torsdag 27. mars 2014

Diesels We Nearly Had: Western Region....

I stood better informed about the warship and western class after an internet expedition into Hymek Land.

The interesting points to me are that

1) we could have had hymeks rated at 1940 hp with the engines as fitted, or even higher with upgrades as Maybach (MTU ) improved the design or modified things like cylinder heads.

2) The Western had a weakness in third gear : it did not have enough grunt in the v12s. Had it been fitted with twin 870 v16s from the Hymek, this would have been solved. Even further derated to 1500 hp or thereabouts, the power and torque would have made the westerns better suited to their envisaged tasks, especially 100mph trains. The V16s would have run cooler than the v12s which were pretty pushed at that rating in 1960. Voith and Mekydro units were in a "footprint" which followed the DB wish to have interchangeability, with V200s sometimes running with BOTH types of transmission, one on each PU. The extra weight would have been a matter of four to six tonnes.

3) Do we have an answer to oil sloshing diesel-hydraulic-mechanical locos vs diesel electric in Brush's Falcon? It seems falcon could start a heavier train on a steeper gradient and achieve 100mph more adequately on 400-500 tonne trains than its' torque convertor cousins. There was a straight head to head trial actually, but no doubt BR did not want to show Brush up or be shown to be lagging in their own Swindon built design. Had the western region been a bit more objective, they should have purchased a fleet of falcons to cover the inter-regional ScR- SW, NW-SW services which were earmarked ETH even by the early 60s.

4) the real trick western region missed was probably to take the best of German transmission design and couple it to the lightest, most powerful English configuration in a twin deltic engined monster of 3300 hp.

The Deltic engine lends itself eminently to the whole design ethos of DH: 1500 rpm in rail application, very light weight, compact, smooth torque curve and rate of acceleration.

Furthermore the advantages over the Maybach powerunits dont stop there. The deltics weigh about 5 tonnes for the PU and the collective gear box, the modern v 12 MTU is about 6 tonnes. The deltic is actually a good deal less complex than the v12 MB650/655 because it has no turbos ( in the preferred rail version 18 Cylinder, 36 piston) , no intercooling and no valves or cam shafts.

The "stack height" is not an issue. Maybach and the now MTU (owned by Rolls Royce Ironically enough now!) have stuck to a design with twin turbos mounted mid engine, which keeps the legnth of the unit minimal compared to the convention on almost all UK and US locomotive prime-mover/power-units with the turbos at the ends of the cylinder banks. This means though that stack height is rather high, and there is little room for free space for the engine radiator cooling groups.

The deltic overcomes this issue, with the Cooling Units being shaft driven directly above the power units,  on the classic twin engined class 55 locomotive in the UK. The "GWR Deltic" would have possibly had three fans per power train, the additional one for the hydraulic cooling groups. They may have also suited themselves to ETH by the rebuilding of the collective gear case to include a running circuit to a dynamo.

One thing which would have suited the deltic power units well, especially with the Voith transmission, would be that both engines are engaged from start and their is less lag in "gear changes" compared to the weak field diversion volt-amp resets on the deltic. The DE locomotive collected power from both PUs to supply both bogies, with the first unit running the train to about 18 mph before the second one comes on line, actuated by a cam on the power controller under the drivers control board. This and the field diversion set up meant that the engines had time to gather lubrication oil while at low rpm which made them very smokey.


Alas all this was  not to be, neither the DE versions of the Hymek and a productin version of Falcon. It is with some irony that the majority of passenger traffic on western region now is handled by DH DMUS mostly with voith transmission and many with MTU (Maybach ) power units.

If the BTC and BRB had in the outset studied the German locos more and had GWR been more cautious with the DH introduction then perhaps certain niches in terms of start-lift, route, speed and tonnage could have been identified and DH locos developed on a national basis. Crazy? Non Standard? Well what do we have today in terms of diesel passenger trains on a national basis?

For me that would mean a few classes of shunter (switcher) locos upto 1300hp the higher ones having mainline potential, while the betting being on the v16 in a type 3 / type 4 development as the Hymek , with engines being swapped out as hp increased over time,  and a twin engined version of this or the v12 by the same merits, with this or the twin DH Deltic being the master of long express traffic in the GWR or further a field.

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