Swing Gate Motor Types: Which Arm Fits Your Pillars?

Swing gate motor types at a glance

South African driveways use three swing gate motor types: linear rams, articulated arms and rotary operators. The right one depends less on brand than on three things at your gate: how deep the hinge sits behind the pillar face, how long and heavy each leaf is, and how much wind the gate catches.

This guide is not a model-by-model comparison. It explains how each arm type works, where it fits and where it causes trouble, so you can narrow the choice before looking at specific kits.

Start with the pillar, not the brand

Measure from the centre of the gate hinge to the inside edge of the pillar before choosing anything. Manufacturers call the limit "pillar maximum". If your hinge sits deeper than a linear motor allows, adjustment will not fix it, and you need an articulated arm or a rotary operator instead.

The limits are tighter than most people expect. Centurion's installation manual for the Vantage SMART range lists a pillar maximum of roughly 90mm for the 300mm-stroke model, 165mm for the 400mm model and 245mm for the 500mm model, all for a gate opening inward to 90 degrees. Ask for a wider opening angle and the allowance generally shrinks.

A gate hung on a thick plastered or face-brick pillar can pass the smaller figures without anyone noticing until installation day. Measure first.

• Hinge centre to the inside edge of the pillar
• Gap between the fully open gate and the nearest side wall
• Length and approximate weight of each leaf
• Whether the gate opens inward or outward, and how far
• Whether the leaves are solid or open (palisade, bars or mesh)

Linear swing gate motors: tidy, but fussy about geometry

A linear motor is the right choice when the hinge sits close to the pillar face and the leaf is light to medium weight. It mounts between a bracket on the pillar and a bracket on the gate, and gives the neatest finished look. It is also the least forgiving of awkward pillars and tight side walls.

The Centurion Vantage 400 single swing kit is a typical example of the type. Centurion publishes geometry tables that fix where the brackets go for each pillar depth and opening angle, and the manual says to use the motor's full stroke. Ignoring those tables is the usual route to trouble: a gate that will not open fully, or a motor working far harder than it should.

Side clearance matters too. The same manual asks for more than 200mm between the open gate and any side wall on an inward-opening install, because the motor needs somewhere to sit. For leaves wider than 3 metres, Centurion advises fitting an electronic gate lock. Plan the lock and its wiring at the start rather than retrofitting it later.

Articulated arm motors: the fix for deep pillars

An articulated arm suits gates hung on deep or wide pillars, where a linear ram cannot find a workable angle. The motor box sits on a post or pillar beside the gate and turns a crank arm, which drives a second connecting arm attached to the leaf. The jointed arm works around the pillar instead of pushing straight through it.

The Gemini single swing kit works this way. Gemini's installation manual has the motor carrier box mounted on a post, with the arm length set on site: the installer measures to the gate bracket in the closed and open positions, cuts the connecting arm to length and welds the gate bracket on.

That welding step is easy to overlook when planning. It makes the job less of a bolt-on than a linear ram, and on galvanised gates the weld burns off the zinc, so it needs treating afterwards. Near the coast, an untreated weld is usually the first place rust appears. Gemini rates its double kit for leaves up to 2.5 metres each, so very long leaves point to a different arm type.

Rotary operators: built for heavy leaves and wind

A rotary operator is the choice for heavy leaves and exposed sites. The motor sits beside the hinge on a pedestal or wall box and rotates a drive arm through the swing. It sits at the upper end of the price range and takes more space, so it is rarely the sensible default for a light, sheltered domestic gate.

The Centurion R6 rotary swing operator is Centurion's current rotary model, and the manufacturer positions it specifically for windy sites. It comes in standard torque (300Nm) and high torque (390Nm) versions, and can be retrofitted to sites running Centurion's older R3, R5 or MaxiMate units. That is useful if you are replacing an old operator rather than starting fresh.

Wind is where rotary operators earn their place. A solid leaf, whether steel sheet, timber or aluminium slats, catches far more wind than palisade or bars. On an exposed hilltop or coastal property, that load works against the motor every time the gate moves, and against the gate whenever it stands open.

Which arm type should you choose?

Choose on measurements first, then leaf weight and exposure, then appearance. If the hinge depth is inside a linear motor's limit and the gate is sheltered, a linear ram is usually the simplest answer. Deep pillars point to an articulated arm. Heavy or solid leaves on a windy site point to a rotary operator.

• Do not buy a linear ram if your hinge-to-pillar measurement exceeds the model's published pillar maximum, or there is no room beside the open gate.
• Do not buy an articulated arm if your leaves are longer than the kit is rated for, or your installer cannot weld on site.
• Do not buy a rotary operator if your gate is light and sheltered and the only appeal is that it looks more serious. A correctly installed linear or articulated arm will do the job.

Power is not a deciding factor between the three. The kits linked here all run battery-backed DC motors, so each keeps working through a power cut within its battery's limits. For sliding and swing options side by side, browse our full range of gate motors.