Classically, all brake designers have used vehicle and dynamometer testing to evaluate new designs of brake. Often there is no vehicle to fully test the design, and when it does arrive, the brake design is well established and changes are more expensive to implement and redesign quickly. On the other hand vehicle testing is subject to the variance of the weather, the state of surface and not least the driver. Neither dynamometer nor vehicle methods therefore are ideal. Confusingly enough, the poorer the perceived performance of the dynamometer the better the correlation with reality in many cases. For instance, the dynamometer with poor main bearings and gearboxes, giving low run-down times is probably more realistically following the losses in a vehicle than a perfect dynamometer. The aim of the paper is to present a case for increasing the accuracy of dynamometer testing, eight sources of error (l.d through l.k) have been identified. Today we routinely correct for six of them on single ended dynamometers. A method has been presented for correcting for tyre losses which have been shown to be the largest error. To accomplish this, data on the tyre, usually from the manufacture, is required. This information is often provided reluctantly and to date two downright refusals have been received. It seems likely that the inclusion of the tyre in the equation will now also be necessary. Significantly this can be done without physically attaching the tyre to the test rig which is a great saving by allowing the use of the existing dynamometers. All that is required to bring this about is the addition to the average dynamometer of a more accurate encoder, at negligible cost, and of course some modern software. However in future the brake manufacturer will need this information. in order to produce the most realistic test.
Towards more accurate brake testing
Wege zu einer genaueren Bremsprüfung
2002
10 Seiten, 3 Bilder, 5 Quellen
Conference paper
English
Towards more accurate brake testing
British Library Conference Proceedings | 2002
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