Things that seemed a good idea at the time, but in practice are pretty useless.

Mixed traffic locomotives. Especially type 4+ diesels.

 

Care to elaborate on this?

 

Things that seemed a good idea... 'Brighton' Atlantic Tanks (bar the I3s), Midland designed axle boxes, and the Class 74 electro-diesels?

 

The Marsh I1 spawned the Maunsell I1x, which put in a good shift on the Oxted lines, so not a complete waste of metal .... plus leaving us one of the more memorable class monikers!

 

What - you mean "Wealden tanks"? Oh, you mean the other nickname ...

The I1s were a classic case of "penny wise, pound foolish". To save money, the first ten utilised the driving wheels, some motion parts and, crucially, the coupling rods from Stroudley D tank 0-4-2T locos. But a consequence of the short coupling rods was a very constrained firebox, such that in boiler power they were scarcely an advance on the D tanks they had been brought in to replace. Hence the reputation for being perennially short of steam. Dropping significant time - twice - when hauling the Royal Train to and from the Epsom Derby, with Marsh himself on the footplate, was probably a nadir in Marsh's career as a locomotive designer ...

Tom

 

Something about Bankers wasn't it?

 

And myself.

 

The requirements for a freight locomotive are significantly different to that of one for passenger use. Look at the difference between a HST and a class 66.

Specialisation was found in the steam fleets with small wheeled heavy freights and the large wheeled express classes.

When it came to the introduction of BR diesels they introduced classes that were expected to cover all tasks. The idea of having a locomotive that can be at home on a heavy coal train and then immediately able to pull an express might sound appealing but how often were these locomotives pooled together where they would be expected to switch between such different roles, aside from failures.

Which in larger classes ends up with subclasses geared towards certain roles, often abandoning the mixed traffic status, but the design is not as optimal as it is still based on a design compromised for the twin role.

I suppose it's more the lack of dedicated freight or passenger classes that was my point. Ultimately the Deltics were acquired, reluctantly, which were very much a passenger type. Then later came the 56s and HSTs. But attempting to cover all duties with a single class was something that seemed good at the time but in practice pretty useless.

 

Class 47s were used on both passenger and freight duties quite successfully, and if we are talking about steam, Black Fives.

 

Some of the first generation of British diesel locos were pretty poor, but that was because what should have been prototypes for evaluation, before choosing one version for each power level*, were rushed into series production, not because they were intended as mixed traffic locos. With electric or hydraulic transmission you can use all the power of the engine over a wide range of speeds, so mixed-traffic makes even better sense for diesels than it did for steam.

*Hence their being called "Type 1", "Type 2" etc and then having to be distinguished as "English Electric Type so-and-so", "Brush Type so-and-so" etc, rather than "Class 1" etc (which my Dad always called them).

 

IIRC, Nos 595-604 were the first lot and managed their 'notable' performances with all new components and that t'was the second batch which were graced with bits of D Tanks from the scrap pile and in the finest Brighton tradition, numbered 1-10. The eventual demise of the I1x class seems to have occured in fairly random fashion, with the last in service, 32005 (the only one to actually carry it's BR number) being one of the 'short wheelbase' examples.

I'd imagine the looming LBSC electrification programme got first dibs on investment back then .... which might also explain the penny-pinching which later afflicted Bilinton's rebuild of his fathers' B4 class, where the original less-than-ideal steam circuit was retained in the B4x. Couple that with reports of instability at speed (apparently in early Southern days) and perhaps you've got the reason why these didn't last as long as Maunsell's D1/E1 rebuilds.

 

Also on the subject of cab visibility from LMS locos, how tall did a driver need to be to see over the tops of the high side-tanks and bunker on the LMS Hughes 4-6-4 tanks?

https://en.wikipedia.org/wiki/L&YR_Hughes_4-6-4T

 

A random minor thing that probably comes under this general category: piston tail rods. Many late-Victorian designers seem to have thought they were vital on theoretical grounds, but they quickly disappeared from locos they were fitted to

 

Different throw coupling and connecting rods probably comes into that category - a few Edwardian designers seemed to be distrustful of large throws on coupling rods, but to avoid short stroke pistons, you ended up with different throw on the coupling and connecting rod on outside cylinder locos.

The Marsh Atlantics are like that (I believe inherited from their GNR cousins) - the coupling rod throw is 12", but the piston stroke is 26" so a 13" throw. Which creates a devil of a job for making, and accurately fitting, crank pins with the coupling rod and piston rod surfaces non concentric, all for the sake of saving 1" of radius on the coupling rod throw!

Another Marsh-ism on the LBSCR: He was distrustful of coupled leading driving wheels on passenger engines, despite a long history without problems on the LBSCR. One solution he used was to remove the leading coupling rods, converting some "Terrier" 0-6-0T into 2-4-0T, and some "Radial" 0-6-2T into 2-4-2T. Needless two say, when he left, his successor quietly returned them to conventional form!

Tom

 

Piston tail rods are quite useful for reducing uneven wear on the cylinder though. Certainly as piston sizes increased in Europe and the US they became essential. The UK is unusual in not adopting them more.

Tim

 

They seemed to find favour on compound locos.

Bavarian S3/6 pacific, later DR/DB class 18, last loco wdn 1966
[Image lifted from Wikipedia, original source unknown]

Is it just coincidence that they were phased out here with the change to more and narrower piston rings?

 

Arguably thats only true if the only freight traffic is slow timed big heavy loads, and the only passenger traffic express speed. That's sort of true today, but it wasn't true in the past. A fast timed vacuum freight was an utterly different traffic to a slow unbraked coal train, and required very different haulage.

If you take the GWR for instance, whilst they had a limited number of headline trains blasting down the mainline on special paths at 90mph plus, its well documented that the typical passenger train would accelerate briskly up to 60mph, and then save coal until the next station, a style of service that was well within reach of all their Halls, Granges and 43s, and not so very different from vacuum freight, milk, fruit etc with the same haulage.

 

Driver and fireman both used such one I guess! https://www.fatmoose.co.uk/media/product/e4c/megaspy-periscope-622843-778.jpg

Knut

 

Don't most German engines have tail rods? Even the Br 52 Kriegsloks seem to have them, so they must have had some (possibly apparent) value.
Pedants hat on: the S/6 Pacifics are Br 18.4-5. We don't want to mix them up with the Saxons, Württemberg or Baden engines, do we.
Pat