I found the fault on a Thursday morning at a delivery yard near Coventry. Went to move the artic forward after tipping, applied the footbrake to release the hand, and the whole unit drifted forward about six inches before the footbrake caught it.
Should have been obvious earlier. Wasn't. The walkaround I'd done at DIRFT that morning was fine on paper but I'd not tested the parking brake the way it should be tested — which is to apply it, let the service brake go, and see what happens. I'd pulled the lever, it felt firm, moved on. That's not a test. That's a tickbox.
The vehicle went in that day. Worn-out parking brake chamber on the rear axle. Not a PG9 as it happened — the fitter decided it was repairable on site and categorised it as a minor defect — but it could easily have been worse. On a loaded trailer at a delivery yard with traffic moving around me, six inches of drift is already more than nothing.
Brake checks on a walkaround are the part most drivers rush. I've watched them. Pull the brake lever, check the marker lights, look at the tyres. Job done. Two minutes. There's a proper brake check procedure that takes longer than that, and if you don't know it, here's what it actually involves.
Why brakes get their own section
Most walkaround defects are visual. Lights, tyres, bodywork, mirrors. You can see a cracked mudflap or a missing number plate light. You can't see a failing brake chamber — not without testing it.
Brakes are the single highest-category defect on DVSA's vehicle defect list. A significantly reduced service brake — not the parking brake, the main footbrake — is a Dangerous defect. That means immediate PG9 prohibition. It doesn't go on the repair-and-return system. It means the vehicle stays where it is until the defect is fixed and inspected.
Parking brake defects that prevent the parking brake holding a stationary vehicle on a gradient are Major — one step below Dangerous. Major defects get a PG9 as well, just not the immediate dangerous category. Either way, you're not moving.
The thing about brake defects is they develop gradually. A worn brake lining doesn't announce itself. Air system leaks develop slowly. Brake chambers wear. The only way to catch them before DVSA catch them for you is to test the system rather than look at it.
The air pressure check
Air brake systems on HGVs need to reach a safe working pressure before you can release the parking brake and move off. On most vehicles with an air dryer, you'll see a low-pressure warning light on the dash — usually red — that extinguishes once the pressure is at operating level.
The check here is simple: start the engine and watch the gauge build. The pressure should climb steadily. If it climbs very slowly, or if the warning lamp doesn't extinguish at the point it normally does, that's a flag worth investigating before you pull away.
The second part is checking for air leaks. With the engine off and the brakes applied, watch the pressure gauge over a minute or two. On a well-maintained system, the pressure shouldn't drop significantly. A steady drop — not a slow bleed, but a consistent fall — indicates a leak in the system. That's not necessarily a prohibition-level defect on the spot, but it's a defect that needs reporting and it's the kind of thing a DVSA examiner will check at a roadside stop.
Trailer connections matter here too. When you couple a trailer, check the brake coupling connections — the red (emergency) and yellow (service) glad-hands. The connections should be secure and the couplings should snap firmly. A loose or cracked coupling can cause air loss and, at worst, automatic application of the trailer emergency brake while you're moving. That's not a comfortable situation on the M6 at 50mph.
The parking brake rollback test
This is the test I wasn't doing properly. The procedure is straightforward — and it's the only way to actually verify the parking brake is holding.
Apply the parking brake fully. Then release the service brake entirely. Let off the footbrake. The vehicle should not move. On level ground, even a minor parking brake fault might not cause visible movement — which is why on a gradient it becomes obvious. But you can simulate the key element of the test on flat ground: parking brake applied, footbrake released, vehicle stationary.
If the vehicle creeps forward with the parking brake applied and the footbrake off, that's a parking brake defect. Not a "I'll mention it to the fitter" situation — a do not drive this vehicle situation. Report it, get a signed defect sheet from the fitter, and don't take the vehicle out until it's been inspected and cleared.
On a fully loaded artic or rigid, the parking brake has to hold the gross train weight on a gradient. It's designed to do this. But brake chambers wear, and the spring that holds the brake on wears with them. The rollback test gives you a basic check. A full brake test under load on a gradient tells you more — but that's for the workshop, not the yard.
Service brake feel
The parking brake test is mechanical. The service brake check is more about feel — and you'll only know what normal feels like if you've been paying attention over time.
Apply the service brake firmly from slow speed in a safe area. It should stop the vehicle smoothly and progressively. A spongy pedal, a pedal that travels further than normal before resistance kicks in, or a vehicle that pulls to one side under braking are all signs of a potential problem.
None of these pass as walkaround defects unless they're obvious. But if you notice anything different from what you're used to on a vehicle you drive regularly, report it. If it's a new vehicle or a hire vehicle you've never driven before, do the check more carefully — you don't have a baseline.
I covered the more general walkaround process and DVSA's defect categories in this earlier post. The brake check sits within the walkaround but deserves its own discipline — because it's the one defect category where the consequences of getting it wrong are immediate and serious.
DVSA defect categories and what they mean
DVSA uses a tiered system for vehicle defects. Minor defects don't require immediate action but must be repaired. Major defects lead to a PG9 prohibition — the vehicle is prohibited from use until repaired. Dangerous defects lead to an immediate PG9 — the vehicle can't move at all until fixed, in some cases requiring the defect to be made safe before the vehicle can even be towed.
For brakes:
- A parking brake that fails to hold the vehicle on a reasonable gradient = Major. PG9.
- A service brake with significantly reduced efficiency = Dangerous. Immediate PG9.
- Excessive air pressure loss with brakes applied = Major. PG9.
- Cracked or leaking brake lines or couplings = can be Major or Dangerous depending on severity.
The practical point is that most of these defects are checkable before you leave the yard. Not all of them — a fractured brake line inside a chamber isn't something you'll spot on a walkaround. But the air pressure test and the parking brake rollback test together will catch a significant proportion of the faults that end up as roadside prohibitions.
What to record if you find a fault
Find a defect — any defect, not just a brake fault — and you have to record it on the defect sheet. Not in your head. On paper, or in the electronic defect reporting system if your operator uses one. I went into the legal position on defect reporting in this post on defect reports — the short version is that a false "no defects found" entry is a criminal offence.
For a brake defect, the operator must decide whether the vehicle is safe to use before it goes out. If the vehicle goes out with a reported brake defect that hasn't been cleared, the operator carries liability for that decision. If they instruct you to take it out anyway, you have the right to refuse — and a reasonable defence if you do.
The transport manager at your yard should be the one deciding whether a reported defect is safe to continue or needs immediate attention. If they're not available, that decision doesn't fall to you to make on their behalf. You report it, you wait for a decision. Don't drive on a brake fault that hasn't been signed off by whoever's responsible for the vehicle.
Quick version for the yard
Turn on the engine. Watch the pressure build, confirm the warning lamp clears. Apply the parking brake. Release the footbrake entirely. Check the vehicle doesn't move. Watch the pressure gauge for a minute after engine off — watch for steady drops. When you couple the trailer, pull test the glad-hands, check the connections are firm.
Then do the rest of the walkaround.
The brake check adds maybe three minutes to the walkaround. Three minutes and the discipline of actually doing it — not just pulling the lever and assuming. If something isn't right, you want to find out at the yard gate, not at a delivery bay or at the side of the road with a DVSA examiner watching.
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Trailer brakes: the specific checks when you couple
Most brake walkaround guidance focuses on the tractor unit. The trailer is just as important and gets less attention.
When you couple a trailer, the brakes are in a specific state: the trailer parking brake — the spring brake — should be applied before you couple. You release it once the airlines are connected and the system pressure is built. That's the safe coupling sequence. If you couple to a trailer with the spring brake not applied, you've got an unbraked trailer on your fifth wheel until the airlines connect properly. That's not a great situation in a busy yard.
Once coupled and with system pressure built, test the trailer service brakes. Apply the footbrake firmly. You should feel resistance — the trailer brakes engaging through the pneumatic system. If the trailer brakes aren't working, the footbrake will feel lighter than normal. A loaded 13.6m curtainsider with no trailer service brakes is a problem that becomes very obvious, very quickly, when you need to stop.
Test the trailer parking brake separately. In most tractor-trailer configurations, there's a control in the cab — sometimes the yellow dash control — that applies only the trailer park brake. Apply it, release the tractor service brake, and check that the combination doesn't move. If the trailer park brake won't hold the trailer on a slight gradient, that's a defect.
The glad-hand connections — where the red and yellow airlines connect — should be pulled firmly after connecting to check they're seated properly. A partially connected glad-hand can lose air pressure gradually and progressively, affecting the brake performance over a long run rather than immediately. You want to find this at the coupling point, not at a delivery yard 200 miles away.
What to record on the defect sheet when brakes are involved
When you report a brake fault on a defect sheet, be specific. "Parking brake seems soft" isn't useful. "Parking brake: vehicle rolled approximately 15cm forward when footbrake released with parking brake applied, on flat surface at DIRFT depot" is specific and actionable. The fitter can reproduce that test and confirm or clear the defect. A vague description creates room for "nothing found on inspection" and the fault going unresolved.
If the vehicle goes out with a brake fault that you've reported and hasn't been cleared, and something goes wrong — that's a completely different legal position from a fault you didn't spot or didn't report. The defect sheet is your protection. Use it properly.
And if someone tells you the vehicle's fine when you've described a parking brake that let the vehicle roll — ask for it in writing. A transport manager or fitter who clears a reported brake fault needs to be able to demonstrate that they tested it and the defect was resolved. "I checked and it's fine" isn't the same as a signed-off inspection record. Push for the proper documentation. It matters later.