Talk:British Rail Class 323

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[edit] Technical and historical questions

1/ anyone know what's going on with the distinctive "18 speed gearbox" type noise that comes out of the drive mechanics as the train pulls away and comes to a halt? i can't figure out if it's actually some kind of heavy duty multi-ratio gearbox that's been fitted (rare on trains as far as i know, but certainly useful for the hard acceleration they do and dragging the things up over the lickeys) or some clever electronic jiggery pokery. I was pre-teen at the time these units were brought into service but i remember some rather vague news story on their arrival saying something like the series vs parallel circuit arrangements of the motors were rapidly changeable for extra power "like gears in a car" or something.... (i'm no electric motor whiz, i'm afraid, though i aim to be someday - my car really needs hybridisation on the ghetto-cheap)

2/ what's this "infamous 1064 day gap in train orders"? it's not infamous enough for joe schlub like myself to know what the heck context is being referenced so please either link it, or provide some inline exposition. cheers

3/ where's the CCTV? all I see are *LCD* TV screens - with overly powerful speakers - that show nothing but crap programs, the more annoying flavour of local news, and both overly earnest advertisements and advocations to spend a lot of money entering SMS-based competitions... the last two types of content, we had originally been promised would not appear. maybe if they HAD invested in CCTV instead the train would be a safer and more preferred way to travel.

-mp

Good questions; I don't know the answers either, but if anyone else does, they would be useful contributions to the article. In particular, I agree that the class 323s make a most peculiar noise when accelerating away from standstill; I initially assumed it was some kind of regenerative brakeing system working in reverse, but I may be quite wrong. DWaterson 00:38, 10 December 2006 (UTC)

I know the answer to number one; the distinctive sound is created by the GTO (gate-turn-off) thyristor (motor), it is also fitted to the British Rail Class 465, and a similar (but not the same) motor is fitted to the London Underground 1996 Stock, used on the Jubilee line. I hope that helps. Meateater 14:31, 10 July 2007 (UTC)

Yes, it is at least a very useful start, so thank you! The linked articles were a little thin on info, and I'm not sure I quite understand the theory/physics in them and in an independent search for GTOs/Thyristors, but I get the main concept; it's an innovative/early use of AC motors for propulsion (before the smaller scale/more high-tech IGBT & heavily computerised applications seen in e.g. the T-Zero and Tesla Roadster cars) instead of DC, with the noise being a characteristic of the components used to vary the effective input current and frequency to get the best torque out of the motor at a range of speeds (unlike the typically single-best-speed running of a household AC motor). No physical gears, or at least only two or three simple ones (e.g. the rather big change in motor tone about halfway through it's usual acceleration), most of the 'gear shifts' being changes in electrical characteristic instead. So I'd say you've pretty much cleared up that side of the query even if it's opened up a new can of worms with it... Unfortunately it seems it's an interesting feature we won't see again as the newer types have a much more continuous and quieter operation (Nottingham trams? and the cars of course) but it probably won't be missed except for us few sad cases heheh. Can't say I even noticed it on the few tubes I've ridden, though perhaps they were the wrong line - seemed more like DC motors or low-frequency AC and had rather ferocious acceleration even compared to the 323's! 82.46.180.56 (talk) 14:53, 6 December 2007 (UTC)