Making maximum traction trucks. part 5

I finally got back to working on the trucks and they are very close to being finished now. I just have to mount the side frames. The brass lugs to hold the side frame spreaders are soldered on to the ends as well. I did decide to mount the pivot point close to the driving axle as per the prototype as can be seen in the photos.

As this was a change of plan, I had to solder on a brass rubbing plate that would overhang the gears. A good thing none of this will be visible in the finished model. The phosphor bronze pick up springs were soldered to small pieces of printed circuit board which were glued to the side frames with epoxy. The pony wheels always cause a problem for me if the pick up spring tension is too high. The wheels won't rotate or only do so intermittently. I have about 1mm side play in the axles and I like to adjust the tension so that the spring barely makes contact when the axle is to that side. Then when I get both springs with the same tension they will centre the axle in the chassis and with luck the wheels will rotate.


The wire from the pick ups to the motors aren't terminated yet because these motors have no markings to indicate which lug should be positive or negative. I could have tested them before assembly but decided to leave the leads long enough to reach either lug and I will figure that out later.

It's not particularly obvious in the photos but the brass cover that holds the motor in place is itself held by two pieces of copper acting as straps. They are soldered lightly with the end of the wire bent outwards so it can easily be unsoldered if I ever need to replace the motor. The backlash is about what I think it should be and I can rotate the motor with a finger with no obvious binding of the gears. So I am happy with the results so far. I have left a space above the pony wheels where I can add some lead weight which I think will be necessary because of the position of the bearing point. So now I just have to mount the side frames and some lead and then I can get back onto the body.