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Beyond the brake test – are you taking action?

Posted by: , Posted on: - Categories: Vehicle testing

Testing lane at an Authorised Testing Facility with a lorry in the entrance approaching For every vehicle you manage, your brake test report can tell you more than whether the vehicle has passed or failed a test. So, you need to give it a good read through – and understand what it’s telling you.  

The report can tell you if it has met various overall efficiencies such as that for service, secondary and park. But it also tells you what you might need to investigate further.  

The report can identify individual braking aspects where extra action is needed to avoid further problems that could result in brake failure. This includes bind, time lag, ovality, imbalance and maximum force. Vehicle details and weight imposed on each axle is shown on each report too. 

If a report shows a brake balance across an axle only just passes, what would you do? Would you know how to find out what was causing the problem? 

You should file the report as a part of your maintenance system and any investigation or repairs should be recorded. 

A key part of your maintenance system 

The brakes are one the most important safety systems in your vehicle and should be a key part of the maintenance system.  

The braking performance needs checking at every safety inspection. This means they must be monitored and correctly maintained to optimise their efficiency.  

Poorly maintained brakes may result in the loss of control of a vehicle with dire consequences. 

Understanding the brake test report 

Operators should always look at their report after the test, regardless of the result. 

So, even if the brake test shows a pass, you need to look at it to identify items that may be getting worse and need dealing with before they let you down.  

And for that you need to understand it.  

DVSA has published some guidance to help you better understand brake testing reports. 

The industry body, Logistics UK has also produced some guidance on this subject for members. 

Review every brake test report before putting it away and carry out any investigation or repair work as necessary. Make sure the work is done correctly and recorded in the maintenance file. And make it available at the next inspection, so the technician can refer to it to check to see if has deteriorated. 

Remember, a pass result does not always mean there is no action to take. 

You or your transport manager/maintenance provider may need to review the report to determine how to improve the vehicle’s braking. 

The ‘other key headlines’ section shows the way in which your fleet is maintained and how your business is conducted. 

The key questions to ask 

Here are some of the things you should be reviewing when you get your brake test reports.  

This list isn’t exhaustive but offers a helpful starting point: 

  • are the figures in the report as high as expected?  Compare them with sister trucks and/or trailers in the fleet 
  • is one vehicle performing differently from a sister vehicle in your fleet?  
  • were the vehicles loaded in a similar way and tested in the same manner?  
  • does the vehicle have the same type of brakes, is it maintained differently or at another location? 
  • are there any differences that could be a cause for investigation? If so, record your investigation and any repairs made to the vehicle 
  • are drivers reporting any braking issues, or were any common faults identified and subsequently repaired by the maintenance provider(s)? 

A few examples  

Possible braking defects 

If axle 2 service brake on the offside shows an imbalance of 26% (offside wheel does not lock) when compared to the nearside brake effort, this indicates a possible braking defect so you would need to investigate further. 

Offside brake issue 

Axle 3 imbalance at 29% with no wheels locking. Although this does not exceed the limit of 30%, it indicates that there is an issue with the offside brake which requires investigation. 

Vehicles with split brake systems that the manufacturer has designated as the secondary brake are not assessed as part of the brake inspection. But the brake report may show efficiency readings for these (failures for these can be ignored but this may be reflected in the service braking aspect so you would need to look into this). 

How park brake efficiencies are tested 

The park brake efficiencies could be tested against the design gross vehicle weight (16%) or the design gross train weight (12%). This is because motor vehicle park brake efficiency should meet the efficiency for whichever is the higher figure. 

It’s worth saying that testing equipment such as roller brake testers must be maintained and calibrated to ensure the readings are accurate. 

To conclude, brakes are a critical part of your vehicle, so you can’t afford to leave them without investigation when something is mentioned in the brake testing report.  

Looking after the brakes will help you keep your vehicles safe to drive. 

A note on slack adjusters 

We’ve recently updated our guide to maintaining slack adjusters. These are a feature of brakes which make sure brakes continue to work well, even as the lining wears down.  

The main issue we see frequently is where automatic slack adjusters are manually adjusted at service because they are not automatically adjusting correctly. 

It’s common to read “adjust brakes” on multiple safety inspections (SIs) and then eventually the automatic slack adjuster may get replaced. 

Manually adjusting the automatic slack adjuster does not fix the problem and can damage the mechanism. The correct way to maintain and check the automatic slack adjuster is covered in our updated guidance. 

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  1. Comment by Nick (DVSA) posted on

    I spend endless amounts of time advising customers regarding brake test results even when the vehicle has passed as they do tell a story, but unfortunately from my experience, if the brake test says passed, that’s all they are interested in and back into service it goes.
    What I also witness on numerous occasions at many different establishments is vehicles ie tractor units having a brake test with no loaded trailer attached, an absolute pointless exercise, and when you say something, itstjust for the records, it shows the operator it’s had a brake test is what comes back. More stringent rules are needed in my opinion.

  2. Comment by David posted on

    Why does the Guide To Maintaining Roadworthiness advise that it strongly recommends that a laden roller brake test is completed at every service. Yet at the top of one of the links "Understanding your HGV or trailer’s brake test report" it advises "You should get your HGV or trailer’s brakes tested by a roller brake tester (RBT) at least 4 times per year, including at the MOT." This guidance is very confusing, which is it every service or 4 times a year?

    • Replies to David>

      Comment by Josh (DVSA) posted on

      Safety inspection braking performance assessments should be carried out at every safety inspection. The most basic form of brake test would be a road test with a brake temperature measurement. However, this type of test is not comprehensive or thorough enough as a testing method to assess brake performance across a year. This is where we would expect operators to undertake 4 laden roller brake tests (one of which can be at MOT) to supplement the road tests and ensure a thorough performance assessment is completed offering reassurances that the vehicle’s brakes work throughout all conditions of service.

      There are other methods of assessing braking performance, such as decelerometer tests suitable for rigid vehicles or electronic brake monitoring systems. Ultimately, the brake testing methods carried out should be those that are suitable for your vehicle and its road use. If you have any questions on this, you can contact your maintenance provider or DVSA directly: for advice.

      We always keep guidance under review and do update guidance to ensure we issue the latest information on best practice to the public.

  3. Comment by Matthew posted on

    It would be nice to have a section explaining reasons why a vehicle for example that has a designed weight of 21tons that is Downrated legally to 15ton , still has to have a brake test at 21ton and not 15ton, but is not allowed to present the vehicle at that mot drivern to the mot station at the weight capacity maximum allowance for the 21 ton test, I understand it’s illegal to carry more than is now registered but if a brake test is done at design weight and not what is now registered and taxed upon it seems a conflict.

    It would also be nice to have a section that when a vehicle has good brakes but shows corrosion eg rust but changes to all brand new parts for a mot but because the mot has expired can not drive to bed in, can an allowance of common sense be used when seeing all brand new parts or should the vehicle be presented with minor corrosion to safeguard passing the test.
    Operators are in fear of failing a visual of brake discs looking low, and don’t want to be reported as not caring, but more in fear if new parts are put on but cannot be bedded in as vehicle has no mot, sometimes because vehicle has been laid up due to no work or seasonal.

    If a vehicle is downrated why is packers needed or removed?
    Would this affect a design weight brake test if the 15ton is tested at 21ton.

    • Replies to Matthew>

      Comment by Josh (DVSA) posted on

      Hi Matthew,
      Thank you for your message.
      The downrate can be due to tax or licensing purposes, it does not change the design weights. There can however, be a change to design weights on a vehicle. This is separate to a downrate due to tax or licensing.
      A brake test will be conducted at the design weights of the vehicle not at the weight you have downrated to for tax purposes.
      Packer plates will be removed or added dependent on the alteration being carried out to affect the carrying capacity of the vehicle. If the alteration has changed the design weights, then the new design weight will be the weight a vehicle is tested against.
      It is possible to bed brakes in by taking a vehicle for road test purposes. A vehicle can be driven on trade plates (provided you comply with the conditions) where you can bed in brakes.
      We have provided guidance on GOV.UK:
      Kind regards.

  4. Comment by Martin Detheridge London Bus 4 Hire. posted on

    This is a really good blog post and basically just common sense.

    It’s Beyond belief why someone wouldn’t bother maintaining their brakes correctly,
    Tyres / Brakes and steering components are key the MOT test is a minimum standard and a safety inspection should carried out to a much higher standard than the annual test itself,

    I had a operator tell me that he doesn’t have a safety inspection done if the vehicle has just had its annual test because the tester has checked the vehicle over,
    I don’t think the traffic Commissioner would agree with him.

    One small point and I’m not saying it’s not correct on a modern vehicle,
    We maintain vintage Routemaster buses and we always manually adjust up all the brakes because the auto slack adjusters allow too much clearance before they adjust up on the Routemasters and we always get 100% pass with no more than 15% imbalance but normally get less than 6% in imbalance.

    • Replies to Martin Detheridge London Bus 4 Hire.>

      Comment by Josh (DVSA) posted on

      Hi Martin,
      Thank you for you getting in touch.
      It is possible that the operator who reported he did not have safety inspection had just had an MOT, and the inspection had been carried out as part of the MOT preparation before the vehicle's test. However, if the safety inspection is being skipped then this should be reported to DVSA’s intelligence team:
      In the circumstances you have described, you are using auto slack adjusters on a vehicle that was never designed to use them. Adjusting an automatic adjuster on a regular basis can lead to premature damage or even failure. We advise you are cautious when adjusting and ensure the vehicle is safe and roadworthy.
      Here is our guidance on maintaining brake automatic slack adjusters:
      Kind regards

  5. Comment by John posted on

    Removing the need for an alternative secondary brake a number of years ago is deplorable. DVSA are allowing vehicles with defective brakes to run on the UK and foreign roads.
    So much for road safesafety and ty.

    • Replies to John>

      Comment by Josh (DVSA) posted on

      Hi John,
      Thank you for your message.
      The removal of the secondary brake performance check on vehicles has only been removed in instances where the manufacturer has designated that the secondary brake is the split system of the service brake. In these cases, secondary brake performances are checked as part of the service brake performance check.
      In cases where the manufacturer of a vehicle designates the secondary brake is a separate system from the service brake, we continue to test secondary brake performance.
      As the check is carried out as part of the service brake performance check or when designated by a manufacture to be a separate system, there is no additional risk to road safety.
      Kind regards.