In article , (Nick
Leverton) wrote:

In article ,
Roger H. Bennett wrote:
"Jack Taylor" wrote in message
k...
Absolutely. The shortest formation for a CEP unit is 2-CEP (both
driving vehicles, which have cabs, pick-up shoes and are motored),
whilst the

I don't know how it affects specific units, but the other thing nobody
has mentioned is the compressor and air reservoirs. If those aren't on
the driving vehicle, it's going nowhere, even with shoes, motors and a
cab.

On the "classic" SR DC units, they were generally on the motor coach.

That changed to use underfloor space more efficiently.

--
Colin Rosenstiel

(Chris Rogers) wrote in message . com...
(Dominic) wrote in message . com...
With an older DC EMU such as a 4-CEP I imagine that the driving motor
car can be uncoupled from the set and run independently under its own
power, and that 2 such cars could form a 2 car train.

This is not always the case with Mk1 EMUs - as I understand it, in
some units (like the 4-CIG IIRC) the driving cars are not the motor
cars - the units have separate driving trailers and a single motor
car. In this case, the 3rd Rail pickup shoes are on the
leading/trailing vehicles and not the motor car itself, so apart from
having no cab, an isolated motor car like this would have no power
supply.

However, in principle, I believe you are correct with some stock which
indeed has driving motor cars.

You're right - I think these units with a central non-driving motor
car started with the 4-CIGs and includes classes 313, 455 and 319.
Equipment on these units appears to be so distributed that I doubt
they can run with less than 4 cars.

Are the driving motor cars of modern DC EMUs such as Networkers,
Junipers, Electrostars and Desiros independent multiple units in this
way? It seems that no set is ever run without a pantograph trailer car
- is this because the motor cars rely on the electronics or other
systems in this car, even when running from the DC 3rd rail? Or can
the motor cars run seperately from the rest of the set?

Modern stock introduces problems through a concept known as
'distributed systems'. The equipment required for the train to work is
not fitted exclusively on the driving or motor cars, but is
distributed along the length of the train. In this case, by removing
one or more cars from the set, some essential equipment would be
removed too.

In the case of Voyagers, you would expect that any formation of 2 or
more cars would be possible as each car has its own engine - in fact
because of distributed systems and other technical limitations, the
minimum consist of a unit is 4 cars.

That's interesting. I didn't know this inflexibility applied to
Voyagers. I thought distributed systems were less common on DMUs.
Maybe it's because of their 3-phase electric transmission?

I was told by a technician that in the case of Class 444/450 Desiros
that it is a very difficult procedure to separate cars in a set
anyway, because they are semi-permanently coupled and not designed to
be separated.

Hope this is of interest,

Chris.

Thanks a lot. Many units have bar couplers within sets, but the number
of cables and hoses connecting Desiro cars is quite incredible.

Dominic wrote:
(Chris Rogers) wrote in message
. com...
(Dominic) wrote in message
. com...

In the case of Voyagers, you would expect that any formation of 2 or
more cars would be possible as each car has its own engine - in fact
because of distributed systems and other technical limitations, the
minimum consist of a unit is 4 cars.

That's interesting. I didn't know this inflexibility applied to
Voyagers. I thought distributed systems were less common on DMUs.
Maybe it's because of their 3-phase electric transmission?

Modern MU's have many systems that if placed in close proximity to each
other can affect performance, ie it is not a good idea to put OTMR
computers close to other stuff pumping out high levels of electrical
energy. The systems are distributed along the train in the same way that
the drive, be it hydraulic or electric is. Cross feeding between cars is
possible so that if one engine cuts out the coach is powered from the
others for ETS/HVAC purposes. It actually is not that inflexible. Modern
depots lifting equipment capable of lifting 5-10 cars at the same time.
By treating it as a unit and not a set of vehicles maintenance is easier
to plan.
The TMS systems in operation are only really effective over a maximum of
5 cars, so when coupling two sets the TMS on both must be able to talk
to the other one and gain information on all the systems by way of data
transfer, with this, the cross feeding etc, a lot of cables run between
the vehicles.
The TMS is usually in one of the outer vehicles behind the cab. Couple
two with the TMS at opposite ends to each other and there can be a few
seconds delay whilst the messages between computers match up and talk to
each other. In the early days of Voyagers 175s, and 180s drivers and
crews would be seen pushing buttons repeatedly after 5-6 seconds thereby
starting the system diagnostic over and over again. Mods to reduce the
complexity and display only the information the driver needs to see have
reduced this problem considerably. To test the viability of the TMS
several very long MU test trains have been run with up to 4 TMS's all
communicating along 20 vehicles. It worked.

Actually I'm wrong about the class 313s. They do have 2 driving motor
cars and not a central non-driving motor car.

In article , Dominic
writes
You're right - I think these units with a central non-driving motor
car started with the 4-CIGs and includes classes 313, 455 and 319.

Class 313 is two driving motors with shoes, separated by a pantograph
trailer.

The only other classes I know off by heart are those on my local line:
- 317 is two driving trailers separated by a pantograph motor and a
trailer, both non-driving;
- 365 is two driving motors separated by two non-driving trailers, one
with a pantograph. [They don't carry shoes round here.]

--
Clive D.W. Feather, writing for himself | Home:
Tel: +44 20 8495 6138 (work) | Web: http://www.davros.org
Fax: +44 870 051 9937 | Work:
Written on my laptop; please observe the Reply-To address

In article ,
(Clive D. W. Feather) wrote:

- 365 is two driving motors separated by two non-driving trailers, one
with a pantograph. [They don't carry shoes round here.]

Nor will any much longer. The number of ex-Connex ones up here is growing
almost daily. Saw two together this morning. The appear likely to retain
their white roofs as the only distinction from the WAGN ones.

--
Colin Rosenstiel

In article ,
Colin Rosenstiel writes
Nor will any much longer. The number of ex-Connex ones up here is growing
almost daily. Saw two together this morning. The appear likely to retain
their white roofs as the only distinction from the WAGN ones.

They also have a set of longitudinal seats in them in one car, whereas
the WAGN ones are all-transverse.

At least one unit has developed a stutter: "Welcome aboard, welcome
aboard the West Anglia Great Northern service to Peterborough, to
Peterborough. Calling at Finsbury Park, Finsbury Park, Stevenage,
Stevenage, ...".

Mind, at least it doesn't say "Peederboru" in that "running out of
breath" way some of them do.

--
Clive D.W. Feather, writing for himself | Home:
Tel: +44 20 8495 6138 (work) | Web: http://www.davros.org
Fax: +44 870 051 9937 | Work:
Written on my laptop; please observe the Reply-To address

Chris Rogers wrote:
(Dominic) wrote in message
. com...
With an older DC EMU such as a 4-CEP I imagine that the driving motor
car can be uncoupled from the set and run independently under its own
power, and that 2 such cars could form a 2 car train.

This is not always the case with Mk1 EMUs - as I understand it, in
some units (like the 4-CIG IIRC) the driving cars are not the motor
cars - the units have separate driving trailers and a single motor
car. In this case, the 3rd Rail pickup shoes are on the
leading/trailing vehicles and not the motor car itself, so apart from
having no cab, an isolated motor car like this would have no power
supply.

However, in principle, I believe you are correct with some stock which
indeed has driving motor cars.

Are the driving motor cars of modern DC EMUs such as Networkers,
Junipers, Electrostars and Desiros independent multiple units in this
way? It seems that no set is ever run without a pantograph trailer
car - is this because the motor cars rely on the electronics or other
systems in this car, even when running from the DC 3rd rail? Or can
the motor cars run seperately from the rest of the set?

Modern stock introduces problems through a concept known as
'distributed systems'. The equipment required for the train to work is
not fitted exclusively on the driving or motor cars, but is
distributed along the length of the train. In this case, by removing
one or more cars from the set, some essential equipment would be
removed too.

In the case of Voyagers, you would expect that any formation of 2 or
more cars would be possible as each car has its own engine - in fact
because of distributed systems and other technical limitations, the
minimum consist of a unit is 4 cars.

I was told by a technician that in the case of Class 444/450 Desiros
that it is a very difficult procedure to separate cars in a set
anyway, because they are semi-permanently coupled and not designed to
be separated.

Hope this is of interest,

Chris.

P.S. This is written from my own, perhaps limited, knowledge and
understanding of the technical aspects. I am not from a railway
technical background, but believe this information to be correct. I am
sure more knowlegeable contributors will confirm or refute what I have
said.

Spot on!

In article ,
(Dominic) wrote:

With an older DC EMU such as a 4-CEP I imagine that the driving motor
car can be uncoupled from the set and run independently under its own
power, and that 2 such cars could form a 2 car train.

Are the driving motor cars of modern DC EMUs such as Networkers,
Junipers, Electrostars and Desiros independent multiple units in this
way? It seems that no set is ever run without a pantograph trailer car
- is this because the motor cars rely on the electronics or other
systems in this car, even when running from the DC 3rd rail? Or can
the motor cars run seperately from the rest of the set?

It's the control electronics which cover more than one motor car with AC
motors isn't it?

--
Colin Rosenstiel

(Dominic) wrote in message . com...
Are the driving motor cars of modern DC EMUs such as Networkers,
Junipers, Electrostars and Desiros independent multiple units in this
way? It seems that no set is ever run without a pantograph trailer car
- is this because the motor cars rely on the electronics or other
systems in this car, even when running from the DC 3rd rail? Or can
the motor cars run seperately from the rest of the set?

AFAIK all the gubbins and even the motors are in the car that has the
pantograph whereas the cars at the front and the rear which although they
have no motors have the shoegear.

B2003