In short:
- Most gate lock trouble starts with the gate, not the lock: a dropped hinge side, a bent stile or grit in a track pushes the bolt out of line with its keeper.
- Take the load off before you blame the key. Lift or push the gate gently while you turn, and note whether that changes anything.
- Trellidor's care advice says plainly: do not spray into the keyhole of the cylinder. Use only what the gate or lock maker specifies, and only where they say.
- A slam lock can lock you out with the keys on the wrong side. Know which type of lock your gate has.
- If the gate is still under the maker's warranty, speak to the supplier before anyone else works on it.
One lock, a lot of steel around it
A security gate lock lives a harder life than a door lock. It sits outdoors or in a draughty passage, the gate it is fitted to is heavy, and on many properties the gate gets pulled, pushed and slammed dozens of times a day. At home that usually means a hinged trellis gate in front of the kitchen or patio door, a retractable gate across a sliding door, or a pedestrian gate in the boundary wall. On business premises it is often a steel gate to a loading area, a staff entrance beside a roller shutter, or a palisade gate into a yard.
Because the lock is only one part of a moving assembly, the fault you notice at the keyhole is often caused somewhere else. Many causes can be spotted without taking anything apart.
Typical complaints include:
- the key goes in but will not turn, or turns only partway;
- the key turns but the gate stays locked, or the bolt will not shoot out;
- the gate locks only if you lift it, push it or lean on it;
- a retractable gate is hard to slide, so it never quite lines up to lock;
- the slam latch no longer catches, or catches and then will not release;
- the key is bent, worn or has snapped off inside.
Reading the symptoms
Use this table to narrow things down. It is a guide to likely causes, not a diagnosis.
| What you notice | Common causes | What you can safely look at |
|---|---|---|
| Key turns when the gate is open, but not when it is shut | Bolt pressing against the keeper because the gate has dropped or the frame has moved | Whether the gap between gate and frame is even from top to bottom |
| Gate only locks when lifted | Worn or loose hinges, a sagging leaf, a bent stile after a knock | Hinge pins, rubbing marks on the frame, fresh scrapes on the paint |
| Retractable gate is stiff to slide and hard to lock | Dirt or debris in the top or bottom track, dry moving parts | Leaves, sand or stones in the track; whether the leaves fold evenly |
| Key is stiff in every position, even with the gate open | Worn key, dust or corrosion in the cylinder, a worn lock mechanism | Whether the spare key behaves differently; the key's edges for wear or bending |
| Slam latch no longer catches | Keeper out of line, broken spring, latch damaged by a hard slam | Whether the latch springs out fully when the gate is open |
| Key snapped or stuck in the lock | Old or cracked key, force used on a stiff lock | Whether any of the broken piece is visible (do not dig for it) |
Where things go out of line
On a hinged gate, weight pulls the free end down over time, especially if people swing on it or it gets bumped by a car or a pallet jack. On a retractable gate, grit in the track stops the leaves closing fully, so the lock stile never meets its receiver squarely. In both cases the bolt is being asked to slide while something is pressing on it, and the key takes the strain.
Safe checks before you call
These are observations, not repairs. Stop if anything feels like it needs force.
- Look at the gap. With the gate shut, is the gap between the gate and the frame even? A wedge-shaped gap points to sag or a bent frame.
- Take the load off. Gently lift the gate at the lock side, or push it towards the frame, and try the key again. If it turns easily, the lock is probably fine and the alignment is the problem.
- Try the spare key. If the spare works smoothly and the everyday key does not, the everyday key is likely worn or bent.
- Check the track. On a retractable gate, look for sand, leaves or stones in the top and bottom tracks. Brush loose debris out by hand.
- Watch the latch or bolt. With the gate open, does the bolt or latch move fully in and out when you work the key or handle? If it does, the fault is in the fit, not the mechanism.
- Think back. Did it start after a storm, a knock, building work or a new gate motor nearby? That helps the technician narrow it down.
If the key won't turn in other locks around the property either, our article on a key that won't turn or a stiff lock covers door cylinders in more detail.
What makes a gate lock worse
- Spraying things into the keyhole. Trellidor's care guidance for its gates warns against spraying into the keyhole of the cylinder. Its own lubricating spray is for hinge points, channels and tracks. Other gate and lock makers have their own instructions, and they are not all the same, so check the maker's guidance for your gate rather than reaching for whatever is in the garage. General oils can collect the fine dust that blows across Highveld yards and turn into paste.
- Harsh cleaners. Trellidor also advises against abrasive, detergent-based or solvent-based cleaners, which it says can shorten a gate's life.
- Forcing the key. Turning harder, or using pliers or a screwdriver through the key's bow, is the classic way keys snap inside gate locks.
- Kicking or slamming. Slamming a gate to make a slam latch catch can bend the keeper and the latch further.
- Welding near the lock. Heat from a welding repair on the stile can damage the lock and its finish. Remove the lock first or ask whoever is welding to keep well clear.
- Leaving it. A gate that locks only when lifted gets worse, not better. Eventually it will not lock at all, or will not open.
Slam locks, deadlocks and getting locked out
It helps to know which kind of lock your gate has. A slam lock locks itself when the gate closes. A deadlock only locks when you turn the key.
Trellidor, which fits deadlocks as standard on several of its retractable gates, points out the main drawback of slam locks: it is easy to lock yourself out by accident, and a child can lock someone in or out. Some slam-lock gates also need two keys in two locks, which tempts people to use only one in a hurry. That is the maker's view, and it sells the alternative, but the lockout risk is easy to picture: keys on a hook inside, a gust of wind, and a gate that has locked itself.
If a security gate covers the only way out of a room or a building, everyone inside must be able to reach the key quickly, including at night. Keep a key in a fixed spot on the inside, out of reach from the outside, and make sure staff on every shift know where it is.
Repair, replace, or call the gate supplier?
Once the cause is clear, there are usually three routes:
| Situation | Usual route |
|---|---|
| Lock works, gate out of line | Realign the keeper or adjust the fit; if the gate itself is bent or the hinges are worn out, we repair that too, though heavy damage may need a welder |
| Lock mechanism worn, rusted or broken | Repair the lock if parts allow, or replace the lock body |
| Keys lost or unaccounted for | Replace the lock or cylinder so old keys no longer work |
| Gate under the maker's warranty | Contact the supplier first: Trellidor, for example, says lock changes should be done by a professional technician through your supplier |
If the lock needs replacing, choose one made for gates. ASSA ABLOY describes its locally made Union 5-lever gate lock as SABS approved, with an anti-saw feature protecting the deadbolt, and suitable for retrofitting to existing gates. Whatever you choose, match it to the gate's lock box, handing and fixing points.
Booking a technician: what helps
Send a few photos before the visit, by WhatsApp if that's easiest:
- the whole gate, closed, so the gap and any sag show;
- the lock box and keyhole, close up, including any brand name;
- the keeper or receiver on the frame;
- the key, both sides, and the broken piece if it snapped;
- for a business gate, how the technician gets to it: the park gatehouse, the yard entrance, who will meet them.
Our lock repair service covers stiff, misaligned and damaged gate locks, lock replacement covers fitting a new gate lock or cylinder, and broken key extraction deals with a key snapped inside. If you're stuck outside or inside a gate, we try non-destructive entry first and ask for proof of residence or authority before opening anything.
As a fully mobile locksmith in Kempton Park, we come out to you 24/7. There's an R250 call-out, the technician quotes on site before any work starts, and nothing is done until you agree. Payment is by EFT, cash or card.
A gate lock that fails right after a break-in is a different job. See securing your home or business after a break-in.
Questions
Can I spray something into the gate lock to free it?
Not into the keyhole. Trellidor's guidance for its gates is not to spray into the cylinder's keyhole, and other makers have their own instructions. Check the maker's care advice for your gate and lock. If the key is stiff, first check whether the gate is out of line.
My gate is a few months old. Should I call a locksmith or the installer?
Call the installer or supplier first if the gate is still under warranty. Work by someone else may affect the warranty. If you're locked out and can't reach them, we can come out, but tell us about the warranty when you call.
Can you make extra keys for my gate lock?
No. We don't cut or copy keys. If you want more keys, a new lock or cylinder comes with the maker's keys, or you can ask the gate supplier about extra keys for the existing lock.
Need a locksmith to look at it?
If this hasn't solved the problem, our lock repairs service covers it. We're a mobile locksmith in Kempton Park, so we come to your door.
Sources and further reading
- Trellidor: Dos and don'ts of retractable security gates — do not spray into the keyhole; lubricating spray for hinge points and tracks; cleaning products to avoid; lock changes through the supplier; change locks after moving in or after a break-in
- Trellidor: Why do security barriers need maintenance? — sticking gates as an early warning sign; warranty and care instructions; keyhole warning
- Trellidor: The myth about slam locks — slam-lock lockout risk, two-key arrangements, deadlocks fitted as standard on Trellidor retractable gates
- ASSA ABLOY: UNION launches its new and improved 5-lever gate lock — locally made, SABS approved, anti-saw deadbolt protection, suitable for retrofitting