Ben
Box Boy
Posts: 65 
|
Post by Ben on Jun 17, 2013 2:03:21 GMT
Thought this might be interesting reading for some of you. From the days when people were proud to explain how things worked, and showing an interest was honourable trait! This is the supplement to an extremely weighty two volume tombe of work Agnew authored on the control systems of electric trains then in use (1938). I am informed that the supplement is far harder to come by than the main books. I do have access to the complete set though, so if anyone has a request that the main work would contain, I should be able to provide further scans. One wonders whether with the right kind of materials (say the Lego Technics pneumatic and electric kits, or Mechano maybe), whether it would be possible to create a working model of the control system? Anyway, enjoy! docs.google.com/file/d/0B9irIhwYmRqxaEg5eGg3VExtTGs/edit?usp=sharing |
|
|
|
Post by Nortube on Jun 17, 2013 9:10:26 GMT
That is very interesting, thanks. Those exact diagrams were still being issued as handouts when I was at the school at White City in 1976 for the Motorman's train equipment course. We would come into the classroom in the morning or afternoon and the Instructor would normally be finishing drawing the relevant diagram on the blackboard. We would then have to copy the drawing into out exercise books and the circuit was explained to us and we were dictated notes to write down. Only afterwards were we given the handout. This was a much better way of learning than the current “here’s a handout, we’ll talk through it”.
As Guards, we were taught the control circuit and the basics of the power circuit, and supposed to know all of the relevant defects that we may have had to deal with (the same as the Motorman). However, as Motorman, the Power and control circuits operation was gone into more thoroughly and in the class we were told that, on exam, whilst we wouldn't be expected to know every detail of every component on the control side, we would be expected to know the complete operation of the power circuit, including the position of al the relays during the sequence steps. In the end, I think that the examiner only ensured that people knew the position of the S, P and G relays and linebreakers at each step. (That was all I was asked. As the exams were oral, it was up to the examiner exactly what they asked).
1938 was the stock that all Motormen were being taught at the time as it was the basis for most of the stock that was then in use, although train equipment did cover unit isolation (for the air supply) as well, although this wasn't relevant.
I don’t see why a working model couldn’t be made, although it may have to be simplified a bit.
About 20 years ago, I made up two MG diagram simulators, one hand-held in a (approx.) 9” x 5” case, the other mounted on a (approx) 2ft x 2ft board. This was to demonstrate the operation of the MG circuit and thus was quite simple – switches that could be operated to signify a blown fuse (or an open switch), LEDs indication whether current was on or off in that part of the circuit, and an audible warning using a sound generator chip. They were basic, but served their purpose. These days a similar thing would probably be computer controlled with a screen display.
> From the days when people were proud to explain how things worked, and showing an interest was honourable trait!
I agree. Sadly this is rarely done any more. Whilst the coming of the PC for everybody has been a good thing, and indeed allows any “author” to create very professional results and, via the internet, make them available to everybody, there are also downsides. One of the offshoots of the PC, such as games consoles etc., mean that younger people are too busy doing other things to be bothered taking an interest in things mechanical or electrical.
|
|
Ben
Box Boy
Posts: 65
|
Post by Ben on Jun 17, 2013 15:24:12 GMT
No worries! Its revealing that the same diagram was used in circulation 40 years after drawn. Certainly, 'if it aint broke, don't fix it'. I'm struggling to remember whether the diagram for the Metadyne stock was in the main book for that might prove interesting. Indeed so. Though you still get (thankfully!) a few people with an interest in mech eng and elec eng, they are perhaps not as common as once, and I would postulate that the average mans basic understanding of electrical and mechanical concepts has too decreased. As to whether its all the PCs fault though I'm unsure. I wonder whether its to do with societies and technologies intentional and unintentional attempts to 'hide' the inner workings of things, or make them increasingly convoluted? For example, when the 'micro-mania' hit in the 80's a lot of people including children learnt how to programme in various computer languages to varying levels. But certainly as computers and software became ever more evolved and all-encompassing, the need and thus the will to delve any deeper went. I would wager that few people deal with MS-DOS for example these days and would be stunned into fear if it popped up demanding a response, yet before Win95 everyone must have had some experience with it, even if it was just to type 'win' at the command prompt! Likewise, the general development away from electro mechanical objects into electronic and firm-ware based solutions. You can actually see how a reed switch works, a camshaft isn't too difficult to imagine, nor are gears and pistons and variable resistors and the like. But once you start to talk of a transistor, you cant physically the process that makes it work. You can't see the electrons, and holes and the three layers of silicone/germanium; you just have to trust in what it does, ultimately. And by the time you get to a microprocessor, even the most basic ones, you can't even see the individual diodes and transistors making them up! People are surely far less likely to become engaged from something if its impossible for them to see how it functions. Not that that is technologies fault, mind. The rise of the semiconductor was based on the 'pure' notions of echnological advancement, not, say, that of barons in the germanium business wanting to tear down those high and mighty fat cats in the bronze and steel industries!  However, the societal aspect of this is far more sinister at its core. Ignorance is, sadly, seen as bliss increasingly now. Why on earth would anyone want to possess such information if not for nefarious reasons? Exactly the same reason as why in another place the question of what various cables in the cable run did met with a firm 'none of youre damn business!'; it is seen as dangerous and potentially criminal to possess an interest in something beyond an arbitary and unquantified level. 'Why do you want to know how the power circuit on an S stock works unless youre a terrorist?', or 'we wont tell you because of contractual confidentiality'. The book above dates from 1938 and was a general publication, dealing with stock that was just being introduced then. It wasn't a more innocent age, as some might have us believe: there was a world war combined with several genocides just around the corner after all! But it was an age proud of its development. On a side note, I read once about a plan to refurbish, repaint and rewire the 38ts to be compatible with the 56/59/62 fleet. Was the latters wiring that dissimilar in principal for this to have been a non-starter, or was it more an evolution, with an extra control wire here and there as needs be, and a subtilly different voltage because of the different equipments installed? |
|
|
|
Post by Nortube on Jun 18, 2013 10:33:20 GMT
I think you're right in what you say. There's not much to hold people's interests these days and there's not the fun (or pride) when doing something on the PC compared to being able to create something mechanical / electrical and say "I did that" and people can see and appreciate what you've done.
I know things continually change and people probably have much better skills in things that I don't (such as social networking), but it does sometimes surprise me when talking to younger people that that don't know some of the basic things or have the basic skills that people older than them have because it was things they did when they were young or they were taught at school. I suppose it's a natural evolution over the years and no doubt said by each generation over the years!
Like many people , I used to have electronics as a hobby. However, whilst I still like to dabble when I get the urge, four things made be give up the sort of things I used to do:
1) computers came along and I got sidetracked onto something new. Not so much for the programming, although I did play around a little with that, but for what the computer was able to be used for, especially as PCs improved, got cheaper, and there was more of a selection of software available.
2) electronics became more and more micro. Chips then took on whole functions and, later on, microprocessors took over. On the whole, a single function chip was a great improvement. In beginnings of the digital clock era, it was cheaper to buy a kit and make it up than buy a digital clock from a shop. Even then, the kits were expensive. I seem to remember paying around £25 for a clock kit in 1975. The bulk of the circuitry was the clock chip which, if bought separately, was around £18 at the time. The other components were just the peripherals, such as the display (7 segment LEDs were the ones I used most), resistors and crystal, plus PCB and optional case and switches.
Likewise a digital thermometer or rugby clock. Both of these are common today, but at the time they were only available in the shops at very ridiculously high prices and so they were a novelty to build and have.
However, a customised chip or microprocessor had its disadvantages. I used to repair various electronic items such as PCs etc. My knowledge wasn’t always that good, but as long as I had a diagram and preferably the voltage shown at test points, I could often identify the faulty component, then it was just a case of fitting a replacement and seeing if it worked. The problem with a specialised chip was that, unlike over the counter components, it was usually only available from one supplier. If you were lucky, they might supply non-trade customers, but the high price of the item and the exorbitant p&p rates made it a very expensive chip to buy when, on replacement, it was found not to be the cause of the fault and so the money was wasted.
I used to get various electronic magazines and sometimes make up projects from them. Apart from the cost of the PCB, the components were usually cheap, either sourced from surplus stores or Maplins (when they were there original shop at Westcliff, later at Hammersmith), before they got taken over and started charging ridiculous prices. However, the trend became more and more that microprocessors were used in the projects. Unless you had your own expensive programmer, these has to bought ready programmed and were usually very costly when compared to the rest of the items.
3) miniaturisation. Components got smaller, double (or even triple, quadruple, or more) PCBs became the norm and most components became surface mounted. It just wasn’t worth the time and effort trying to do any work with these things, although I have done some amBX light repairs with Surface Mounted Devices, it’s way too fiddly.
4) cost. In these days of cheap imports, it’s just not worth it trying to repair anything in most cases. Either the time spent to do the repair far outweighs the cost of buying a replacement, or the cost of a single component will probably be a lot more expensive that the original item, especially when the crippling p&p costs are taken into account if a component has to be ordered.
I suspect that these may be similar reasons to why others no longer pursue these types of hobbies any more.
|
|
