Cascades Talgo options
From: Hans-Joachim Zierke
Newsgroups: misc.transport.rail.americas
Subject: Cascades Talgo options (long and complicated - masochist readers only)
Date: Tue, 22 Feb 2005 15:32:50 +0000 (UTC)

Thomas White schrieb:

>> Both the AEM 7 and the HHP 8 are too heavy for tilting trains.
> So are F59s, F40s, P40s as well as any recently suggested "new" passenger
> locomotives (for US use) that I have seen.  Among other elements, there is
> the weight of the electric
> transmission.  "Everybody knows" hydraulic transmission doesn't work in a
> railroad
> application, so D-E is what there is and will be.  Perhaps the one positive
> aspect of the
> promoted use of the Colorado DMU as a locomotive with seats rather than a
> DMU is that they will demonstrate that D-H works, even here.

Maybe I have some good news for, brand new from the press. The whole
thing is a little complicated and based on several of my own conclusions,
but I'll try to sort things out as good as I can. I say, that since a few
days, gaining a loco for the service got much easier.

Let's first describe the task:

For operating at 9 or 10 inches of cant deficiency, you need a maximum
axleload of 20 tons (18 metric tons). With a very low center of gravity,
or with link-steering 2-axle bogies, a slightly higher value might work.

Curve radius on the route can be quite small, so using 3-axle bogies,
even with steered wheelsets, won't work at high cant deficiency.

Even with tilting, the route has several speed changes. Acceleration is
important therefore, and will become more important, once top speeds
exceed 79 mph. This raises power requirements.

And finally, it is my understanding, that manufacturing a high percentage
in the USA would help a subsidized service a lot.


Available technical options are:
1)  80 ton 4-axle loco.
2) 120 ton Bo-Bo-Bo loco.
but at the moment, only one manufacturer (Alstom) is prepared for the
Bo-Bo-Bo option.

As demonstrated by the ALP-46, FRA regulations add about 4 metric tons to
a heavy European loco box. When doing the same with a lightweight box,
the price will be higher. An 80-ton US loco, 72 metric tons, would have
to have a weight of perhaps 67-68 metric tons (74 tons) in Europe, or
even less.

The problem: Nobody needs such a loco in Europe. The laws of physics are
the same, so a European design would try to achieve the same end result
in weight. While the ALP-46 has been derived from a European design with
the help of adding weight, the same approach is impossible for a tilting
train loco.

Conclusion: Such loco can possibly use an existing drivetrain, but needs
its own one-of-a-kind box. There is no way around this, if that Talgo is
supposed to operate at tilting train speed ever.


The drivetrain options are ... let's start with the motors: While one
look at the weight of GE and GM prime movers ends any attempt to reach
the weight goals, both Cummins and Detroit Diesel will happily deliver a
suitable product in the 2600 - 2800 kW range.

US product, major part of the loco price, great.

For the Cascades service, a motor in the 3500 kW range would be better,
but this option does not exist within FRA regulations, sorry.


For the transmission, there is no doubt, that AC-AC dieselelectric should
be used. This gives the highest efficiency and best traction control, and
there is another recent advantage: HEP can be seamlessly integrated with
asynchronous generation. The first trains with this setup are currently
delivered: You may stand in the station at low rpm, and still produce
But even today, AC-AC might not allow to stay within the weight limit for
the 4-axle loco. In addition, having a generator set in one of the end
cars is a standard Talgo option, and the Talgo workshops are prepared to
maintain these. If HEP production in one end car is available in a
reliable and cost-effective fashion ... why doing it in the loco, if you
are low on traction power anyway? A 2700 kW motor without HEP production
is about as good as a normal 3100 kW motor, moving the whole thing
towards high performance.

For a Bo-Bo-Bo loco, AC traction is right, but in the last years, only
one such loco type was built: The Channel tunnel locos. These are
electric locos, and the whole setup is seriously overbuilt for the
power of a diesel. Direct adaption won't be possible, and it is my
prediction, that the Bo-Bo-Bo option will get killed by the costs.


And now, the promised news. Citation of the German text for precise
reference, but I will add explanations. The single surviving manufacturer
of hydro gears announces a new gearbox, plus complete development, for
diesel locos up to 5000 kW (6705 hp). The offer is: Prototype development
including approval procedure, for license production of the loco using
Voith drivetrain components.

|Voith Turbo entwickelt eigene dieselhydraulische Großlokomotive
|Dieselhydraulische Antriebskonzepte für Lokomotiven im Leistungsbereich bis
|2.500 kW haben sich in den vergangenen Jahren bei Staatsbahnen, privaten
|Eisenbahn-Verkehrsunternehmen und Leasing-Gesellschaften fest etabliert.
|Grundlage dieses Erfolgs sind die niedrigeren Investitions- und
|Betriebskosten der hydrodynamischen Antriebstechnik, die sich in
|verschiedenen Leistungsklassen und Einsatzgebieten weltweit bewährt haben.
|Diesen Erfolg hat Voith Turbo nun mit der Entwicklung des neuen Getriebes
|Turbo-Split® LS 640 auf Antriebsleistungen bis zu 5.000 kW konsequent
|ausgeweitet und stößt mit diesem Schritt in ein Marktsegment vor, das
|bislang elektrischen Lokomotiven vorbehalten war. Um diese Technologie auch
|in dieser schweren Leistungsklasse erfolgreich auf die Schiene zu bringen,
|hat sich Voith Turbo dazu entschlossen, ein entsprechendes Lokomotivkonzept
|für diesen Leistungsbereich zu entwickeln.
|Voith Turbo plant, dieses Lokomotivkonzept interessierten Kunden - wie z. B.
|den Herstellern von Schienenfahrzeugen oder auch
|Eisenbahn-Verkehrsunternehmen - auf der Basis zugelassener Prototypen zum
|Lizenzbau anzubieten und den Kunden den Antriebsstrang, sowie einzelne
|zusätzliche Kernkomponenten zu liefern.

<the usual "we are a great company" end of the text snipped>


The whole thing might not be easy to understand without a considerable
amount of additional information.

Part 1:

In the late 1970s, the first prototypes of AC-AC locos were delivered. In
1981, there were first deliveries of production locos. Back then,
everybody assumed, that AC-AC traction would blow away everything else
within a few years.
The production of the Mekydro gears (the hydraulic transmission once
delivered into the USA) was given up.

Until 1992, 1993, almost all the diesel locos were transformed to AC
traction over here. Even the small shunting / switcher locos were
delivered with dieselelectric AC-AC. The Dutch 65 and the Norwegian Di8
are examples. The first AC-AC drive DMUs were delivered.

In the early 1990s, Voith started the big backlash, with a simple
concept: "We are cheaper". They targeted the small diesel market, DMUs
and shunting / switcher locos. Within 10 years, they raised their market
share in the shunting / switcher market to ... I think it's about 90%.

While AC-AC is technically superior, and the low weight of hydraulic
transmission is of no concern in a switcher loco, Voith won the hearts of
the beancounters: Lower investment cost, lower maintenance cost.

How could they do it? I don't have any knowledge about the company, but
the reasons are obvious: The 1980s have been the times of transition in
the metal industry, from assembly line production towards flexible
automatisation based on computer-controlled multifunction machinery.
Any machinery product got considerably cheaper to produce, but the
highest gains were achieved for
- high precision parts.
- small series.
Hydraulic gears are high precision metal parts manufactured in small


Part 2:

The main partner in Germany was Vossloh. Small Vossloh locos with
hydraulic gears are the best selling diesels in Europe.

About 2 years ago, Vossloh started the development of a mainline diesel.
First customer was supposed to be Connex, with a 3000 kW passenger train
loco. For this project, Vossloh talked Voith into the development of the
LS 640. Yes, that's the new gearbox in the press bulletin.

Within the last year, it got very quiet around this project. My
assumption is, that Vossloh didn't find enough "startup" customers for
the project.

So most probably, Voith is now sitting there with a newly developed
gearbox, but without a customer. And obviously, they are NOT planning to
write that cost off. This is successful machinery industry with worldwide
sales and a well-filled wallet, they have chosen to move forward instead.

My interpretation of the text is, that their main target will be a
6000 hp diesel within the restrictions of a 135 metric tons Euro box.
(Weight of the transmission, dynamic brake included, is 7 metric tons,
which isn't a bad start to stay within the weight limit.)

But my expectation is, that during the next years, they will be looking
for partners. I don't think, that a tilting train loco for US conditions
will ever get in closer reach. The normal situation is, that the
manufacturer wants to sell you a loco, not a blueprint for license
production. But Voith does not intend to become a loco manufacturer
anyway. So in addition to the motor, it should be quite easy, to organize
a considerable share of US production.

How's that?