Re: Puffing Billy, Zig Zag and the Mt Lyell Abt

["Spare" <grimegrime@hotmailnospam.com>]

"David Bromage" <dbromage@fang.omni.com.au> wrote in message
htZT5.12$8V2.2843@news0.optus.net.au">news:htZT5.12$8V2.2843@news0.optus.net.au...
> Chris (chrisc@fl.net.au) wrote:
> > A classic case of rail museum empire building (PBR & ARHS), they
originally
> > get it for nothing and then won't let it go for restoration  to
operational
> > condition because someone else will have control.
>
> The Mt Lyell cars at PBR have been operational for decades.
>
> Doesn't the Abt system provide traction only from the rack? IIRC, the
> wheels are free running. At least that's the case on the Snowdon Mountain
> Railway. If the railway in Tasmania hasn't put in the rack, the Abt locos
> wouldn't be much use.
>
> Cheers
> David
When the rack system was engaged the rack cylinder of the loco turned the
cogged pinion wheel,which fitted into the toothed rail and allowed the
engine to haul itself up the line.
Whilst the rack cylinders provided the power over the rack rail,the ordinary
cylinders also continued to drive the wheels on the outside rails,providing
a duel means of locomotion.
Once the rack system was disengaged the steam supply to the rack cylinder
was shut off and the loco gained its tractive power from the conventional
cylinders only.
The Abt System not only assisted the locos up the hills it also acted as a
breaking means on the downhill slopes and enabled heavier loads to be
carried on a much safer basis.
HTH
Graeme