Why the auxiliary generators on the Deltic Engines

[GreensandsParticipant @greensands]

Here’s one for the Deltic locomotive enthusiasts. The attached photo shows a Deltic engine as fitted  to the D59xx series (Baby Deltics) but I think the same general arrangement was also used in the 55XXX series. Given the otherwise very compact nature of the design can someone explain why it was decided to fit an auxiliary generator mounted on top of the engine as shown in place of say simply tapping off the required auxiliary services from the main generator?  For completeness the photo was taken from the booklet “Baby Deltic – The story of an engine’s rebirth” published by The Baby Deltic Project.

[John HaineParticipant @johnhaine32865]

Was there an auxiliary engine too?  I can imagine if the starting battery (did it have one?) was flattish it might be difficult to start the loco.

[bernard towersParticipant @bernardtowers37738]

Or could be for non motive power, lights/kitchen etc. could then be different voltage.

[noel shelleyParticipant @noelshelley55608]

AUX services or is it an exciter for the main alternator. It is driven off the main engine, not a separate engine. Noel.

[duncan webster 1Participant @duncanwebster1]

The main generator would produce a variable voltage up to about 600v depending on controller setting and speed. And it was DC. This is before switch mode converters. Not much use for auxilliaries. My money is on it being the exciter generator.

[Anthony KendallParticipant @anthonykendall53479]

Firstly, the battery is situated in the middle on each side and is 120v.
The auxilliary generator charges the battery but some supplies start off on battery and switch directly to the auxilliary generator when available e.g. fuel pumps. The aux supply feeds…
Lights
Boiler
Compressors (for braking and contactor control)
Exhausters
Traction motor blowers
Fuel supply pump
Generator field.
I may have missed something, but you get the drift.

[Anthony KendallParticipant @anthonykendall53479]

Yes, I did miss something – the battery supplies the start windings which are situated on each main generator on a Deltic loco. in order to start them. 2 engines, 2 main generators, 2 aux.
The battery also supplies the field for the aux generator.
There is no sophisticated electronics, no transistors or valves – all relays and contactors, just magic.

[Anthony KendallParticipant @anthonykendall53479]

Reply to John Haine….
I can see the case for having an auxilliary engine John, but no there isn’t.
Later, when the Mk2D coaches arrived, needing a supply for aircon etc., it was taken from the main generators. This obviously had an affect on the power available for traction and to help with this the supply was removed when starting off from a station. Thus, you could always tell when you were off – the aircon closed down.

[Don CoxParticipant @doncox80133]

This is probably tosh, but I remember when I was tasked with teaching about them as part of a C & G motor mechanics course, 2 stroke Diesels have to be supercharged and this was usually achieved by fitting a Roots blower.  As a Deltic is a 2 stroke might it be that device in the photograph was used to ram air into the engine to get it started as well as generating electricity?

[john fletcher 1Participant @johnfletcher1]

In the 1950/60 I worked on many type of diesel electric locos, but rarely a baby Deltic, they had special workings diagrams, all makes had auxiliary generators. As Anthony Kendall above say before the main engine would start up a definite procedure took place, most had a triple pump, lub oil, fuel transfer and coolant. All beyond the driver control. Not all makes quite the same, some had a Clayton steam generator for train heating, when more modern coaches with electric heating became available they were remove. The steam generator was one long coil of high pressure steam tubing, many were carelessly damaged beyond repair during chemical wash out. John

[Don Cox]

On Don Cox Said:

This is probably tosh, but I remember when I was tasked with teaching about them as part of a C & G motor mechanics course, 2 stroke Diesels have to be supercharged and this was usually achieved by fitting a Roots blower.  As a Deltic is a 2 stroke might it be that device in the photograph was used to ram air into the engine to get it started as well as generating electricity?

Good tosh I think Don, it has me convinced.

The device ringed in blue looks very much like a centrifugal blower to me, including a hefty air pipe passing over the main generator to the big diesel at the back.

Same blower type as this smaller example:

I think the drum like object ringed in red is the powerful electric motor needed to drive enough air into the engine.   Might be an auxiliary generator.

If it is a centrifugal blower, providing volume rather than pressure, then like as not it fed a Roots compressor on the engine, and that  super-charged the cylinders.

Pretty sure I got a good book on Deltics out of the library about 40 years ago.   I remember it damning the development process, which led to deltics gaining an instant reputation for poor reliability.   Later Deltics were better, but never good to have the customer find serious design problems that should have been obvious to the maker!  My memory is terrible, but I don’t recall the book going into the exact layout of the engine in locomotives or boats.   Anyone know what the book was,  proper hardback, not a pamphlet.

Dave

 

 

 

[Michael GilliganParticipant @michaelgilligan61133]

Clearly this is not a book:

https://oldmachinepress.com/2019/09/05/napier-deltic-opposed-piston-diesel-engine/

… but it has some excellent photos, drawings, and references, which might trigger memories.

MichaelG.

 

[HopperParticipant @hopper]

The blower, or two blowers on some models, was mechanically driven on the other end of the engine, looking like a very large compressor section of a turbocharger with the familiar snail shell shape.

The auxiliary generator in the position shown in the OP pic was driven off the phase gearing at that end of the engine, it put out (on some models, perhaps not all) 110 volts to power lights, controls etc and also acted as exciter for the main tractive generator. That blower shape on the end is most likely cooling air for the generator/exciter. It would blow a nice cooling breeze but not enough to aspirate all those cylinders at full chat. But maybe it did feed the main blowers through some missing ducting? I think you can see the intake trunking on the other end of the engine, large round pipe leading from the blower on the far end to lower nearside cylinder bank intake port area.

 

[Charles LamontParticipant @charleslamont71117]

I ran a project once that had a 190kW thyristor controlled motor. It came with a 20kW motor sat on top to drive the cooling fan for the main motor.

[Hopper]

On Hopper Said:

…

The auxiliary generator in the position shown in the OP pic was driven off the phase gearing at that end of the engine, it put out (on some models, perhaps not all) 110 volts to power lights, controls etc and also acted as exciter for the main tractive generator.

Does hopper, or anyone else, have the technology and engine nous needed to label Greensands’ photo?    I see a big diesel on the right with, I believe, the cover off revealing one bank of 6 cylinders.  On the left is a big generator.  I don’t see anything I can positively identify as an auxiliary generator.   Might be me though, I’m not an expert!

Next photo doesn’t help  it’s a Naval Deltic with no generators at all!

That blower shape on the end is most likely cooling air for the generator/exciter. It would blow a nice cooling breeze but not enough to aspirate all those cylinders at full chat. …

That’s a big motor driving the fan though.  A 10HP motor will blow over 60,000 cubic feet of air per minute out of one.  That’s 1.7 million litres, and doing a guesstimate, guided by this website:

The Napier Deltic had a 5.125 in (130 mm) bore and a 7.25 in (184 mm) stroke (x2). This gave each cylinder a displacement of 299 cu in (4.9 L), and the 18-cylinder engine displaced 5,384 cu in (88.2 L) 

As 1.7 million / 88 is enough air to run the engine at 5900 rpm, I suggest a 10HP fan is more than capable of aspirating a deltic.  In fact 10HP is over the top, making it likely the fan motor is only 5 or 6 HP.

Happy to be shot down in flames!

Dave

 

 

 

[duncan webster 1Participant @duncanwebster1]

Shooting down in flames follows :

An article from model engine news by Edgar T Westbury states that the blower is balanced centrifugal driven at 5 times engine speed direct from the engine by flexible shaft. I think that means it is double sided, effectively two centrifugal fans back to back

https://modelenginenews.org/etw/deltec.html

[BazyleParticipant @bazyle]

Without checking the books I think you will find a locomotive diesel engine uses 1/3 of its peak output power just running the compressor – so maybe 1000hp.

[duncan webster 1]

On duncan webster 1 Said:

Shooting down in flames follows :

An article from model engine news by Edgar T Westbury states that the blower is balanced centrifugal ….

https://modelenginenews.org/etw/deltec.html

Not even close!

ETW’s mention of seawater and “starting is effected by a combustion type starter, in which a cartridge is fired into a piston” make it clear he’s not describing a locomotive deltic.

Under the heading “Scavenging blower” ETW says: Air is supplied to the inlet belts of all cylinders by a centrifugal blower of the double-entry balanced type, gear driven from one end of the engine, and coupled by flexible shafts, running at a little over five times crankshaft speed. It delivers air at about 8 lb. per sq. in., in sufficient volume to fill the cylinder displacement plus wastage, but is not normaIly intended to act as a supercharger in the true sense of the term.  Not what I see in Greensides photo.

Although the fan seen in the photo could be a scavenging blower, it’s clearly not an auxiliary generator!

Dave

 

[duncan webster 1Participant @duncanwebster1]

So have a look at

Deltics in Retrospect – Part 1

Scroll down near the bottom and there is a cutaway drawing of the engine. The blower is at the opposite end to the generator with 3 outlets connected to the ports on the sides of the cylinder blocks. This is the loco, not the boat. If you’ve got a working design in the boat you wouldn’t redesign it without good reason. I’ll go for the blower on the end of the auxiliary generator being for cooling the main generator

[HopperParticipant @hopper]

Click HERE to download a PDF of the information sheet from “The Model Delta Locomotive at Riverside Musuem”, or Google that phrase. It shows the mechanically driven blower at one end of the engine and the mechanically driven auxiliary generator at the other on top of the main gen.

The tech info with it is an interesting read. I read elsewhere the aux gen doubled as the exciter for the main gen as well as supplying 110 volts for lighting and controls etc. In answer to the original question, why not use the main gen to power these things, the main gen put out widely variable voltage DC depending on load and speed etc, so not suitable for running auxiliary plant such as pumps, compressors, lights, controls etc.

There is even a steam boiler shoehorned in between the engines to supply heating to passenger carriages so it was all quite the arrangement and components did double duty wherever possible. The fan on the end of the aux gen appears to be used to cool the main gen through the trunking/ducting at the end .

Starting on the loco Deltics, it says, was by running current from a bank of batteries through the main gen so it acted as a motor.

[SillyOldDuffer]

On SillyOldDuffer Said:

On Hopper Said:

…

The auxiliary generator in the position shown in the OP pic was driven off the phase gearing at that end of the engine, it put out (on some models, perhaps not all) 110 volts to power lights, controls etc and also acted as exciter for the main tractive generator.

Does hopper, or anyone else, have the technology and engine nous needed to label Greensands’ photo?

Well, yeah. I made a living as a diesel fitter on and off for some years after doing a post-apprenticeship tech college course in which the famously bizarre Deltic was inevitably studied, although I never got to work on one. I did mostly diesel generator work on standby power generators used in various hospitals and power stations where I worked and main power at remote outback mining and construction sites etc. I’m no expert but familiar with the basics. Plenty of others who posted above have far more relevant experience and training.

[duncan webster 1Participant @duncanwebster1]

Hopper’s info seems to confirm mine. I hope SOD has a parachute, or he’ll be needing an appointment with the burns unit. 😜

[Hopper]

On Hopper Said:

On SillyOldDuffer Said:

On Hopper Said:

…

The auxiliary generator in the position shown in the OP pic was driven off the phase gearing at that end of the engine, it put out (on some models, perhaps not all) 110 volts to power lights, controls etc and also acted as exciter for the main tractive generator.

Does hopper, or anyone else, have the technology and engine nous needed to label Greensands’ photo?

Well, yeah. I made a living as a diesel fitter on and off for some years …

I don’t doubt Hopper’s diesel qualifications – exactly what I’m looking for.    But Hopper hasn’t gone the next step and labelled Greensands’ photo, probably because he doesn’t have the technology – an image editor like Photoshop, gimp etc.

We can meet in the middle.   Deltic experts, on Greensands’ photo below what do you think items A to G are:

My guesses:

A: Centrifugal Fan
B: Electric Motor driving the centrifugal fan
C: Pipe driving air into the engine OR extracting exhaust.  Extracting seems unlikely, because exhaust goes to the other end of the engine.   I don’t know which way scavenging works – blow clean air in, or suck mucky air out.
D: Main Generator
E: Gearbox increasing RPM to drive the generator, attached to the engine’s phasing gearbox behind
F: cylinder head on the engine, cover removed.
G: Exhaust

There might be an H hidden at far right behind the engine.  If present, it’s the turbo-compressor.

The big unanswered question for me, is B an auxiliary generator or a fan motor?

Dave

 

 

[duncan webster 1]

On duncan webster 1 Said:

So have a look at

Deltics in Retrospect – Part 1

Scroll down near the bottom and there is a cutaway drawing of the engine. … I’ll go for the blower on the end of the auxiliary generator being for cooling the main generator

Possibly for cooling the main generator except the pipework head towards the engine.  I don’t know though.

This is the diagram pinched from Duncan’s Railway Matters link:

Problem is, it labels the engine only, and doesn’t identify A and B in greensands’ photo.   I’m fairly sure the turbo-charger unit has been removed from the greensands engine.

This image is from hoppers link:

Now this is interesting because it shows, top right, an auxiliary generator mounted on top of the main generator, and – exactly as Hopper said, it’s driven by a drive shaft. (Connected to the ‘Radiator Fan Gearbox’.)  Makes sense to me, except it doesn’t match the greensands photo!  That there’s no sign of a drive shaft might be because greensands’ photo shows the engine with the input blower on the right, whilst all the others have the blower on the left;   the shaft could be hidden behind, or possibly it was removed before the engine was put on the pallet!   But there’s no sign of the big blower mounted as in greensands’ photo.

Duncan’s article mentions there being about 90 variants of the Deltic.  The greensands photo doesn’t seem to match anything else we’ve found so far, and, because there are only a limited number of examples on the internet, it’s possible his example is unique.

At the moment, I like the idea that greensands’ photo shows a motor driven fan that helps cool the engine by drawing air over it, before blowing it out through a water filled radiator, also removed, with much else, from the greensands engine.   Could be wrong, and what I think is a motor, is an auxiliary generator.

This is why it’s so hard to work out how things like Stonehenge and the Antikythera mechanism functioned!  A few missing clues, and a shower of alternatives become possible.

I admit to be bleeding from near misses, but so far there hasn’t been a direct hit.

Dave

[duncan webster 1Participant @duncanwebster1]

A centrifugal fan for cooling main generator, hanging off the end of

B which is the auxiliary generator which is driven via whatever is inside the casing C from the gears which synchronise the 3 crankshafts

D is the main generator

F is the engine, which appears to have one of the covers off

G is one of the ducts leading from the blower at the extreme right hand end which can’t be seen in the picture, but is clearly shown in the link I posted earlier

Parachute on fire yet?

[Author]

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