Got a Pass last week
Got the mechanism 'softened' a bit to reduce the snatching effect and took the mh back for a re-test.
During the retest, I saw the rear axle being chained down which is against the RSA's own written procedures for testing motor caravans which says
Brake performance testing on all Motor Caravans (including those over 3,500 kgs tested in a
HGV Test Lane) will be carried out on the basis of the weight presented as per the current Light
Goods Vehicle (LGV) brake performance test. It will not be necessary to present a weight docket
for the purpose of undergoing brake performance testing.
I contacted The RSA pointing out what their own written procedure sets out in relation to the testing of motor caravan brakes asking for their take on what happened and this is their reply
There has been no change in the methods used to test brake performance on motor caravans since 2010. If necessary, the load simulator may be used to “hold” an axle in the rollers during a brake test to assist the tester in obtaining the required brake efficiency or the maximum efficiency available on the vehicle. However, no load must be imposed on an axle by the simulator during this process, the equipment is used to just hold the axle in the rollers, as vehicles sometimes have the tendency to kick out of the brake tester before the required efficiency is achieved.
The above confirms to me that there is some kind of inherent problem with getting a realistic efficiency value using the published method and it is down to the initiative of a tester to employ the 'holding down' equipment used for commercial HGV's to overcome the phenomenon of the rear axle 'kicking out' prematurely.
The above begs the question, how many false fails are there?
I followed up with a further email in which I queried if presenting the vehicle for test empty or loaded with the usual sh1te we carry around makes any difference and there is their answer to that
The presented weight of a vehicle will not increase the available brake effort on a vehicle or the result of a brake test. However, additional axle weight may make it easier to achieve the required brake efficiency or the maximum efficiency available on the vehicle by holding the axle in the rollers. Provided of course the presented axle weights do not exceed the manufacturer`s design weights.
So, in a nutshell, emptying out all the 'stuff', as I've been doing for years is a waste of time, just take it in making sure it's not overweight either in total or per axle.
I hope the foregoing will help someone else avoid having to go through the pain and expense of a retest following an avoidable parking brake fail
