Shear locks combine the power of an electromagnet with the strength of a mechanical interlock to produce a locking solution which can be used on bi-swinging doors. The electrified portion of the lock is mounted on the door frame, and the armature is mounted on the door. Most often the shear lock is mounted horizontally so when power is applied the armature is pulled up to the electromagnet. Therefore gravity works for releasing the lock, and against relocking it.
Initial adjustment of the shear lock is performed with the door aligned (zeroed) in the frame, and the height of the door at a particular point. Once the shear lock is in service, the door may eventually fail to close to the zero position, or it may wear on the pivots or hinges, and the gap between the armature and the electromagnet will increase. The result will be the shear lock will not operate as intended; the armature will not interlock with the electromagnet or the power of the electromagnet will not be sufficient to overcome the increased gap between it and the armature and the magnetic bond will not happen or it will be less than intended.
Electric bolts were once used extensively in door control. As with shear locks, alignment is critical for these to lock and unlock properly. The failure to lock is a security issue. The failure to unlock is a safety issue.
I still remember the very long Friday evening I spent carving up the door header brick, and plaster on an ornate lobby door when the electric bolt froze up in the locked position.
Besides the potential for an internal failure in an electric bolt, they may also be subjected to excessive side pressure from pedestrians ploughing into the locked door.
I have read in reliable industry reports that electric bolts have been outlawed in certain jurisdictions and if you encounter a defective one, to not simply install another one or repair it, but rather provide an alternative locking solution.
There are some quality electric bolts on the market, and in my market, electric bolts are not forbidden. Check with your AHJ, and be especially astute when you encounter an electric bolt, especially a defective one.
All security troubleshooting is as much an art as it is a skill. Experience is the best teacher, so my advice is for you to hurry up and get started
Important: Before installing electronic locks, it is important to check with the “Local Authority Having Jurisdiction” (LAHJ). An electromagnetic lock is designed to provide security for a...
Electromagnetic locks are sometimes regarded as an “idiot-proof locking solution” for unskilled installers or for use on problem doors.