A method for keeping wheels with a modicum of springing
John Shaw
Gazette February 2014 (Vol 19 No.2)
The completed model
I model Victorian Railways (VR)
prototypes in O Scale, 1:48, as do most
other VR modellers. This is the same ratio
used by modellers of Canadian and United
States prototypes. Our northern neighbours
in New South Wales, and Victoria based
British expatriates, model in 7mm: 1 foot,
which scales around 1:43. This has little to
do with this article, but I thought you might
be amused that our national railway gauge
disaster has permeated the modelling scene.
The model and parts shown in the photos are of my scratch built Victorian Railways A2 Class 4-6-0 No 995, express passenger locomotive prior to painting and final assembly. I use Slaters wheels, bearing bushes and plunger pickups. I don’t like locking wheels and gearboxes up in frames, which means the frame bearing holes have to be slotted. This of course means a method of keeping the wheels and bearings from dropping out of the frames has to be devised. One day I had a brain wave in relation to keeping the wheels in place in the frame, with a modicum of springing thrown in at the same time. A flat is filed on the Slaters bearing bush and a piece of tubing is soldered on. A flexible wire is threaded through the tubes and over the Slaters pickups and there you have it, we have a keeper and some springing all in one.
Photo 1
Photo 1 shows the general setup with the slotted main frames and the wire through the tubes. This can be done of course by any support sticking out from the frame over which the wire can rest. Photos 2 and 3 are close ups of the wheels in place in the frame showing the tubes soldered onto the bearings leaving space for the frame. The blue wires are speaker wires and Photo 3 shows the EDM sound cam which drives a Soundtraxx DRGW K Class Tsunami in the tender. This decoder has the correct VR US Nathan chime whistle
Photo 2, gear wheel on the rear
driver
My tender locos are driven by a motor in the tender to the rear driver through North West Short Line universal couplings and ball bearing gear box as shown in Photo 4. This allows easy fitting of a large motor and flywheel. The drive shaft is virtually invisible and nicely enters the firebox through the open firebox door. I haven’t done firebox flicker yet. The flywheel is turned from a white metal casting, the mould being a cardboard tube from a loo roll.
Photo 5 shows that the ends of the keeper wires don’t need to fixed as they are threaded under a mainframe stretcher at either end of the loco frames. The loco springs and brake hangers are required to be removable and this is achieved as shown in Photo 6. The brass angles simulate the brake rodding running length ways behind the wheels. The loco springs are soldered to the angle. The brake hangers are fixed using a soldered lace pin into a 1mm brass tube between the angles. The brake hangers are in turn fixed by removable lace pins into 1mm brass tubes which span between the mainframes, as shown in Photos 2 and 3. Removing these pins thus allows the whole assembly to drop down by removing the 6 pins. The trapezoidal shape represents the ash pan sides.
All of the above requires careful design in the set out of the holes and slots in the mainframes. In this case the frames and motion gear were custom etched in nickel silver.
The finished but unpainted components are shown in Photo 7. Designing and building the model as a series of subassemblies greatly facilitates painting. I was motivated to build the model after seeing a photograph of the prototype.
Photo 4
Photo 5
Photo 6
Photo 7
This picture appeared in a booklet, Locomotion A2,
by RL Hudson, Windsor Publications (Australia) which motivated me to build the
model. A “real flying machine” says it all.
About the Prototype
185 A2 locomotives were built between 1907 and 1922 in the Victorian Railways workshops at Newport in Melbourne. 125 were built with Stephenson valve gear and the last 60, built between 1915 and 1922 were fitted with Walschaerts valve gear. Originally built with saturated boilers, they were later progressively fitted with larger superheated boilers. They had a boiler pressure of 185 psi and developed a tractive effort 27,480lbf. They were fitted with 73in driving wheels and were permitted a maximum speed of 70mph. (Hold on for dear life)
The model represents how they looked beween1926 and the mid 30s when they received modified front ends based on the work of Dr. Wagner of Deutsche Reichsbahn, and E.C Young of the University of Illinois. The modifications dramatically improved their power and performance. The softer exhaust required the fitting of smoke deflectors.
The last locomotive to be withdrawn in December 1963 was A2 986, and it is pleasing that operational restoration is well under way by Steamrail Victoria in the old Victorian Railways workshops where it was built. A2 995 is preserved at the Australian Railways Historical Society’s Museum at Williamstown, next to the Newport Workshops.
