Why the auxiliary generators on the Deltic Engines

[noel shelleyParticipant @noelshelley55608]

From a drawing in a British Railways book on diesel traction, there are NO cylinder heads on a Deltic engine, though the crankshaft cover, F may be missing. A is a blower for cooling air, daisy chained to B, an aux generator, C is the housing and support for the driveshaft to A & B. D is the main generator. The air intake to the blower is in the eye or centre and vents to the housing on the left. The Napier Deltic started life in the 1930s as a Junkers design. Noel.

[SillyOldDuffer]

On SillyOldDuffer Said:

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

 

 

Stop guessing and look at the links that have been provided already and google around a bit yourself and see.

B is clearly labelled in several places as the auxiliary generator driven by a shaft from the phasing gear up the housing C.

The fan A tacked on the end of the aux gen shaft blows cooling air out the square flange at the rear, pointing down toward the main generator. It draws air in that round hole on the left hand end of the fan housing. Nothing to do with the drive shaft tunnel C.

F is a cylinder head???? No. The whole point of the Deltic opposed piston arrangement was there is no cylinder heads. The two pistons meet in the middle of the bore, each being the “head” for the other. What you are looking at is the crankshaft end of the arrangement. Those visible webs are most likely the main bearing holders.

G is the exhaust manifold from the lower cylinder bank, taking exhaust over to the circular collector at the far right in the picture. Later models had a turbocharger there, but this one looks to have the same circular collector as in the PDF I linked to. Two mechanically driven high-speed centrifugal blowers sit direclty above it, driven from the ends of the two upper crankshafts. From the collector exhaust goes to a muffler and then out the roof. Nowhere near the drive shaft housing C. Fresh air from the two blowers goes directly through manifold and ports cast into the engine block. Again, nowhere near drive shaft housing C.

No, scavenge pumps do not “suck mucky air out” as you speculate. Exhaust temperatures are damagingly hot so nice cool fresh air is always pumped in. And hot exhaust gases are certainly not passed through an electric motor and lightweight fan as you also speculate.

Take a look at the links posted. It is an interesting study. A wonderful piece of British engineering but a lot to get your head around.

 

 

 

[duncan webster 1Participant @duncanwebster1]

Having seen SOD latest it might be that G is an exhaust duct and that we can’t see the inlet ducting.

All big generators have a smaller generator to provide the field current to the big one. Little ones use permanent magnets to get a residual field. Anyone remember ‘flashing’ the field on a car dynamo?

[HopperParticipant @hopper]

Yes, I still have to flash the generators on my old Harley generators every now and then. (Harley used 12 volt DC generators up to about 1980!)

G is the water cooled exhaust manifold. Inlet manifolds are cast into the block, leading from the blower to the cylinder ports.

Lots of info and good pics  HERE

[Howard LewisParticipant @howardlewis46836]

As Hopper says, scavenging of the cylinder happens by one piston uncovering the Inlet ports while the other piston has uncovered the Exhaust ports. The air for scavenging comes from a blower, often a Roots type, (If it is, you hear the characteristic howl)

The scavenge blower is mechanically driven, as in engines such as the Commer TS3, or the GM V71 and 92, and other more conventional two strokes. The EMD and GM two strokes are uniflow engines in that the exhaust is controlled by a normal poppet valve.

Small two stroke motor cycle engines are often “loop scavenged”, without a blower, by having the transfer port and exhaust port open at the same time. The exhaust system also has a hand in scavenging, by being tuned to produce a sub atmospheric pressure at the cylinder end, when the exhaust port is open; but this can work against you at speeds other than the optimum for scavenging.

In an opposed piston two stroke, one piston controls the inlet port, whilst the other controls the exhaust port. The combustion chamber is the small space remaining between the two pistons, and the recess within the piston heads, when the pistons are at their closest point.

After a short period with both ports open, the exhaust port is covered by the piston, and the cylinder begins to charge. (In the case of a turbocharged two stroke, such as the EMD railroad engines, the scavenging is made more effective by the boost pressure. As it is in a turbocharged four stroke.  This “blow down” effect helps to lower temperatures within the cylinder, to benefit the pistons and liner lubrication)

Then both pistons approach each other to compress the charge air, ready for the fuel to be injected.

As combustion comes to an end, the exhaust port is uncovered by one piston as it descends.

What we are discussing is most probably the mechanically driven exciter for the main generator, which also delivers cooling air to the main generator.

Howard

[Andy StopfordParticipant @andystopford50521]

On these opposed piston engines the crankshafts can be arranged to be slightly out of phase, so that the exhaust ports are uncovered slightly before the inlets, and likewise covered slightly in advance on the next stroke, thereby getting the exhaust gas moving in the right direction before the inlets are opened, and providing a small degree of supercharging by the blower after the exhausts are closed.

I’m pretty sure this was the case with the Deltic.

As an aside, Fairbanks Morse made opposed piston two strokes for submarines (and other uses); the training manuals for the US Fleet submarine can be found here:

https://maritime.org/doc/fleetsub/index.php

and contain much information on the engines and other systems for those interested.

[noel shelleyParticipant @noelshelley55608]

I’m with Duncan ! The design started with Junkers in the 30s, Napier licence built an engine that eventually became the Deltic. Noel

[Robert Atkinson 2Participant @robertatkinson2]

For a IC / Electric drive train of this era (i.e no electronic drives) the main generator output is directly related to the traction power requirement. This range of output is, as others have noted, not suitable for running pumps, lighting and other services. I agree with Duncans labels.

Robert.

[duncan webster 1Participant @duncanwebster1]

To broaden this out a bit, check out the Doxford (UK) engine

Slow running about 300 rpm, but run for ever. Opposed pistons but only one crankshaft and over 2000 hp per cylinder. A bit bulky and heavy for a loco, only used in ships and stationary generators. The lower piston connected direct to the crankshaft, the upper one had a cross head and side rods to the same crankshaft, but with pins 180 degrees out of phase,so as the lower piston went down the upper one went up.

[Anthony KendallParticipant @anthonykendall53479]

There seems to be a confusion here about the deltic engine in the deltic locomotives and that in the baby deltic locos.

The deltic loco engines, two of them of 6 banks of 3 cylinders, are governed at 1650bhp, running at up to 1500revs. This was a compromise between power output and times between overhauls, reliability etc. These engines are scavenge-blown from a blower on the main shaft. Scavenge in the sense of low pressure (about 12psi) clearing out the cylinders. The same engine heart was taken and supercharged to give 4000bhp for other uses outside railway.

The baby deltic locomotives had a single engine of 3 banks of 3 cylinders producing 1100 bhp, governed to 1600revs. These were exhaust gas turbocharged and obviously more highly stressed.

Both of these engines had main generator and auxilliary generator, powering the auxilliaries I defined in my first post. Both of these engine types were used in navy patrol boats. You can tell a marine engine – no generator on the main shaft, but a big clutch/reversing mechanism.

[duncan webster 1]

On duncan webster 1 Said:

…
Parachute on fire yet?

I’m too scared to test it!   Thinking about this last night I became increasingly uneasy about my ideas.   Though I could be right in an alternative universe,  my interpretation isn’t well supported by any of the evidence, and part of it flies in the face of at least one contemporary diagram!

I fear I based too much on a photo of a part-stripped engine on a pallet, which happens to be back to front compared with all the other views.   If Greensands’ photo had been taken from the other side might have saved me from a faux pas.  As is, my new pilots uniform may be sackcloth and ashes.   It’s getting far too hot in the cockpit!

🙁

Dave

[SillyOldDuffer]

On SillyOldDuffer Said:

On duncan webster 1 Said:

…
Parachute on fire yet?

I’m too scared to test it!   Thinking about this last night I became increasingly uneasy about my ideas.   Though I could be right in an alternative universe,  my interpretation isn’t well supported by any of the evidence, and part of it flies in the face of at least one contemporary diagram!

I fear I based too much on a photo of a part-stripped engine on a pallet, which happens to be back to front compared with all the other views.   If Greensands’ photo had been taken from the other side might have saved me from a faux pas.  As is, my new pilots uniform may be sackcloth and ashes.   It’s getting far too hot in the cockpit!

🙁

Dave

Ah, well. As they say, a man who never changed his mind never thought about anything! 🙂

With, what?, 90 variants of Deltic and then there was the Baby Deltic Anthony Kendall references above, there certainly was a variety of set-ups.

Asbestos underpants are what you need!

(PS, Dave, I missed your post yesterday where you posted one of the pictures from the link I posted with your text below it. I could swear I read through the thread before posting to advise you to look at the links posted but did not see that post. Seems to have happened a couple of times lately. Either the grey cells are getting cloudier or forum is delaying some posts from appearing? Most likely the former!! Apologies for telling you to read the links when obviously you had.)

[Anthony KendallParticipant @anthonykendall53479]

To sum up then, I think it’s like this, if it is a baby….
A is the traction motor blower – providing much needed cooling for the 4 traction motors
B is the auxilliary generator powering auxilliaries previously mentioned
C is the encased shaft drive for A and B from the end gear chain.
D is the main generator
E is the main generator cooling fan, fitted to the main shaft
F is one of the crankshaft points, inside are big ends of conrods going both backwards and down – one crank at the front, one at the back and one at the bottom underneath, which rotates in the opposite direction to the other 2.
G is one of the exhaust manifolds. There are 2 more. All 3 feed into a collector drum at the right hand end.
I have studied these for a while now but still prepared to be wrong.

[David AmbroseParticipant @davidambrose86182]

Most Doxfords ran at about 110 rev/min, apart from the later Seahorse and its derivatives.  And although they could run forever, the piston cooling system was prone to leaks, and required frequent re-packing of joints on the swinging arms and elbows.  But a magnificent sight in full gallop.

[Hopper]

On Hopper Said:

…<br class=”bsp-quote-title” />(PS, Dave, I missed your post yesterday where you posted one of the pictures from the link I posted with your text below it. I could swear I read through the thread before posting to advise you to look at the links posted but did not see that post. Seems to have happened a couple of times lately. Either the grey cells are getting cloudier or forum is delaying some posts from appearing? Most likely the former!! Apologies for telling you to read the links when obviously you had.)

I’m looking for evidence that the forum sometimes skips over posts so members don’t see them.   Like you I initially suspected my increasingly unreliable grey cells.  I’ve started half-heartedly to collect evidence.   There may be at least 3 variants:

• Post appears but photos/videos are missing
• Post fails to appear immediately after Submit,
• Post that did appear, goes AWOL later, temporarily.

Apparently random, and not everyone is bitten at the same time.

Half-hearted because persistent gut-ache is wrecking my concentration;  still undiagnosed after 6 months.  Not because the NHS aren’t trying, I must be costing them a fortune.  Three different specialists on the case and I’ve lost count of the tests, endoscopies, MRI and CT scans! Today started well, now I’m hurting.  If I have to take painkillers nothing gets done!

Back to Deltics, if can summon the will-power needed to pull everyone’s A-G identifications together,  I’ll list what’s agreed and what’s not.   Other than agreeing I was wrong, we don’t have a full consensus yet.

This is a very interesting engine.   Antony reminded us that the OP photo is of a Baby Deltic.   Certainly likely to confuse me, because all the info I’ve found only covers the larger versions.

Dave

[HopperParticipant @hopper]

SOD, I hope you get the old guts sorted out. Sounds miserable.

No need to spend valuable time collating opinions on the Deltic components. I think Anthony Kendall above has absolutely nailed it. He obviously is familiar the the engine’s history and his callout seems to be in line with everything I have read in a few hours down the Deltic rabbit hole the past few days. It certainly is an interesting study!

The fact that Greensands’ OP picture is a Baby Deltic explains why the auxiliary generator looks so big there in comparison to other pics including the one from the PDF I linked to and you posted here earlier. Very confusing. The aux gen is most likely the same on both engines as its duty powering lights and controls etc would be much the same in either case. But it is dwarfed by the fullsized Deltic and looks a bit overblown on the Baby.

[Howard LewisParticipant @howardlewis46836]

The M O D issued a spec for engines capable of running on a variety of fuels (The intent being that the military could run their transport on whatever fuel came to hand overseas)

The outcome was the Rolls – Royce K Range of 4 and 6 cylinder opposed piston engines. (Leylands were working on the larger version of the engine, L60, for tanks) The compression ratio was changed by altering the phasing of one crankshaft relative to the other by removing a gear in the train and moving one crankshaft a tooth or more before refitting the gear. This changed the compression ratio and the port timings to suit the different fuel.

I don’t think that the project was ever pursued to completion.

A six cylinder engine was fitted into a Dennis Max tractor unit which did the overnight spares run from Crewe to Hythe Road in London. It was mated to a Twin Disc three speed transmission (Not that they ever ever need to change ratios apparently)  The driver claimed that the tractor and single axle trailer could out accelerate a Jaguar from 0 – 30 mph! When asked “What’s it like on hills?”  The reply was “What’s a hill?” With at least double the normal horse power available; no wonder!

The land based application of the Fairbanks Morse engine was in their locomotives, such as the Trainmaster.

Howard

[David AmbroseParticipant @davidambrose86182]

I think that the K30 did go into production – possibly in the Chieftain as the auxiliary engine, and the K60 in the FV432.  I seem to recall Wellworthy making the liners for the K30 and the L60.

[duncan webster 1Participant @duncanwebster1]

One widely used opposed piston engine was the https://en.m.wikipedia.org/wiki/Commer_TS3

I’ve read that the problem was they liked to run at high (for a diesel) revs, but drivers were used to the likes of Gardners and let them slog at low revs.

I think that having 2 out of phase pistons in one cylinder opens up the possibility of a valveless steam engine. I worked out the dynamics once whilst bored at work, it’s probably lurking on my PC somewhere

[noel shelleyParticipant @noelshelley55608]

2 years ago I hired a new transit van and found it most disconcerting that the electronics kept telling me to change up and it seemed to go surprisingly well for the low revs eg 1200rpm. I felt this was rather to low to be good for the bearings, may be ok for fuel consumption. I have read somewhere recently that some of these low reving engines are now having bearing trouble. May be my gut feeling was right ? Any comments ? Noel.

[Howard LewisParticipant @howardlewis46836]

The TS3, like all scavenge blown two strokes, lacked low speed torque.  They needed to be kept spinning above 1600 rpm. Driven like a Triumph TR2, they sounded like one, and for a commercial vehicle, went like one!

Our drivers, used to Gardner 6LWs and Leyland 0600s used to slog the TS3. This caused the wet liners to shift and coolant leaked into the sump. I never saw an engine that exceeded 65,000 miles before having to be changed.

I once had a coach, on a Commer Avenger chassis, reach 2300 rpm in fith gear.  The 0-70 speedo was showing 6:30 on the watch at the bottom of the dial!

Unless good quality oil was used, they were prone to crankacse explosions when driven hard for long.

The Foden FD4 and FD6 powered lorries used a 4 speed gearbox, with a 3 speed range change. They needed all 12 ratios!

The FD6 was used by the Admiralty, in launches, where speeds were fairly constant, and torque back up was not required. But having a Roots scavenge blower, were not stealth vessels!

The Admiralty did try a TS4, but it never went into production, as far as I know.

EMD perfected the uniflow scavenge blown (Later turbocharged as well) two stroke for rail use. Driving a generator, or alternator, speed could be limited in range, and the electric transmission provided the toque back up when needed.

Howard

 

[duncan webster 1Participant @duncanwebster1]

Very good link to the Foden engine here

https://www.thefodensociety.org.uk/the-foden-engine/

Wonderfu what could be achieved 60 years ago

[Howard LewisParticipant @howardlewis46836]

I have an idea that Fodens were early in turbocharging a 4 cylinder, the FD4, although never heard of it actually going into production.

The trouble with turbocharging engines with only a few large cylinders, is that when the inlet valve opens, for a short time the compressor loses all load, and begins to overspeed. Then when the valve closes, the load builds up again rather suddenly, tending to produce surging.

Rolls Royce turbocharged the four stroke C6 and C8, but the C4 caused the problems outlined above, even with a large volume inlet manifold, to reduce the effect of the cylinder taking a big gulp. (Which then led to delayed throttle response!)

A large volume inlet manifold, on the other engines did give better cylinder filling, since it acted as a pressure reservoir.

Careful attention to Induction and Exhaust systems can produce improved power outputs (Witness speedway bikes “getting on the meg”) but sometimes with less desireable consequences, elsewhere.

The Deltic was a compact engine, each bank only being about the length of a Perkins 6.354, and using much shorter injectors (BKBS rather than BKBL bodies) than in line engines.

Effectively, each bank produced 500+ bhp, helped by the doubled number of power strokes compared to a four stroke.

Howard

[Howard Lewis]

On Howard Lewis Said:

 

The trouble with turbocharging engines with only a few large cylinders, is that when the inlet valve opens, for a short time the compressor loses all load, and begins to overspeed. Then when the valve closes, the load builds up again rather suddenly, tending to produce surging.

 

Howard

Other way around. Zero flow=zero load. Max flow=max load 😀

[bernard towersParticipant @bernardtowers37738]

Hopper if you have to “Flash” your gennys now and again have you been using a dc welder on the bike?

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