Roadworthiness · 4 min read · Updated
Brake testing and roller brake tests explained
DVSA expects brake performance to be measured at every safety inspection, normally by a laden roller brake test on a calibrated machine. It checks efficiency, imbalance and binding, with broad HGV pass figures of 50% service, 25% secondary and 16% parking, and the printout kept as evidence.
Brakes are the single item DVSA and the Traffic Commissioner care about most, and the one operators most often cannot evidence properly. The DVSA Guide to Maintaining Roadworthiness is clear: brake performance must be measured at every safety inspection, not judged by eye or by a quick push on the pedal.
The roller brake test
The standard method is a roller brake test (RBT) on a calibrated test machine. It measures the brake force at each wheel, so it reveals three things a visual check never will:
- Efficiency - the total braking force as a percentage of the vehicle's weight.
- Imbalance - one side braking harder than the other across an axle.
- Binding or ineffective brakes - wheels that drag or barely contribute.
The efficiency figures
For heavy goods vehicles, the pass thresholds are broadly:
| Brake | Minimum efficiency |
|---|---|
| Service brake | 50% |
| Secondary brake | 25% |
| Parking brake | 16% |
These are the figures used at annual test and expected at safety inspections. The Inspection Manual is the authority on the exact requirements for a given vehicle, so treat the table as the working benchmark, not the last word.
Why "laden" matters
A brake test on an empty vehicle flatters the result - there is little weight to stop, so even weak brakes look adequate. The Guide expects tests to be carried out at or close to laden weight wherever practicable, because that is the condition the brakes actually have to perform in. An unladen test with no explanation is a classic weakness an examiner will pick up.
When an RBT is not practicable
Some vehicles and trailers cannot easily be roller-tested laden. Accepted alternatives include a decelerometer test in the right conditions, or Electronic Brake Performance Monitoring (EBPMS) for trailers, which builds a performance picture from real braking data over time. Whatever the method, the principle is the same: measure it, and keep the evidence.
Record it as proof
A brake test only counts if you can show it. Keep the machine printout or the EBPMS report and attach it to the safety inspection record for that date. The recurring failings examiners find are unladen tests, no printout on file, and axle imbalance that was measured but never acted on.
How OperatorCompliance helps
When a workshop submits an inspection through OperatorCompliance, the brake performance figures are captured against the vehicle and the roller printout is uploaded and stored with the inspection - so every safety inspection carries its brake evidence, and it is all there when DVSA asks. See how it works or start a free 14-day trial.
This guide is general information, not legal advice. Always check the current requirements in the DVSA Inspection Manual and the Guide to Maintaining Roadworthiness on GOV.UK.
Frequently asked questions
Do I need a laden roller brake test at every safety inspection?
The DVSA Guide to Maintaining Roadworthiness expects brake performance to be measured at every safety inspection, and a roller brake test at or close to laden weight wherever practicable. An unladen test flatters the result. Where a laden test is not practicable, an accepted alternative such as a decelerometer test or EBPMS for trailers should be used and the reason recorded.
What brake efficiency does an HGV need to pass?
As a working benchmark, heavy goods vehicles are expected to achieve about 50% service brake efficiency, 25% secondary and 16% parking brake efficiency. These are the figures used at annual test. The DVSA Inspection Manual is the authority on the exact requirement for a particular vehicle, so treat the percentages as the benchmark rather than the last word.
What is brake imbalance and why does it matter?
Brake imbalance is when one wheel on an axle brakes significantly harder than the other, which can pull the vehicle to one side under braking. A roller brake test measures each wheel individually and reveals it. Imbalance that is measured but never acted on is a common failing examiners find, so any adverse figure should be investigated and rectified.
Can EBPMS replace a roller brake test on trailers?
Electronic Brake Performance Monitoring Systems build a braking performance picture from real data over time and are an accepted way to demonstrate trailer brake performance where a laden roller brake test is not practicable. Whichever method you use, the principle is the same: measure the performance, keep the report, and attach it to the inspection record.
Sources
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