fredag 3. desember 2010

The CSVT / RK270 mm

As an interesting anorak worthy excursion back into "what might have been" about the CSVT and EE D6700 variants.

The malaysians are jsut decommissioning the last Class22, which were a 1710hp set up made in Austrailia (AEI?) Previous references to this a few years ago noted it as a 12CSVT, but in fact it was a v8

So there are two fossils in the evolutionary pathway for the CSVT which mark power developments for rail traction beyond that of the DP2/ class 50.

The other "Missing Link" was the Hunslet built BoBo's which ran on the DUblin: Belfast Route in the 1970s. They were rated at allegedly 1500hp but more likely 1350. Unlike the reliable portuguese application of this PU, at 1350hp, now finding extending lives in Argentina, the V8s suffered major and catastophic failures on the "enterprise service"

The Malaysian locos are pretty hellfire, being like a fifty crossed with a 40 with some 37/31 thrown in for good measure as the thrash enthalls through the rev range. A relatively long life for the humid environment, and as with all type 3s really, performance punching above its weight.

At app 115 bhp per cylinder this means the v12 version of the CSVT from AEI at least, would have been around about 2600bhp!

Only a couple of years later in the late 70s, the T bone class 37 was of course realised as a potential export loco for BREL as lead supplier: viz a vis, class 58 with the RK and a big nasty silencer to plague fitters and enthusiasts.

As mentioned before, even with 2200hp, an alternator, CP7 bogie gearing, and a KV10 style load management system, the super-syphon-that-never-was would have been an impressive beast, probabkly managing 75 000 lbs

In the late 50s there was still rationing of most materials useful in a DE loco in the UK; EE 's ruston division probably knew that with better materials they could achieve outputs of 200hp per cylinder _: I dare say the old RK test beds, class 08 engines basically and straight 6s I have heard of, were run to failure with high power.

What they could have offered BTC/BRB was a lease engine scheme with lifetime upgrades as the higher horse power units came on line. However the locos were purpose built to the three power types EE supplied with SVT/CSVT engines eventually and with limitations on electrical materials, over-engineering was largely avoided.

In considering specific power output for a cylinder unit on a diesel engine, the developers take into account the major parameters. compression/decompression, fuel/turbo pressures, effective combination of the latter two and heat dissapation. (Lubrication relates to compression)

Eventually of course the smooth cycle of the V12 lead to the RK270 engine being developed to have almost 500 hp per cyclinder unit; but this entailed a larger size and much larger turbo chargers, thus resulting in the 270 being "out of gauge" to be fitted into a UK loco.

Also there is the issue of heat dissapation and thermal cycling; these are less prominent in shipping or other marine environments because water is a good conductor of heat, is usually relatively cool, and in plentiful supply. A loco has to pump air, which is a poor conductor, rather an insulator, and that air can be up to 50'C in some operating environments. For example the paxman "cousin" to the RK, the now VP developed from the Valenta, which itself as the Venture created 2250hp in the IC 125, where as it output almost 5000 hp ( 7000 kw ) in heat, most of which had to be radiated away.

However Rustons prior to absorption into MAN, found demand for a lighter and very compact unit for various more limited marine, generating and traction "footprints" for a PU:

It comes very full circle at this point becasue the PRIMA locos ( eg the horrid class 67 in the uk, but with electro-mechanical routes traceable to GEC Alsthom and hence EE) built for Sri Lanka ( and in fact another non US super-friendly country, Syria), where the difficult working environment has necessitated a major reduction in power output. To between 1700 and 1850 hp in fact.

Long live the EE type 3.