King Pin Locks: Prevent Unauthorized Trailer Hookups
A king pin lock provides a direct physical barrier against trailer theft.
The king pin is the connection point underneath the front of a semi-trailer that allows a tractor's fifth wheel to engage with it. Without a lock, someone with a compatible tractor can potentially back up, connect to the trailer and drive away.
A king pin lock covers and secures that connection point, preventing a tractor's fifth wheel from properly engaging.
The ENFORCER® King Pin Lock is manufactured from heavy-duty cast steel and incorporates an ABLOY® high-security lock cylinder. It is portable, requires no permanent trailer modifications and can be removed when the trailer is ready for an authorized pickup.
Why choose a king pin lock?
It directly blocks the connection a tractor needs to hook up to a dropped trailer. This makes it an excellent option for loaded trailers sitting in distribution yards, retail lots, truck terminals and other unattended locations. One consideration is installation. Because the king pin is located underneath the front of the trailer, drivers must reach beneath the trailer to apply and remove the lock. For some operations, that's not a problem. For others, especially those with frequent trailer drops and pickups, a more accessible locking point may be preferable.
Landing Gear Locks: Strong Security Without Getting Under the Trailer
For fleets that want heavy-duty dropped trailer security with easier installation, a landing gear lock is an excellent alternative.
When a trailer is disconnected from a tractor, its landing gear supports the front of the trailer. Before the trailer can be moved normally, the driver must raise the landing gear to provide ground clearance.
A landing gear lock prevents that step.
The ENFORCER® Landing Gear Lock, Model 1213, uses a heavy-gauge, high-carbon steel housing to cover and secure the landing gear crank handle. When locked, the handle cannot be operated to raise or lower the landing gear.
It is designed to be secured with an ABLOY® 341-25 high-security padlock, available separately.
The biggest advantage is accessibility.
Unlike a king pin lock, the landing gear lock can be installed and removed without reaching underneath the front of the trailer.
For drivers making multiple drops or yard personnel responsible for securing numerous trailers, that convenience matters. A lock that's easy to use is more likely to be used consistently.
The Landing Gear Lock is especially well-suited for:
- Distribution centers with frequent drop-and-hook operations
- Retail lots and warehouse yards with unattended trailers
- Fleet terminals and trailer staging areas
- Trailers parked for extended periods
Both the King Pin Lock and Landing Gear Lock provide substantial physical protection against unauthorized trailer movement. The choice often comes down to where the fleet prefers to secure the trailer and how easily drivers can access the locking point.
Glad Hand Locks: Another Way to Prevent Trailer Movement
A third option is to secure the trailer's air brake connection.
Glad hands are the fittings used to connect a tractor's air lines to a trailer. When a trailer is disconnected, its spring brakes are normally engaged. The tractor supplies air pressure through the emergency air line to release those brakes for movement.
A glad hand lock prevents an unauthorized operator from making that connection and releasing the brakes through the normal process.
Glad hand locks are frequently used at warehouses and loading docks as part of lockout/tagout safety procedures, helping prevent trailers from being moved while loading, unloading or maintenance activities are underway.
But they can also serve as an effective physical security measure.
Transport Security offers ENFORCER® Glad Hand Locks, including:
Model 1350: Secures the emergency air brake connection, preventing the air line from being connected until the lock is removed.
Model 1450: Covers the glad hand mounting bolts to prevent unauthorized removal or tampering with the brake line connection.
For applications where theft prevention is the primary concern, the security of the locking cylinder also matters. Transport Security can help customers evaluate high-security locking options, including ABLOY cylinder solutions, for their equipment and security requirements.
Glad hand locks are particularly useful for distribution centers and warehouse operations where preventing unauthorized trailer movement is important for both security and workplace safety.
King Pin Lock vs. Landing Gear Lock: Which Is Better?
Both are excellent choices for securing a dropped semi-trailer. Neither requires a permanent modification to the trailer, and both create a physical obstacle that must be addressed before an unauthorized tractor can move the equipment normally.
The main difference is how they accomplish that protection.
Choose a King Pin Lock if: You want to physically block a tractor from connecting to the trailer's king pin. It's a proven, heavy-duty approach to protecting parked trailers.
Choose a Landing Gear Lock if: You want comparable heavy-duty protection with a more convenient installation point. Drivers can secure the landing gear crank without reaching beneath the trailer.
Consider a Glad Hand Lock if: You want to prevent unauthorized air brake connections, particularly in warehouse, loading dock or distribution center environments.
For higher-risk loads or trailers left unattended for extended periods, using more than one type of lock can provide additional protection. A king pin lock and landing gear lock, for example, protect two separate points involved in moving a trailer.
Don't Forget to Secure the Trailer Doors
Preventing someone from taking the entire trailer is important, but it doesn't prevent someone from breaking into a stationary trailer and removing cargo. If a dropped trailer contains valuable freight, door security should be part of the plan.
ENFORCER offers heavy-duty trailer door security solutions, including Adjustable Trailer Door Locks, Hasps and Roll-Up Door Locks, many featuring ABLOY high-security padlocks or cylinders. Combining trailer immobilization with door protection helps address both unauthorized trailer movement and cargo theft.
The Best Dropped Trailer Lock Is One Your Fleet Will Use
A good security program has to work in the real world. Drivers are managing pickup schedules, tight delivery windows, changing weather and busy yards. If a security device is difficult or inconvenient to use, compliance can suffer.
That's one reason the Landing Gear Lock is an attractive option for many fleets. It offers a high level of physical protection while keeping installation simple. The King Pin Lock remains an equally strong choice for operations that prefer to secure the tractor's connection point directly.
Whichever you choose, the goal is the same: make it significantly harder for an unauthorized person to hook up to and move your trailer.
Protect Your Dropped Trailers with ENFORCER®
| Lock Type |
How It Works |
Key Advantage |
| King Pin Lock |
Blocks the tractor's fifth wheel from connecting to the trailer. |
Secures the trailer's hookup point. |
| Landing Gear Lock |
Prevents the landing gear crank from being operated. |
Easy to install without reaching under the trailer. |
| Glad Hand Lock |
Secures the trailer's air brake connections. |
Useful for security and lockout/tagout applications. |
Since 1982, Transport Security, Inc. has helped carriers, retailers and fleet operators protect their trucks, trailers and cargo with heavy-duty physical security solutions.
Not sure whether a King Pin Lock, Landing Gear Lock or Glad Hand Lock is the best fit for your operation?
Contact Transport Security to discuss your trailer security needs, product options and fleet keying requirements.
Frequently Asked Questions About Dropped Trailer Security
Is a king pin lock or landing gear lock better?
Both provide strong physical security for dropped semi-trailers. A king pin lock blocks unauthorized tractor hookups, while a landing gear lock prevents the trailer's landing gear from being raised. Landing gear locks are generally easier to access because installation doesn't require reaching underneath the trailer.
How do you prevent someone from stealing a parked semi-trailer?
Use a physical security device such as a king pin lock or landing gear lock to prevent a normal unauthorized pickup. Glad hand locks offer another layer of protection by securing the air brake connection. For loaded trailers, additional door locks can help protect the cargo inside.
Can you use more than one lock on a dropped trailer?
Yes. Using a king pin lock and a landing gear lock protects two different points on the trailer. Multiple physical barriers can make unauthorized trailer movement more difficult.
Are glad hand locks used for security or safety?
Both. Glad hand locks are commonly used during loading, unloading and maintenance to prevent unintended trailer movement. They can also be used as a theft deterrent by restricting unauthorized access to the trailer's air brake system.
