Re: [SA] Jumbo question (TransAdelaide)

[Hazy <hazy5343@aol.com>]

Chris Brownbill wrote:
> 
> Ther were not "ordered for country services" - they were always intended to be
> suburban trains.  They would not have been planned to run any further than
> Bridgewater and Virginia (if that).
> 
> It might be true that they are not suited to suburban service, and that the STA
> should have purchased suburban railcars to some other design - but that's a
> different point altogether.

The unsuitability of the the 2000 class for suburban work was a result
of STA specifications, not the design per se. Inthe mid-70s, the STA
called tenders in the mid 70s for locomotive hauled suburban trains. STA
officials had seen locomotive hauled push-pull trains in the USA and
liked the concept. However, they specified that the locomotive had to be
in the middle of the train. Driving was to be from cabs in driving
trailers at each end. A corridor had to pass through the locomotive so
that staff could access both halves of the train for ticket collection,
which precluded the use of an off the shelf locomotive.

Comeng tendered for this contract and was obliged to put in a bid that
complied with the specification. An alternative was proposed for
conventional diesel railcars with traditional underfloor engines, a
design which later evolved into the 3000 class. The railcar alternative
was cheaper and more practical than the locomotive version. However,
since they had not called tenders for 'railcars' they could not easily
purchase the Comeng alternative without there being a 'locomotive'. The
'power car' had to be just that, a single vehicle with all the traction
and auxiliary supply on board just as it would be on a 'locomotive'.

Comeng had the unenviable task of trying fit all this equipment onto one
car. Since the performance and train make-up requirements were
stipulated, it meant that this one car had to have enough power to haul
at least two trailers. Two traction engines of 500hp would be needed
plus, and auxiliary set of 175hp (130 kW).

Since it was impossible to accommodate all this on the underframe of the
power car, the only option was to house the auxiliary generator inside.
This was hardly a good solution, but there was no way out. In reality it
made no sense to have all this gear on the power car when there was so
much space to spare on the trailer cars. But STA insisted that the power
car must be fully self-contained. In effect. the power car became a
1000hp passenger-carrying locomotive!

There is a common misconception that the 2000 was based on the
Prospector, but you can be forgiven for this. The shape of the cars was
based on the Budd SPV2000. STA officials had seen these cars and wanted
the same basic (bigger than necessary) shape. It seems the Webb
influence was still alive and well in the 1970s. See
http://www.cwrr.com/Lounge/Feature/ccr/ccr12.jpg for the obvious
similarities with the Jumbo. The misconception about the design comes
from the fact that at one stage Budd claimed that the Prospector WAS the
SPV2000 (albeit with flat sides) so they could cite overseas sales to
potential buyers. In reality the Prospector was bigger and faster than
aything Budd ever built.

As the design progressed, it became obvious that the mass limit could
not be met on the power car. Since it was only a small contract, the
heavy frame and its hefty bogies had to be carried over into the trailer
car for economic reasons. That meant the trainer was about 12t heavier
than it needed to be, and a three car set was really significantly
heavier compared to conventional diesel multiple unit. The end result
was hardly satisfactory for suburban services in Adelaide, especially on
the hills route.

The STA also wanted a high cab. The tender documents came with an
artist's impression showing this high cab and curved body. The main
advantage of the high cab was that the drivers had an excellent 180
degree view and gave them a sense of security when approaching level
crossings.

The cab was impossible to achieve in accordance with the artist's
impression as it was located too far back from the nose for the driver
to be able to see the track immediately ahead of the car. The compromise
shape was agreed to only after some considerable debate with the STA and
the use of full-size mockups and models to prove the point. The cab as
built was very difficult to design, not only because of the confined
space constraints, but also because STA wanted an end door in all cars.
This meant the driver's seat had to be far enough off-centre so that
that passengers could access the end door below his feet.

In addition, the collision end loads specified by STA made it necessary
to design a complex structure around the driver to take these forces
from the collision posts each side of the front door out to the
bodysides. Normally the collision posts would connect into the roof to
take collision end loads.

Although not specified by STA, the 2000 class was the first passenger
trains in Australia to have a structure which complied with overseas
crashworthiness standards. Comeng used these cars to perfect this
methodology in preparation for the XPT contract. It meant that in a
head-on collision, the cars would not telescope but crumple
progressively. The STA had at least two major collisions which proved
the success of this design. In both cases passengers and the drivers in
their high cabs survived without major injury.

Despite being a hideous compromise and unsuitable due to inflexible STA
management, they were successful as a piece of engineering.