Modernisation Plan Diesels

[Baby Deltic]

DMU engines were generally flat with horizontal cylinders facing outwards on either side of a crankshaft so they could be mounted in the relatively small confines beneath the floors on some buses.

[jonny777]

I can't really comment properly on a best and/or worst DMU because I have never travelled on some of them (126s for instance) and many had a life of being thrashed up and down hills, or on high intensity suburban services; whereas others pottered around rural shires for most of their lives.

 

However, the 125s must be in the bottom few.

[rockershovel]

The Bantam was indeed a mirror-image copy of the 125cc DKW, the same as the Harley 125 (right way round, with American thread sizes) - both bikes would grow to 175cc before fading away in tne 1960s. MZ used the same starting point for a series of 125cc and 250cc strokers of notably eccentric styling which long outlasted the Bantam and Harley.

 

But, as has been noted already, the Japanese picked up the REAL talent and the rest we know...

 

 

Ben

[PatB]

Yup, stolen acquired in war reparations.  Some of it was made a mirror image in the backward engineering exercise.  They were, of course, crap really.  Kaaden defected from East Germany IIRC, and he knew how to make a stroker that really worked!

 

 

I've always been slightly puzzled by the idea that taking a 2-stroke off someone is a punishment .

 

The Bantam was a DKW design that most of the Allies got a piece of. Even Harley Davidson built a version, although H-D enthusiasts seem to prefer not to talk about it.

 

Villiers engines, however, were, AFAIK, an all British effort, although the Jawas and CZs I became too familiar with in my poverty stricken days bore a remarkable  resemblance to the Wolverhampton product. I'm of the understanding, though,  that the technology transfer there was a British export rather than an import.

[Nearholmer]

Aha! We are well OT now, but, while we are OT, I must point everyone to this brief history of DKW http://www.odd-bike.com/2014/02/dkw-supercharged-two-strokes-force-fed.htmlit contains the best descriptions of supercharged and split-single two-strokes that I have read.

 

I too had a MZ and CZ phase ........ Both of them are DKW........ I think that MZ came literally from the same factory. There are a few DKW125 in this country, a chap at a vehicle rally let me ride a 1939 one round the field.

 

Better let that subject disappear in a cloud of blue fumes and ring-a-ding-ding-ding noises!

 

K

[stewartingram]

I would have thought that another factor that helped the BRCW class 33 on the SR, was that the SR had a relataively small steam fleet and lots of electrical experience. So they were not maintained under steam conditions.

 

Stewart

[PatB]

Aha! We are well OT now, but, while we are OT, I must point everyone to this brief history of DKW http://www.odd-bike.com/2014/02/dkw-supercharged-two-strokes-force-fed.htmlit contains the best descriptions of supercharged and split-single two-strokes that I have read.

 

I too had a MZ and CZ phase ........ Both of them are DKW........ I think that MZ came literally from the same factory. There are a few DKW125 in this country, a chap at a vehicle rally let me ride a 1939 one round the field.

 

Better let that subject disappear in a cloud of blue fumes and ring-a-ding-ding-ding noises!

 

K

 

At risk of deviating even further off-topic, it's worth noting that MZs came in two distinct flavours, at least by the 1970s when the machines I was familiar with originated. The 125s and closely related 150s (identical save for a bigger bore, leading to interesting possibilities for cheating the 125 learner law) were very closely related to the ancestral DKW and were, mechanically, as unpleasant as a 1930s utility stroker might be expected to be. They had an unusual, part cast aluminium frame but were otherwise fairly conventional. Indeed, the chassis was the nicest part of them, being superior to the competing Japanese commuters of the day in every respect apart from brakes. The 250, OTOH, had deviated sufficiently from the original DKW that it shared nothing with it beyond being a piston ported 2-stroke.  Other than that, the five-speed gearbox, crankshaft mounted clutch (which should have been awful but wasn't) and, particularly, the porting design were all new. Indeed, the engine bore a closer resemblance to pukka dirt bike motors from manufacturers like Montesa and Bultaco than it did to anything else. It's performance certainly outstripped the feeble brakes which, on mine, assisted me in keeping up with nominally superior machinery, because they would slow down for hazards and I couldn't. Fortunately the weird but effective spine frame, from which the engine and rear suspension were rubber mounted, worked very well indeed and usually allowed me to steer around obstacles.

 

To attempt to make a token on-topic comment, though, the suggestion upthread, that mass diesel orders were placed prematurely because of fears that the finance would dry up, strikes me as the most plausible explanation I've seen.

[cheesysmith]

the DMU were a good design, that did what was asked of it. Although they were a bit backwards in design in the use of the engine and gearbox combination used. The engine and gearbox had both been replaced with more modern versions in road use (read busses), and the overriding success of these in rail use was not down to BR, but due to the fact the manufacturers made a joint company to supply BR with the drive trains it required.

 

Faults that the DMMUs had can be judged thus

-Engine injectors pipework was mounted on to of the engine, requiring either accessing the engine through access panels in the saloon (a source of noise/dirt, as well as a fire risk) or the dropping of the engine off the unit for maintenance.

 

The gear box used bands on the driveshaft that required adjusting, which could lead to slipping and excess wear. Body shells that on some designs to meet the power/weight specs were too lightweight (derby suburban units, that fully loaded they bent and doors wouldn`t open or close), and not as strong as they should have been (using a more modern, turbocharged engine would have solved this).

 

Then there was the use of hydraulic transmission, which BR decided to use as the transmission fluid the diesel fuel in the tanks (this strikes me as a bad idea even now, and a source of so many potential fire problems, how it was even used in the first place?). Also, poor under frame layout (example, the cravens 113 with hydraulic gearboxes, in which the driveshaft ran in a tunnel through/between the fuel tanks. Anybody care to guess what would happen if a drive shaft came loose?).

 

The DEMUs were not without there own problems, such as cracked cylinder heads, especially the uprated 600bhp versions. Also, they had the power bogie mounted at the opposite end to the engine because of axle load problems with the big heavy engine mounted at the other end (try mounting a motor bogie in a model and putting all the ballast over the other, unpowered bogie).

[Nearholmer]

PatB

 

Yes, I had MZ 125, MZ 250, CZ125 and CZ250, plus old Excelsior 98 (Villiers engine, rigid rear) and Excelsior 250 (very rare beast), one of which would be running at any given moment. One of my brothers is still a major two-stroke fanatic, and has quite a collection, including cars, a Berkeley and a SAAB, as well as many bikes/scooters, of which my favourite is the Durkopp Diana, which is a "Rolls Royce" in build quality.

 

Not really sooooo far OT, in that two-stroke gas-engines and diesels for locos bring up many of the same issues as occur with little engines for bikes!

 

Stewart

 

Some truth in what you say, I think. Diesel locos certainly used to come into the clean, warm, dry at Selhurst for some work (not to engines, IIRC) and Hither Green was pretty "slick and span" indoors.

 

Kevin

[PatB]

the DMU were a good design, that did what was asked of it. Although they were a bit backwards in design in the use of the engine and gearbox combination used. The engine and gearbox had both been replaced with more modern versions in road use (read busses), and the overriding success of these in rail use was not down to BR, but due to the fact the manufacturers made a joint company to supply BR with the drive trains it required.

 

Faults that the DMMUs had can be judged thus

-Engine injectors pipework was mounted on to of the engine, requiring either accessing the engine through access panels in the saloon (a source of noise/dirt, as well as a fire risk) or the dropping of the engine off the unit for maintenance.

 

The gear box used bands on the driveshaft that required adjusting, which could lead to slipping and excess wear. Body shells that on some designs to meet the power/weight specs were too lightweight (derby suburban units, that fully loaded they bent and doors wouldn`t open or close), and not as strong as they should have been (using a more modern, turbocharged engine would have solved this).

 

Then there was the use of hydraulic transmission, which BR decided to use as the transmission fluid the diesel fuel in the tanks (this strikes me as a bad idea even now, and a source of so many potential fire problems, how it was even used in the first place?). Also, poor under frame layout (example, the cravens 113 with hydraulic gearboxes, in which the driveshaft ran in a tunnel through/between the fuel tanks. Anybody care to guess what would happen if a drive shaft came loose?).

 

The DEMUs were not without there own problems, such as cracked cylinder heads, especially the uprated 600bhp versions. Also, they had the power bogie mounted at the opposite end to the engine because of axle load problems with the big heavy engine mounted at the other end (try mounting a motor bogie in a model and putting all the ballast over the other, unpowered bogie).

 

I guess using diesel oil as the working fluid in a transmission is no dafter than using petrol vapour as the working fluid in a steam engine, which was also tried once upon a time, though not on the railways.

 

I believe the whole driveshaft-in-proximity-to-fuel-tanks issue did result in a number of fires although presumably none were too disastrous. Years ago I read a few of the railways' annual safety reports and, along with trespassing civilians coming into contact with 3rd-rail or OH electrical equipment, self-igniting DMUs seemed to be a recurring theme.

[Nearholmer]

My ignorance of the DMMUs and DHMUs built for BR is deep and wide, other than two points: they were very unpleasant to ride on, because of all the rasping and rattling, and fumes in the saloons; and, I was once at the line-side, near Reading, when one rasped past, and a rain of chunky bits and pieces fell/flew off the engine, all over the track, and nearly all over self and look-out. On the phone to the box, quick as a flash! That rather put me off them.

 

On DEMUs, the concept goes back a very long way and was made practical in the early 1900s (think the NER Autocar, US "Gas-Electrics" etc), the LMS cobbled one together, they were used in Ireland, and the SR had the idea firmly in their plans c1947, for use on branch lines. Added to which,there is a direct line of descent from Hastings Unit, through Blue Pullman, to HST.

 

But, Cheesy is spot-on with the 600hp engines and with adhesion. I commuted on them for c10 years, and sometimes an entire 9-Car formation, so three motor bogies, would be bought to a complete stand by the odd leaf on the rails as they clambered up to the Downs from Oxted. They were also a bit iffy to start in cold weather, so the residents of Tunbridge Wells were plagued by them on "throb over" in Winter.

 

K

[Tim H]

Since the Southern had no problems running a power bus along the length of an EMU, I wonder why nobody thought of putting a second power bogie under one of the trailers, as was done on the Blue Pullmans? Or was it just a case of them working well enough under normal conditions that it wasn't worth the additional expense?

[Northroader]

Please, no motor bikes on this thread, I like em, Triumphs anyway, but let's stay on track, pleasey please? Now, DMUs, oh yes. The first Derby units, which went to Cumbria? Built of aluminium, if you saw them in the shops with their engines off they were banana shaped, straightening up when the engines were fitted. The controls were a problem, in that the drivers controller fed the whole train epvalves for throttle speed, gear change, so there was considerable drain on the leading car batteries. Later builds had relays, which drew far less current, on each car to energise the epvalves locally from that cars batteries, which reduced the juice through the lead end controller. Batteries were always fun, on arrival at a depot the set went straight on charge, not taken off til she went. The carriage cleaners would always leave the lights switched on, though... A dmu depot was a very seasonal place, in winter you would be amassing and changing radiator units, which had been thoroughly cleaned at works, ready for the summer. In the summer ditto with batteries, also ditto, ready for winter. Out in service, the drivers always left them idling, just in case they wouldn't start when you wanted to. There were various tries at double battery systems, ones set for starting, one set for everything else.

Engines, fluid couplings, gearboxes, were pretty well equivalent to that fitted on road transport, coming from the same sources. The final drive/ reverse unit was specifically railway, but no trouble. All this was tucked underfloor, engine accessible from the side, but some of the other units central with access hatches in the floor, and not much wriggle room over the item (dirty) being maintained, so filter changes could get missed. (Ho hum) The bulk of the dmu fleet were much alike underneath, probably the tops were the West Riding sets.which had Rolls engines and torque converters, although I didn't see anything of them.

Then there was the heaters, little units burning fuel in a heat exchanger warming up air which had been drawn in adjacent to the heater exhaust, hence the smells in the coach already referred to. They needed changing, decoking, stripping out and fiddling with, on a regular basis.

By and large, great fun to work with, and delivering a fair service to vast chunks of the railway. Then again, I thought the southern demu sets had got things right, probably more reliable, just a bit old fashioned with the coach arrangement.

[AberdeenBill]

I guess using diesel oil as the working fluid in a transmission is no dafter than using petrol vapour as the working fluid in a steam engine, which was also tried once upon a time, though not on the railways.

 

I believe the whole driveshaft-in-proximity-to-fuel-tanks issue did result in a number of fires although presumably none were too disastrous. Years ago I read a few of the railways' annual safety reports and, along with trespassing civilians coming into contact with 3rd-rail or OH electrical equipment, self-igniting DMUs seemed to be a recurring theme.

 

Accident reports: 

 

http://www.railwaysarchive.co.uk/docsummary.php?docID=1083

 

http://www.railwaysarchive.co.uk/docsummary.php?docID=1099

[jonny777]

".....you can't write off the Deltics as a bad locomotive. "

 

Which is why I didn't.

 

I chose my words carefully, although, as I confessed at the outset, I was turning the key too.

 

And, I have read Fiennes (long time ago, so probably forgotten many nuances), and I do thoroughly get why he pushed for what he pushed for, but if you "zoom out", there must surely be questions over the wisdom of buying and keeping this stable of Arab thoroughbreds. Might Fiennes departure have had something to do with that?

 

Kevin

 

 

 

I am reading Fiennes again, and he calculated figures which suggest that to compete with road and air over long distances, the railways had to average 70-75 mph on end-to-end timings.

 

As he says, 2000hp is not capable of achieving that figure but 3000+hp is.

 

As early as 1955 he had written in a paper to the Railway Students Association that "the policy of building express passenger locomotives of 2000hp lies already in ruins about us" - a comment made after reading the recent Modernisation Plan no doubt.

 

However, he blames the wedding of the railways to 2000hp on...... wait for it....... (better don big tin hats here)....... Sir Nigel Gresley who proved to the board of the LNER that steam traction could do the job as well as the high speed diesels being developed (Flying Hamburger and others), thus putting back any real diesel development for many years (although wartime did not help).

[jjb1970]

I guess using diesel oil as the working fluid in a transmission is no dafter than using petrol vapour as the working fluid in a steam engine, which was also tried once upon a time, though not on the railways.

Organic Rankine cycle systems sometimes use flammable gasses such as pentane and propane as the working fluid. The Rankine cycle is the classic thermodynamic cycle which is the basis of steam turbine power plant.

[Tim H]

We've only really touched on type 4s in passing, so..

 

What's the verdict on the Pilot Scheme Type 4s, apart from the accepted fact that the power range was too conservative?

 

I'm going to be controversial and suggest the best Pilot Scheme Type 4 was actually the Swindon-built Warship.

[Zomboid]

Were there any true pilot scheme type 4s other than 40s, 44s and the D600 warships? Only the 40s had a production run, though the 45s weren't that far removed from the 44s really. As for the D600s, how on earth did the WR think it would be a good idea to build anything similar to those in larger numbers?

[The Stationmaster]

Were there any true pilot scheme type 4s other than 40s, 44s and the D600 warships? Only the 40s had a production run, though the 45s weren't that far removed from the 44s really. As for the D600s, how on earth did the WR think it would be a good idea to build anything similar to those in larger numbers?

The D800 'Warships' were also Pilot Scheme - the Swindon design being, in theory, a supposed direct comparison with the private enterprise offering from North British but far more radical in concept when it came to construction methods.   So there were two Pilot Scheme Type C diesel electrics (although originally there was only one - the EE design) and two Pilot Scheme diesel hydraulics (although, again, there was originally only one - the NBL design).

 

I don't think anybody ever seriously considered building extended numbers of the NBL design once they had a little experience of it - it was simply a Pilot Scheme design and that was it.  Don't forget the whole original point of the Pilot Scheme was try out various ideas and components/mixes of components and not necessarily to produce designs which would be the subject of mass orders.

[Talltim]

Presumably being happy with using pairs of type 2s on the LMR was just a hangover from the Midland small engine policy?

 

 

Coat, gone...

[Reorte]

Presumably being happy with using pairs of type 2s on the LMR was just a hangover from the Midland small engine policy?

 

 

Coat, gone...

Still with us - what else is a multiple unit if not a bunch of small engines?

 

...sorry...

[pete_mcfarlane]

I don't think anybody ever seriously considered building extended numbers of the NBL design once they had a little experience of it - it was simply a Pilot Scheme design and that was it.  Don't forget the whole original point of the Pilot Scheme was try out various ideas and components/mixes of components and not necessarily to produce designs which would be the subject of mass orders.

It is impressive how NBL managed to take the German V200 design and turn it in to the D600 class (adding 50% weight in the process). With hindsight BR should have gifted them to university engineering departments rather than scrapping them, as examples of how not to do things. 

[cheesysmith]

The type 4s can be boiled down thus-

The EE (class 40) was actually underpowered and overweight. EE could offer the engine in 2400bhp with charge air cooling, and if built using the warren truss frame as used in the 45s, could have been built on a Co Co instead.

 

The BR built sulzer ones were reliable, with good performance, but they too suffered from the engine problems the same as the 47s. Also, because they were hindered by the same bogie design as the EE versions, they suffered from the poor suspension design and cracked bogies.

 

The WR hydraulics were hampered with a limited braking force, and engines that required too much TLC for use in BR at that time. Also, they were limited in what upgrades could be done late on in life (lack of dual brakes/eth).

 

I think the best were the EEs, followed by the BRs, then the hydraulics. I say this because remember these were mixed traffic desings, and the hydraulics were the most limited in this respect (they were ok for fitted freights, poor on unfitted).

[Nearholmer]

Jonny

 

My memory isn't too bad then, because I certainly recalled the gist of that from when I read the book, which might have been as much as 40 years ago.

 

The basic logic of needing 3000hp to obtain a "commercial" schedule with the selected train length/weight makes sense, although an obvious alternative, of course, is a more frequent service of much lighter trains, which will actually earn more (higher frequency services generate extra custom) but also cost more to run (two train crew).

 

However, sticking at 3000hp, it didn't necessarily all have to be on one chassis, and if one goes back to the 1947 investment decision, at that point the LNER envisaged using two chassis (locos) in tandem. And, of course, the HST is nothing more than two very good single-cab locos ......... So I don't think that 3000hp necessarily dictated Deltic (imagine a pair class 33, with specially sorted bogies!); I think that Fiennes may have been seduced by what was, after all, a damned sexy prototype, thereby bringing on a high unit cost fleet.

 

And, why, in a unified National industry did ECML have to compete with WCML? It didn't. BR could have prioritised one of the two for "high speed" treatment (WCML is actually an odd choice for that,because it is so twisty and hilly) - having competition within BR was tantamount to wasteful in-fighting, losing sight of the common enemy. So, had Fiennes ever so slightly overlooked the fact that peace had been declared between the LNER and the LMS?

 

I need to re-read, because the crucial question is whether he was talking about competing for the Tyneside and Yorkshire traffic, where, especially in the latter case, the nascent motorway network must have been beginning to look threatening.

 

Kevin

[Zomboid]

My mistake on the D600s then. I'm not sure any of the Type C locos were really that great objectively, 2000hp was probably not enough power for such a large machine to be truly useful - as the next phase of locos with 2500+ kind of proved.