Why didn't we categorise DMUs built in the 1990s as "third generation"?

[Inthewest]

There's an obvious split between 1st generation DMU's and the rest.
I guess the turning point was the 14x and above. But why was the 165 (and newer) not classed as 3rd generation DMU?
And the latest trains built after the Meridians named as the 4th generation?

 

[Domh245]

Because pigeonholing trains into generations is secondary to ordering them when it suits? The easier way to group them is by family (ie pacers, sprinters, networker turbos, turbostars, CAFs), which implies the generation too.

For what it's worth though, "post-privatisation DMU" is a thing, applying to 168s onwards. There's probably an argument for the current crops of CAFs to be viewed as a 4th generation, but for what purpose

 

[Philip Phlopp]

There's not the same progression with DMUs as there has been with EMUs.

EMUs - We've gone from camshaft controllers and DC traction motors with mercury arc rectifiers for 6.25kV/25kV AC stock through thyristors, GTOs and now IGBT/IGCT rectifiers/inverters with the benefit of being able to use vastly more reliable AC motors. Huge technical changes in recent decades.

DMUs - We've gone from a Leyland engine bolted to a Self Changing Gears (SCG) mechanical transmission through Cummins engines bolted to Voith hydraulic transmissions, onto MTU engines bolted to Voith hydraulic transmissions and finally onto MTU engines bolted to ZF mechanical transmissions.

 

[yorkie]

But why was the 170 (and newer) not classed as 3rd generation DMU?

It's just a matter of semantics and pigeonholing, nothing more than that.

 

[rebmcr]

EMUs - We've gone from camshaft controllers and DC traction motors with mercury arc rectifiers for 6.25kV/25kV AC stock through thyristors, GTOs and now IGBT/IGCT rectifiers/inverters with the benefit of being able to use vastly more reliable AC motors. Huge technical changes in recent decades.

Even more to come, with Gallium Nitride rather than Silicon semiconductors beginning to ramp up production for power electronics.

 

[Philip Phlopp]

Even more to come, with Gallium Nitride rather than Silicon semiconductors beginning to ramp up production for power electronics.

Indeed - and with more material development and better heat management on circuits and components feeding through all the time. Thermal cycling being such a killer, if you can keep your electronics at the same temperature across their whole duty cycle and range, they'll normally reward you with greater life expectancy and reliability.

 

[Bletchleyite]

DMUs - We've gone from a Leyland engine bolted to a Self Changing Gears (SCG) mechanical transmission through Cummins engines bolted to Voith hydraulic transmissions, onto MTU engines bolted to Voith hydraulic transmissions and finally onto MTU engines bolted to ZF mechanical transmissions.

AKA round in a massive circle

I think uk.railway did call post-privatisation DMUs (i.e. 168 and later) third-generation DMUs, but it's got a bit blurry since then.

 

[HSTEd]

Even more to come, with Gallium Nitride rather than Silicon semiconductors beginning to ramp up production for power electronics.

Also Silicon Carbide MOSFETs that are as voltage capable as silicon IGBTs.

 

[LOL The Irony]

I'd say;

DMUs:
Slammers = 1st Generation
Sprinters & Pacers = 2nd Generation
Turbostars (172s would come under the "B" moniker), Coradia 1000's & Class 185s = 3rd Generation
Civity's & Flirt's = 4th Generation

EMUs:
BR Slammers = 1st Generation
PEPs = Gen 2A
Mk3 based= Gen 2B
Electrostars, Desiros (380s would come under the "B" moniker) & Coradia Junipers = 3rd Generation
Desrio Cities, Aventras, Civitys & Flirts = 4th Generation

 

[DustyBin]

I'd say;
DMU:
Slammers = 1st Generation
Sprinters & Pacers = 2nd Generation
Turbostar's (172's would come under the "B" moniker), Coradia 1000's & Class 185's = 3rd Generation
Civity's & Flirt's = 4th Generation
EMU:
BR Slammers = 1st Generation
PEP's = Gen 2A
Mk3 based= Gen 2B
Electrostar's, Desiro's (380's would come under the "B" moniker) & Coradia Junipers = 3rd Generation
Desrio City's, Aventra's, Civity's & Flirt's = 4th Generation

Thats all quite logical actually, my only question would be where do you put the Networker family?

 

[LOL The Irony]

Thats all quite logical actually, my only question would be where do you put the Networker family?

Oooh, good question.
I have 2 options;
The less likely Gen 2C

Or the more likely, Gen 3A, with the rest going into a Gen 3B and the 380 into Gen 3C.

 

[DustyBin]

I was thinking 3A as well.

 

[yorksrob]

There's not the same progression with DMUs as there has been with EMUs.

EMUs - We've gone from camshaft controllers and DC traction motors with mercury arc rectifiers for 6.25kV/25kV AC stock through thyristors, GTOs and now IGBT/IGCT rectifiers/inverters with the benefit of being able to use vastly more reliable AC motors. Huge technical changes in recent decades.

DMUs - We've gone from a Leyland engine bolted to a Self Changing Gears (SCG) mechanical transmission through Cummins engines bolted to Voith hydraulic transmissions, onto MTU engines bolted to Voith hydraulic transmissions and finally onto MTU engines bolted to ZF mechanical transmissions.

The Bullied 4SUB's were an odd one. Second gen but with many technical aspects similar to the 1st !

 

[Philip Phlopp]

The Bullied 4SUB's were an odd one. Second gen but with many technical aspects similar to the 1st !

Everything is complicated by the Southern Railway/Region and their obsessive recycling activities.

The Class 442 fleet arguably started as a 1st gen unit and now are moving to 4th gen with their new traction package.

 

[yorksrob]

Everything is complicated by the Southern Railway/Region and their obsessive recycling activities.

The Class 442 fleet arguably started as a 1st gen unit and now are moving to 4th gen with their new traction package.

Ah yes, Southern Region frugality.

L&SWR branded EPB's anyone !

 

[quantinghome]

Wasn't there a big time gap between 1st and 2nd generation DMUs? 1st generation were built up to the early 60s, 2nd gen from the early 1980s. Describing them as generations kind of made sense from a chronological perspective regardless of technology. Since the 80s there hasn't been an equivalent gap so talk about generations doesn't make as much sense.

 

[Philip Phlopp]

Wasn't there a big time gap between 1st and 2nd generation DMUs? 1st generation were built up to the early 60s, 2nd gen from the early 1980s. Describing them as generations kind of made sense from a chronological perspective regardless of technology. Since the 80s there hasn't been an equivalent gap so talk about generations doesn't make as much sense.

There was a train of thought once (umm) that anything with an auto-coupler was a second generation unit, anything with traditional manual couplers/buffers/drawgear was first generation.

 

[yorkie]

BR Slammers = 1st Generation
PEP's = Gen 2A

it's all very arbitrary; you are categorising a Class 312 express unit built in 1978 as a previous generation to a Class 313 unit built a couple of years earlier.

 

[Ianigsy]

Turbostars and second generation DMUs can and do work in multiple so should probably be in the same bracket.

 

[yorksrob]

it's all very arbitrary; you are categorising a Class 312 express unit built in 1978 as a previous generation to a Class 313 unit built a couple of years earlier.

Indeed. Only a couple of years between the last VEP's and the PEP's I think.

 

[LOL The Irony]

it's all very arbitrary; you are categorising a Class 312 express unit built in 1978 as a previous generation to a Class 313 unit built a couple of years earlier.

Older technology and older carriage construction makes it previous gen vs next gen. Sony were still putting PS2's into tv's long after they started making the PS3. The PS2 in the tv is newer than the first PS3, but the PS3 is still the newer technology.

 

[randyrippley]

Modernisation plan DMUs were second generation: first generation were the GWR and LNER railcars

 

[LOL The Irony]

Turbostars and second generation DMUs can and do work in multiple so should probably be in the same bracket.

The newest 323 can interwork with the oldest 313, but would you put them in the same bracket considering they're separated by 20 years and the 323's are a lot more modern? In fact, I wouldn't even put them in the same league as Mk3 EMU's.

 

[DustyBin]

it's all very arbitrary; you are categorising a Class 312 express unit built in 1978 as a previous generation to a Class 313 unit built a couple of years earlier.

You can’t really base it purely on age though. IMO the Class 312 (slam door, MK2 based) isn’t of the same generation as the aluminium bodied, sliding door PEP stock which is as you say in some cases older. Thinking about it, the Class 310 and 312 were a bit of an anomaly in their own right being MK2 based.

Indeed. Only a couple of years between the last VEP's and the PEP's I think.

Yes but as above....

Modernisation plan DMUs were second generation: first generation were the GWR and LNER railcars

The same could apply to EMU’s but for the purpose of this discussion I took first generation to mean early BR. Otherwise we’d be talking about wooden bodied stock!

 

[yorksrob]

You can’t really base it purely on age though. IMO the Class 312 (slam door, MK2 based) isn’t of the same generation as the aluminium bodied, sliding door PEP stock which is as you say in some cases older. Thinking about it, the Class 310 and 312 were a bit of an anomaly in their own right being MK2 based.



Yes but as above....



The same could apply to EMU’s but for the purpose of this discussion I took first generation to mean early BR. Otherwise we’d be talking about wooden bodied stock!

Yes, I agree. Particularly as VEP's were proper trains, whereas PEP's were slidy-door things.

 

[DustyBin]

Yes, I agree. Particularly as VEP's were proper trains, whereas PEP's were slidy-door things.

I loved the VEP’s, I spent many a happy hour riding on them purely for fun! And the CIG’s and CEP’s....

 

[yorksrob]

I loved the VEP’s, I spent many a happy hour riding on them purely for fun! And the CIG’s and CEP’s....

Indeed. The VEP's get a poor reputation, but the trip from Ashford to Victoria in the standard class compartment, on a summers day with the droplight down was an absolute delight !

 

[coppercapped]

Modernisation plan DMUs were second generation: first generation were the GWR and LNER railcars

Thank you - saved me from posting!

(And very good they were too!)

 

[LOL The Irony]

The same could apply to EMU’s but for the purpose of this discussion I took first generation to mean early BR. Otherwise we’d be talking about wooden bodied stock!

That's why I didn't include them in my list, because it just opens a Pandora's box. I'd just classify them as pre-Mk1's.

 

[yorksrob]

That's why I didn't include them in my list, because it just opens a Pandora's box. I'd just classify them as pre-Mk1's.

Absolutely. The slammers we know and love are very much second generation EMU's. Always have been. Now't controversial in that.