for locking and unlocking the lock as usual, but the control key removes the entire core from the lock. To replace the lock, you only have to insert a new core into the existing hardware already installed in the door. These locks come in both small format and large format interchangeable core.
13. Rim Latch Locks
Rim latch locks are a specific style of lock that utilize the earlier mentioned rim cylinder. They have a rim latch on one side of the door and a latch lock mounted on the surface of the other side.
Rim latch locks are unique in that they can be designed to auto lock when the door shuts and are found in many newer apartment complexes. These locks are not designed to withstand a significant amount of force, though, and should always be accompanied by another form of lock when used on exterior doors.
14. Key In Knob (KIK) Cylinders
While key in knob cylinders are extremely common, you probably didn’t realize you were using them. The KIK cylinder is not its own type of lock so much as the type of cylinder found within several of the locks listed above. They are found in most knob locks, lever locks, and even some deadbolts.
There is no standardized design for these cylinders, meaning they can be harder to replace when switching between different brands. KIK cylinders can come in a wide variety of shapes and sizes and can have either a floating or fixed tailpiece.
Euro Profile Cylinders
More than 150 years ago, European locksmiths agreed on a standardized lock to use that would make lock manufacture and service more straightforward. The Euro profile cylinder was agreed upon as a compromise between several of the time’s leading lock designs and is now widely used in Europe and other parts of the world in a variety of applications.
In the United States, Euro profile cylinder locks are generally used on sliding glass doors and on the dividing doors between two rooms.There is only one point of attachment for these locks, which makes them relatively easy to snap in half with the application of enough force. Similar to deadbolts, there are three main varieties of the Euro profile cylinder, though their standardization leaves room for little variation beyond the main three types.
15. Single Euro Profile Cylinder
The single cylinder variety is only operable on one side with the use of a key.
16. Double Euro Profile Cylinder
A key can be used on both sides of a double Euro profile cylinder lock.
The thumbturn variation has a key-operated locking cylinder on one side and a thumbturn on the other.
A furniture lock is not so much a specific kind of lock as it is a category of similar locks. These locks are predominantly found on desks, filing cabinets, even sliding glass doors. There are two major types of furniture locks: the bolt style and the push button style.
18. Bolt Style Furniture Locks
Desks, drawers, and cabinets often have bolt style locks, which have a flat piece of metal that extends out of the side or top of the lock in order to secure it.
19. Push Button Style Furniture Locks
Push button style locks are most often seen on filing cabinets and sometimes sliding glass doors. These locks have a rod that extends out of the back of the lock while it is locked. When unlocked, the lock pops out and retracts the rod into its body. All you have to do to re-secure the lock is press it back down into its shell.
Other Lock Types
20. Cam Locks
Cam locks are simple, low-security locks most commonly found on filing cabinets and mailboxes. They consist of a base and a cam, the base being the part into which the key is inserted and the cam being the tail part that acts as the latch.
21. Wall Mounted Locks
The Knox box or fireman’s box is the most commonly used style of wall mounted locks, which are, as their name implies, actually mounted in the wall. These are generally used to hold keys or as a small safe and are often utilized by large businesses to provide emergency access to their buildings.
New Lock Technology
22. Electronic (Digital) Locks
Digital lock technology has been used on cars and in hotels for years but has only recently been utilized in a broader spectrum of applications. There is a wide variety of different forms electronic locks can take and often use either a swipe card or pin code to unlock them.
These locks are convenient to “rekey” because they can be reprogrammed without having to change the lock hardware, but a new threat comes in the form of technology advancements allowing people to hack rather than pick electronic locks.
23. Smart Locks
Smart locks are a new lock technology that has recently emerged in conjunction with the increased use of smartphones. They replace the thumbturn side of the lock and can be operated remotely using an app on your phone.
One of the most useful things about some smart locks is that they can be added directly on top of your existing locks. There are many options to consider when choosing a smart lock, based predominantly on your level of comfort with the technology and the purpose for which the lock is being used.
Which Locks Are You Using?
As technology continues to change and advance, locks may take on an entirely new look and be utilized in a wider range of applications, but the basic function will remain the same. Locks have been used throughout the ages and will continue to play a significant role in society as long as people have things they wish to protect.
Here at Mr. Rekey, we understand the importance of protecting not just your belongings, but also your family and your home. We have serviced more than 3 million locks since our company started in 1995, and we put our 20+ years of locksmith experience to work to make sure your locks are secure.
As America’s Largest Residential Locksmith®, we offer a wide variety of services and can repair, replace, or install most of the locks listed above. We offer all of our services at an affordable, upfront price that is backed by our 100% Lifetime Workmanship Guarantee.
Locks are all around you, and the strength of your home locks largely determines the security of your home. Make sure you know which locks are right for you with the help of a locksmith you can trust today.