Saturday, January 18, 2014

Further information on train loads and locomotive combinations

Colin Hussey has just posted more information on his Essence blog following on from his comments I published in my last post. I advise you to have a read and study the photos as it is very interesting and shows the complications the railways had to deal with when determining the train load for a section. I particularly like the additional information related to steam passenger and goods locomotives and their respective minimum hauling speeds and the effect that this had on the train load along with ruling grade and any sharp and/or reverse curves encountered in a section.

Colin is to be congratulated for his desire to impart his NSWGR knowledge gained during is working life as a driver and presumably fireman.

Thanks Colin.

Also of interest is a comment on my last post from Bob Stack of South Coast Rail which I post here:


The 10% reduction in load does exist today but is applicable to diesels only.

It is brought about when different locos have various balancing speeds on the ruling grades making certain locos try and do more work. Their maximum tractive effort can be at different speeds.

The Train Operating Conditions Manual (which I use to maintain) sets out these conditions on Pages 45 to 49 (Locomotive Operations) in the following link:

Look in TS TOC 1.

Certain combinations work successfully together and these are set out in the tables.
So in fact the real world is similar to our models in that certain model locos won't run with others straight out of the box.

A lot of other interesting stuff in the manual as well.


A quick look at page 45 2.11 Mixing Locomotive Types and Table 3 shows which diesel locomotives can be mixed to retain a full train load capacity and which when mixed together must have the train load reduced by 10%. 

It would be possible to build this information into my Train Load Calculator spreadsheet with appropriate formulae for the 10% reduction but it would start to make it not so easy to change to suit other State railways, etc. By all means, do download the spreadsheet and modify to suit your own railway or era.

A couple of interesting sections of the Train Operating Conditions Manual that I found are:

Page 56, 3.3 Holding a Stationary Train on a Grade - This will have an impact on any timetable you are using, Cox's Gap loop for instance is on a 1 in 80 grade.

Page 58, 3.7 Track Speed Signs, Table 11 - These would be useful for the modern image modeller

The steam era modeller may not get much from this manual but it can still be interesting to flick through it.


Colin Hussey said...


I have had a bit of a skim through that link from Bob, but have not got to the section on the combinations of loco types & train loads.

What I see though in what I have seen is that this is relevant to operations today or since it was published in 2013, the set up also is vastly different to my time which was pre 1988. Up to that point of time, the only engines that were downrated when coupled to early series engines was the 81cl. When coupled in MU with any other class type other than another 81, the load of the 81 was dropped to that of an 80cl.

I understand that no longer applies. Another condition that was put on the 81cl was the same as applied to loaded CHS type vehicles & any wagon that had a load all up in mass of over 90tonnes, this applied over certain old culverts, & the 81 just as a loaded CHS was restricted to 50Km/h over the culverts, There were several such locations between Muswellbrook & through to Gunnedah.

The 10% reduction in MU of diesels did not apply in my time, as usually they were permitted to operate at the exact same double load as a single, the conditions that restricted them once again was the length, also it depended on the schedule applied for the various express goods services.

For many years the 900 ton load for garratts & big engines between Enfield & Glbn was not permitted for 44cl or other diesels & they hauled only 800tons, this was changed around 1967 IIRC.

In the 1955 WTT, all garratts that had the short bunker were restricted to 680 tons just 105tons more than a freighter, reason, they would run out of coal.

Loads for heavy garratts were also never issued for the blue mountains, & the short bunkered garratts were loaded at 30tons less than the big engines, & they were kept off the working where possible, when electrification came, & garratts were transferred west they did so on loads, but rare prior to that.

Thus the aspect of loads for the earlier days will always find some sort of confusion associated with it. Not only for steam but also for diesels.

For those modelling the transition period, I would recommend that a similar approach to what are run behind the models are close to those that I have pointed out with steam.

Basically then 1st gen diesels, prior to the 80cl 42, & up would all take the same load as a garratt, 600tons on 1:40. Branch line engines, around 20 tons more than a standard goods. Lengths would be similar also.

A 40cl on 1:40 grade (Tumulla) was 460tons, 630tons Lithgow - Georges Plains, & back to 600 from Wimbledon. Not much more than a single standard goods.

PS, I have to do another proof read of what I said on my blog as I do not think I put the mileage above Tumulla where the loads changed.

Ray P said...


Since Bob was good enough to supply the link to the modern operations I thought it would be of some interest for comparison and also for those modern image modellers who follow my blog.

Of course the 10% reduction today did not apply to diesels back in the 1950-60s; the Working Time Table has them as double the single load which I have in the spreadsheet, I just found the shift in thinking interesting.


Colin Hussey said...


The way so many things operate these days is a wonder in more ways than one.

Certainly the link & information is both interesting & a huge benefit to the modern day modeller, & from what I have seen of it, it looks as if one publication provides all the details of all lines in one comprehensive publication, rather than the different WTT's for each district.