torsdag 13. august 2015

Why was 2000 bhp a bridge too far for the EE type 3?

The class 37 was often proposed under powered by type 4 fans, but in fact of course it prove to be a very good horse power rating in keeping the fleets reliability up, and rendering their longevity only as finite as the HGR avoiding private owners would allow. At various points in the 1960s and 70s they hauled the heaviest and longest frieghts in the UK, in multiple admittedly, while also turning out for fairly racey diagrams on the non stop summer Skegnes services amongst others, even working the famous 1S45. However an uprated version of the locomotive was of course not just proposed, but also tried out.

The irony is not lost on us that the original EE general arrangement drawings of the Type 3 (evt Class 37) included a position for a secondary diesel generator, thus rendering the class with dual heat potential on outset. By the mid sixties though, EE were confident enough to offer the loco as a 2000hp performer in a new, flat end cab version similar to the 2050bhp export models which went to the then East Africa. BRB at the time were wise enough to know they were onto a good thing, with type 2s proving underpowered and various lesser types already earmarked for the scrap heap as "non standard".  So the final order for 37s remained standard and some of the best examples of their class to my experience, rolled off the assembly lines in 1964 and 65. Amongst them was one example which would go on to be fairly infamous. 37 292.

I have the pleasure of being hauled by the beast, all be that it was somewhat underperforming, running unevenly on idle and not opening up completely. It did whizz along the Kilmarnock to Ayr route, and further to Stranrær, which in any other year than 1984 would have been a rarity for a 37 in itself!

Scottish depots were pretty bad at under maintaining locos given the demands of damp, occasionally salt water laced conditions, icy and greasy rails and more than a fair share of gradients, curves and variable speeds. It seems 37292 was in a state of "returning soon to works, don't spend any money on it" at ML in 1984 unfortunately. It worked a few times that summer out of Glasgow central, with perhaps only a handful of other passenger workings in the period 1981-83 as a break down recovery loco. Perhaps due to this latter day unreliability, it remained probably the "largest" syphon on ML shed through 1984 and prior to its long booked return to works for HGR and "four-ing" in 1985. (37 137 and a 200 series being pretty rare out on seated rolling stock too it has to be said)

As I blogged before, the evolution of the CSVT to to the RK traction took a little back water via Australia and also 47 601/901. The maximum rating of a "csvt" badged v12 is 2350 b.h.p. in Aus, and despite a single turbo being employed, they still sound decidely CSVT and not V16 jumbojet like. The aussie engine was probably a metric one, but possibly did not get gear driven cams- so together with the thoarty, pulse type turbo exhaust roar then we can presume that this is as far as the CSVT got.  2000 hp was enough out of a v12 from EE/ GEC until 47901 reared its ugly head!

Reports on the electric internet show us to 1981 as the year that a very nicely prepared EX works 292 exited Doncaster on a test train. Given that ETH'ing was carried out toute suite in 1985, then a two year test and evaluation period plus then a two year planning and material procurement period seems about right for 1980s Britain.

It has been said that the alternator alone contributes about another 100 hp efficiency to the system, and with the lower CP4 gearing chosen, the need for 2000hp and possibly a shorter service interval was considered avoidable.  A single 37/4 could be used to pick up the aluminium ingots train at Corpach as against a pair of "zeros" and acceleration on passenger services was by in large not much different, even when producing ETH. Top speed on the other hand.....

 In standard rating the welsh depots and Stratford could keep well on top of valve and timing chain issues with preventative servicing. Miles-Per-Casualty would be interesting to compate with 31s and of course much better than 47s which broke down a lot, having never been able to handle their class wide uprating. So probably a very wise choice to stick to the lovely 1750bhp.