Creation of class 230 DEMUs from ex-LU D78s by Vivarail

[samuelmorris]

As I would have expected. Going to be a headache inducing ride if they have any long stints at low speed!

 

[felixthebadger]

The motors in the video above sound suspiciously like D78 motors still!

There's another video taken at Bo'ness where the Vivarail chap is explaining the technicalities to interested passengers, he said the motors were AC supplied by TSA TraktionSysteme Austria.

 

[gingertom]

There's another video taken at Bo'ness where the Vivarail chap is explaining the technicalities to interested passengers, he said the motors were AC supplied by TSA TraktionSysteme Austria.

do you have a link to that video?

 

[apk55]

There's another video taken at Bo'ness where the Vivarail chap is explaining the technicalities to interested passengers, he said the motors were AC supplied by TSA TraktionSysteme Austria.

Would replacing the traction motors give improved performance?
Generally induction motors can spin faster due to the more robust armature and you could make the active armature area longer due to the lack of brushes. Therefore you could increase top speed and higher tractive effort.

 

[felixthebadger]

do you have a link to that video?

Yes, it was made by Trains TrainsTrains & is about 16 minutes long.

 

[swt_passenger]

There's another video taken at Bo'ness where the Vivarail chap is explaining the technicalities to interested passengers, he said the motors were AC supplied by TSA TraktionSysteme Austria.

That’s the firm who provided the new motors for the SWT/SWR 455s.

 

[felixthebadger]

That’s the firm who provided the new motors for the SWT/SWR 455s.

I thought they were supplied by Kiepe? I know the new Northern CAF Civity Class 331 use TSA motors & they supplied Traction Alternators for the Hitachi IET's. I think Stadler use them as well.

 

[swt_passenger]

I thought they were supplied by Kiepe? I know the new Northern CAF Civity Class 331 use TSA motors & they supplied Traction Alternators for the Hitachi IET's. I think Stadler use them as well.

Kiepe managed the whole project and supply the traction electronics on the 455s so get the majority of the publicity. The 3 phase motor is just a relatively minor part of the whole job, effectively just a “bought in component” so rarely get mentioned.

 

[gingertom]

Would replacing the traction motors give improved performance?
Generally induction motors can spin faster due to the more robust armature and you could make the active armature area longer due to the lack of brushes. Therefore you could increase top speed and higher tractive effort.

I spoke to the chap in the video (see post #6725) and he suggested 75mph might be achievable. I know there's other factors to consider but if it happened then that would make for competition for the 14x 150 153 and 156.

 

[gingertom]

Yes, it was made by Trains TrainsTrains & is about 16 minutes long.

An interesting talk about some of the technology. I was standing next to Trains TrainsTrains when this video was being shot.

 

[Journeyman]

I spoke to the chap in the video (see post #6725) and he suggested 75mph might be achievable. I know there's other factors to consider but if it happened then that would make for competition for the 14x 150 153 and 156.

The biggest issue is the size of the wheels, I would have thought. Previous surface stock on London Underground had full-size wheels, but the D Stock shared motors and wheels with the 1973 tube stock, which makes the wheels very small compared to most main line trains. I'm assuming that modifying the size of the wheels is a big job and so probably hasn't been done. Small wheels give good acceleration but make high speeds problematic - hence the raised eyebrows when 9Fs topped 90mph in the sixties!

 

[edwin_m]

The biggest issue is the size of the wheels, I would have thought. Previous surface stock on London Underground had full-size wheels, but the D Stock shared motors and wheels with the 1973 tube stock, which makes the wheels very small compared to most main line trains. I'm assuming that modifying the size of the wheels is a big job and so probably hasn't been done. Small wheels give good acceleration but make high speeds problematic - hence the raised eyebrows when 9Fs topped 90mph in the sixties!

Container flats are allowed 75mph and have quite small wheels, though I don't know how the axle loads compare. I suspect the suspension may be more of an issue, as the Underground tends to use lumps of rubber instead of proper springs or airbags.

 

[samuelmorris]

I don't imagine that's likely to be an issue per se given that I don't think the wheels on stock that does 125-140mph are anything like twice the diameter, but I thought it was more a question of what the bogies themelves were designed to support.

Edit: Just looked it up
D78 wheels: 790mm new, 710mm worn
Mk3 wheels: 914mm new, 842mm worn

so less than a 20% difference between 60mph units and 125mph stock. I don't think wheel diameter alone is the reason.

 

[gingertom]

I don't imagine that's likely to be an issue per se given that I don't think the wheels on stock that does 125-140mph are anything like twice the diameter, but I thought it was more a question of what the bogies themelves were designed to support.

Edit: Just looked it up
D78 wheels: 790mm new, 710mm worn
Mk3 wheels: 914mm new, 842mm worn

so less than a 20% difference between 60mph units and 125mph stock. I don't think wheel diameter alone is the reason.

The crashworthiness of the aluminium bodyshell may rear its ugly head again.

 

[The_Engineer]

The crashworthiness of the aluminium bodyshell may rear its ugly head again.

Use of Aluminium is immaterial (pun intended!). The end structure and underframe are steel, cab ends have already had some strengthening added to meet current NR standards, proven by calculation and tests. After all, some DMUs and EMUs used all aluminium welded bodyshells such as Classes 465, 165 and 158.

 

[gingertom]

Use of Aluminium is immaterial (pun intended!). The end structure and underframe are steel, cab ends have already had some strengthening added to meet current NR standards, proven by calculation and tests. After all, some DMUs and EMUs used all aluminium welded bodyshells such as Classes 465, 165 and 158.

there's a perception amongst some that lightweight=flimsy/weakness. I don't subscribe to that.

 

[Bletchleyite]

there's a perception amongst some that lightweight=flimsy/weakness. I don't subscribe to that.

The main issue with ally is that it cracks rather than deforming so is harder to repair than steel - but there is no reason a suitably specified ally structure would in and of itself be any weaker than a steel structure of the same specification - but it absolutely will be lighter.

 

[gingertom]

The main issue with ally is that it cracks rather than deforming so is harder to repair than steel - but there is no reason a suitably specified ally structure would in and of itself be any weaker than a steel structure of the same specification - but it absolutely will be lighter.

yep. IIRC the Vivarail tekky guy said a 230 vehicle was 30 tonnes. Can't remember if that was with or without engine or battery rafts but still pretty lightweight when compared to steel-bodied vehicles.

 

[Dstock7080]

yep. IIRC the Vivarail tekky guy said a 230 vehicle was 30 tonnes.

By comparison in LU days, with heavier DC motors and very heavy camshaft equipment; 30.742T in refurbished condition (-1000 in as built)

 

[Goldfish62]

Use of Aluminium is immaterial (pun intended!). The end structure and underframe are steel, cab ends have already had some strengthening added to meet current NR standards, proven by calculation and tests. After all, some DMUs and EMUs used all aluminium welded bodyshells such as Classes 465, 165 and 158.

The Junipers also have aluminium bodyshells.

 

[gingertom]

By comparison in LU days, with heavier DC motors and very heavy camshaft equipment; 30.742T in refurbished condition (-1000 in as built)

talked about the weight of the motors, he said they were similar. Might mean they are more powerful? AC motors are allegedly lighter that DC ones of the same rating.

 

[felixthebadger]

Use of Aluminium is immaterial (pun intended!). The end structure and underframe are steel, cab ends have already had some strengthening added to meet current NR standards, proven by calculation and tests. After all, some DMUs and EMUs used all aluminium welded bodyshells such as Classes 465, 165 and 158.

Actually in the technical video the Vivarail man said the underframes are also Aluminium on the D78. The PEP derived units, 313, 314, 315, 507 & 508 have Aluminium bodies on steel frames.

 

[100andthirty]

talked about the weight of the motors, he said they were similar. Might mean they are more powerful? AC motors are allegedly lighter that DC ones of the same rating.

In general, modern motors are smaller than older motors for the same rating. There is, however, a big "but". To deliver the same output, smaller motors run at higher speed and therefore need a different gearbox. If we assume that the class 230 has retained the original D stock gearbox (something I believe is true, but I don't know for a fact), the AC motors will have to run at the same speed as the DC ones. This means that the size will be about the same. D stock motors were quite an efficient design produced in volume, so it's not unreasonable to imagine that the class 230 AC motor is about the same weight as the DC ones.

 

[apk55]

In general, modern motors are smaller than older motors for the same rating. There is, however, a big "but". To deliver the same output, smaller motors run at higher speed and therefore need a different gearbox. If we assume that the class 230 has retained the original D stock gearbox (something I believe is true, but I don't know for a fact), the AC motors will have to run at the same speed as the DC ones. This means that the size will be about the same. D stock motors were quite an efficient design produced in volume, so it's not unreasonable to imagine that the class 230 AC motor is about the same weight as the DC ones.

The fact that the motor could spin faster because of the more robust nature of the armature means that they could raise the units speed to maybe 75 or 80MPH assuming there is no other limiting factors.
Also with a significant part of the length of the motor being taken up by the commutator assembly you could increase the armature length and get more torque or tractive effort from the same length of motor. However the gears may be a limiting factor

 

[DarloRich]

I wonder how the testing on the Vale is going.......................

 

[Chris125]

The biggest issue is the size of the wheels, I would have thought. Previous surface stock on London Underground had full-size wheels, but the D Stock shared motors and wheels with the 1973 tube stock, which makes the wheels very small compared to most main line trains. I'm assuming that modifying the size of the wheels is a big job and so probably hasn't been done. Small wheels give good acceleration but make high speeds problematic - hence the raised eyebrows when 9Fs topped 90mph in the sixties!

A very common misconception, but they actually have wheels little (if any) smaller than most modern multiple units.

In fact the D78/73TS have wheels larger than 125mph Voyagers and Meridians: 788mm vs 780mm.

Most Sprinters, Electrostars and Turbostar fleets aren't much larger (840mm), nor current designs like the 700 (820mm).

 

[Bletchleyite]

A very common misconception, but they actually have wheels little (if any) smaller than most modern multiple units.

In fact the D78/73TS have wheels larger than 125mph Voyagers and Meridians: 788mm vs 780mm.

Most Sprinters, Electrostars and Turbostar fleets aren't much larger (840mm), nor recent designs like the 700 (820mm).

I think it comes from the days of steam when the driving wheels were part of the gearing - because the pistons drove them directly, there was no way to "regear" so as to have smaller wheels. With modern rolling stock, the wheels can be more or less any size - otherwise how would there be cars that do well over 100mph on wheels that are, with tyres, barely 500mm in diameter?

 

[AndrewE]

I think it comes from the days of steam when the driving wheels were part of the gearing - because the pistons drove them directly, there was no way to "regear" so as to have smaller wheels. With modern rolling stock, the wheels can be more or less any size - otherwise how would there be cars that do well over 100mph on wheels that are, with tyres, barely 500mm in diameter?

2 things: Bearings and lubrication - and probably tyre structure & materials - have got very much better, so RPM isn't the limiting factor any more, for rail as well as rubber-tyred road vehicles, but on the other hand as steel wheels get smaller the point load on the rail increases. I think our earliest high-box container wagons had tiny wheels but 3-axle bogies because of this. (Nothing to do with axle loading per se.)

 

[sw1ller]

Going back to the video above. The bloke talks about the suspension and how they've split a solid bogie so it rides better. Is that instead of having lateral dampers like on a 158/175? How does it compare to a 150? He said it runs very smoothly over jointed rail, I’m just interested to work out if he means compared to the old D78 or if he’s now comparing it to 150s / 158s??

 

[gingertom]

Going back to the video above. The bloke talks about the suspension and how they've split a solid bogie so it rides better. Is that instead of having lateral dampers like on a 158/175? How does it compare to a 150? He said it runs very smoothly over jointed rail, I’m just interested to work out if he means compared to the old D78 or if he’s now comparing it to 150s / 158s??

IIRC from the chat with him the bogies were always split so they could negotiate tight bends on parts of the district line, giving a better ride.