Gate Systems

The rolling or sliding style is better suited for areas where space is a premium, as it does not require the opening space of a swing style gate.

Movie stars, politicians, professional athletes, parking lots, and apartment complexes have them: mechanized gates that provide security to entrances. These gates are powered by electric controllers that communicate with mechanical gate operators to open the way to visitors and residents.

Generally, three kinds of gates make up the bulk of manufacturers' catalogue: swing gates, sliding gates, and barrier (lifting) gates. The efficiency of the device that opens the gate panel, or gate operator is based not only on the design of the product, but the installation of the gate.

The FAAC Model 750: The Rotary actuator installed below finished grade, functions as a power hinge, with hydraulic pumps installed in a remotely located control cabinet. All copper tube hydraulic plumbing and control wiring are below ground, which provides for a clean installation, not visible from either side of the gates.

To control gate operation, a gate controller must also be installed. Shown here is FAAC Model 400 gate automation control panel, which features a 24 x 16-inch steel lockable weather tight enclosure housing a 220v disconnect switch, 110v duplex receptacle, required circuit boards, gate operator microprocessor, surge protection, cycle counter, hold-open relay, and interface modules for access control & alarm system outputs.

Barrier (lifting) gates are those often seen at parking lots. They are basic machines (sometimes run by human operator that takes your money) with a swinging arm that rises to let a vehicle pass. Residential gates are usually of the swing or slide variety, depending on the space available.

The gate industry debates the criteria for choosing a gate operator. While industry standards dictate that fence operators be chosen based on the weight of the gate, the size of the opening, and the duty cycles of the operator (how much it opens and closes), some professionals believe the criterion should be based on the force used to open a gate.

Manufacturers make gate operators with different handling capacities. While one side-arm swing-gate operator may be able to handle a 16-foot panel weighing 600 pounds, another company's model may only be able to handle a 12-foot gate weighing 400 pounds. However, many companies throughout the world produce variations of the three main gate types.

This RoboSwing R900 light-duty, commercial, gate operator from Elite Access Systems, Inc., is equipped with an automatic closing timer, two-way reversing sensor and electronic shut-off system. The operator runs off a 12-volt battery that can be charged through the solar panel or plug-in transformer.

The Model 415 swing gate operator from FAAC is designed for residential applications, its features include: Sealed limit switches, slow down ''soft stop'', reverse on contact, sleek design and a battery back-up unit.

Slide-Gate Operators

Slide-gate operators are available with a mechanical or a hydraulic motor. A chain-driven slide-gate operator is opened by a mechanical motor, which pulls a chain along an open circuit around three sprockets. Using a pulley-type system, the operator uses tension to open and close the gate.

Swing Gates

Other popular gate models fall into the swing gate category. Swing gates require more room than slide gates, but also provide an elegant and dramatic entrance to a facility. Depending on the positioning of the entrance, swing gate panels and operators must be configured to open at the correct angles so as to fit within the corridor. Swing gates operator models include the linear actuator operator, the side arm operator, and in-ground, concealed operators.

Side-arm operators are often outfitted to handle heavier traffic than their fellow swing models. An arm attached to a gear-driven motor opens and closes the gate.

In the drive-rail slide-gate operator, a rail is attached to the side of the gate between three spring-loaded wheels (two on top of the rail, and one on the bottom). As the operator turns these wheels concentrically, it pulls the rail through in a manner similar to getting one's tie caught in the paper shredder.

The two main types of gates a landscaper would be specifying and installing are the swing gates and sliding (rolling) gates. The swing gate style shown here is opened with either an swing-arm motor or an actuator.

The Linear Actuator Operator

These are usually installed on a lower-traffic gate. These operators less noticeable, as they are attached to the post and the fence panel and lack a ground mounting. Linear actuators are available in screw-drive models, which includes a threaded rod strung around a gear that moves the operator open and closed (like a garage door), and a hydraulic linear actuator, which uses water pressure to function. Linear actuators generally move slower than side-arm operators, and usually require positive stops, or physical obstructions, to stop the gate from swinging open too far.

Concealed swing gate operators are generally buried side-arm operators with the tops exposed. Some operators have three-inch arms that open the gates. According to Sullivan, these gates are not as efficient as the other gates, wasting power and wearing out the bearings (not to mention getting worn down in snow).

Sullivan describes how in Europe, concealed swing gateposts are mounted directly on the operator, eliminating the need for an arm. He also says that Europeans gates tend to include sealed bearing hinges and a sealed track. Although this is more costly, the gate performance ends up being much more efficient, he says.

Another concealed model, such as the FAAC 750, uses a small hydraulic pump operator positioned beneath the gatepost, while the drive unit is hidden underground (see photo).

The Controller

However, the operator does not act alone. Operators are employed by the controller, which usually uses a telephone line to send information back and forth. The controller is the ''brain,'' or the primary device. The controller is attached to the arming loop, which in the ground on either side of the gate. An inductive field is continually created by this loop. However, when a vehicle pulls up on it, the inductive field is temporarily interrupted, almost like stepping on a hose while the water is running. The controller senses the break in the field, which indicates that it is to tell the gate operator (the secondary device) to open. If the gate requires an active form of access control, or a keypad, remote control, etc., the effect is the same. The controller registers a change and flips from its ''closed'' mode to its ''open'' mode.

Gate operators come in many models, but with the correct installation and choice of device, a gate could provide desired safety and beauty to a property for a long time.