This heavy-duty metal housing contains the internal mechanisms that control locking and unlocking functions. Typically, you’ll find lock bodies constructed from solid brass, stainless steel, or zinc alloy materials that withstand constant use in high-traffic environments.

During installation, the mortise lock body fits into a rectangular pocket cut into the edge of the door. This method provides superior strength compared to cylindrical locks because it distributes force across a larger area of the door. The body houses the latch mechanism, deadbolt, and all internal springs and levers that enable smooth operation.

When you select a lock body, consider the backset measurement (the distance from the door’s edge to the center of the cylinder hole). Standard commercial applications usually use 2 to 3/4-inch backsets, although you may encounter 2 to 3/8-inch or 5-inch backsets, depending on the door preparation.

This part contains the key-operated mechanism that controls access to your commercial space. Cylinder assemblies include the cylinder housing, plug, springs, and pins that create the unique keying system for each lock.

Commercial cylinders come in several formats. Rim cylinders mount on the door’s surface, while mortise cylinders thread into the lock body from the outside. Interchangeable core (IC) cylinders enable you to change keying without replacing the entire cylinder. For facilities that require frequent key changes, this feature is immensely valuable.

The cylinder’s security level depends on the pin configuration and construction quality. High-security cylinders incorporate additional features like sidebar mechanisms, mushroom pins, or specialized keyways, all of which resist attempts to pick or bump them. You’ll want to specify cylinders that meet your facility’s security requirements while maintaining compatibility with your master key system.

When you close a door, the strike plate anchors to the door frame and receives the latch and deadbolt. This component transfers the force from attempted break-ins to the frame structure, making proper installation critical for security performance.

Commercial strike plates need robust construction to handle the stress of heavy doors and frequent use. Look for plates made from 16-gauge steel or heavier, with reinforcement that extends deep into the frame. The strike box—the recessed area behind the plate—must provide adequate space for the latch and deadbolt to engage fully.

Depending on your door and frame type, you’ll encounter different strike plate configurations. Standard strikes work with most applications, but you may need specialized versions for narrow stile doors, hollow metal frames, or electric strike integration. Remember that the strike plate’s lip configuration affects how smoothly the door closes and how securely it locks.

The latch assembly controls the door’s basic closing function and provides the primary retention mechanism for everyday use. This spring-loaded component automatically engages when you close the door and retracts when you turn the handle or thumb turn.

Commercial latches must withstand thousands of cycles while maintaining smooth operation. The latch bolt itself—generally crafted from hardened steel—extends from the lock body into the strike plate. Anti-friction latches include a small auxiliary latch that reduces wear and helps the door close more smoothly.

The latch’s projection determines how securely it holds the door closed. Standard commercial latches extend 3/4 of an inch into the strike, though you may specify longer projections for enhanced security. Some applications require adjustable latches that accommodate variations in door and frame alignment.

The deadbolt is the primary security feature in commercial door locks. Unlike the spring-loaded latch, the deadbolt needs a deliberate key or thumb turn operation to engage or disengage. This makes it resistant to force attacks.

Commercial deadbolts feature solid steel construction with a minimum 1-inch throw—the distance the bolt extends into the strike. The bolt’s design includes anti-saw pins or hardened inserts that resist attempts to cut it. However, some deadbolts incorporate throw monitoring switches that integrate with alarm systems to verify proper engagement.

You’ll find deadbolts in single-cylinder (key outside, thumb turn inside) and double-cylinder (key on both sides) configurations. Double-cylinder deadbolts provide enhanced security by preventing unauthorized access from the inside without a key, but they may violate egress codes in certain applications. Before deciding on double-cylinder locks, verify code compliance.

The handle and trim components provide the user interface for your commercial door lock while contributing to the overall aesthetic of your facility. These elements must strike a balance between ergonomic function, durability, and visual appeal.

Commercial handles typically come in lever, knob, and pull configurations. Under heavy loads, lever handles offer superior accessibility compliance and easier operation. The handle connects to the lock body through a spindle that transfers rotational force to the latch mechanism.

Trim plates conceal the door preparation and provide a finished appearance. Also, they reinforce the door around the lock to distribute stress and prevent damage from heavy use. Choose trim materials that complement your facility’s design and provide the durability necessary for commercial environments.

For convenient egress that still maintains security, the thumb turn allows occupants to operate the deadbolt from inside without a key. This component typically features a textured grip surface and clear visual indicators for locked and unlocked positions.

Many commercial applications require key override capability on the thumb turn. This feature enables authorized personnel to unlock the door from inside using a key, even when the thumb turn has been removed or disabled. Key override systems help maintain security protocols while ensuring emergency access capabilities are available.

The thumb turn’s mounting method affects both security and maintenance. Removable thumb turns can be taken off to prevent unauthorized unlocking, while fixed units provide permanent inside access. Take the time to select the configuration that best aligns with your facility’s security protocols and operational requirements.

Armed with this complete guide to the parts of a door lock, you’re ready to select, install, and maintain commercial door lock systems that deliver reliable security performance. If you’re on the hunt for the perfect lock, reach out to Door Hub today! Our experts will help you find the perfect solution for your organization.