The doors are located in the corridors of a transportation complex where dramatic changes in air pressure cause doors to slam, closers to fail and door locks to vibrate so much that their case screws loosen and sometimes fracture. As a result, the components disengage, often resulting in mortise lock failure.
Rubber gaskets and screw adhesives failed to resolve this problem. Then the locksmiths decided to convert two of the mortise locks to cylindrical lock door prep for the SARGENT T-Zone locks. Each lock conversion door prep required two face (Remodeler) plates, a full opening ANSI strike plate and a filler plate for the door edge. A decision was made to use Don-Jo Mfg. parts for this installation.
The Remodeler plates are flat, 3-1/2" by 9", manufactured of stainless steel with an opening to accommodate a cylindrical lock in the center. For this installation, these plates are large enough to cover the mortise lock openings. The offset filler plate provides two choices for locating the 2-1/8" cross bore. This increases the likelihood of finding metal for the hole saw pilot bit. In addition, for some doors, offsetting the lock and latch may limit the amount of reinforcement that must be removed.
The SARGENT T-Zone is an ANSI Grade 1 bored-in cylindrical lever lock designed to fit in a standard 161 door prep, operating without thru-bolting. The non-handed T-Zone lever lock incorporates interlocking construction, having the latch assembly installed into the lock body (bearing assembly). Because of the interlocking construction, the SARGENT T-Zone requires only 45- degree lever rotation to fully retract the latch.
Note: The T-Zone for this installation was configured for a Best-Falcon interchangeable core. This T-Zone will accommodate a six- or seven-pin core.
The SARGENT T-Zone lever lockset has a cast stainless steel bearing assembly, latch assembly head, and sleeves. The levers are manufactured of solid zinc die cast. The T-Zone lock's standard configuration is a 2-3/4" backset into 1-3/4" to 2" thick doors. The T-Zone locksets can be ordered for 2-1/4" to 2-1/2" thick doors. This lever lock comes with a 1/2" throw stainless steel latch bolt. The front of the latch bolt is self-adjusting up to a 1/8" bevel to accommodate the door edge. For pair of doors, a 3/4" throw latch bolt is available.
To maintain an at-rest horizontal lever position, the bearing assembly has four torsion springs. To accommodate new construction and retrofit applications, the T-Zone is available with three sizes of roses: 2-3/4" and 3-1/2" diameter and 3-1/8" square. The 3-1/2" diameter rose is designed to cover existing door prep that has thru-bolting.
For this installation, the T-Zone lever lockset was ordered in the storeroom function, configured for Arrow/Best/Falcon Interchangeable Cores, with the 3-1/2" diameter roses.
The door into which the T-Zone was installed contains mortise pocket reinforcement. For this door, the reinforcements were steel plates forming the pocket and lock support clips to strengthen the door around the mortise lock body and keep the mortise lock body centered in the door cavity.
IMPORTANT: When drilling through a heavy-gauge hollow metal door or reinforcement using a hole saw, drill at a speed between 500 and 600 rpm. Should the hole saw jam, a 500 to 600 rpm drill motor will probably cause minimal damage, whereas a 1,500 rpm or faster drill motor could result in a battered if not broken wrist.
When drilling, spray a lubricant occasionally to keep bit cool. This increases cutter longevity, and improves the cut.
For this article, the SARGENT T-Zone lever lockset was installed into a hollow metal door prepped for a mortise lock. The T-Zone lockset requires a 2-1/8" cross bore with a 1 inch edge bore. The T-Zone lever lockset comes partially assembled, and must be disassembled prior to install into the door.
Step 1. Unscrew the inside collar and remove the inside sleeve from the bearing assembly.
This modification provided the capability of a deadbolt and dead latch in one lock (mortise) mechanism while maintaining the integrity of the door.