Are Top Speeds Really Just the Recommended Speed?

[TRAX]

Here's a hypothetical question for you. I understand the 350 Desiros had substantial modifications to allow them to run at 110 on the WCML. Could another 10mph feasibly be wrung out of them or are they screaming on the limit at 110? Just asking out of vague interest before anyone bites my head off.

it think the issue would lie more on crash worthiness than technical capabilities at this point.

 

[DJ_K666]

it think the issue would lie more on crash worthiness than technical capabilities at this point.

Possibly. That said I wouldn't want to be on a train that crashed at either speed.
To be honest, I wouldn't want to be in a 10 mph crash either.

Or a 1.2mph one, although that would involve a lot of swearing rather than death. And paperwork. Oh gods the paperwork. Begone foul beast.

 

[Brissle Girl]

Here's a hypothetical question for you. I understand the 350 Desiros had substantial modifications to allow them to run at 110 on the WCML. Could another 10mph feasibly be wrung out of them or are they screaming on the limit at 110? Just asking out of vague interest before anyone bites my head off.

I believe the non-passenger sections at either end would need to be a little larger above 110 than purely a cab’s depth, so would make them unviable given the lost space, particularly as units are often coupled together.

 

[hexagon789]

Here's a hypothetical question for you. I understand the 350 Desiros had substantial modifications to allow them to run at 110 on the WCML. Could another 10mph feasibly be wrung out of them or are they screaming on the limit at 110? Just asking out of vague interest before anyone bites my head off.

They have to be tested to a 10% overspeed, so should have been up to at least 121mph. As others say though - they won't be doing that in service of course

 

[DJ_K666]

They have to be tested to a 10% overspeed, so should have been up to at least 121mph. As others say though - they won't be doing that in service of course

I didn't know that. I can imagine them being more than a little uncomfortable at that speed.

 

[Jamesrob637]

Slab-ended trains have done more than that in passenger traffic - Stateside!

 

[nlogax]

Slab-ended trains have done more than that in passenger traffic - Stateside!

Budd Metroliners per chance?

 

[Railperf]

The original HST overspeed worked off wheel diameter, so on new tires it would cut power at 132mph, on fully worn at 128mph. I believe most (all?) power cars are now 132mph cut-out regardless, certainly those with Knorre Bremse WSP are. Presumably the way speed is measured is no longer fully dependant on measuring the rotation of the wheels?

I had an LNER HST accelerating down Stoke Bank cut out at 129mph!! .
But post ATP GWR ones would rarely be driven at more than 122 to 123mph ..as i understand the ATP could start warbling at those speeds when tyres were worn.

 

[JN114]

They have to be tested to a 10% overspeed, so should have been up to at least 121mph. As others say though - they won't be doing that in service of course

I hear this bandied around a lot, but little evidence ever that it has been done nor references that outline such a requirement.

We’ve certainly never run our 387s at 121mph...

 

[Boodiggy]

I hear this bandied around a lot, but little evidence ever that it has been done nor references that outline such a requirement.

We’ve certainly never run our 387s at 121mph...

i may be wrong (usually am) but I believe it is tested at the 10% following any line speed increases. The cl.390 were definately tested at 10% above (138mph) following the increase to EPS Speeds on WCML. Not sure if there is a requirement for all traction to be tested. I will see if I can dig anything out in the standards when in the office.

 

[hexagon789]

I hear this bandied around a lot, but little evidence ever that it has been done nor references that outline such a requirement.

We’ve certainly never run our 387s at 121mph...

Afai knew it was standard practice including for any stock which subsequently has its maximum speed raised.

 

[hexagon789]

I had an LNER HST accelerating down Stoke Bank cut out at 129mph!! .
But post ATP GWR ones would rarely be driven at more than 122 to 123mph ..as i understand the ATP could start warbling at those speeds when tyres were worn.

Should be 132mph cutout with the modern Knorr Bremse WSP for all wheel diameters and max 132 reducing to 123 on minimum tyres for those with the original BR WSP such as GWR's.

 

[hexagon789]

I didn't know that. I can imagine them being more than a little uncomfortable at that speed.

350s ride quite roughly at anything over about 75, most Siemens units are the same.

 

[delticdave]

I hear this bandied around a lot, but little evidence ever that it has been done nor references that outline such a requirement.

We’ve certainly never run our 387s at 121mph...

ISTR that 3x4 car 357's were tested to 110 mph on the East Coast Mainline at night, 'cos the LTS has an overall limit of 70 / 75 mph.

 

[hst43102]

350s ride quite roughly at anything over about 75, most Siemens units are the same.

350's at 100-110 feel smooth enough to me. Certainly not as smooth as a 390 or HST but not bad

 

[Railperf]

I didn't know that. I can imagine them being more than a little uncomfortable at that speed.

Depends how flat the track is. My understandibg is that the basic Desiro design is good for 200km/h (124mph) . In my experience they run smoothly at 100mph on good track. Some of the GE 360s seem to be riding roughly now..i hear it is due to dampers needing replacement which is unlikely to be done as they go off lease imminently.

 

[Railperf]

Should be 132mph cutout with the modern Knorr Bremse WSP for all wheel diameters and max 132 reducing to 123 on minimum tyres for those with the original BR WSP such as GWR's.

Didn't ATP cut-in well before 132mph - nearer 128mph on fresh wheelsets?

 

[Railperf]

350's at 100-110 feel smooth enough to me. Certainly not as smooth as a 390 or HST but not bad

Was on a 390 a few days ago. I had forgotten how well they ride. And they offer good sound insulation too. You barely hear any track noise, the traction motors are quite quiet too. Still feel slightly nauseous when on full tilt if i am not looking out the window.

 

[43096]

i hear it is due to dampers needing replacement which is unlikely to be done as they go off lease imminently.

They can't decide to just not do maintenance - if the dampers need changing (or bogie overhauls need doing) then they will have to be done by GA.

 

[hst43102]

Was on a 390 a few days ago. I had forgotten how well they ride. And they offer good sound insulation too. You barely hear any track noise, the traction motors are quite quiet too. Still feel slightly nauseous when on full tilt if i am not looking out the window.

390s are built to ride and feel like an airliner.

 

[SteveyBee131]

I wasn't meaning the 87mph value specifically, the class 90 and 87 had higher 110mph speeds and the 92 seems quite low in comparison given it's a powerful engine. I assume the trade off is it's much better for freight although I always think of 92's in passenger service as my only experience with them is on the sleeper.

On the subject of top speeds did the 67's ever run at 125mph? Assuming that figure on wikipedia is correct as it seems high when the 68 has a maximum speed of just 100mph.

They're certainly authorised to. I read somewhere fairly recently (apologies I can't recall where!) that they might take forever to get up to 125 with a load though!

 

[hst43102]

They're certainly authorised to. I read somewhere fairly recently (apologies I can't recall where!) that they might take forever to get up to 125 with a load though!

During testing (without a load) one of the 67's reached 143 mph. Very close to HST max speed!

 

[Jamesrob637]

Budd Metroliners per chance?

Yeah I read they were capable of something ludicrous like 180. Probably exaggerating Yanks

 

[hst43102]

Yeah I read they were capable of something ludicrous like 180. Probably exaggerating Yanks

A Budd RDC (predecessor to the Metroliner) reached 184 mph - powered by a jet engine!

M-497 Black Beetle - Wikipedia

en.wikipedia.org

 

[Speed43125]

During testing (without a load) one of the 67's reached 143 mph. Very close to HST max speed!

That was on spanish bogies though. As they are now, I suspect that would be harder to acheive.

 

[43096]

That was on spanish bogies though. As they are now, I suspect that would be harder to acheive.

Was it? I thought it was on the high speed line, which is standard gauge.

 

[hexagon789]

Didn't ATP cut-in well before 132mph - nearer 128mph on fresh wheelsets?

Sorry I was taking about the overspeed limiter fitted not long after introduction to service.

ATP is supposed to be:

3mph over - warning
6mph over - intervention

I believe it does vary a bit for the same reason as the limiter can

 

[hexagon789]

350's at 100-110 feel smooth enough to me. Certainly not as smooth as a 390 or HST but not bad

I always find Siemens stuff rides quite hard, the suspension isn't very good at absorbing track irregularities

 

[Jamesrob637]

I always find Siemens stuff rides quite hard, the suspension isn't very good at absorbing track irregularities

It's used to the smoother and more "regular" German rails I think. 185s at full chat are the same.

 

[hexagon789]

It's used to the smoother and more "regular" German rails I think. 185s at full chat are the same.

Quite possibly but I've even found the supposedly excellent SIG type bogies ride roughly on well maintained Swiss track, so I'm not sure it's 100% down to the track quality