Marks USA Classroom Intruder Series Locks

May 1, 2006
Teachers can lock or unlock their classroom doors from the inside for added safety in an emergency.

Marks USA developed the Intruder Series Locks to improve the level of safety and security in the classroom. During an emergency situation, school personnel are able to restrict access from within the classroom when each door is equipped with a Marks Intruder Series Lock. The exterior lever is disabled by operating the interior lock cylinder, unlike standard classroom function locks that require the exterior lock cylinder to be operated in order to enable or disable the exterior trim. During an emergency situation, having to open the door in order to lock it is not a good idea. For the Intruder Classroom function locks as well as the standard Classroom function locks, the interior lever is capable of retracting the latch at any time.

NOTE: Requiring a key to lock or unlock the exterior trim eliminates the possibility of the teacher being locked out of the classroom.

The Intruder Series Locks are available as cylindrical locks and mortise locks. The cylindrical lock function is the ANSI #F110 (Marks USA function DB). The F110 Classroom Intruder function is deadlocking latch by lever either side, except when outside locked by key inside. Key outside locks or unlocks outside; inside is always open.

Two double-cylinder mortise lock Intruder Series functions are available: the ANSI #F32 Intruder Latch Bolt (Marks USA function GC) and the ANSI #F34 Intruder Dead Bolt (Marks USA function FA). Both the F32 and F34 function mortise locks operate the deadlocking dead latch in the same fashion. The F34 Intruder deadbolt can be operated by the key from either side; the inside is always open.

The Marks Intruder is a double-cylinder cylindrical lockset built to ANSI/BHMA Grade 1 specifications. This lockset can be ordered with levers that meet the ADA, Life Safety and local jurisdiction codes. It is designed for a 2-1/8" cross bore opening with 5/16" thru bolts at 12 and 6 o'clock in doors with thickness from 1-5/8" to 1-7/8". For 1-3/8" thick doors, Marks offers a set of spacers. The Marks J295 installation tool is designed to locate the through bolt openings using the cross bore opening as the guide in wood and hollow metal doors. This tool is designed to operate with any backset.

The Marks Intruder mortise locks meet or exceed ANSI/BHMA 156.13 Grade 1 specifications. These mortise locks are UL Listed three-hour fire rating, and available with a variety of trim options. The case is manufactured of stamped steel. The front is 1-1/4" by 8". The bevel is adjustable. Four thru bolts are used to not only strengthen the operation, but also to secure the trim to the door.

The Intruder mortise and cylindrical locks are designed for abusive conditions. The cylindrical lock is equipped with the Marks clutch system, which disengages the outside lever, allowing it to turn freely without engaging the latch mechanism. The latch mechanism is constructed with a cast stainless steel retractor having bronze roller bearings. These Grade 1 thru bolted cylindrical locks are equipped with a 3-7/16" diameter rose. Contained within each rose is a proprietary high strength lever support spring.

The mortise lock bodies are equipped with override guard/spindle assembly manufactured of .125" thick case hardened steel. The guard/spindle assembly engages the hub follower and thru post stop that protects against unlimited torque. The stainless steel anti-friction latch has a 3/4" throw. Deadbolt equipped mortise locks have a one-inch throw. Mortise locks are equipped with independent exterior and interior lever support springs.

For this article, we will install the Marks Classroom Intruder Function cylindrical lockset onto the provided mount. The mount has been predrilled and mortised for the latch front. This lockset requires a 2-1/8" diameter cross bore opening at 2-3/4" backset, two 5/16" diameter thru-bolt openings, and a one inch diameter edge bore opening for the latch bolt. The Intruder lockset is factory set for a 1-3/4" thick door.

Note: The levers come pre-assembled in the box. The interior rose is separate to insure proper assembly.

  1. Remove the inside lever by inserting the key and rotating the plug a quarter turn. Depress the lever catch.
  2. With the lever catch depressed, pull the lever off the lockset.
  3. Carefully remove the inside rose assembly.
  4. Install the latch into the mount. Secure using the two Phillips head screws.
  5. Slide the lock housing into the cross bore opening, making sure the thru bolts (rose posts) slide into the openings. The retractor must engage the latch tail, and the latch prongs engage the inside lock housing. Check to make sure the latch retracts.
  6. Slide the inside rose assembly onto the spindle. Secure using the two Phillips head screws.
  7. Install the rose cover onto the inside rose assembly. The notch in the rose cover must align with either the notch at the 3 o'clock or 9 o'clock positions in order for the cover hole to align with the lever catch.

IMPORTANT: When completing the following steps, be sure the key is removed from the outside lock cylinder.

  1. Insert a Phillips screwdriver into the inside key cam slot and turn counterclockwise as far as possible. This times the inside mechanism with the outside lock cylinder mechanism.
  2. Insert the key into the inside lever lock cylinder.
  3. Rotate the key approximately one-quarter turn counterclockwise.
  4. Slide the inside lever onto the lever tube. The lever should click into place as the lever catch latches. Test the operation of the outside and inside levers using a key to be certain they are properly timed.

Using the key in the outside lever should engage and disengage the outside lever. Using the key in the inside lever should also engage and disengage the outside lever. If not, repeat steps eight through 11.

The Intruder Function cylindrical locksets accept many other original equipment standard, high security and interchangeable core cylinders using the Marks adapter tailpieces. The Grade 1 factory standard is the Marks "C" keyway six-pin lock cylinder. The Intruder Function cylindrical locksets are available in six- or seven-pin interchangeable core models for Best™, Corbin/Russwin, Keymark™, Schlage, and Yale.

The Intruder Function latch bolt and deadbolt mortise locks are handed. The handing is field changeable without requiring any additional parts.

Marks USA Classroom Intruder Function cylindrical locksets and mortise locks have a lifetime mechanical limited warranty.

For more information, contact your local locksmith wholesaler or Marks USA, 5300 New Horizons Blvd, Amityville, NY 11701. Telephone: 631-225-5400 or 800-526-0233. Fax: 631-225-6136. Web site: