In my previous post I made a mistake and an assumption or two that were corrected in a comment on the post by Colin Hussey a retired NSWGR driver, both steam and diesel.
The mistake was that I referred to the General Appendix and this should have been the Working Timetable. I made this mistake as the document I was looking at starts at page 7 and when I thought about it, I realised that it is a working timetable. I have now corrected my previous post.
One of the assumptions was that I assumed that the 10% reduction for two steam locomotives may have been to allow for inefficiencies between two crews, my apologies Colin, I didn't mean to throw discredit on the drivers and this has been deleted from my previous post.
Anyway, here is Colin's comment in full as it adds greatly to our knowledge:
The primary & best place to look for
loads is in the Working Time Tables (WTT), these came out more frequently, showing
changes to loads, & train working conditions, much more reliable &
easier to keep updated.
Updated loads & conditions also came out in depot affected weekly General
orders as well as the State wide Weekly notices.
The load of a double header while slightly less than that of 2 combined single
engines, depended more on the added length of the train rather than the actual
load itself, which took the amount of curves & train drag into account.
Another point was that it was quite possible by adding an extra wagon to the
load, the train was then overloaded.
The WTT gave loads, for individual sections over the length of the whole line,
with general ruling grade made that making up the through load. Also found was
the length limits for single & doubles, another consideration was the
length of crossing loops.
Another aspect was momentum grades that allowed for more than the standard load
to be taken. Heavier loads were taken from Hornsby - Broadmeadow than from
Enfield to Hornsby e.g.: & IIRC (if I recall correctly), a freighter was allowed 360tons Enfield -
Hornsby but 390 from Hornsby. Tumulla, Molong – Oge (Orange) & Ardglen had the same
loads as those from Enfield – Hornsby.
The 75% load was maximum & no more of the full through load used for
accelerated running of old fruit expresses when the train consisted of 4
wheelers, it was primarily meant for faster grade climbs hill grade in order to
keep the speed up.
The best example found on the west from Lithgow to Orange, with the influx of
36cl to the area & removal of the freighters almost all through trains were
listed in the WTT's as 75% loads.
The reason was to simplify/standardise rostering of engines, set loads were
compiled that allowed for single running times for the goods trains, with all
running to 36cl running times & loads. For freighters they worked up the
grades at the same speed as a pig.
The benefit of this arrangement beyond Lithgow was that when a steam service
was programmed for any load single or double header all the trains needed to be
made up based only on that load & not of the engine type as it did not
matter whether it was a freighter or pig or combo of the two. In these cases,
the Pig led owing to operational reasons, when doubled with a freighter.
Rear end banking was not permitted on passenger trains, some notable
exceptions, but not on mixed trains, empty 4 wheel stock wagons, which had to
be located at the rear.
When working double headers, I would not say there was anything to do with
drivers inefficiencies or crews at all, & really is a put down of the men who
laboured on the engines.
Every time crews worked a double header there was always a confab between the
drivers regarding the trip ahead, rarely did it mean any adjustments to the
standard drivers way to drive the engine & train. If either crew needed to
communicate it was done with the whistle to attract attention of the other,
usually meant to slow down or crack the whip, these were known hand signals that
could be seen from cab to cab. Smooth working of the train did not depend on
the aspect of single or double heading but on the train composition. We felt it
just as much up front as did the guard if the train had been made up badly.
When composing trains, I have worked more on the length based NSWGR form of an
S truck is a single wagon, while every other wagon is listed compared to it,
e.g: K is 1.2, BWH & early bogie vehicles are 2. Initially I worked on
having a load of around 30 S trucks & van, with loops around 2.4 metres,
but a train that long looked far too long. I changed the loops bringing back to
2mtrs in clearance which looks quite ok. This allows for train lengths of
around 23 S trucks & single loco, without problems.
In modelling the adage of less is more, really comes true & your 57cl load
shows that up well.
In the wagon length data of the spreadsheet I used 2 for a K truck to keep it simple, so if anyone wants to they can easily change this to 1.2, similarly any other wagon lengths can be changed/corrected.
My intention is to keep things simple to enhance my hobby to gain the flavour of the NSWGR operations without tieing myself in fully prototypical knots (still pondering on signalling). Colin is luckier than most of us as he worked with and has an in depth understanding of the rules pertaining to the NSWGR.
Thank you Colin for clarifying these issues for us.
Now of course you also need to look at the maximum allowable speeds for various wagons which can be found in a Working Time Table and which will also have an impact on the setting up and operation of timetables for your layout.