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COMPLEX ISSUES
Page 22
If you've noticed an error in this article please click here to report it so we can fix it.
I refer to the article in Commercial Motor ( CM19-25 June) entitled "To Dump or not to Dump?".
Can I start by correcting the false impression given at the beginning of the article that BPW is in favour of exhausting the air suspension when tipping? This is most definitely not the case. Furthermore, to my knowledge BPW has never made any statement to this effect.
The label attached to the trailer at the Lyon show referred to in the article was put there by the trailer manufacturer, and the inference that this information came from BPW is not correct.
The question of tipper stability is considerably more complex than merely deciding whether air should or should not remain in the suspension system. BPW's view is that both 'air in and 'air out' have their own pros and cons, but a number of other factors also need to be considered. Principle amongst these are chassis construction and suspension configuration.
Just as different trailer builders will use different chassis designs, so too axle manufacturers use differing designs of suspension. BPW suspensions use a 'road spring*type trailing arm linked to the hanger bracket through a rubber-steel-rubber bush which is less compliant than the large rubber bush used with the box-section fabricated trailing arm favoured by other axle manufacturers. As a result the stability characteristics of the two types of suspension are different.
We applaud the work being undertaken by the IRTE's Vehicle Stability Working Group and have offered to assist in any way we can. However, as far as providing a definitive answer to the particular problem, we are not sure there is one.
Richard Gibbs,
BPVV,