Trailer Brake Technology Problems

Getting the Wheel End Right

Trailer Brake technology problems have seen the National Heavy Vehicle Regulator and Road and Maritime Services announce a brake testing transition extension in NSW until January 31, 2017. This is due to incompatibility between traditional testing procedures and modern, safer, braking systems.


Trailer Brake Technology Problems


“The problem is the number of modern trailers having difficulty meeting the 4.5 kN/t requirement,” said Daniel Elkins, NHVR Director Safety. “When we we examined it, we found an issue when the interaction between all of the systems the trailers are deployed. They are doing exactly what they should do, sharing the load across each of the axles and giving us a false reading on the axle being tested.


“It is only giving a false reading because of the type of test being conducted. There are two types of test, the static test and the dynamic test. When we do the dynamic test, there’s quite a range in the results. Whereas, when you do a static test, they are very close together, the axle group’s result are closely aligned. There is quite a spread in the results for an axle group in the dynamic test.


“We just need to understand why that is occurring and how it might effect the pass/fail rate. What we are seeing is older vehicles passing without a problem, but it’s the new, modern vehicles with all the new technology in brake systems, which are struggling to pass. We want to do some more experimentation to understand what the interaction between roll stability, ABS, EBS, AEBS and the suspension systems is.”


The initial transition period in NSW allowed heavy vehicles which achieve a brake test result greater than 3 kN/t, but less than 4.5 kN/t, to be given an official warning on first time detection. The current transition period was due to end on 30 September 2016.


“The brakes are proportioning their braking according to the weight, and that’s fantastic, it’s what they should be doing,” says Elkins. “Whereas, the old brakes jam on, lock up and stop. The systems are doing what they should , but the testing equipment hasn’t kept up to speed with the interaction between all of the systems.


“We are very confident we will resolve this quickly, hence, we only need a four month extension. We think we can do some more testing to get a better understanding of this dynamic vs static results issue. They are flying well past the 4.5 kN/t result, it’s just the variation in results, the band between the results, is quite large. We need to find out what we need to do, in terms of our test procedure.”