Deltic questions

[heart-of-wessex]

Hello all,

Even though my top loco of all time is the racehorses, especially D9000, there is a couple of things I am stuck on, can someone help me answer the questions?

1. Clag. AFAIK it is not actually clag, its just a normal proceedure that the engine causes, but what exactly? I know usual clag is overheated or broken injectors, but is the Deltic white plumes to do with a 2 stroke engine or something?

2. The second engine cut in. When does this actually happen, is it 20 or 25? And when the train reaches this speed I presume the 2nd engine powers up to whatever notch the train happens to be in (and I guess when re-applying power from 0 at, say, 80mph, the 2nd engine works with the 1st immediatley in tune, or is there a delay between the two?)

3. how many times does it work through the field diverts? I know it sounds like the engine is winding down a notch for a whilst before powering up again, I forget how many times and it there is certain speeds this happens at?



any help appreciated!


cheers,

James.

 

[37401]

Engine 2 Kick in is at 30 IIRC

 

[43034 The Black Horse]

Engine 2 Kick in is at 30 IIRC

I read this on another forum;

"It was to do with ETH, just take power from one engine so as to keep the rpm high enough to keep the ETH volts high enough, as it was fed off the main gen, then around 20mph the other engine sped up.
Or something like that."
--- old post above --- --- new post below ---

Hello all,



1. Clag. AFAIK it is not actually clag, its just a normal proceedure that the engine causes, but what exactly? I know usual clag is overheated or broken injectors, but is the Deltic white plumes to do with a 2 stroke engine or something?

Clag can be a number of things. Over fueling, burning fuel and/or oil, dodgy govenor.

Although, I believe it is just normal emissions from the napier engines. Although I am willing to happily be corrected.

 

[bluebottle]

The plumes are oil being burned. Most older two stroke engines are designed to burn a little oil.

 

[DaveNewcastle]

Yes, these engines draw an astonishing amount of oil into their cylinders. This is a feature of two-stroke designs in general, but additionally, the deltic design tried to improve performance by using a "scavenger blower" which helped to extract exhaust and draw in fresh air as quickly as poss (these would be during quite separate "strokes" of a 4-stroke engine). So a comination of the high oil content of a 2 stroke and the blow of the scavenger contributed to their distinctive exhaust plumes.

Yes, they had fuel injectors, (36 of them), but they didn't need a fault to produce a lot of smoke!

As for revs, there was an unusually narrow band of speed between the very fast idling speed and the top speed. Each engine could be switched on or off from the driver's desk, and were started seperately - I don't remember for sure but I seem to recall just that just one engine might be started up for some light loco moves (which in those days would occur at each end of each journey). Each had its own primary & aux generators, so total power to the traction motors would clearly be be increased with both engines taking power, but there was no need to synchonise them in any mechanical sense. The field divert will have been a simply controlled mechanical relay (unlike any modern semiconductor load controller) but I don't know at what point they switched.
But I can't recall how the 2 engines behaved when power was drawn to add to the other posts, though yes, the power surge when pulling away is another characteristic of those unusual machines.

 

[mumrar]

From driving the new Deltic on openBVE it seems there are 3 field diverts. They're in the region of 33, 52 and 70mph if my memory is correct.

 

[37401]

From driving the new Deltic on openBVE it seems there are 3 field diverts. They're in the region of 33, 52 and 70mph if my memory is correct.

You gotta love the noise on the openBVE Deltic, East Linconshire Railway full notch my lordz

I was going on the Rail Sim Deltic which is 30mph-ish then it sounds like its taking off

 

[DaveNewcastle]

From driving the new Deltic on openBVE it seems there are 3 field diverts. They're in the region of 33, 52 and 70mph if my memory is correct.

Its so embarassing to realise that a computer simluation is likely to be more accurate than my memory! But . . .
52 sounds about right, 33 seems a bit too high (I would guess 23), and I just don't know about 70.

 

[heart-of-wessex]

Thanks for the replies and help!

So with the 2nd engine kicking in, if switched on of course, it simply sings its own tune rather than balancing with the no.1 engine?

Might take a spin on the BVE 4 one again to see when the field diverts come in.



Cheers,

James.

 

[25322]

Clag is the effect of unburnt diesel in the exhaust system. The black smoke is the direct result of too much fuel been injected into a cylinder and incomplete combustion occurring.

Its called 'over fuelling' and is caused by a variety of reasons. too much fuel, busted injectors and failed turbo's to name a few.

With the napiers the blue smoke is part of the engine oil vapour being drawn through the cylinders and not combusting at all!

 

[kestrel]

You have 3 field diverts when running on ONE engine generally around 25/50/75 give or take a few mph, when running with both engines there is only TWO diverts 50/75. (thats real life not simulator ;o) )

2 strokers or smokers are well known for there clag,as said above its just oil drawn into the combustion process quite normal.

I've seen deltics in service on both engines from as low as 15mph, when D9000 was a regular on the Ramsgates and the drivers got the hang of the machine they regularily floored it on both engines before the platform ends!, you have to watch the ammeter like a hawk tho!

 

[25322]

2 strokers or smokers are well known for there clag,as said above its just oil drawn into the combustion process quite normal.

Not completely true. You don't see yings/sheds/skips smoking like the Deltics and they are 2 stroke engines.

 

[heart-of-wessex]

Not long watched the power hour 1/2/3 vids, on there is some massive deltic smoke!!!!!

Maxey himself mentions about the 2 stroke engines usually producing smoke as a normal procedure (and carries on to say 'as any moped rider will tell you..')

The sheds and skips though, even 2 stroke, have emission things anyway don't they? Surely with that taken out it might produce white smoke?

 

[DaveNewcastle]

Ah, but you are now comparing a radical 1960's diesel engine in a steam age (a very novel engine, but only a radical engine as a just power unit - not as part of a bigger environmental context) with a 2000's engineering system which is concieved and built to be integrated with its environmental supply and delivery impacts ; ( I guess the modern diesel locos use electronic control of a wide range of operating parameters. I know that Napier's Deltics didn't. - I was there.)
The earlier point stands - the 2-stroke as a basic principle simply cannot provide the environmentaly clean exhaust for each cycle's fuel to enter & exit the cylinder; it deliberately allows oil to be drawn into the cylinder (vital to lubricate the bores); PLUS the deltic's "scavenger blower" on the exhaust was the complete opposite of a contemporary exhaust management system - (it forcibly and intentionally extracted as much exhaust, unburnt fuel and any other oil-based products into the atmosphere, and in those days, that was a good thing to achieve! And in contrast, any modern system tries to minimise the exhaust impact, doesn't it?)

When making these comparisons, we have to go beyond the engineering and look at the social expectations of their times. These were times when diesel was good - coal was bad. Groups of concrete tower blocks were good, brick terraces were bad. Almost any engineering or chemical technology was good. Letting nature and the environment influence our designs was "old-fashioned". All that changed AFTER Deltics, and I'm sure you know what I'm getting at . . .

I remember the introduction of those machines on the ECML, and all the debate was 1) the differrence between coal shovelling, crewing, heat and mess vs. one or two men on padded seats watching a few dials, or 2) the economic benefits of moving cheap diesel & oil rather than coal, and 3) the greater staff reductions made possible with double-ended diesels locos after decades of turning steam locos and tenders, and 4) what was, at the time, a naescent form of environmental awareness, that diesel would stop the blackening of buildings, people, washing lines of whte shirts etc. that coal had been producing for nearly a century.
Of course all that applied to ANY diesel vs coal powered transition, on rail or land-based, but the issues were magnified by the Deltic's ability to reach high speeds, high power, high in-service ratios and rapid repair/replacement/maintenance turn-rounds. /rant