D7666

I am not talking about computer operating systems. It is about electrical communications along copper wires between electro mechanical human manned signal cabins done by relays. Zilch to do with operating systems in the same way that Linux / Windows / whatever O/S has nothing to do with how bits and bytes go along copper or fibre or radio. In fact it has nothing to do with computers at all. It way way predates computers in any kind of railway command and control scenario. And even today no business case to migrate from 000-777 octal to 000-999 decimal the increased number range is not needed anywhere.

And don't forget the valid digit range is not 000 to 999 but 000 to 777 without any 8s or 9s. It is an OCTAL range not a decimal range. Not withstanding that the /general/ numbering is 0xx 1xx 2xx 3xx 4xx passenger, 5xx 6xx engineers, 7xx empty and things like RAT, TRV, etc, each series are still for example 6xx 600-607 610-617 etc 670 to 677 So beware if making up fictitious numbers that you want to look real. It's origins lies in legacy train describer system with cabin to cabin comms signalled by a 3 relay set (so only 8 combinations from 0 0 0 to 1 1 1 ) to send each digit, and there is no business reason to alter this even on lines where this legacy kit is no more.

What an irritating OP question 😄 Irritating because after 60+ years of looking at Mk1 and Mk1 EMU I'd never noticed the things before. Must stop asking questions like this, I can't take the stress level..............😂😭

Which is why the world trades with China. With going i to the whys and wherefores of politics, their labour and production costs are low, the sea transit is low cost, the expensive bit is within the destination country. You can be sure if we in GB were still allowed to power station burn coal as our base load we'd be bulk importing by sea from China.

[1] 1991 Cannon Street accident train - to which I was refering - was more Mk1 then SR. The train was 10EPB formed 4EPB + 4EPB + 2EPB of which the first and last units were BR Mk1 EPB and only the middle unit SR EPB => the train was 60% Mk1. The principal damage was to the 1st 2nd 5th and 6th cars => 50% of the principal damage was to Mk1. It is the end cars that are most vulnerable in an accident. I rechecked the accident report before posting that; the report gives the unit and car numbers so there is no doubt. [2] Cannon Street 1991 followed the 1988 Clapham accident; the latter raised big questions about Mk1 + any other seperate body on underframe crashworthiness, Cannon Street catalysed action. But aftermath of Clapham focussed on the signalling issues not train destruction. [3] Swing doors (their correct name; slam doors is the popular but technically incorrect name) is a different issue. Up thread i was refering to construction, and construction only, where the body is seperate from the underframe. This applies to all TRUE Mk.1 and includes majority of predecessor designs like the SR EMU rebuilds. [4] The underlying reason for Mk1 elimination was crashworthiness not swing doors nor lack of central locking. That is why they did the 'cup and cone' anti over ride device experiments, and why the prototype 'networker classic'; the latter still suffered from it being a seperate body on underframe even though it welded not bolted, and was rejected for that reason, it was seperate. "slam doors" is the popularist version if only because doors are tangible and underframes not. [5] Those remaining Mk1 on main line are not permitted to carry passengers when they are the end vehicle. This is due to crashworthiness lack of. Both ends - of any formation; that is why there either a Mk2 (at least) if carrying passengers or a utility/generator/out of use coach at either end. The generator coach doubles in this function. [6] The NIR 450s were similar seperate body on underframe; welded or not, they were still seperate which is why, when the leasco that did the investigation, rejected them. Simply welding a few bodyside panels of one type to an underframe of a wholly different type is a production method of fixing the two together, not a method of structural integrity that meets crashworthiness need.

Also not fully true. BP are vastly more complex. The SR DEMU motor coach is fully independant - the engine and motors are all in one car, the other other cars are all trailers. The BP sets different in that they are distrubuted traction technology. Each half of a BP set has one diesel engine (in the lead car) driving 4 traction motors - but - only 2 of those motors are in the lead car, on the inner bogie; the other two motors are on the adjacent bogie under the adjacent car. The same is mirrored at the opposite end. No SR DEMU is like that. Further, on a BP an auxiliary diesel engine for train electric power is fitted to one of the other intermediate cars relieving the main engine of some of that load; again no SR DEMU is like that.

Sorry You are wrong The issue with Mk1 arose after the Cannon Street accident with bodies seperating from frames. That is the underlying issue demanding removal of Mk1. construction - not just actual Mk1 coaches. Swing doors (as they are properly called) and lack of locking is a secondary and more recent issue. The NIR DEMU are Mk1 construction. It was looked at by one of the leascos to see if they could be used in GB. Not feasible because they are of Mk1 construction.

By "80s EMUs" do you mean GB EMU built 1980s onwards and mating them with EMU cars to form a DEMu ? If so, the answer is no. Because the NIR 450s power cars were Mk.1 construction. They were not of the Mk3/Sprinter type construction. They had bodies built from Mk3 parts, but the fundamental issue that a Mk1 body is seperate from the underframe therefor liable to seperate in an accident remains. They would not have got through the main line normal TOC passenger stock Mk1 ban, and unikely to have got a derogation.

Yes and no. Like Mk2 yes, but all not Mk2, no. The resultant train might have looked like that but actually not. NIR DEMU motor coaches ARE NOT Mk.2 construction they are Mk.1. They /look/ like Mk2 but are not. It is a oft quoted mistake. A Mk2 structure could not bear the weight of that engine lump in one place. What they did was the motor coaches are strengthened Mk1 per BR SR DEMU with bespoke Mk2 style - but style only - body parts. Only the NIR DEMU trailers were Mk2.*** That is why I commented on the Dart engine under an AM10 was unclear where the engine might go. A Dart might be lighter than a DEMU EE 4SRKT but still a lump. *** a similar thing with BR class 210 DEMU. The 210 motor coach is NOT a Mk3 EMU shell, but structurally an HST frame and floor pan with Mk3 style body parts on top. Again, this is because the standard Mk3 structure can't take that engine lump, Paxman or MTU or anyone else's, in one place. ((I have questioned - on forums only - how this planned potential preservation attempt of recreating a 210 out of 455 cars is going to work. Good luck to them if they wish to try, but i do wonder if they have actually looked at original drawings.)) No idea on the NIR cab ends. But then why does any one type of train not look any other type of train ? One idea was the NIR motor coaches could be used as "locomotives" (presumably back to back pairs) which is allegedly why they had type EE538 motors as used in BR 37s and 50s and not EE507s per SR DEMU. Maybe, guessing, the cab ends had something to do with uses a locos ???? Just a guess.

digressing, up to about c.1970 Derby was looking at a gas turbine 'D'EMU; a couple of vague descriptions and an outline sketch appear one time; a sort of AM10 type MU body and powered by RR Darts and EE546 motors. It was not clear form the sketch where the gt would be mounted, it really was vague. One proposed gtmu route was Edinburgh FalkirkHigh Glasgow; the gtmu idea being around the time the Swindon dmu were getting clapped out but before the 27/27 push pull idea came about. Every time I mention this someone has to come along and post AM10 was a "door at (almost) every bay" suburban body therefore unsuited to IC type work. But it was never said the AM10 body was for that route - merely one fact was gtmu was suggested for the route, another fact was AM10 was suggested for a gtmu type.

For which I was the SEG train manager. I wanted to do another one - the Long Thin Drigg - out via Shap and back via Drigg........

Not sure I either understand or believe that. And certainly never heard that at the time or ever since. What is true is that any non electrified line - in general - there were very few exceptions then - was not shoe gear cleared => must have retractable shoes. But that is not Hastings line specific it applied everywhere else.

You beat me to it. 1111 got a 4 position EMU controller instead of the 7 position DEMU controller, but the control wires remained DEMU only.

Considering D800s with 2 x 1152 hp = 2304 installed hp MD650s reigned the Exeter line for 7 years, they "stacked up" pretty damn well.

AIUI some of the coal on the Aberdare to Salisbury and Southampton coal trains were for Salisbury and Southampton power station respectively. Salisbury was a tiny power station it barely reached 3 MW at its highest installed capacity. so the coal take was not significant. I wrote a paper on Salisbury PS that was privately published; Salisbury library have a copy + the research material I accumulated. Southampton PS was up to 88 MW at its maximum, although it got to 88 in the early 1950s but by then the rail link had been disused early after WW2 and coal came by road. It was an interesting rail served PS in that it was one of those with its own electric railway and one of the 3 locos was built by Southampton corporation tramways. I can't find a inter war year MW rating for the PS buts lets say it was half at 40-50 MW that takes quite a bit of coal. Ports ships needs notwithstanding - but that is where a good portion of the Aberdare Southampton coal went - to the PS. In back reading this thread, some of the postings are a little confusing reading now. At least three different posts refers to imports but then go on to talk about coastal colliers. Imports - to me at least - means from overseas not domestic. Coastal colliers - by definition were domestic.