Ok, more mutants. Since I'm currently beta testing a revamp of the Blue Mountains scenario I'm naturally thinking about more NSWGR choofers.
The 9 Class (or 5N on the Newcastle network) shown in the previous post was built by E.B. Wilson & Co. The same company also built the 8 Class and 12 Class 2-2-2 well tanks for the Sydney network, and I have about as much information for them as I have for the 9 Class (IOW, some basic dimensions and stats, along with a profile drawing). Since I was getting a feel for the Wilson locos anyway, I whipped up the 8 Class to a basic level. It's a rather weird thing though and I'm not sure it'd be much use for RT3, so I haven't taken it further.
That got me thinking the next Wilson that would be useful was the 6N Class: an 1863 4-4-0T for Newcastle coal haulage. There is
one photo of this thing that I know of, and no other details whatsoever. Fortunately the photo is pretty good, and having got a feel for the Wilson style I figured I was capable of making some educated guesses that were near enough for RT3. This turned out well. It's a decent looking loco and should provide a useful little freight hauler for some scenarios. It wouldn't be hard to do an express version later either (Beyer Peacock built express 4-4-0T's for a range of railways in the 1860's). This one isn't running yet, but is at the stage where getting it running will be pretty simple.
![6N_Class_shot_1.jpg (102.44 KiB) Viewed 4984 times 6N_Class_shot_1.jpg](./download/file.php?style=46&id=6000&t=1&sid=1d4a28daa6178de365225427aa358511)
![6N_Class_shot_2.jpg (102.93 KiB) Viewed 4984 times 6N_Class_shot_2.jpg](./download/file.php?style=46&id=6001&t=1&sid=1d4a28daa6178de365225427aa358511)
The differences between it and the 8 and 12 classes are interesting. The 8 and 12 classes were well tanks, with most of the water carried underneath the crew/footplate area and the filler coming up through the coal bunker. It had to be carried here because the firebox and valve motion were taking up the space between the frames further forward. I was wondering why they would have changed from well tank to pannier tanks for the 6N Class, but think I have figured it out.
In the 1890's the NSWGR got a bunch of Baldwins (Ten Wheelers and Connies) and there ended up being a Royal Commission (ie: high level investigation) into whether they were too much for the NSW track. The Baldwins were found to be fine (problems raised were due to poor track maintenance in some spots, along with a bad batch of axles that were replaced under warranty) but one odd detail mentioned in the evidence was that the early Wilson well tanks had a tendency to break rails.
Looking at the way they were arranged, it's clear that with the well tank full the load on the rear axle would be much greater than it would be with the well tank empty. I think what happened is that, when the tank was full of water, the rear axle overloaded the rails that were available in the early 1860's. This would explain why after experience with two Wilson well tanks, the NSWGR would want a change to pannier tanks for their new freight units. With pannier tanks the weight of the water is spread evenly over the two driving axles, which is the best place to have it for adhesion and would keep the axle loads within the rail's limits.
As near as I can figure it, by taking measurements from the available photo and running comparisons with known factors from other locos of the time, the 6N Class has 16" x 26" cylinders and 54" driving wheels. This would have given it around 1/3 more hauling power than the 1 Class 0-4-2 that the NSWGR started with, and slightly more than the 23 Class 2-4-0 that would be introduced in 1865. The front truck seems to have been 36" wheels with 4 feet between axles, which was common for four wheel front trucks of the period. Bissel trucks weren't in use at this time, so the four wheel front truck was presumably to deal with tight curves around collieries and docks. By 1865 Bissel trucks were in use, so the 23 Class had them.