British Train Drivers Handbook?

[faedundee2]

Well put!

It was at the East Lancs in No.22 with Martin Walker (top bloke!). They do a "freight" diesel experience, though it was a parcels working when I did it. 250 ish, details on the site.

B

You got one of the best guys to do show you the ropes as he owns both ELR based deltics... The RW Deltic physics really need an overhaul to be honest...

[bdy26]

It was one of the afternoons I've ever spent. Rules of the forum prevent me saying much more :shock:

The physics are not right. In particular, there is a mythical notch 3 1/2 you have to find when starting off. Less and you get noise and no amps; more and you spike the pressures. Deltics are incredibly sensitive and responsive given the high revs, completely different to any other DE of that era.


B

[faedundee2]

It was one of the afternoons I've ever spent. Rules of the forum prevent me saying much more :shock:

The physics are not right. In particular, there is a mythical notch 3 1/2 you have to find when starting off. Less and you get noise and no amps; more and you spike the pressures. Deltics are incredibly sensitive and responsive given the high revs, completely different to any other DE of that era.


B

Plus the 2nd engine only starts up around notch 6(if it is actually running in the first place), while in RW it seems to be set to start running at over about 25mph, most locos are incredible senstive I advise don't try a footplate experiance course with 37518 if it ever shows up as it is incredible lively...

[AndyUK]

....Plus the 2nd engine only starts up around notch 6(if it is actually running in the first place)...

You've confused me here, how can it start up if it's running in the first place?

Andy L

[bdy26]

It idles, but doesnt contribute power other than in the higher notches. You can hear it spool up in videos. They can run on one engine quite happily and still outwit a 37

B

[GerardFiennes]

I think you will find that what appears to be the second engine starting to contribute power is in fact the field weakening where the current flowing through the DC traction motor field is reduced to allow the engine(s) to speed up (to counter the back emf produced by the DC TM).Deltics, I believe have two stages of field weakening,the second operating at 100mph and when the 100 mph limit on them was lifted,there was at least one occasion when 125 mph was achieved..Most locos have only one stage of field weakening although the Class 60 has computer controlled continuosly variable fields and there is no discernable transition.

[AndyUK]

On the other hand the explanation I've just deduced from the book on the Deltics by Brian Webb is that the apparent 'springing into life' of the second engine is down to the way the Deltics were modified to supply ETH. Space constraints prevented the use of a separate ETH generator and consequently the ETH supply is taken from a tapping on one of the main generators, although both are capable of supplying it. Because the main gen voltage is low when starting away the ETH supply is turned off automatically as the controller is opened and not restored until the voltage has risen to a usable level. As the main gen voltage output depends, amogst other things, on the controller position the ETH isn't turned on until the loco has picked up speed and the controller open up some more. The sudden application of the ETH load, which could be as high as 350 kW, onto the engine supplying it is, I believe, the reason why the second engine seems to burst into life. Being connected in series both main generators and consequently both engines supply traction power when both are running irrespective of the controller position.

If anyone can point me in the direction of another, preferably documented, explanation I'd be grateful.

Andy L

[faedundee2]

It idles, but doesnt contribute power other than in the higher notches. You can hear it spool up in videos. They can run on one engine quite happily and still outwit a 37

B

One engine running is the ONLY good thing about those droning devices... As in BR days they had a tendancy to break one engine alot meaning they had to get home on one engine, go to Doncaster for a replacement then to break that...

[jbilton]

Hi

See this thread

http://forums.uktrainsim.com/viewtopic. ... eth+deltic

Its a bit complicated, but in very simple terms, the leading power unit provides the traction power (and ETH) until about 28-30 mph, then the rear power unit, runs up to match the revs of the leading one.

Cheers
Jon

[GerardFiennes]

Re Deltics,I asked the experts and got this answer:"The first field divert came in at 50mph, the second at 75mph. The result was a locomotive that was rather slow to get away but once that first divert came in it would accelerate like a bat out of hell. From 75mph a Deltic could out-accelerate a class 84. The final ETH solution saw the power being taken from both engines. The control circuits were modified resulting in the leading engine having it's idle RPM speeded up to supply sufficient voltage. The result was to allow even wear on both engines and a happy effect was to make pulling away a less dramatic and less circuit breaker tripping experience".

[faedundee2]

Re Deltics,I asked the experts and got this answer:"The first field divert came in at 50mph, the second at 75mph. The result was a locomotive that was rather slow to get away but once that first divert came in it would accelerate like a bat out of hell. From 75mph a Deltic could out-accelerate a class 84. The final ETH solution saw the power being taken from both engines. The control circuits were modified resulting in the leading engine having it's idle RPM speeded up to supply sufficient voltage. The result was to allow even wear on both engines and a happy effect was to make pulling away a less dramatic and less circuit breaker tripping experience".

One problem with the Deltics lack of an ETH generator/alternator(depending on if reliabilty is your thing) is that if you are down to one engine and the ETH is required fro over half a dozen coaches the loco doesn't exactly like it... All power no amps as they say...