I really do not mean to make this post technical; but It doesn’t really matters what kind of automatic gate opener you have in mind; they all are in need of a motor.
The gate motor is the core of the whole system. It is in charge of providing the mechanical power responsible for opening the door; regardless of the controls and electronics. Selecting the gate motor an important task; specially if you are thinking into automate a custom made gate. Usually this type of gate is heavy and requires some good amount of horsepower.
Like any other electrical motor, we need to take into consideration some facts that are usually overseen, such as the motor efficiency, the torque and the output of energy it provides.
The truth is that, eve if these facts are important, you really don’t care about them as automatic gate openers are sold in kits; but there are some times in where you are on special needs, as in when you have a custom made iron gate that weights a ton.
There are two types of electric gate motor as far as I know. They all work with a wide variety of swing gates and sliding gates. Swing gate motors come in two basic styles: Linear and Articulated. An Articulated Arm style automatic gate motor is pad mounted and more suited to heavier than normal gates and high use situations. The idea is to have a set of sprockets and gears that reduce the mechanical tension on the gate motor and adjust torque and speed like a car transmission.
Also, depending on the use cycle, the gate motor may be electro-mechanical or electro-pneumatic on a swing gate. Electro-mechanical devices are designed for light to middle duty as residential and commercial use. Due to the energy input and the leaser tear and wear on pneumatic systems, the electro-pneumatic actuators are often seen in heavy duty industrial applications and custom made iron gates as well. This are not recommended for wood and wooden framed gates.