When undergoing a roller brake test, a vehicle is subject to individual checks of the braking force of each wheel of each axle and an overall calculation is performed upon the values recorded to give the braking efficiencies.  

A test can be failed either, by one of the individual checks recording an unsatisfactory wheel performance that is then listed at the bottom of the test, or where the overall braking effort does not meet the test pass value of the applicable braking system despite the individual tests each passing.  

However, a spanner is thrown into the works, so to speak, when the wheels lock. Provided that no unsatisfactory wheel performance is recorded, where the wheels lock the test will pass. This is frequently seen in the industry where vehicles are tested unladen.  

An empty vehicle does not require anywhere near as much braking effort to stop as a fully laden one, and whilst this point seems glaringly obvious, unladen brake tests are all too common and go unchallenged by operators.  

Where a vehicle is presented for a safety inspection and is roller brake tested empty, passing ‘on locks’ below the test pass value, all which is being confirmed is that the brakes work well enough to lock the wheels when the vehicle is light, it is still not known if they work sufficiently when the vehicle is laden. In other words, these tests in are not meaningful, merely functional, under the conditions in which the vehicle was presented: these terms are often referred to by maintenance providers upon a safety inspection sheet.  

Reliance upon an unladen test puts many operators into the scenario where a piece of paper with the word ‘pass’ printed upon it would be a failure if the vehicle were to be tested under laden conditions.  

Conversely, Item 72 of the inspection manual, Secondary Brake Performance, has posed many headaches to operators, and no doubt will continue to do so, where a brake test is reported as a failure but in fact it has passed. The inspection of Item 72 applies to all motor vehicles where the designated secondary brake operates independently of the service brake, and upon vehicles where the service brake split system is designated as the secondary option the performance of this brake is not required to be assessed. Therefore, as taken from the Heavy Good Vehicle Inspection Manual: “Any brake test printout indicating failure to meet the secondary requirements must be overruled along with any prompts for an alternative option.”  

So, imagine a transport manager amid a DVSA (Driver and Vehicle Standards Agency) maintenance investigation with a roller brake test reporting a failure that is in-fact a pass as described. The facts of the matter are that the vehicle has been put back into use following an inspection with a reported roller brake test failure. The test is not a failure, and the Vehicle Examiner would know this, but unless the transport manager knows explicitly the reason, it would be somewhat difficult not to form the view that vehicles are being returned to service without scrutiny of, nor confirmation of the results, of the brake testing regime. It would be unattractive to any operator to find themselves in this position.  

This is a complex area so if you have any questions or need advice, then please contact us.

* This article is based on the regulations and interpretations on the day of publishing 31/05/2023

Coming soon! Imbalances on brake tests and what should happen!