Electrically locking boom barrier for control of vehicle access

摘要

The electrically locking barrier has a moving barrier arm (2) that is raised to allow passage of vehicles and lowered to prevent passage. The underside of the arm has a loop (5) that enters a recess (8) in the top of an upright post that limits the downward movement of the arm when it is lowered. The loop under the arm is engaged by a cam (6). The cam is actuated by an electromagnet (4). The electromagnet is energised through a switch (7) operated by passage of the loop. When the cam engages the loop under the barrier arm the arm is locked in the down position.