By Kent · Lock Depot Staff Writer

Walk a college classroom building between periods and watch the doors. Hundreds of hands an hour, backpacks shoving through, doors caught on the swing and yanked, levers hung on. That kind of traffic eats residential-grade hardware in a semester. You do not always need a mortise lock to survive it, but you do need Grade 1, and you need it in the extra-heavy-duty tier. The Corbin Russwin CL3300 Series is the extra-heavy-duty Grade 1 cylindrical lock built for exactly this door.

Extra-heavy-duty cylindrical, and why it earns its place

A cylindrical lock installs into the standard bored prep, the 2-1/8 inch cross-bore through the face and the 1 inch edge bore, so it fits the door most buildings already have without cutting a mortise pocket. The catch is that not all Grade 1 cylindrical locks are equal. The CL3300 is Corbin Russwin's extra-heavy-duty line, built with a heavier chassis and a stronger lever return spring than a standard bored lock, so the lever does not go sloppy and droop after a couple of years of abuse, which is the classic failure on a cheaper lock. Corbin Russwin is an ASSA ABLOY brand, the same house as Sargent and Yale, and the CL3300 is what I reach for when a door is going to get pounded but a full mortise is more prep and more money than the opening needs. On a campus classroom, a tenant corridor, a busy office suite, this is the sweet spot.

Function: classroom, storeroom, or passage

The function code lives in the model number, and three cover most of a building. Read them off how the room is used:

• CL3355, classroom. The outside lever locks and unlocks with a key; the inside lever is always free to exit. A teacher keys the door locked or unlocked from the hall. The CL3355 classroom function is the traditional lock for a classroom or lab where the room is controlled from outside.
• CL3357, storeroom. The outside lever is always locked and needs a key every time; the inside lever always exits. There is no unlocked state. The CL3357 storeroom function is for the supply room, the AV closet, the mechanical and IT rooms that should default to secure.
• CL3310, passage. No lock at all, both levers always retract the latch. The CL3310 passage function is for a door that needs to latch and pull closed but never lock, a lecture hall entry, a corridor cross-door, a restroom lobby.

Cylindrical or step up to mortise

Here is the honest line on when the CL3300 is enough and when it is not. The extra-heavy-duty cylindrical handles high traffic and abuse on a normal door all day long. Step up to a mortise lock, like the Corbin Russwin ML2000, when you need a function the cylindrical does not offer, when the door takes a deadbolt-and-latch combination in one body, or on a monumental or exterior door where the extra mass and the mortise pocket's rigidity are worth the cost and the prep. For the interior classroom and corridor door, the CL3300 gives you Grade 1 durability without paying for a pocket you did not need. Do not over-buy the whole building into mortise out of habit.

Lever and finish

The AZD in these SKUs is the Armstrong lever, a clean, ADA-compliant commercial lever with a solid return. Finish rides on the end: 626 satin chrome is the standard institutional finish and hides wear, with 605 and 606 brass, 613 oil-rubbed bronze, and 630 satin stainless available where the design calls for it. A less-cylinder (LC) option ships the lock without the cylinder so you can drop in your own campus keyway. Match the lever finish across the building so the doors read as one system.

Common questions

Is an extra-heavy-duty cylindrical lock as tough as a mortise?

For high-traffic interior doors, the CL3300 handles the abuse and installs into the standard bored prep. A mortise earns its cost where you need its extra functions, a deadbolt-and-latch body, or the mass for a monumental or exterior door.

What is the difference between classroom and storeroom function?

Classroom (CL3355) locks and unlocks from outside with a key and can be left unlocked. Storeroom (CL3357) is always locked outside and needs a key every time. Classroom for controlled rooms, storeroom for rooms that should stay secure.

Can teachers lock the door from inside during a lockdown?

Not with standard classroom function, which keys from the hall. Ask us about a classroom-security or intruder function that locks from inside the room, and tell us your lockdown plan so we spec the right function.

Can these be keyed to our campus system?

Yes. Give us the keyway and master system, or order the less-cylinder (LC) version and drop in your own cores.

Lock Depot stocks the Corbin Russwin CL3300 in classroom, storeroom, passage, and the other commercial functions, keyed to your system. Start at the Corbin Russwin hub, or if your doors call for a mortise body instead, read Corbin Russwin ML2000: Which Mortise Function for Restroom vs Office. Or call 877-365-5625 with the function, hand, and keying, and we will build the locks to match the building.