If I were to put forward a scenario which probably would not happen.. maybe? 
well not yesterday or even tomorrow.
Say,.........

"1M17 Pendolino has been misrouted in to platform 6 at Preston which is 
currently isolated.
Standby from Carnforth to drag the train back onto the energised section".

The question is... How does the Pendo' stop?  When power is lost would it 
stop automatically or with difficulty.

The above example having any resemblance to event which may or may not have 
happened today are purely coincidence .  :-)

KW

"Ken Ward"  wrote in message
news:_VKNe.12341$4y6.4902@newsfe7-gui.ntli.net...

> If I were to put forward a scenario which probably would not happen..
maybe?
> well not yesterday or even tomorrow.
> Say,.........
>
> "1M17 Pendolino has been misrouted in to platform 6 at Preston which is
> currently isolated.
> Standby from Carnforth to drag the train back onto the energised section".
>
> The question is... How does the Pendo' stop?  When power is lost would it
> stop automatically or with difficulty.


You mean something in the shape of a long pointy tube hit the buffers?

-- 
M Stewart
Milton Keynes, UK

Ken Ward wrote:


> "1M17 Pendolino has been misrouted in to platform 6 at Preston which is 
> currently isolated.
> Standby from Carnforth to drag the train back onto the energised section".
> 
> The question is... How does the Pendo' stop?  When power is lost would it 
> stop automatically or with difficulty.


I believe it would simply coast along until it came to a stand by 
gravity or the driver applied the brakes, which (I sincerely hope)
would work quite normally whether the overhead line was energised or not.

Charlie

"Malcolm Stewart"  wrote in 
message news:de7utb$9nn$1@newsm1.svr.pol.co.uk...

> "Ken Ward"  wrote in message
> news:_VKNe.12341$4y6.4902@newsfe7-gui.ntli.net...
>> If I were to put forward a scenario which probably would not happen..
> maybe?
>> well not yesterday or even tomorrow.
>> Say,.........
>>
>> "1M17 Pendolino has been misrouted in to platform 6 at Preston which is
>> currently isolated.
>> Standby from Carnforth to drag the train back onto the energised 
>> section".
>>
>> The question is... How does the Pendo' stop?  When power is lost would it
>> stop automatically or with difficulty.
>
> You mean something in the shape of a long pointy tube hit the buffers?



My "Track Diagrams" show platform 6 as the most easterly through platform.

KW

"Charlie Hulme"  wrote in message 
news:4bLNe.12391$4y6.6683@newsfe7-gui.ntli.net...

> Ken Ward wrote:
>
>> "1M17 Pendolino has been misrouted in to platform 6 at Preston which is 
>> currently isolated.
>> Standby from Carnforth to drag the train back onto the energised 
>> section".
>>
>> The question is... How does the Pendo' stop?  When power is lost would it 
>> stop automatically or with difficulty.
>
> I believe it would simply coast along until it came to a stand by gravity 
> or the driver applied the brakes, which (I sincerely hope)
> would work quite normally whether the overhead line was energised or not.




NRE website states....
This train has been cancelled.
This train has been cancelled because of a problem currently under 
investigation.
KW

"Ken Ward"  wrote in message
news:trLNe.2651$i1.373@newsfe3-gui.ntli.net...


> NRE website states....
> This train has been cancelled.
> This train has been cancelled because of a problem currently under
> investigation.


Unfortunate use of the word "currently", since the problem seems to be lack
of current.

Jonathan

On Sat, 20 Aug 2005 18:48:26 GMT someone who may be "Ken Ward"
 wrote this:-


>The question is... How does the Pendo' stop?  When power is lost would it 
>stop automatically or with difficulty.


Regenerative braking system would not work. I assume rheostatic
braking should still work (I have not studied the precise details of
rheostatic braking on these trains). The air brake would still work.
The normal braking controller should still work and this blends in
the various braking systems as necessary to give the driver control
of the process. If the normal controls fail then there is an
emergency plunger, though using this removes control from the
driver.

When power is lost the train will not stop automatically. The driver
is able to coast along and decide on the best place to stop;
avoiding if possible stopping on bridges, tunnels and other places
that might make things more difficult.




-- 
 David Hansen, Edinburgh | PGP email preferred-key number F566DA0E
 I will always explain revoked keys, unless the UK government
 prevents me by using the RIP Act 2000.

Charlie Hulme  wrote:


> Ken Ward wrote:
> 
> > "1M17 Pendolino has been misrouted in to platform 6 at Preston which is
> > currently isolated.
> > Standby from Carnforth to drag the train back onto the energised section".
> > 
> > The question is... How does the Pendo' stop?  When power is lost would it
> > stop automatically or with difficulty.
> 
> I believe it would simply coast along until it came to a stand by 
> gravity or the driver applied the brakes, which (I sincerely hope)
> would work quite normally whether the overhead line was energised or not.


We were on that train- joining at Oxenholme. The stop just north of
Preston was 'normal'- no jolts. Also, just south of Carnforth, there
seemed to be some problems, and the train slowed to a stop. The TM
announced that there were overhead power problems in the area, and we'd
be moving soon, which we did, getting into Lancaster 15 minutes late. (I
suppose the two incidents were unrelated.) Just north of Preston (could
only have been around 100 yards away from a platform) the train stopped
again. The TM announced a few minutes later she would find out what was
going on. 15 minutes of rumour later, she made an 'important'
announcement, and explained the power situation (though didn't explain
we'd been misrouted) and said it would take an hour for another engine
to be on the scene, and warned that it would get very hot on the train.
(There must be auxilliary power which operates the a/c etc. for a while
after losing power, as this ran for a while before stopping.) In
reality, it didn't seem too bad- luckily the outside temperature wasn't
hot- it was stuffy though. The TM's warning was a good idea, as most
people just stayed calm, and tried not to make themselves any hotter! 

This announcement was basically the only official information we got
from anyone- though staff made various comments as they ran up and down
the corridors- didn't catch all of them. I don't remember exactly when
the train stopped- just before 6 I think. The train didn't move into
Preston until around 2015. Passengers remained pretty calm, but some
were becoming impatient and irrate, especially given the lack of
information- and this would probably have been a lot worse if it had
been warmer outside. After about 90 minutes, the shop manager just let
people help themselves to the stock, which caused rather amusing scenes
as kids ran down the aisles with arms stuffed with crisps and sweets.

Ironically, we thought we were being 'clever' catching an earlier train
from Windermere which, with changes, would get us in to Manchester 30
minutes before the direct service.

-- 
David Horne- http://www.davidhorne.net
usenet (at) davidhorne (dot) co (dot) uk
pictures at http://homepage.mac.com/davidhornecomposer

On Sun, 21 Aug 2005 09:47:13 +0100 someone who may be
this_address_is_for_spam@yahoo.com (chancellor of the duchy of
besses o' th' barn and prestwich tesco 24h offy) wrote this:-


>Ironically, we thought we were being 'clever' catching an earlier train
>from Windermere which, with changes, would get us in to Manchester 30
>minutes before the direct service.


I once stood on the concourse at Glasgow Central debating catching
the first train and changing, or waiting at central for about 30
minutes and catching a direct train. I decided to do the latter.

Having almost got to Carstairs the train came to a standstill. After
a while the guard came round to say that the train in front of us
had hit a car on a level crossing. I was glad I had chosen the
direct train.

What was left of the car could have been put into a rucksack.


-- 
 David Hansen, Edinburgh | PGP email preferred-key number F566DA0E
 I will always explain revoked keys, unless the UK government
 prevents me by using the RIP Act 2000.

David Hansen  wrote:


> On Sun, 21 Aug 2005 09:47:13 +0100 someone who may be
> this_address_is_for_spam@yahoo.com (chancellor of the duchy of
> besses o' th' barn and prestwich tesco 24h offy) wrote this:-
> 
> >Ironically, we thought we were being 'clever' catching an earlier train
> >from Windermere which, with changes, would get us in to Manchester 30
> >minutes before the direct service.
> 
> I once stood on the concourse at Glasgow Central debating catching
> the first train and changing, or waiting at central for about 30
> minutes and catching a direct train. I decided to do the latter.


I usually do, though a station guard once gave me the advice (from his
experience) that it was better to always get on the first possible
train. Virgin station guard at Macclesfield, as it happens. As for
yesterday afternoon, probably sounds a bit pathetic, but another
incentive for the earlier train was that I'd never changed from Wigan
Northwestern to Wallgate stations before, and wanted to try it...

To add insult to injury, I saw the direct train pass by while we were
stuck outside Preston!

-- 
David Horne- http://www.davidhorne.net
usenet (at) davidhorne (dot) co (dot) uk
pictures at http://homepage.mac.com/davidhornecomposer

"chancellor of the duchy of besses o' th' barn and prestwich tesco 24h offy" 
 wrote in message 
news:1h1n15i.1ek2iu015ev08wN%this_address_is_for_spam@yahoo.com...

> Charlie Hulme  wrote:
>
>> Ken Ward wrote:
>>
>> > "1M17 Pendolino has been misrouted in to platform 6 at Preston which is
>> > currently isolated.
>> > Standby from Carnforth to drag the train back onto the energised 
>> > section".
>> >
>> > The question is... How does the Pendo' stop?  When power is lost would 
>> > it
>> > stop automatically or with difficulty.
>>
>> I believe it would simply coast along until it came to a stand by
>> gravity or the driver applied the brakes, which (I sincerely hope)
>> would work quite normally whether the overhead line was energised or not.
>
> We were on that train- joining at Oxenholme. The stop just north of
> Preston was 'normal'- no jolts. Also, just south of Carnforth, there
> seemed to be some problems, and the train slowed to a stop. The TM
> announced that there were overhead power problems in the area, and we'd
> be moving soon, which we did, getting into Lancaster 15 minutes late. (I
> suppose the two incidents were unrelated.) Just north of Preston (could
> only have been around 100 yards away from a platform) the train stopped
> again. The TM announced a few minutes later she would find out what was
> going on. 15 minutes of rumour later, she made an 'important'
> announcement, and explained the power situation (though didn't explain
> we'd been misrouted) and said it would take an hour for another engine
> to be on the scene, and warned that it would get very hot on the train.
> (There must be auxilliary power which operates the a/c etc. for a while
> after losing power, as this ran for a while before stopping.) In
> reality, it didn't seem too bad- luckily the outside temperature wasn't
> hot- it was stuffy though. The TM's warning was a good idea, as most
> people just stayed calm, and tried not to make themselves any hotter!
>
> This announcement was basically the only official information we got
> from anyone- though staff made various comments as they ran up and down
> the corridors- didn't catch all of them. I don't remember exactly when
> the train stopped- just before 6 I think. The train didn't move into
> Preston until around 2015. Passengers remained pretty calm, but some
> were becoming impatient and irrate, especially given the lack of
> information- and this would probably have been a lot worse if it had
> been warmer outside. After about 90 minutes, the shop manager just let
> people help themselves to the stock, which caused rather amusing scenes
> as kids ran down the aisles with arms stuffed with crisps and sweets.
>
> Ironically, we thought we were being 'clever' catching an earlier train
> from Windermere which, with changes, would get us in to Manchester 30
> minutes before the direct service.


Thanks for the 1st. hand report of the incident David.  I was under the 
impression that it had come to a stand "in the platform".
It does seem a long time for "a quick push into the station".
It looks like Virgin won't be paying compensation out of their own pocket 
then.

KW

On Sun, 21 Aug 2005, chancellor of the duchy of besses o' th' barn and...:


> I usually do, though a station guard once gave me the advice (from 
> his experience) that it was better to always get on the first 
> possible train.


On the principle of a train in the hand being worth two in the 
timetable, it does seem a generally good idea.

But it doesn't always figure.  On arriving northwards into Carlisle, 
I've often found a Scotrail/SPT train available to Glasgow Central, 
and it's pretty sure that it's going to arrive there - later rather 
than sooner :-} - but it may nevertheless be a better bet (unless you 
*prefer* a slow pootle up a rural line) to await the next Virgin to 
GLC via the WCML.


> To add insult to injury, I saw the direct train pass by while we 
> were stuck outside Preston!


Frustrating when that happens, isn't it, but there's no point in 
getting worked up about it.  One has to make a choice, and then live 
with it.  Having a goodly selection of fallback alternatives for when 
things go wrong can be useful (at present, for a serious trip, I tend 
to prepare web printouts off one or other of the planners - the German 
one, often referred to by its old name of "HAFAS", is particularly 
good, as it can show all intermediate stops *and* the ultimate 
destination of any train involved - but you have to confirm that the 
train's really going to run, since late amendments don't get notified 
to that planner).

(One of these days I'll get the technology to access the planners from 
the train...)

Mind you, the woman sitting next to me when we were stuck at 
Motherwell recently, waiting for the southbound line to be cleared of 
a "failed" train, used up a considerable amount of the TM's time 
discussing alternative strategies to get to her destination 
(Sheffield, I think it was) - (he advised her to disembark and head 
for Edinburgh, and go down the ECML instead, but she insisted on 
hearing as many other options as he could come up with), but then she 
discarded all of them, including his advice, and stayed on the delayed 
train.  Oh well, it gave her the opportunity to phone lots of friends 
and business contacts and whine to them about how tired she was as a 
result of the delayed train.  Some people love complaining, it seems.

Alan J. Flavell  wrote:


> On Sun, 21 Aug 2005, chancellor of the duchy of besses o' th' barn and...:
> 
> > I usually do, though a station guard once gave me the advice (from 
> > his experience) that it was better to always get on the first 
> > possible train.
> 
> On the principle of a train in the hand being worth two in the 
> timetable, it does seem a generally good idea.
> 
> But it doesn't always figure.  On arriving northwards into Carlisle, 
> I've often found a Scotrail/SPT train available to Glasgow Central, 
> and it's pretty sure that it's going to arrive there - later rather 
> than sooner :-} - but it may nevertheless be a better bet (unless you
> *prefer* a slow pootle up a rural line) to await the next Virgin to 
> GLC via the WCML.
> 
> > To add insult to injury, I saw the direct train pass by while we 
> > were stuck outside Preston!
> 
> Frustrating when that happens, isn't it, but there's no point in 
> getting worked up about it.  


I think that people on the train last night seemed fairly sanguine about
it, and as I noted, the lack of a/c made people a bit careful about
getting any hotter!

I'd considered getting off earlier at Lancaster after the first delay,
because I doubted we'd make the connection at Wigan, so I'd already had
my chance! I think being on a Saturday evening made things less
stressful too- I've noticed a lot more stress, and phone calls, when the
train has been delayed during weekdays. For ourselves, we'd been
fellwalking earlier in the day, and were too tired to get really worked
up anyway.

I took a couple of pictures of the train as it came into Oxenholme, so
if I want to get worked up about it at a later date, I can fall back on
that! :)


> One has to make a choice, and then live 
> with it.  Having a goodly selection of fallback alternatives for when
> things go wrong can be useful (at present, for a serious trip, I tend
> to prepare web printouts off one or other of the planners - the German
> one, often referred to by its old name of "HAFAS", is particularly 
> good, as it can show all intermediate stops *and* the ultimate 
> destination of any train involved - but you have to confirm that the 
> train's really going to run, since late amendments don't get notified
> to that planner).
> 
> (One of these days I'll get the technology to access the planners from
> the train...)


You don't have a WAP phone? I use the WAP information frequently, and
it's very useful. Indeed, I was using it last night, as when I doubted
I'd make the Wigan connection, I could see there were other trains to
Manchester shortly after- one reason we stayed on at Lancaster! I use
the wap.bahn.de for continental information (I've used their live info,
but I think that only works for German stations), but if you use the
national rail WAP site (I use it via Orange's portal, but I presume
natrail provide the info) you indeed get all the intermediate stop
information. Of course, one problem which I've mentioned before with the
Pendolinos is that the mobile reception is very difficult- last night I
was only really able to use it when it had stopped outside Carnforth,
then again outside Preston. (Makes me think it _is_ a power issue which
affects the reception.)

-- 
David Horne- http://www.davidhorne.net
usenet (at) davidhorne (dot) co (dot) uk
pictures at http://homepage.mac.com/davidhornecomposer

chancellor of the duchy of besses o' th' barn and prestwich tesco 
24h offy wrote:


> You don't have a WAP phone? I use the WAP information frequently, and
> it's very useful.


Agreed, though I would warn that even wap.nationalrail.co.uk is 
not totally reliable. Early 2005, just a few days after New Year's 
Day, I was on a late running VXC service from the south west that, 
to my surprise, bypassed Birmingham New Street. I was trying to 
get to Nottingham, so looked on the WAP site to find the next 
train from Tamworth. (I had loads of luggage and bike, so did not 
want to change at Derby) I discovered there was one just a few 
minutes after the VXC service was arriving, so I staggered off the 
train and walked to the centre of the platform with all my junk, 
only to find not a single Nottingham service on the departure 
board, and no station staff in sight. Thankfully the VXC service 
had not quite departed (though the TM was just about to blow his 
whistle when I looked back.) I asked him, he looked puzzled, 
chatted to a colleage who thought they'd all been cancelled, and 
told me to get back on the train and change at Derby. So much for 
saving effort, I then had to lug all my stuff back up the platform 
again to the end of the platform to where the bike spaces were, 
only to have to repeat all this pantomime at Derby 20 minutes 
later, and Derby required a change of platform. I was not 
impressed....

David Hansen wrote:


> Regenerative braking system would not work. 


   Can the regen system actually detect that there is no power in the 
OLE? My initial thought was that there was the chance it may in effect 
energise an otherwise dead section, but then I guess being AC it would 
need something to synchronise with so hopefully if this is not present 
it will know not to put anything out on to the line.

"Stephen Hughes"  wrote in message
news:FpKOe.168$Or3.154@newsfe4-win.ntli.net...

> David Hansen wrote:
>
> > Regenerative braking system would not work.
>
>    Can the regen system actually detect that there is no power in the
> OLE? My initial thought was that there was the chance it may in effect
> energise an otherwise dead section, but then I guess being AC it would
> need something to synchronise with so hopefully if this is not present
> it will know not to put anything out on to the line.
>


Any power fed back into the OHLE has to be in phase.
So to that end, you've got to have the OHLE energised before you put any
power
back in to it.

Also I would imagine that you would have to have a load to drive elsewhere
on
the OHLE.

I'm sure Mr Catlow will be along shortly to put us all straight!

/John

On Tue, 23 Aug 2005 19:03:01 GMT someone who may be Stephen Hughes
 wrote this:-


>   Can the regen system actually detect that there is no power in the 
>OLE? My initial thought was that there was the chance it may in effect 
>energise an otherwise dead section, but then I guess being AC it would 
>need something to synchronise with so hopefully if this is not present 
>it will know not to put anything out on to the line.


Before and during regenerative braking the braking system must work
out whether the line is able to accept the regenerated electricity.
I assume this includes the voltage and frequency.

If the line is not receptive, or becomes not receptive (for example
a train that was taking the electricity is shut off), then the
braking system switches to rheostatic braking. 


-- 
 David Hansen, Edinburgh | PGP email preferred-key number F566DA0E
 I will always explain revoked keys, unless the UK government
 prevents me by using the RIP Act 2000.

"David Hansen"  wrote in message
news:vd4ng19rafmbbdubvkpt8uluqbbbo9gd04@4ax.com...

> If the line is not receptive, or becomes not receptive (for example
> a train that was taking the electricity is shut off), then the
> braking system switches to rheostatic braking.


But in the context of the original question, does rheostatic braking still
work on a dead (or non-existent) overhead line?  My 1960s book on the 86s
states that rheostatic braking is lost in neutral sections, although it
doesn't specify whether this is due to the lack of power or the breaking of
circuits by the APC magnets.  Of course, technology has advanced somewhat
since then.

Roger

On Tue, 23 Aug 2005 21:43:33 GMT someone who may be "Roger H.
Bennett"  wrote this:-


>But in the context of the original question, does rheostatic braking still
>work on a dead (or non-existent) overhead line?


Bearing in mind that diesel locomotives have rheostatic braking
(which works well in some parts of the world, but was removed from
the Class 50s as part of their simplification) an energised line is
not necessary.

What is necessary is a method of exciting the "motors". In ye olden
days this was often from the line (for relative simplicity of the
installation), so rheostatic braking collapsed in a neutral section
or if the line was not energised. An alternative (still with
traditional traction motors) is the "well known figure-of-eight
circuit", where the armatures of one motor send current through the
field windings of another motor during braking. The 313s were
probably the first "modern" trains in the UK to have this
arrangement, though it is many decades older than them. Modern
trains with three phase drives undoubtedly have all sorts of
devilish tricks as well.

Whether rheostatic braking on 390s works with the pantographs down I
have no idea.


-- 
 David Hansen, Edinburgh | PGP email preferred-key number F566DA0E
 I will always explain revoked keys, unless the UK government
 prevents me by using the RIP Act 2000.

On Tue, 23 Aug 2005 23:52:29 +0100, David Hansen
 wrote:


>. An alternative (still with
>traditional traction motors) is the "well known figure-of-eight
>circuit", where the armatures of one motor send current through the
>field windings of another motor during braking. The 313s were
>probably the first "modern" trains in the UK to have this
>arrangement, though it is many decades older than them.


I always wondered why, despite (I'm told) having no regen, the
Merseyrail units seem to brake almost entirely using their traction
motors.  Do I understand the above correctly that you are effectively
using energy "generated" from one traction motor to push the other one
in the opposite direction, thus causing deceleration?  If so, that's
quite a neat solution.

Neil

-- 
Neil Williams in Milton Keynes, UK
When replying please use neil at the above domain
'wensleydale' is a spam trap and is not read.

"David Hansen"  wrote in message
news:gq8ng1d3iqqr53ss2vo0espcb1fi33f0kb@4ax.com...

> Bearing in mind that diesel locomotives have rheostatic braking
> (which works well in some parts of the world, but was removed from
> the Class 50s as part of their simplification) an energised line is
> not necessary.


Yes, but they have an engine and generator instead.


> What is necessary is a method of exciting the "motors". In ye olden
> days this was often from the line (for relative simplicity of the
> installation), so rheostatic braking collapsed in a neutral section
> or if the line was not energised. An alternative (still with
> traditional traction motors) is the "well known figure-of-eight
> circuit", where the armatures of one motor send current through the
> field windings of another motor during braking. The 313s were
> probably the first "modern" trains in the UK to have this
> arrangement, though it is many decades older than them. Modern
> trains with three phase drives undoubtedly have all sorts of
> devilish tricks as well.


OK, the figure or eight circuit was not "well known" to me.  I wondered
whether something of the sort would be possible, but wasn't sure whether
there was sufficient magnetism in the motors to start the process.


> Whether rheostatic braking on 390s works with the pantographs down I
> have no idea.


Which is where we came in...  Does anybody know?

Roger

"Neil Williams"  wrote in message
news:430bab38.6637033@news.tesco.net...

> I always wondered why, despite (I'm told) having no regen, the
> Merseyrail units seem to brake almost entirely using their traction
> motors.  Do I understand the above correctly that you are effectively
> using energy "generated" from one traction motor to push the other one
> in the opposite direction, thus causing deceleration?  If so, that's
> quite a neat solution.


Layman's explanation follows:

What happens is that the motors are reconnected so that instead of using
power to drive the train, the movement of the train is used to power the
motors which now act as generators, and the energy they produce is then
converted to heat by banks of resistors.

So they don't actually push in the opposite direction - it is just that
generating electricity requires energy which can only come from slowing the
train.

Roger

Roger H. Bennett wrote:

> "David Hansen"  wrote in message
> news:vd4ng19rafmbbdubvkpt8uluqbbbo9gd04@4ax.com...
> > If the line is not receptive, or becomes not receptive (for example
> > a train that was taking the electricity is shut off), then the
> > braking system switches to rheostatic braking.
>
> But in the context of the original question, does rheostatic braking still
> work on a dead (or non-existent) overhead line?  My 1960s book on the 86s
> states that rheostatic braking is lost in neutral sections, although it
> doesn't specify whether this is due to the lack of power or the breaking of
> circuits by the APC magnets.  Of course, technology has advanced somewhat
> since then.


Rheostatic braking was lost on Class 86, 87 and 90 (and on the 85s
during the rare periods that it was operational) whenever line power
was unavailable.  Traction motor field excitation was provided by No.4
powerpack during braking.  Rheostatic braking was also lost if the
Rheostatic Breaking MCB, mounted on powerpack 4, tripped.

Moral:  Always consider rheostatic braking as a bonus.

>> "David Hansen"  wrote in message
>> news:vd4ng19rafmbbdubvkpt8uluqbbbo9gd04@4ax.com...
>
> Rheostatic braking was lost on Class 86, 87 and 90 (and on the 85s
> during the rare periods that it was operational) whenever line power
> was unavailable.  Traction motor field excitation was provided by No.4
> powerpack during braking.  Rheostatic braking was also lost if the
> Rheostatic Breaking MCB, mounted on powerpack 4, tripped.
>
> Moral:  Always consider rheostatic braking as a bonus.
>


90s should be able to continue to rheo brake through a neutral section (or 
other loss of overhead supply), though they cannot "start" rheo brake with 
no overhead supply.

With dc traction motors it's all about powering the field circuits during 
braking. 91s (and the 89) have a big battery that can power the fields even 
when there's no overhead, so that they can stop a train from full speed with 
as much rheo brake as possible.

On most modern high speed trains that have rheo and/or regen brake, if a 
full brake application is made from full speed, the brakes on the coaches 
become overstressed and have to be checked.

Paul Steane wrote:


>
> 90s should be able to continue to rheo brake through a neutral section (or
> other loss of overhead supply), though they cannot "start" rheo brake with
> no overhead supply.


86s and 87s certainly can't.  What do 90s have that makes it possible
for them to do so?