Openers · Hamilton
Chain-Drive Opener Repair
The rail shakes when the door runs.
In plain words
The most common chain-drive failure happens out of sight. Inside the motor head a plastic drive gear meshes with a steel worm on the motor shaft, and after years of lifting a door that has grown heavier its teeth wear away. The motor keeps running, but the sprocket above it turns weakly or not at all, and pale shavings collect under the cover. The repair fits a new gear and sprocket assembly made for that model, greases it properly, and then asks why the gear wore out. Usually the answer is a door that needs spring attention, and settling that is what protects the new gear.
How the visit goesThe rail shakes when the door runs. The steel straps holding it to the ceiling have worked loose, the chain rattles the length of the garage, and a bolt has already dropped onto the hood of the car.
Chain-Drive Opener Repair
How the visit goes
Where the door stops and how hard it pushes
Two settings on the head decide the door's behaviour, and both are checked against what the door is doing. Travel limits set where the door stops in each direction; a door that stops shy of the floor, reverses on touching it or opens partway is out of adjustment. Force sets how much effort the operator treats as normal; too little and the door reverses for no reason, too much and the operator stops noticing an obstruction. The technician notes the current screw positions or the learned values, watches a full cycle and compares what the door does with what the settings say, before deciding whether the fault is in the drive parts or only in the settings.
Bringing the chain back into phase
If the drive has been run without the chain on the sprocket, the motor and the trolley disagree about the door's position and the door travels partway no matter how the limits are set. The technician slackens the chain and lifts it off the sprocket, then runs the operator and watches the sprocket: when it turns and stops on its own in the closed direction, the motor is at its closed position. The trolley is moved to the closed end of the rail, the chain is refitted over the sprocket, and tension is set. On some heads the internal limit assembly is aligned instead. The limits are then adjusted so the door reaches the floor and its full open height.
Getting the chain drive through the cold
In a detached or unheated garage the drive has been set up for winter: force adjusted so the door moves at low temperature without the operator being oversensitive, the rail greased, and the door hardware lubricated before frost. Two habits help. Keep the threshold clear of snow and slush so the bottom seal does not freeze to the slab, and if the door reverses on a bitter morning, free the seal rather than pressing the button repeatedly; the operator is doing what it should. Expect the chain to sound a touch different at minus twenty, and let the garage warm before deciding something is wrong.
Chain-Drive Opener Repair
In the van
RPM sensor
Idler sprocket or pulley
Rail hangers and header bracket
Cold-rated garage door lubricant
Chain tensioner nuts and shaft
Chain-Drive Opener Repair
What affects the quote
Which parts of the drive have worn
A chain that only needs tensioning, a chain that must be replaced, and a stripped gear and sprocket assembly are three different jobs, and the inspection under the head cover decides which one the quote describes.
Door work found at the balance check
If the door is heavy or drops when lifted by hand, spring adjustment or replacement is quoted as door work in its own right, ahead of the drive repair that depends on it.
Age of the operator and parts supply
Parts for recent heads are on the van; parts for a unit several decades old may need ordering, and where a maker no longer supplies them the conversation turns to what can be done instead.
What to have ready
- Does the door stop short, reverse at the floor, or open only partway?
- Does the motor run when you press the button, and does the door move at all?
- Is the garage attached and heated, or detached and unheated?
Chain-Drive Opener Repair: questions
QuestionsIs a chain drive supposed to be this noisy?
A chain drive has a steady mechanical sound that a belt drive lacks, and that much is normal. What is not normal is change: a slap along the rail from a loose chain, a clack at one spot from a worn sprocket tooth, grinding from the head as a gear wears, or a rattle from hangers or a header bracket that have loosened. Each of those has a fix, and a repaired chain drive should sound the way it did when it was new.
Why does the door open only partway and stop?
Three causes account for most cases. The up travel limit has drifted short and needs turning out. The door has become heavy or stiff somewhere in its travel, so the operator senses resistance and stops, which points to the springs, rollers or track. Or the chain has slipped out of phase with the motor, in which case the limit screws have no effect and the chain must be re-set on the sprocket with the trolley at the closed position.
Why does the door jerk or jump at the same spot every time?
A repeatable jolt at one point on the rail is usually a chain problem meeting a sprocket problem: a stiff link or a spread master link passing over worn sprocket teeth, so the chain rides up and drops a tooth. It can also be a burr or a splice plate on the rail where the trolley catches, or a roller on the door hanging up in the track at that height. The technician runs the door by hand first to tell the two apart.
Related services
- Belt-Drive Opener RepairPress the remote and the motor runs its full cycle, lights on, the usual whir, but the door does not move a centimetre.
- Garage Door Opener ReplacementPress the button and the motor hums, but the door stays exactly where it is.
- Photo-Eye Sensor Alignment or ReplacementThe door will only go down while a finger stays on the wall button; let go and it stops or reverses.