'Vintage' Diesel Loco Design

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.

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In the US, when hood type diesels became a thing, several of the railroads ordered theirs set up to be driven long hood forwards

Spartacus said:

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.

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Interestingly there seems to have been a revival in continental Europe of single cab locos, to the UK eye they look like shunting/trip freight locos, but they seem to be used for mainline freight. I'm thinking particularly of the MaK/Vossloh G1206 and G1700 ranges

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.

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Thanks, that had never occurred to me, though it's inevitable now I think about it. His was 3-rail, and IIRC, though it's a long time ago, his controllers were marked forward and reverse, whereas my 2-rail Tri-Ang ones of course weren't. So it would have been confusing when running multiple trains to have had the type 1 running cab first.

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.

Click to expand...

The 20s have full dual controls (I had a drive of one a few years ago on a heritage line). The windows facing down the hood are not that small, and you sit quite close to them (that vintage of loco has a minimal set controls and gauges to accommodate compared to today's traction). Also the loco is quite short which helps the visibility running 'long hood forward' (as the Americans would say), and when they were originally introduced having a second person in the cab (fireman/secondman) who could read any 'wrong side of the line' signals would have been normal practice.

Re. having a short 'nose' in front of the cab - in most of world, railways are not fenced, so having some collision protection in front of the crew is very important. English Electric (for one) would have been exporting locos to Empire and Commonwealth countries with those sort of issues, so it's not surprising they producing designs with 'noses' which got carried over into the cl. 55/40/37 designs.

I suspect the 1930's American EMC/EMD diesels gained a short nose for similar collision protection reasons, with GM's styling dept. refining it into the iconic compound-curved design of the E and F series locos.