andrew jukes wrote:Will L wroteThere is no question that equal distribution of weight will improve haulage power. We can argue the toss over whether our CSBs or your fully equalised chassis are best at this, but compared with many compensated or rigid chassis, they win hand down.
I bought into most of this but have had great difficulty demonstrating it in comparative testing. Taking achieved coefficient of friction as a measure of haulage power, my best performers were not the all-sprung designs nor those with equal axle loads. The locos tested admittedly did not include a CSB-fitted loco but the results were such that it is hard to believe CSBs would add enough magic to win hands down.
My feeling is that there is nothing like enough comparative testing and that we end up taking firm positions without the necessary real data. Perhaps my fault to some degree as, when Deputy Chairman, I did nothing to encourage continued Deputy Chairman's Cup testing.
This remark was made in the context of an ongoing discussion with Andy concerting the relative merits of CSB or equalised suspension. However we would share the view that equal weight distribution is the place to start when trying to maximise haulage performance. For public consumption I should perhaps have added that some, but not all, compensation configurations are just as effective at produce equal weight distribution, but as we have seen, knowledge of which is which and what in general terms the impact of compensation on weight distribution is, isn't that common knowledge.
At to the truth of the assertion that equal distribution maximises haulage power, we have had this discussion on the forum before, although on the last occasion it was because I was questioned in my assertion that the pulling power of a coupled chassis is limited by the most lightly loaded driving wheel, which is just another way of saying the same thing. For my explanation of why it is true, see this post viewtopic.php?p=30700#p30700 This is, of course, just a starting point, and there are always other factors which will also affect the pulling power of a given loco and will modify the basic result and cloud the result, but that doesn't make it less true. I agree it is perhaps a pity we didn't keep up with the comparative testing.