Cam Locks: The Turning Tab Behind Cabinets, Drawers and Panels

Parts of a Cam Lock

A typical cam lock has three parts:

• Cylinder. It holds the keyed mechanism and passes through the panel.
• Mounting hardware. The CompX catalog lists mounting nuts for some models and spring mounting clips for others.
• Cam. The tab fixed to the back of the plug.

Manufacturer catalogs show how much variation fits into that basic design. CompX National's StockLocks catalog lists cams in several families:

• straight cams;
• straight hook cams;
• single formed cams;
• double formed cams, which are offset so the tab sits at a different depth from the cylinder.

The right cam depends on how the panel is built. CompX matches straight cams to "lipped/overlay construction" and formed cams to "flush construction," where the door sits inside the frame. Its catalog notes one more limit for overlay doors: the combined thickness of the front and frame "cannot exceed the cylinder length."

How Much the Key Turns

Most cam locks turn a quarter turn. CompX lists "90° cam turn" for its disc tumbler cam locks, with the key "removable in both locked and unlocked positions."

Some designs separate the key turn from the cam turn. For one line of pin tumbler cam locks, CompX explains that "through the use of a shifter, the 360° key turn turns the cam 90° in either direction." The installer decides which cam position is locked. Each lock comes with an alternate cam for the opposite direction.

Tumbler Types

"Cam lock" describes what the lock does, not the mechanism inside the cylinder. One CompX catalog contains separate sections for:

• Disc tumbler cam locks. "Disc tumbler" in this catalog refers to flat sliding tumblers, which this encyclopedia covers under wafer locks. It is not the rotating-disc disc detainer design.
• Pin tumbler cam locks. These use the same principle as a pin tumbler lock.
• Interchangeable cylinder locks. In one CompX drawer lock, the cylinder can be "attached or removed through the use of a special key at back of lock." Building-scale versions of this idea are covered under interchangeable cores.
• Combination cam locks. CompX's "keyless combination cam lock" can be opened by a combination or by a key. See combination locks.

Keying options appear in the same catalogs. CompX lists keyed-alike, keyed-different and master-keyed options, and says its pin tumbler locks "will key together" when they share a key blank. For how those hierarchies work, see master keying.

Lockwiki notes that cam locks are "generally considered low-security," while some manufacturers, including Medeco and Abloy, offer more advanced versions.

The Standard: ANSI/BHMA A156.11

In North America, cabinet locks, including cam locks, are covered by ANSI/BHMA A156.11, Cabinet Locks. The full text is sold by BHMA. Its public "Hardware Highlights" summary of the 2024 edition says:

• The standard covers "cam, chest, drawer, cabinet door, file cabinet, lever and tee handle, locker, and sliding door locks," and which tests apply depends on the lock type.
• Grade 1 locks "must pass a rigorous test through 40,000 cycles."
• There are seven strength and security tests, "including a 1,200 in-lbf locked lever torque and two directions of impact."
• Purchasers can check certification through BHMA's certified products directory.

A156.11 is a durability and strength standard. BHMA's summary does not describe pick-resistance testing. For locks rated on that basis, see UL 437 and high-security locks.

Related Topics

• Wafer locks
• Pin tumbler locks
• Tubular locks
• Interchangeable cores
• Combination locks
• Master keying
• Medeco
• Abloy
• UL 437
• High-security locks

Sources