building an 0-6-0 tank engine (mark cox)

Overview

I chose to model this engine for my layout, Whitney, because I wanted a small goods engine that I could double head and was something a little bit out of the ordinary .

Reference for the engines came from Wild Swan publications Midland engines no5 The Johnson 2441 class .The book gives detailed drawings and photos of the class through the years and is an excellent source of reference to any modeller.

The Model

I started this project by placing my order with the 2mm society for wheels gears etc . When they arrived I began the process of constructing the frames. Four strips of brass were soldered together. Then with the aid of a mill they were cut to size .The wheel bearings were marked along with the secondary gear shaft then drilled. After this the frames were milled to shape. The frames were separated and cleaned. The frame bushes were soldered in place and I added 0.3mm double sided copper clad board to provide insulation. The spacers are made from 0.25mm brass as were the frames and are just folded to right angles.

Milled frames from PCB	The assembled frames

The secondary gears were fitted first. Using two half shafts 3.2mm long each .I don’t know if I’m doing something wrong but the muff always has to be shortened to fit between the frames . Once this shaft was running freely the centre wheels and gear was added. This proved to be the first problem, the mesh was to tight.

The wheels and gear shaft were removed, frame bush for the gears and the holes elongated. Using a gear meshing tool the bushes were resoldered into place then gears and wheels reassembled.

The motor chosen for this project was 6mm x 12mm long and a resistor would need to be fitted as it was 6v. As the shaft was only 1mm in diameter a bush was pushed into a worm drive then glued to the shaft. A shelf was added between the frames for the motor to rest on and frames bent over to hold the motor in place.

Motor fitted and driving the centre wheel

After some fiddling with the gear alignment the centre wheel set was running well. Next the two other wheel sets were added but again the muffs had to be shortened , possibly the wheel bushes are being soldered in the wrong way round, they are inserted from the inside. The wheels were all quartered and back to back checked. The connecting rods were then fitted being held in place with wire insulation sleeve and after a little fiddling the chassis was re run. There was a little stiffness to the movement so toothpaste was applied to the moving parts to act as a cutting paste and the engine re run. This all seemed too much for the over heating little motor so the decision was made to change it to a 8mm faulhaber motor.

Running Chassis	Testing the operation on the track

The motor now had to drive directly on the worm gear mounted on the rear set of wheels. This seemed to be the simplest option as slow speed running was still obtainable and the worm gear is still virtually invisible.

Some more images showing the construction

More will follow as construction continues.

Mark Cox.