'Vintage' Diesel Loco Design

Norther Monkey · 25 Nov 2019

A random, somewhat trivial question. What was the reason behind the extended noses on some of the older diesel locos such as Deltic, 37s and 40s. It appears impractical as it limits crew visibility and must make judging distances for 'delicate' shunting work more difficult.
Therefore I presume there's a technical reason, possibly one that subsequently became redundant.

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pdeaves · 25 Nov 2019

Norther Monkey said:
A random, somewhat trivial question. What was the reason behind the extended noses on some of the older diesel locos such as Deltic, 37s and 40s. It appears impractical as it limits crew visibility and must make judging distances for 'delicate' shunting work more difficult.
Therefore I presume there's a technical reason, possibly one that subsequently became redundant.

Some of the reason (a very small part, I expect) is 'why not?'. Remember that the early diesels were designed when steam ruled supreme, so those bulbous noses would actually be an improvement on visibility compared to what went before. Traction experts will be along shortly to give all the other reasons (e.g. why certain equipment had to be mounted in front of, rather than behind, the cab).

DarloRich · 25 Nov 2019

Got to put the toilet somewhere..................

MarlowDonkey · 25 Nov 2019

Norther Monkey said:
. What was the reason behind the extended noses on some of the older diesel locos such as Deltic, 37s and 40s.

It was something of a styling choice for English Electric products. The Class 40 was a hybrid apparently between the mechanics of the Southern design (10201-3) and the styling of the LMS design (10000-10001). Their export designs usually had noses as well and for that matter it had been a feature of some American designs of the 1940s.

37057 · 25 Nov 2019

Some benefits for the train crew may include the crashworthiness and reduction of 'sleeper vision', but not that it's an issue anyway. Visibility isn't such an issue especially when you consider that the original crews would have had a boiler in their view! Shunting, or at least coupling isn't so bad in reality and the driver side buffer is in view when looking out the side window (on the large round OLEOs at least). Probably one big disadvantage for the crew, especially at no.1 end of a 37 is the racket created by the compressors.

From a maintenance point of view it's an advantage having better access to the machines that fitted there. It also provides easier access to the roof too. By comparison they layout in a 47 makes for a nightmare with most of it's machines, brake valves and a fuel tank all wedged beneath the radiators.

hexagon789 · 25 Nov 2019

Mostly design preference but on earlier locos it was useful for gangway connectors, somewhere to put a toilet, house some equipment (such as traction motors blowers) and as a by-product of the design improved protection in a collision.

Strat-tastic · 25 Nov 2019

DarloRich said:
Got to put the toilet somewhere..................

And a little shelf for the driver's sandwiches.

eastwestdivide · 25 Nov 2019

If the 'nose at each end' configuration is better for maintenance access, why do virtually all modern locos conform to the 'box on wheels' configuration? Perhaps better use of the available length, for bigger engines and more on-board equipment?

37057 · 25 Nov 2019

eastwestdivide said:
If the 'nose at each end' configuration is better for maintenance access, why do virtually all modern locos conform to the 'box on wheels' configuration? Perhaps better use of the available length, for bigger engines and more on-board equipment?

I think as time went by, locos started to benefit more by having roof sections (and even body sections such as 59 and 66) be easier to remove. Also worth mentioning 58s and 70s with the equipment being encased in framework rather than a body. I mentioned the 47 earlier, all the main equipment under the cooler group, which isn't a quick job to undo! I can imagine motor blowers were always going to be a tricky component to place correctly as they need as simplistic ducting as possible and in close range of the bogies - now with AC motors they aren't necessarily required.

Also worth mentioning that 1960s locks also had vacuum exhausters and maybe even boilers. The size of the components in general also being larger.

Richard Scott · 25 Nov 2019

I thought idea was that crews may suffer from a hypnotic effect of watching sleepers pass by so nose got rid of this issue. Obviously found not to be an issue hence subsequent flat fronted designs.

ic31420 · 25 Nov 2019

37057 said:
Probably one big disadvantage for the crew, especially at no.1 end of a 37 is the racket created by the compressors.

Another of life's questions, why are compressors so bloody noisy! locos, units, kwikfit, mates garage, dentist, little thing I have in the shed, all of them create a frenzied racket.

ExRes · 25 Nov 2019

Richard Scott said:
I thought idea was that crews may suffer from a hypnotic effect of watching sleepers pass by so nose got rid of this issue. Obviously found not to be an issue hence subsequent flat fronted designs.

An interesting theory and one I've never heard of, I simply can't imagine any driver staring at the sleepers

John Webb · 25 Nov 2019

ic31420 said:
Another of life's questions, why are compressors so bloody noisy! locos, units, kwikfit, mates garage, dentist, little thing I have in the shed, all of them create a frenzied racket.

Deviating a little from the OP's subject, but if you run a compressor venting freely to atmosphere you'll find it quite a bit quieter than when it is actually pumping the air at pressure - all a case of the work being put into the compression. There are compressors working on intermeshing screws which are quieter than the piston in cylinder type.

edwin_m · 25 Nov 2019

ExRes said:
An interesting theory and one I've never heard of, I simply can't imagine any driver staring at the sleepers

I've heard of this before and I think it was a possible hypnotic effect of the flicker of the sleepers disappearing from the bottom of the field of view. I don't know if any serious research was ever done but may everyone just thought they would look pretty silly spending multi-millions on a fleet of flat-fronted engines only to fine the drivers going goggle-eyed and crashing them.

TRAX · 25 Nov 2019

37057 said:
Some benefits for the train crew may include the crashworthiness and reduction of 'sleeper vision', but not that it's an issue anyway. Visibility isn't such an issue especially when you consider that the original crews would have had a boiler in their view! Shunting, or at least coupling isn't so bad in reality and the driver side buffer is in view when looking out the side window (on the large round OLEOs at least). Probably one big disadvantage for the crew, especially at no.1 end of a 37 is the racket created by the compressors.

From a maintenance point of view it's an advantage having better access to the machines that fitted there. It also provides easier access to the roof too. By comparison they layout in a 47 makes for a nightmare with most of it's machines, brake valves and a fuel tank all wedged beneath the radiators.

What is ‘sleeper vision’ ?

Dougal2345 · 26 Nov 2019

I was wondering something similar about the Class 20 - it looks as though it's all been styled so that it's to be driven 'nose first' with the driver peering through the tiny forward-facing windows. There's no concession to streamlining on the back of the cab which suggests it was rarely to be driven in reverse.

Is this correct, was the original cab interior designed such that forwards was the 'priority'? If so, why would they be designed to be driven from a position where forward visibility was poorest?

These days they're always driven 'backwards' of course.

MarlowDonkey · 26 Nov 2019

Dougal2345 said:
Is this correct, was the original cab interior designed such that forwards was the 'priority'? If so, why would they be designed to be driven from a position where forward visibility was poorest?

It was designed in the 1950s, so I imagine they took steam tank engines as the design cue. There were also similar lower powered single cab locos in the USA. The unsuccessful other type 1 designs all had similar one cab styling. Their maximum speed was relatively low, so streamlining would not have been a priority.

matchmaker · 26 Nov 2019

MarlowDonkey said:
It was designed in the 1950s, so I imagine they took steam tank engines as the design cue. There were also similar lower powered single cab locos in the USA. The unsuccessful other type 1 designs all had similar one cab styling. Their maximum speed was relatively low, so streamlining would not have been a priority.

Claytons?

DelW · 26 Nov 2019

Dougal2345 said:
I was wondering something similar about the Class 20 - it looks as though it's all been styled so that it's to be driven 'nose first' with the driver peering through the tiny forward-facing windows. There's no concession to streamlining on the back of the cab which suggests it was rarely to be driven in reverse.

Is this correct, was the original cab interior designed such that forwards was the 'priority'? If so, why would they be designed to be driven from a position where forward visibility was poorest?

These days they're always driven 'backwards' of course.

In "35 years of Main Line Diesel Traction", published in 1982, Colin Marsden included two early photos of class 20s on passenger workings (in 1957 & 1960), both of which were running nose first. There's also a photo of a single loco working nose-first on a freight train in 1979, with the caption mentioning that that was "increasingly rare". All the other photos are from the late '70s and show them in pairs with cabs outward.
His description of the class 20s doesn't mention control layout, but that for the class 15 (also with a single cab, close to one end) stated that they had dual controls so that the driver could face the direction of travel.
[Sixty years or so ago, one of my uncles had a Hornby Dublo layout with a model class 20 (then called EE Type 1 of course) which was always run nose first, all his other locos being steam outline.]

Kingspanner · 26 Nov 2019

"Sleeper flicker" is definitely a thing, in the sense that I once read that it's absence was an advantage of big nosed locos. So not much evidence there really...

Black Lane · 27 Nov 2019

In the recent BBC Chunnel series it said the loco cabs where designed with a restricted view to stop the drivers being hypnotized.

squizzler · 27 Nov 2019

I think that a lot of the nose designs originate from the fashions and realities of US railroading. Art deco (rather than purely functional) streamlining was big when the first US passenger diesels came in, and this seemed to favour long noses in front of the cab.

The American scene would have (and still does AFAIK) involved more crashing than in other countries, particularly at rural level crossings. this also would have favoured longer noses.

When the EMD E- and F type became the breakout product it became the visual archetype of diesel locomotives of the first generation, not just in the USA but internationally too.

I understand that British postwar loco manufacturers had expected they would supply the Commonwealth (India, Australia, Canada etc) although sadly these countries normally just brought American products. Nonetheless the UK builders probably styled their products with noses simply because the EMD and Alco designs looked that way.

Spartacus · 28 Nov 2019

The 'sleeper effect' was certainly a factor when the early diesels were being specified, although it turned out to have minimal effect when analysed, dropping to zero with modern ballasting.

Having a nose in front probably went some way to helping steam drivers transitioning to diesel, suddenly finding yourself at the very front could well have been a bit unnerving to some, I've read tales of drivers who finally made top link after years of progress only to find they couldn't cope with driving at speeds of 80 mph or more and having to drop back down the links, often quite a way, and that's still with most of a loco in front.

37057 · 28 Nov 2019

I think the seating also has a play to part in modern trains too, quite often I get into cabs and find the seat at it's lowest position - that certainly reduces the view of the line ahead. Not much adjustment in an old loco though and something like a 47 certainly has you looking down naturally.

Journeyman · 28 Nov 2019

I can't understand why all the type 1 designs only had one cab. A lot of effort went into designing a type 1 with decent vision in both directions, in the form of the centre-cab Class 17, but it ended up being disastrously unreliable. They built more 20s afterwards which only had decent vision in one direction. The 15s and 16s were pretty rubbish whichever way they faced. How come there was never a version of the 20 with a cab at each end?

delt1c · 28 Nov 2019

Journeyman said:
I can't understand why all the type 1 designs only had one cab. A lot of effort went into designing a type 1 with decent vision in both directions, in the form of the centre-cab Class 17, but it ended up being disastrously unreliable. They built more 20s afterwards which only had decent vision in one direction. The 15s and 16s were pretty rubbish whichever way they faced. How come there was never a version of the 20 with a cab at each end?

A 20 with a cab at each end would have been longer and heavier, remember only 1000hp

Spartacus · 28 Nov 2019

They'd have been more expensive too, particularly important given the lifespan many type 1s ended up having, a 20 was more or less in type 2 territory for length and weight already if you compare it to a 24 for example. For size, weight and purchase cost you'd be firmly in Type 2 territory for them all, so you might as well built more type 2s..... It can't have been too much of a disadvantage otherwise I'm sure BR wouldn't have ordered more in the mid 60s and would have gone for type 2s like the 24 instead.

Regarding 17s though, I've heard people comment that unlike most type 1s they've poor vision in BOTH directions, as neither gives you a particularly good view of what you're going to couple to.

JohnElliott · 28 Nov 2019

DelW said:
[Sixty years or so ago, one of my uncles had a Hornby Dublo layout with a model class 20 (then called EE Type 1 of course) which was always run nose first, all his other locos being steam outline.]

On a three-rail Dublo system, the wiring / magnetisation in the locomotive defines which end is the front and which is the back - unlike on a two-rail system, turning the locomotive round doesn't swap the positive and negative feeds. The steam locos would have been manufactured with 'forward' corresponding to boiler-first running, and the single-cab diesels were made in the same orientation.

NIRCLASS80 · 29 Nov 2019

There is a double ended class 20 in the form of Northern Ireland Railways 101 Hunslet class.

https://www.flickr.com/photos/15977833@N07/26027128207

Dougal2345 · 29 Nov 2019

JohnElliott said:
On a three-rail Dublo system, the wiring / magnetisation in the locomotive defines which end is the front and which is the back - unlike on a two-rail system, turning the locomotive round doesn't swap the positive and negative feeds. The steam locos would have been manufactured with 'forward' corresponding to boiler-first running, and the single-cab diesels were made in the same orientation.

Interestingly with the two-rail version, you can't run two 20s nose-to-nose (or indeed in any combination) without getting a short circuit through the metal couplings...

'Vintage' Diesel Loco Design

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