Porterbrook Cl.769 'Flex' trains from 319s, initially for Northern

[AM9]

317-322 (bar 319s) have Thyristor control, so yes. Meanwhile the 319s have GTO Chopper control, which is a lot more complex (hence the need to keep the trailer coach).

OK, I stand corrected. I assumed that the ac only sets had tap changers as for MKIs. I assume that getting the EMC clearance for either of those systems was a major task, even with the more relaxed RFI limits of the '80s. Hi speed semiconductor power switch design is a mature technology now so Brush probably didn't have too many problems integrating the diesel gensets.

We have far too many EMUs. What we need is more independently powered trains. That's why so much rides on the 769.

Hopefully that is only a short-term requirement. Given the recent acceptance of the pollution issues of diesels and the greater environmental issues of hydrocarbon IC engines, it may be politically more acceptable to convert redundant EMUs with modern IIIb and later engines than putting whole new diesel-only trains into service. The potentially limited life of vehicles that have already given 30 years of service means that they are not regarded as a 30 year commitment to continued pollution.
I hope that they are successful in the roles envisaged for them. They may encourage more infill electrification schemes so that they can be moved on to the next line needing bi-modes, (much the same justification for the class 80xs). It seems that the low speed torque benefits of electric motors over hydraulic converters live on way after the GWR gave up on them. Maybe there is an opportunity for a battery/supercapacitor booster addition to supplement the finite power available from the diesel engine to make use of the non-continuous rating of the motors as is normal when in electric mode.

 

[edwin_m]

Quite apart from all the other stuff, the 319 has a 750v bus line throughout the train, and plugging the diesel engines into this made conversion much simpler (at least in theory).

Although they did have to add another cable for the return current that would go through the rails in DC mode, so I think that advantage has been overplayed. The fact that they could re-use the existing control equipment by "fooling" it into thinking it was on third rail is probably more significant.

Perhaps for any future conversions the soon to be surplus I believe Renautus retractioned 321s or the very powefull 323s may be a better choice. AC motors and IGBT electrics.
K

The 323 has the traction equipment on the two end coaches and the transformer on the middle one, so probably no room for diesels. The 319 has very little equipment on the end coaches and the 321 also has very little on the intermediate trailer.

 

[big all]

as for being a bit underpowered in general
25% in general will not cause excesive delays yes you have to work harder and use up all the recovery time but often you will be within on time to 5 %
indeed during busy times squeezing into a 3 car can cost more time than than lost elsewhere

with a class 73 on diesel was a 60% reduction in load on diesel for the same timings over electric or a 40% increase in journey times

 

[gingertom]

as for being a bit underpowered in general
25% in general will not cause excesive delays yes you have to work harder and use up all the recovery time but often you will be within on time to 5 %
indeed during busy times squeezing into a 3 car can cost more time than than lost elsewhere

with a class 73 on diesel was a 60% reduction in load on diesel for the same timings over electric or a 40% increase in journey times

these class 73s wouldn't have been the re-engined 73/9s. That extra 1000bhp would have worked wonders.

 

[big all]

these class 73s wouldn't have been the re-engined 73/9s. That extra 1000bhp would have worked wonders.

i am going back 25 years so no
also keep in mind a 73 is 2000hp max and 1600 continuouse at the rails
you then take the diesel with 600 shaft hp you then remove power for traction motor blowers compressor exhauster cooling fan not including smaller things like lighting control or charging
you are perhaps down to maybe 450 useful at the rails horsepower
the point i am making is a 77% less power dosnt directly equate directly to a 77% reduction in performance more like maybe 35-40% so a 25% reduction may equate to perhaps 12% so fairly close to coasting and recovery time gains

 

[js1000]

The 323 has the traction equipment on the two end coaches and the transformer on the middle one, so probably no room for diesels. The 319 has very little equipment on the end coaches and the 321 also has very little on the intermediate trailer.

This is what I thought. The end carriages of the 319s are just shells with bogies underneath whereas the under carriages on the 323s are all fully loaded. Like the 319s, the 321s have some space on the end carriages making it more amenable to a bi-mode conversion.

 

[K.o.R]

Those two videos both show off something that I really miss: the sound of a train at speed on old-fashioned jointed track. Brilliant sound.

 

[61653 HTAFC]

This is what I thought. The end carriages of the 319s are just shells with bogies underneath whereas the under carriages on the 323s are all fully loaded. Like the 319s, the 321s have some space on the end carriages making it more amenable to a bi-mode conversion.

Where the 321s come in will be if there's demand for a 3-car bi-mode unit, as installing a bus-line to a 321 would (I imagine) be easier than moving all the ancillary stuff from the trailer on a 319. Besides, the Dusties don't look like they've collided with a particularly hefty fallen ugly tree, unlike the 319s!

323s would probably have to sacrifice some passenger accommodation if you were turning them into bi-modes. A genset at one end would be workable in theory, if one would be needed at both ends maybe not.

 

[AM9]

323s would probably have to sacrifice some passenger accommodation if you were turning them into bi-modes. A genset at one end would be workable in theory, if one would be needed at both ends maybe not.

With 1566hp of motors, a single genset would give such a reduced performance that it wouldn't be worth the exercise. Even two would reduce the power to near 50%

 

[edwin_m]

323s would probably have to sacrifice some passenger accommodation if you were turning them into bi-modes. A genset at one end would be workable in theory, if one would be needed at both ends maybe not.

With 1566hp of motors, a single genset would give such a reduced performance that it wouldn't be worth the exercise. Even two would reduce the power to near 50%

If you were prepared to sacrifice passenger space, and the structure allowed, you could have a much bigger engine in the space between floor and ceiling.

 

[hooverboy]

If you were prepared to sacrifice passenger space, and the structure allowed, you could have a much bigger engine in the space between floor and ceiling.

gas turbine dear boy......you want tonnes of power in limited space/weight.....that's the way to go.

we also have quite a significant indigenous supply of LNG round these here parts.

 

[hooverboy]

With 1566hp of motors, a single genset would give such a reduced performance that it wouldn't be worth the exercise. Even two would reduce the power to near 50%

rolls royce do a car engine turbine with 500bhp,not such a big deal to upscale to truck size with 1500bhp at all.

 

[edwin_m]

The snag with gas turbines in rail applications has always been the fuel consumption - something to do with having to work at a wide range of power demands. They were fitted to a few trains in the 1970s but went out of favour with rising oil prices. Are more modern ones any better?

 

[a_c_skinner]

having to work at a wide range of power demands

Hybrids then?

 

[edwin_m]

Hybrids then?

Could be, but you might lose the size/weight advantage of the gas turbine.

 

[a_c_skinner]

Not really, you'd need a diesel there for the hybrids we are currently contemplating, so the saving is there but I'm not sure rail will take to gas turbine and vice versa.

 

[AndrewE]

The snag with gas turbines in rail applications has always been the fuel consumption - something to do with having to work at a wide range of power demands. They were fitted to a few trains in the 1970s but went out of favour with rising oil prices. Are more modern ones any better?

I think it was also found to be almost impossible to adapt their bearings to cope with being bolted to a railway vehicle. "Tractionising"

 

[AM9]

rolls royce do a car engine turbine with 500bhp,not such a big deal to upscale to truck size with 1500bhp at all.

I doubt that a road vehicle IC engine would survive for long as part of a rail genset. Just how long do you think that a car engine is rated to deliver the output written in the glossies. Even some marine engines struggle when used in rail vehicles.

 

[Emblematic]

I think it was also found to be almost impossible to adapt their bearings to cope with being bolted to a railway vehicle. "Tractionising"

Both France and the US had gas turbines in rail applications with service lives of several decades, which shows that any technical obstacles were overcome, at least in these countries. However most turbine interest was in the fifties and sixties, when the heavy grades of petroleum had a very limited market and consequent low prices. Developments in the petrochemical industry created additional demand for these products, so by the seventies the economics of a relatively inefficient power source no longer stacked up for land transport.

 

[a_c_skinner]

I doubt that a road vehicle IC engine would survive for long as part of a rail genset

IIRC it used to be the case that engines needed to pass a type approval test for rail use, which was a bit of a torture test. I've heard it said that the very binary use of engines in UK rail (ON or OFF!) made it (and rail use) so very demanding. Perhaps we can look forwards to trains driven by software and hybrid power systems making life less testing.

 

[hooverboy]

The snag with gas turbines in rail applications has always been the fuel consumption - something to do with having to work at a wide range of power demands. They were fitted to a few trains in the 1970s but went out of favour with rising oil prices. Are more modern ones any better?

yes, newer microturbines also feature egr so efficiency is at or better than diesel.(typically now 30-40%)
as you say, efficiency improves with higher rpm....thats why a microturbine will work, when connecting up to a battery bank, from which the power source for the drive can be used.

exhaust gas can be routed to fire up a boiler for train heating.
...or an even newer approach would be to use thermoelectrics in the exhaust system as well to provide hotel load power for lights,doors,aircon,comms etc

 

[adrock1976]

Did the early designs of the APT (Advanced Passenger Train - where the present day Class 390s had their tilting designs developed from) have gas turbine propulsion? This was obviously in the days before the OPEC crisis in the mid 1970s happened in North East Africa and North West Asia.

 

[LOL The Irony]

Did the early designs of the APT (Advanced Passenger Train - where the present day Class 390s had their tilting designs developed from) have gas turbine propulsion? This was obviously in the days before the OPEC crisis in the mid 1970s happened in North East Africa and North West Asia.

They did but the 1973 oil crisis nuked most if not all GT plans from orbit.

 

[hooverboy]

They did but the 1973 oil crisis nuked most if not all GT plans from orbit.

APT-P was around after that....it was doing the rounds about the same time as HST was put into commercial service

that was the blue+grey one.

APT-E(electric version) did some commercial service on WCML but was withdrawn after a couple of years

 

[43096]

APT-P was around after that....it was doing the rounds about the same time as HST was put into commercial service

that was the blue+grey one.

APT-E(electric version) did some commercial service on WCML but was withdrawn after a couple of years

Wrong way round. APT-E (for Experimental) was the gas turbine version. APT-P (for Prototype) was the Class 370 electric version.

 

[LOL The Irony]

Wrong way round. APT-E (for Experimental) was the gas turbine version. APT-P (for Prototype) was the Class 370 electric version.

And the -E was silver & blue not blue & grey.

 

[absolutelymilk]

Richard Clinnick is on a test unit and is commenting on how quiet it is compared to a normal DMU (with a video)
https://twitter.com/Clinnick1/status/1051851920942555136

The engine accelerating on @PB_Leasing 769434. Very quiet and, unlike a DMU, no vibration.

 

[samuelmorris]

Sounds promising, certainly considerably quieter than a 150.

 

[507021]

Sounds promising, certainly considerably quieter than a 150.

Yeah, I think they are too.

 

[The_Engineer]

Going back to earlier posts:
Gen-set or battery conversions of DC motor EMUs to DEMUs can only really be done with a dual voltage AC/DC unit or straight DC units. It requires a DC stage for the DC genset to feed into. A lot of AC and DC only units produced more recently with three-phase motors use a 750 V DC nominal output from AC via a thyristor controlled rectifier, hence are easy to convert between AC and DC, and also to dual voltage EMUs and/or DEMUs for the best re-leasing prospects.

Class 317 through to Class 322 AC EMUs (but not Class 319s, of course) take AC from the transformer, and it goes through a thyristor controlled rectifier to provide variable voltage DC direct to the DC motors. They do not take readily to genset conversions there is no suitable DC link for them to feed into.

Dual voltage AC/DC EMUs with DC motors feed DC voltage either from third rail or AC overhead via a transformer and uncontrolled rectifier into a DC chopper to produce variable voltage DC to the motors. The value of this DC varies with line and overhead voltage variations, and the DC voltage from the overhead CAN be set lightly higher (as on Class 319) to give higher performance on AC line voltage than DC voltage. Class 313 was an odd-one out as it still used old-tech resistor-camshaft control to produce variable voltage DC to the motors from DC line volts.

Concerning tap-changers on AC rolling stock, they finished with Class 312s, and Class 87/0s, Class 87/1 being our first AC locomotive to use a thyristor controlled rectifier to produce variable DC voltage to the motors.

Concerning Class 769, I see Porterbrook have just announced that they are considering now adding batteries to Class 350s due to come off-lease to BEMU (battery-electric MU, not a bi-mode please!) which could steal some of Class 769s work on shorter off-wire work especially as they are much newer units too....