Re: More from the Terrorgraph

["Rod" <comtrain@mpx.com.au>]

Ross (Goldie) Goldspink <goldicom@powerup.com.au> wrote in message
3860a697@grissom">news:3860a697@grissom...
> How short does a short circuit have to be to activate the track detection?
>
> Or to put it another way, regardless of profile, how much resistance is
> there between rail and wheel with about ten tonnes (or more) on each
wheel?
>
> Goldie
cannot remember how much a Sprinter weighs, but I guess the axle load would
be about 15 tonnes that is about
7.5 tonnes a wheel.
Now for about 8 months, flagmen were placed on all level crossings, and
Sprinters were restricted to running on lines that did not have modern solid
state detection systems, mostly non track detected areas.[Ballarat and
Bendigo lines] It seems that the older inner areas were still running
"ancient" resistance / relay devices which were able to detect all these
vehicles. After all they were designed to work with empty 4 wheel vehicles
were they not?
Rumours abounded but I think some of the blame for the problem [ oh
yes...losing the Sprinter, that is going dark, or not setting level crossing
warning devices off] was that as the Sprinters did not have brake blocks
cleaning the wheel surface, they instead used disks, and they operated on
lines more and more frequented by vehicles using new composite brake
material, they might be picking up an insulating film of composite material,
and their light weight, and short consist [mostly one car] meant that they
could go dark. Heavier Diesel Locomotives had both weight and 'cleaning'
blocks to keep things working.
The problem was overcome when British Rail sold us the fix they worked out
when similar vehicles over there suffered the same problems. There is a loop
fitted behind the cow catcher, and this sends a signal ahead of the
railmotor and activates all signal circuits. The Driver runs a test on this
device each time he prepares a Sprinter.
If it fails, Sprinter may not enter service. Hope this information is still
up to date, I have had nothing to do with them for a few years now
Rod