metman
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Post by metman on Apr 29, 2008 18:03:24 GMT
With all this terrible rain over the last day or two, it once again reminded me how much the A stock hates the rain. On the way home from work one of the brakes locked into Pinner and there was much skidding! When winding up, I have noticed that the motors can struggle, reaching some strange notes and often causing the line breakers to kick in with that wonderful 'pop' noise and causing the PCM and relays to reset!
Can anyone comment on what and why this is happening
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Deleted
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Post by Deleted on Apr 29, 2008 19:22:05 GMT
I remember a similar situation at Northwick Park on an westbound train. Lovely noises, think he had it in notch 1 [shunt] and still slipped... He ended up having to apply the power in very small steps, more or less apply power, for less than 2 seconds, notch off... try again... I think we took 11 minutes to reach H-o-t-H...
The PCM was having a field day... tak tak tak... CLUNK...tak tak tak... CLUNK... Nice smell when we started spinning, LB's kicked in, with a nice huey cloud billowing up from the 1st bogie... Cor! Sniff Thaat!
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metman
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Post by metman on Apr 29, 2008 22:58:44 GMT
Love it!!! I'll miss all that! One thing DC has over AC motors-character!
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Colin
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Post by Colin on Apr 30, 2008 0:37:40 GMT
Can anyone comment on what and why this is happening Whilst no expert on stock (especially A stock), I should think it would be something along the lines of: wheels spin as they can't get any grip on the wet rails, as they spin too fast power is cut until they slow down, then power is re-applied.......this cycle continues until suitable grip is achieved. As "Artery" says, the train op can manually apply the power as he pleases to achieve the same effect. As for the lack of grip......take a six car train as an example: 48 wheels, each with a contact area on the rail of about a quarter of an inch = 3 square inches of wheel to rail contact per six car train! Add some water (or even some dodgy leaves), and you can perhaps see why trains can have grip issues.... |
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metman
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Post by metman on Apr 30, 2008 7:02:09 GMT
Thanks Colin!
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Deleted
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Post by Deleted on May 4, 2008 15:52:30 GMT
A skill full driver can apply one notch at a time to aid acceleration and not to spin the wheels. Concerning skidding during braking, well a good prayer mat helps. ;-)
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metman
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Post by metman on May 4, 2008 20:28:52 GMT
Yes, I can hear that happening sometimes!
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a60
I will make the 8100 Class DART my new A Stock.
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Post by a60 on May 4, 2008 20:33:49 GMT
More to do with the A62 Units, whenever they pop on sudden changes to power levels, they seem to throw you forward a lot more than A60 units. A60 fan units rumble a bit more than A62 fan units. I love A60/62 units me.
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Deleted
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Post by Deleted on May 5, 2008 11:02:39 GMT
That sounds absolutely awful! Hope the new S-stock has better provisions for wet driving. I've been on trains in other countries which doesn't seem show any issues in the wet.
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metman
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Post by metman on May 5, 2008 11:11:35 GMT
I doubt it! Being automatic could be even worse...
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Post by superteacher on May 5, 2008 11:19:44 GMT
I doubt it! Being automatic could be even worse... It took them a long time to get the 92 stock to stop properly in tbe wet. Not sure how many overruns they experience now. I know that when the rails are really slippery, they instruct the drivers to use coded manual. |
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metman
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Post by metman on May 5, 2008 11:22:31 GMT
That makes sense!
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Chris M
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Post by Chris M on May 5, 2008 11:42:17 GMT
Either the drivers or the system in the central sometimes overcompensate now in the wet - I've experienced several occasions where the train has stopped up to a car length short before drawing forwards. Particularly at Stratford and Leyton eastbound.
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a60
I will make the 8100 Class DART my new A Stock.
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Post by a60 on May 5, 2008 13:00:10 GMT
The S Stock is now starting to sound like a euphamism for something terrible.  |
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Deleted
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Post by Deleted on May 5, 2008 15:43:40 GMT
I doubt it! Being automatic could be even worse... It took them a long time to get the 92 stock to stop properly in tbe wet. Not sure how many overruns they experience now. I know that when the rails are really slippery, they instruct the drivers to use coded manual. Yes, even worse when ATO first came in and before WSP mods to the software... Auto would apply brake, WSP cuts in and throws it off, ATO tries to apply brake again, WSP cuts in... result...? over-run! |
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Deleted
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Post by Deleted on May 6, 2008 12:08:13 GMT
Are other LU stock in general more resilient to the wet than the A stock? The inital acceleration rate of the A stock isn't exactly staggering compared to other stocks.
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Deleted
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Post by Deleted on May 7, 2008 10:21:59 GMT
A skill full driver can apply one notch at a time to aid acceleration and not to spin the wheels. Concerning skidding during braking, well a good prayer mat helps. ;-) You don't need to pray. When you shut off and start braking, if the wheels lock up, throw off the brake and wind up into series. You then start to apply the EP brake again, while still in series. That keeps the wheels turning while you apply the brakes. Keep in series until about 10mph then shut off and the train stops with no problems, apart from a slight jolt as you shut off as the brakes are still being applied. Obviously you need more of a braking distance than normal, but that's the way we always stopped in the leaf fall season, in the days where you could hardly see the rails for the leaves. Try telling that to the S Stock project team, "Wind up and brake at the same time? Naaaa, don't be silly, our trains will easily stop in the wet with all that mulch".  |
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Deleted
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Post by Deleted on May 7, 2008 13:31:26 GMT
Hm...the train I was on was an 11-car with 6 motor, 5 trailer configuration with a single power handle, much like the modern LU stocks. Brakes were very consistent, with the train stopping from 48mph to 0 in 220 metres (720 feet) in the wet.
I know the UK have had Japanese consultants in the past - time to actually implement what they said? :/
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