Diesel Hydraulic Locomotives

[pitdiver]

Something that has puzzled me for a long time. Why was it Diesel Hydraulic Locomotives weren't more widely adopted by British Railways and not just the Western Region?

 

[Acathater]

Basically it was because hydraulic transmissions were not something that British companies developed in any significant way.

British technology went down the route of developing electrical generation, transmission and control systems; think GEC, EE, AEI, BTH, Brush/Hawker Siddeley, Crompton Parkinson and others. All experienced in electrical power systems.

We didn't have any UK companies who invested in hydraulics on the same scale. Those who did invest in hydraulics simply built licenced German designs. And in the late 1950s it would be a brave person who specified spending government money on German industrial products

 

[norbitonflyer]

The Western had little experience with electricity - alone of the Big Four it had no electrified mileage (unless you count the section from Paddington to Westbourne Park, owned by the GWR but operated by the Metropolitan Railway - and the GWR did part-own the original H&C EMUs of 1906) . It its entire history I think the GWR built one diesel-electric locomotive - GWR No 2 of1936 (BR No 15100), although several others were on order at the date of nationalisation (No 1 had mechanical transmission)

Hydraulics are lighter. This is not necessarily a good thing, especially with unbraked freights which rely on loco weight for brake force.

Hydraulic fluid is messier to handle than electricity, which is only there when you want it

No indigenous hydraulic transmission manufacturers - both Voith and Mekydro (Maybach) were German. NBL, wanting a slice of the diesel pie but having litttle electrical experience, went for licencing the foreign technology, but other loco builders (particularly English Electric and Brush), had a lot of electrical know how

What finally killed the DHs off though was aircon - for that you need the loco to supply electricity, so you need a generator however the wheels are driven

 

[Acathater]

......... but other loco builders (particularly English Electric and Brush), had a lot of electrical know how .........

That's a good point, EE, Brush, Birmingham RC&W and others had all been exporting diesel electric locomotives and multiple units around the world, mainly to the Commonwealth and South America
It's an interesting note that the most successful UK diesel loco builders were those who transitioned from building trams and multiple units using coach type bodies, rather than companies like NBL who tried to jump straight from steam loco building with no understanding of how to build carriage-derived bodyshells

 

[Irascible]

Indigenous builders ( some of which made a fairly significant contribution to GDP ) having quite some sway politically skewed decisions towards slow speed D-E. Theoretically D-H should have been more reliable ( they could well have been, I haven't looked anything up ) than early DC electricals & there was the ability to use full power from a standing start, but needing multiple torque converters & gearboxes was a pretty major downside too. AC did a lot for reliability & eventually for efficiency.

 

[Harlequinuk]

I do understand it was a question of economics ; UK was in a poor financial place, the diesel hydraulics were on 1 region vs all the others on diesel electrics. NBL had gone bust which meant everything had to go back to Germany (MAN Engines and Voith transmissions), Rolls-Royce had no interest in German diesels, so support for the Maybachs would have been German as well. Parts were also non standard vs German spec, so all would have been special order. 1 solution would have been to use Paxmans, but pre valenta they didnt have a good reputation. Biggest advantage was traction effort , especially the 52; the 56 that replaced it on stone trains (out of Westbury) just wasnt anything like as good

ETH could have been fitted - the DB Class 218 had it.

2600+ diesel electric vs 400 diesel hydraulics

 

[Taunton]

What finally killed the DHs off though was aircon - for that you need the loco to supply electricity, so you need a generator however the wheels are driven

And, an allied point, main line hydraulics had multiple, smaller, high-speed engines, for anything larger than a Hymek. If you have a twin-engined loco, how do you tap the power for ETH supply, without unbalancing the power distribution to the wheels. It was this that likewise prevented straightforward ETH supply in the USA from the classic streamlined E-unit passenger locos, which although electric transmission have twin engines and associated generators.

The general workaround was to provide a separate, third, engine, just for ETH generation. This was then wasted deadweight and unable to be used to supplement haulage power for freight usage. The same was applied to the 1970s Edinburgh-Glasgow 2xClass 27 push-pull, which were effectively twin engines on a train, and some were reconfigured with a Deutz auxiliary diesel generator, which turned out to be among the most unreliable pieces of kit BR ever bought (and there are a range of competitors for that honour!).

 

[Acathater]

ETH could have been fitted - the DB Class 218 had it.

bigger loading gauge = more room to fit it

 

[MarlowDonkey]

What finally killed the DHs off though was aircon - for that you need the loco to supply electricity, so you need a generator however the wheels are driven

The Thames and Chiltern Turbos, 165 and 166 are hydraulic, although their attempts at air-con are a little suspect.

 

[Acathater]

The Thames and Chiltern Turbos, 165 and 166 are hydraulic, although their attempts at air-con are a little suspect.

new generation of smaller lighter transmissions, more akin to a bus or truck design so more familiar to fitters
also easier to fit underslung than an electric transmission + generator set

 

[WesternGiraffe]

Warning, this may be hearsay .... discussing Westerns with a member of the WLA at Bridgnoth in the '80s, the opinion was offered that as DH was in use for construction and agricultural machinery, the DH equipment could be scaled up for railway use. However, German manufacturers were decided as the best source due to their existing railway experience and reliability.

IMO, from the WR's standpoint, DH at the time was a lot more efficient than either DE or DM, but whether this proved correct in practice is another matter.

 

[Sir Felix Pole]

The big advantage as far as the WR was concerned was the weight-saving compared to the contemporary blunderbuss diesel-electrics. This was worth a coach or two more on the difficult route west of Newton Abbot and that the new depots (Laira, Landore etc.) could be built to a lighter specification for overhead cranes etc.

NBL had built some diesels (hydraulic and electric) for overseas customers from the early '50s so it wasn't a totally alien concept to them, but the company was in serious trouble after a big South African steam order had been cancelled. Its works machinery was clapped out and unable to conform to the much tighter tolerances needed for the new era. A probably apocryphal story is that something was also lost in the translation of the metric measurements of the German drawings to Imperial. There was also an element of government 'direction' in placing the order - the whole Scottish economy was in serious decline at the time with the collapse of shipbuilding etc.

 

[Acathater]

NBL had built some diesels (hydraulic and electric) for overseas customers from the early '50s so it wasn't a totally alien concept to them.........

Weren't they mostly 0-6-0 trip workers / shunters? I've seen a photo online of two pulling a passenger train on test into a Glasgow station.
Bit different from a mainline loco

 

[Harlequinuk]

Weren't they mostly 0-6-0 trip workers / shunters? I've seen a photo online of two pulling a passenger train on test into a Glasgow station.
Bit different from a mainline loco

Ceylon Government railway G2 and the Paxman Voith Hydraulic 1 (PVH1) for Tasmania

 

[Rescars]

Does anyone know when hydraulic drive was invented? Electric drive has quite a long history. Heilmann in France experimented with steam-electrics in the 1890s and Dr Porsche built petrol-electric cars in the early 1900s.

 

[Harlequinuk]

Does anyone know when hydraulic drive was invented? Electric drive has quite a long history. Heilmann in France experimented with steam-electrics in the 1890s and Dr Porsche built petrol-electric cars in the early 1900s.

First loco was 1935, the V140

 

[edwin_m]

there was the ability to use full power from a standing start

I'd question if that's possible. Power equals tractive effort multiplied by speed, the tractive effort is finite so power actually used will correspondingly be low at low speeds. The engine might be at full revs but I suspect most of the energy is heating up the oil in some converter somewhere. I agree electrics do have a constraint that full voltage can't be applied to the voltage until the back EMF builds up with speed.

The Thames and Chiltern Turbos, 165 and 166 are hydraulic, although their attempts at air-con are a little suspect.

These are providing air conditioning within the same vehicle as the engine. A locomotive needs to transmit the power to the coaches it is hauling, and unless you're fitting hydraulic pipes down the train that has to be electric. The 170s, despite having similar transmissions to those earlier classes, went for electric air conditioning and I don't think anyone has regretted that decision.

 

[Acathater]

Does anyone know when hydraulic drive was invented? Electric drive has quite a long history. Heilmann in France experimented with steam-electrics in the 1890s and Dr Porsche built petrol-electric cars in the early 1900s.

According to Wiki

The first diesel locomotives using fluid couplings were produced in the 1930s

Fluid coupling - Wikipedia

en.wikipedia.org

Apparently the torque converter was invented separately in 1933

 

[Taunton]

The big advantage as far as the WR was concerned was the weight-saving compared to the contemporary blunderbuss diesel-electrics. This was worth a coach or two more on the difficult route west of Newton Abbot and that the new depots (Laira, Landore etc.) could be built to a lighter specification for overhead cranes etc.

NBL had built some diesels (hydraulic and electric) for overseas customers from the early '50s so it wasn't a totally alien concept to them

This didn't apply to the first main line hydraulic loco, designed and built by North British, the D600 class, 2,000 hp from twin high speed engines, which weighed 122 tons, and needed 6-wheel A1A bogies, though only four were powered. North British were then sent the drawings from Swindon for the main Warship class, which had more powerful engines but were only weighed 80 tons.

 

[Irascible]

I'd question if that's possible. Power equals tractive effort multiplied by speed, the tractive effort is finite so power actually used will correspondingly be low at low speeds. The engine might be at full revs but I suspect most of the energy is heating up the oil in some converter somewhere. I agree electrics do have a constraint that full voltage can't be applied to the voltage until the back EMF builds up with speed.

Well, yes, unless the wheels are slipping then the transmission is certainly slipping a lot at low speed - the more slip ( difference between input & output rotation speed ) in a torque converter the more torque is transmitted. Any excess work done will certainly end up as heat & as far as I remember the transmission wasn't really any more efficient than contemporary electrics, but it won't break in the same way an unprotected electric transmission will even with the engine sending full power into the input. Been a very long time since I studied specifics - very curious about transmission cooling now - I'll have to go dig some books up.

These are providing air conditioning within the same vehicle as the engine. A locomotive needs to transmit the power to the coaches it is hauling, and unless you're fitting hydraulic pipes down the train that has to be electric. The 170s, despite having similar transmissions to those earlier classes, went for electric air conditioning and I don't think anyone has regretted that decision.

158s have the same arrangement, and we know how many complaints they've generated over the years...

All production Sprinters were hydraulic. I'm not counting the 210 & not entirely certain what the 151 had.

 

[D7666]

I see the same old gen has been trotted out, none of which answers the following points :

• If WR was "anti electric" pro hydraulic transmission, why did they not have any DH shunters (D9500s are not shunters) ?
• WR had no hydraulic transmission DMU - yet both LMR and ER did - so why did not the WR if all the pro-hydraulic reasons are valid ?
• And LMR and ScR both had DH shunters as well as DE - so ditto why not WR ?

It is true the precise detailed type of DH transmissions in shunters and DMUs are slightly different to the WR main line locos, but the same arguments apply, no electrics, lighter, etc, irrespective of the detailed type.

If you take hydraulic transmission as a general term encompassing all technical variations, the WR only had around half those delivered to BR (here meaning 1950/1960 deliveries under the modernisation plan, not the later BR 15x 165x etc DMU).

The stats that I worked out years ago, and have posted more than once on assorted forums are -

WR took
class....total in class... transmissions total
D600....5....10
D800....3....6
D803....34....68
D830....1....2
D833....33....66
D1000....74....148
D6300....6....6
D6306....52....52
D7000....101....101
D9500....56....56
total....365....515

All main line locos, WR had no d-h shunters and no d-h DMU - points always omitted in "experts" writings. Never mind the reasons why WR went for main line d-h - that only explains what they did - it does not explain what they did not. GWR was the first diesel railcar user of any size, And WR was a big DMU user, yet not one d-h transmission DMU. Nor shunter. Not explained by any author I know of in the past 70 years since 1955 modernisation pln started.


Now look at LMR.
51591-51650....60....120
51681-51780....100....100
D2850-D2869....20....20
D2900-D2913....14....14
total....194....254

Big hydraulic user no ?

And the rest
D2700....78....78
D2700....3....3
50988-51007....20....40
51154-51173....20....40
79000-79007....8....8
79500-79507....8....8
total ....137....177

All this totals

TOTAL....696....946

of which

WR %....52%....54%

i.e. only just above half the total vehicles and half the total transmissions.

You can say 'lies damned lies and statistics' if you like, but this whole subject is never mentioned in either pro DH or anti WR diatribe no matter which side the writer is on.

(All Regions had DM shunters therefore can be discounted as examples or exceptions to proves rules).

 

[norbitonflyer]

First loco was 1935, the V140

LMS No 1831 built in 1932 was a diesel hydraulic

 

[edwin_m]

All production Sprinters were hydraulic. I'm not counting the 210 & not entirely certain what the 151 had.

The 151 had some kind of gear changing transmission, possibly similar to the 172.

 

[hexagon789]

The 151 had some kind of gear changing transmission, possibly similar to the 172.

They used a Twin Disc transmission, but whether that was a mechanical, hydro-mechanical or hydraulic transmission isn't clear.

"Twin Disc" being the name of a company that still manufactures transmissions.

 

[Taunton]

The 151 had some kind of gear changing transmission, possibly similar to the 172.

So did the Class 52 D1000 Western locos, they had three speed transmissions, changing up from 1st to 2nd automatically at about 25mph. Departing Taunton westbound they could be heard to do so, and the engine note fell, as they passed beneath the footbridge west of the station.

 

[Rescars]

Three speeds eh - just like my bike

Presumably the three speed transmissions on a 52 were not the same thing as the Self Changing Gear arrangements fitted to first generation DMUs etc. These were close relatives of Armstrong-Siddeley's pre-selectors and Daimler's fluid flywheels.

 

[MarlowDonkey]

. GWR was the first diesel railcar user of any size, And WR was a big DMU user, yet not one d-h transmission DMU. Nor shunter.

Weren't the 1930s DMUs partly based on contemporary bus and lorry technology? The AEC factory being next to the main line in Southall having some connection. To what extent did the 1950s designs of first generation DMUs build on GWR experience?

 

[norbitonflyer]

Weren't the 1930s DMUs partly based on contemporary bus and lorry technology? The AEC factory being next to the main line in Southall having some connection. To what extent did the 1950s designs of first generation DMUs build on GWR experience?

Very much so. Most 1st generation DMUs (those numbered in the 79xxx range, with "yellow diamond", "white circle" and "blue square" coupling codes, followed GWR practice with mechanical pre-selector gearboxes - the difference was in how control was communicated between vehicles.

Introduction

Coupling Codes

However, the first eight units built in 1954 (79000/500 to 79007/507) had an already out-dated hydro-mecahnical transmission system similar to that used in the LMS 1938 prototype and were coded "red triangle". (After their withdrawal in 1964 the code was re-used in 1969 when it was found that Classes 113 and 127 were not as compatiitble with other blue square types as intended)

 

[Harpo]

The GM class 59s were the point where electric transmission on locos used in the UK made an incredible step change, enabling one loco to move 5000 tons+ unassisted. Would hydraulic transmission have been capable of matching it by that point?

 

[Taunton]

The GM class 59s were the point where electric transmission on locos used in the UK made an incredible step change, enabling one loco to move 5000 tons+ unassisted. Would hydraulic transmission have been capable of matching it by that point?

It wasn't just electric transmission, it was GM devising through research their adhesion control "creep control" mode. Their previous electric transmission locos couldn't do this. Similar research on hydraulic transmission control would doubtless produce similar results.

One of the key issues that made Foster Yeoman buy their initial Class 59s was that when the Class 52 Westerns were withdrawn from the Westbury stone trains, the Class 47, supposedly the same horsepower, couldn't handle their same loads, which had to be reduced. Not for nothing did FY support the preservation of Western Yeoman, but no replacing Class 47 or 56 ...