Deleted
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Post by Deleted on Jun 26, 2007 7:07:29 GMT
Does anyone know where i can get some info on the operation of the PCM controller used in the 38TS and others. On the 38 tour at the weekend i believe i was sat right over it and being an electician would love to know what all the ratcheting, clanking and popping was doing under my feet.
Darren.
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Post by tubeprune on Jun 26, 2007 14:20:38 GMT
A full description is in the supplement to "Electric Trains" by W A Agnew, Virtue, 1937. It has diagrams of power and control circuits and a detailed description of the operation. I know the system quite well as I was the advisor for setting up the rig in the LT Museum and getting it to work off 240 volts AC instead of 630vDC.
Copies of the Book (2 volumes and the supplement make the set) sometimes appear on ebay. It also has a good description of almost every stock in use on electric railways in the UK at the time including Standard tube (3 varieties), two types of District stock, Met stock (Vickers) and Sarah.
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Deleted
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Post by Deleted on Jun 26, 2007 15:35:05 GMT
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DrJimi
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Post by DrJimi on Jun 26, 2007 16:01:19 GMT
Well worth the money Darren! I lucked into the 2-volume set in excellent condition from a bookstore in New York city for a 'reasonable price'. As an electrician you will drool over it (as I do). As TP notes, there are circuit diagrams as well as illustrations and detailed explanations. I'm very tempted to try and build a current-limit driven RPA setup for a small motor - just to see/hear it work ;D I can still hear the notching relay sounds in my mind, despite my last trip on LUL was likely over 30 years ago. I'd rate Mr Agnew's hefty tome as likely the definitive reference work on the subject. EDIT: Found some useful references about DC traction motor control that include notes on notching relays and RPAs: www.railway-technical.com/elec-loco-bloc.shtmlwww.railway-technical.com/tract-01.shtml/Jimi |
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Post by tubeprune on Jun 26, 2007 18:24:33 GMT
This is my original website. |
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Post by tubeprune on Jun 26, 2007 18:40:53 GMT
No 3 in your Googled list is the most cost effective offer in the list. It will be money well spent if you want to become the traction expert who can simulate LU stocks past. For example, there are lots of pictures of cab equipment like master controllers. Once you understand the 38 PCM system, you will know all stocks up to 1967TS. After that, you get into twin camshaft systems with rheostatic braking added. Oh I wish I still had my car examiners diagrams for all stocks from 1923 to 1973. |
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Deleted
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Post by Deleted on Jun 26, 2007 19:44:00 GMT
Thanks Tubeprune/Jimi. I must say you guys are really selling me this book. I'm very tempted now especially containing pics of master controllers and the like aswell. I suppose i better get permission from the financial controller (wife) before ordering.  |
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Deleted
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Post by Deleted on Jun 26, 2007 19:54:25 GMT
The PCM noise is a lovely sound... tak-tak-tak-tak... Was even better on Sarah Siddons, but was accompanied by many bangs and a virtual firework diaplay...
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Deleted
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Post by Deleted on Jun 26, 2007 20:50:51 GMT
I now have a superb recording of the PCM gear in the motor trailer in the '38. I recorded on the tour with an MD recorder. The recording is from Kennington loop. I've listened to it a few times through the 'phones, and it sounds superb.
What is the first initial (and louder) clunk from the PCM when the controller is moved to shunt?
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Deleted
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Post by Deleted on Jun 26, 2007 20:54:09 GMT
The loud clunk is actually the Line Breaker closing... LB1, followed by LB2...
All described in a 'how it all works' in a book, by Piers Connor!
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Deleted
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Post by Deleted on Jun 26, 2007 20:56:28 GMT
The loud clunk is actually the Line Breaker closing... LB1, followed by LB2... All described in a 'how it all works' in a book, by Piers Connor! Never heard of him  |
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Deleted
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Post by Deleted on Jun 26, 2007 20:58:58 GMT
ISBN 1-85414-115-5, Capital Transport [who else?] £9.95 and probably now out of print, since I ain't seen it for ages...
Got a nice bright yellow spine and a lovely piccy on the front!
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Oracle
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Post by Oracle on Jun 26, 2007 21:15:47 GMT
Never heard of him  He's that geeezer what's on the telly (satellite/cable) in repeats.  |
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Deleted
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Post by Deleted on Jun 26, 2007 21:34:25 GMT
I was joking  |
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DrJimi
Virtual District Line construction engineer and arborist
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Post by DrJimi on Jun 26, 2007 21:43:58 GMT
This is my original website. I'm sorry TP, I was unaware else I would have given you due credit. I did sense the author 'knew his stuff'. My hat's off to you once again! Artery - I have found 3 copies of the '38 book available - ranging from $57 to $164! I'm tempted... |
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Post by tubeprune on Jun 27, 2007 6:07:34 GMT
This is my original website. I'm sorry TP, I was unaware else I would have given you due credit. I did sense the author 'knew his stuff'. My hat's off to you once again! None taken Blimey, I wish I'd kept a few in stock to sell now  |
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Deleted
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Post by Deleted on Jun 27, 2007 6:37:18 GMT
The loud clunk is actually the Line Breaker closing... LB1, followed by LB2... All described in a 'how it all works' in a book, by Piers Connor! O.K. Artery, what's the loud pop when the train is accelerating. I'm thinking it's something tripping because power gets cut to the motors, but it seems to happen at random places in the acceleration. |
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Post by tubeprune on Jun 27, 2007 14:32:56 GMT
The loud clunk is actually the Line Breaker closing... LB1, followed by LB2... All described in a 'how it all works' in a book, by Piers Connor! O.K. Artery, what's the loud pop when the train is accelerating. I'm thinking it's something tripping because power gets cut to the motors, but it seems to happen at random places in the acceleration. You are correct, CabDarren. The power is being cut off during acceleration. As high currents are drawn during acceleration, the line breakers (LBs) open under load and the "pop" is the arc being extinguished by the "blow out coil" fitted behind the LB contact tips. The random nature of this is because it depends where you are and what the speed is supposed to be. If you are leaving a station with a gap in the current rails immediately ahead of the platform, the power will be cut off each motor car as it passes over the gap. As each motor car will be doing a different speed and drawing a different amount of current as it goes over the gap, the "pop" will sound slightly different. The PCM is designed to automatically reset if a gap is detected under power, so the driver doesn't have to shut off, the equipment does it with a "no volt" relay. If this happens, you will hear the PCM return to off and then, after detecting power again, notch up quickly to where it needs to be to match the current draw. Also, if a driver shuts off at any point, there will also be a "pop" - with varying intensity depending on speed. If you want to hear this these days, sit near the middle of any A Stock motor car. It has virtually the same equipment underneath. |
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Deleted
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Post by Deleted on Jun 27, 2007 15:52:55 GMT
Fascinating stuff, TP.
I'm hoping to be able to produce a few copies of my 38ts recordings. I'm a bit busy this week, but hope to have them transferred to CD from MD soon (I need to send them to one of the members on here).
David
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Deleted
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Post by Deleted on Jun 28, 2007 6:51:45 GMT
Thanks Tubeprune. Great stuff. I haven't had a chance to play my video on the tv yet with extra volume, but judging from the camcorder playback i've caught plenty of popping and ratcheting of the PCM.
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Post by abe on Jul 6, 2007 18:39:15 GMT
ISBN 1-85414-115-5, Capital Transport [who else?] £9.95 and probably now out of print, since I ain't seen it for ages... Got a nice bright yellow spine and a lovely piccy on the front! There's a copy up on eBay at present, ending tomorrow: LinkCurrently only £5.50... |
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Post by programmes1 on Jul 7, 2007 9:57:45 GMT
Now £22.77 + postage at the moment.
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Post by Deleted on Dec 2, 2008 13:54:06 GMT
I just received my copy of Mr Agnew's Supplement on Electric Trains and what an awesome read for a maintenance electrician as myself. Thanks for the recommendation guy's.  I can now fully understand what all the clicks and pops are that were going on under my feet when on the 38 tour last year and I think you could also determine exactly what the driver is doing with the throttle handle just by sitting over the RPA unit and listening to it. The reason i wanted to know so much information is because I want to try and replicate the sound of the PCM Control in Rail Simulator. I have all the required sounds i can rip from my camcorder footage. The only snag will be it will have to work off the speed instead of current drawn through the motors as I don't know if Rail Simulator will sense the current change in doing Series/Parallel switching. Unfortunately Mr Agnew doesn't say at what speeds the resistances stepped out but then that would be dependant on the load of a full or empty train i would imagine. I would have been fascinating to have be able to watch the notching relay at work on a normal working service. Darren. P.S Mr Agnew dosen't mention what RPA stands for. My guess is something along the lines of Rotary Pneumatic Actuator. |
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Post by 21146 on Dec 2, 2008 15:20:34 GMT
I P.S Mr Agnew dosen't mention what RPA stands for. My guess is something along the lines of Rotary Pneumatic Actuator. Rapid Pneaumatic Accelator |
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solidbond
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Post by solidbond on Dec 2, 2008 15:48:13 GMT
I P.S Mr Agnew dosen't mention what RPA stands for. My guess is something along the lines of Rotary Pneumatic Actuator. Rapid Pneaumatic Accelator Although some people have claimed it is Rapid, I've always been taught, and have taught others, that it is Rotary (since it goes round ) |
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Post by 21146 on Dec 2, 2008 15:58:58 GMT
Rapid Pneaumatic Accelator Although some people have claimed it is Rapid, I've always been taught, and have taught others, that it is Rotary (since it goes round ) I was taught 'Rapid' at White City RTC |
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Colin
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Post by Colin on Dec 2, 2008 17:19:39 GMT
Well I was taught by Solidbond (hopefully he's recovered by now! ;D ;D), so I only know it as rotary.
There was a thread which went on at great length many moons ago IIRC about which term was correct - I can't remember if it ever reached a definitive conclusion, but I'll see if I can sniff it out......
EDIT: I found the thread (dates back to 2005) - there's no point referencing it as no conclusion was reached - other than it was agreed that it was called 'rapid' in White City days but that it is now known as 'rotary'.
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towerman
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Post by towerman on Dec 2, 2008 19:03:24 GMT
Fleet maintenance always called it rotary,including their instructors at White City!!!
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Ben
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Post by Ben on Dec 2, 2008 19:24:08 GMT
Fascinating info all round, especially TP. When I came across your first site whilst in secondary school it inspired me to build a simple dc motor where the field current could actually be modified. Regrettably, a temporary head of science threw it out before completion. That was the end of that I love the sound of an A stock DM. I just wish I were around years before to hear the standards, the T's, the F's, Q's and other stocks. Presumably each different control system sounds vastly different; if so how many have been used over the years? |
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Post by tubeprune on Dec 2, 2008 21:54:36 GMT
I've always thought of it and taught it as "Rotary".
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