LiftMaster Swing Gate Arms — LA400, LA412 & LA500

A swing gate arm is a linear actuator: a motorized ram that mounts between the gate post and the gate leaf and pushes the gate open, then pulls it closed. LiftMaster builds three of them for residential and light-commercial driveway gates — the LA400, the LA412 and the LA500. All three run on 24 VDC with battery backup, use soft start and soft stop to reduce shock on the gate frame, and work with MyQ and Security+ 2.0 accessories. One arm per leaf: a single gate takes one, a bi-parting double gate takes two.

Which LA model do I need?

Gate weight by gate length

This is the specification most often quoted wrongly. The weight rating and the length rating are not independent — you do not get the maximum length and the maximum weight at the same time. The longer the leaf, the greater the leverage on the arm, and the less weight it will carry. Measure your leaf and read across.

Ratings are per leaf, for a level, free-swinging gate in good condition. A sagging leaf, a shifted post or a binding hinge will overload an arm that is correctly sized on paper.

What comes in a package, and what does not

LiftMaster sells these both as bare arms and as complete PKG kits, and the difference catches people out. A bare LA400DC or LA500DC is the actuator only — no control box, no board, no safety devices. A PKG kit is the installable system.

Second gate leaf, no trench: the primary and secondary arms communicate wirelessly, so a double gate does not need conduit cut across the driveway.

UL325 and monitored safety devices

These operators are UL325 compliant for Class I through IV, but compliance is conditional on the monitored entrapment protection being installed and working. A photo eye or edge that is missing, misaligned or unmonitored will put the operator into a fault and, on current boards, stop it running at all. If your gate has started refusing to close after a repair, check the eyes before you suspect the board.

Common questions

One arm or two? One per moving leaf. A single-swing gate takes one arm; a bi-parting pair takes two.

Can I run an LA400 on solar? Yes, with an add-on kit, but the LA412 is engineered for it and manages power better. If the gate has no AC and cycles more than a few times a day, start with the LA412.

How long does the battery backup last? Days of standby, or a few hundred cycles, depending on which accessories draw from the board. Cold weather shortens it considerably — below freezing for extended periods, 33 Ah batteries are specified in place of the standard 7 Ah.

Do I need an electrician? The gate-side wiring is low voltage. The 120 VAC supply to the control box still needs to meet local code.

My gate drags or judders. Almost always the gate, not the operator — a sagged leaf or a moved post. An arm forced to fight a binding gate will fail early. Fix the structure, then reset the limits.

Parts, boards and accessories

Replacement control boards for this family are the K1D8052-1CC and the K1D8388-1CC, with the K1D8387-1CC expansion board for the added-input configurations. Boards changed across generations — read the number printed on the board in your control box rather than ordering by model name.

Also see: LiftMaster gate operator parts · LiftMaster solar gate operators · LiftMaster remotes

Questions on sizing a gate? Call 866-965-5599.