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A sliding door actuator is a mechanical device designed to remotely open and close sliding access barriers, such as gates and doors. These devices are typically motor driven and feature a pair of pulleys around which a continuous flexible belt runs. Brackets are attached to the belt and the door so that when the motor turns the belt moves pulling the door along with it. The sliding door actuator will generally include at least two sets of safeguard mechanisms that prevent the door from opening or closing beyond its limits or colliding with any obstructions in its track path. Many high-traffic systems also include automated operation via proximity sensors that open and close the door when someone approaches or leaves the door area.
Sliding pedestrian access doors in homes, shops and commercial complexes as well as the doors on elevators are very often automated relying on a sliding door actuator for their operation. These doors include most of the sliding barrier types such as exterior single and double leaf and single or double pocket designs. The actuators which operate these doors are, more often than not, belt and pulley types although rack and pinion or worm gear actuators are sometimes used on very heavy security barriers.
The belt-and-pulley sliding door actuator is the most common type of sliding door operator and consists of an enclosed square channel located at the top of the door sill that contains the actuator mechanism. This mechanism is typically made up of a small electric motor located at one end of the channel, which drives a toothed pulley through a reduction gearbox. The gearbox allows the speed of the motor to be dropped while increasing the output torque of the actuator. A second, non-driven guide pulley is located at the other end of the channel. A flexible rubber-toothed belt passes around both pulleys with a set of flat brackets attached to it between the pulleys.
These brackets mount onto the top edge of the door and, as the motor turns and moves the belt, pull the door along on a set of guide rollers located at the top and bottom of the door frame. In other words, when the motor turns in one direction, the door will open, and, when it is reversed, the door closes again. The fully open and closed positions will be controlled by a set of sensors that will cut the motor when the door reaches those points. An additional safety sensor is usually also included, which prevents the door closing on any obstruction in its path. Many sliding door actuator systems, particularly in very high traffic areas, include additional sensors that detect people approaching and leaving the door area, opening and closing the door automatically.