Making maximum traction trucks. part 4

Everything stopped during the lead up to Christmas so not a lot has been done lately. The axles gears and wheels have been fitted to the chassis and the brass holders for the motors made. The driven axle is kept centred by the gear on the axle. I like a little sideways movement so the side frames were made a millimetre wider than necessary and a couple of brass washers threaded onto the axle along with the gear wheel which gave me just what I wanted. The pony wheels are kept centered with a piece of brass tube that is a sliding fit over the axle. The piece of tube has a hole filed in it at it's centre. When everything was lined up a dob of flux and a small amount of solder was used to lock the tube to the axle. Once the pick up springs are fitted and tensioned they will hold the axles centred but will also allow a small sideways movement if necessary while running.
The first photo shows a truck with the motor disassembled. I like to start off with the motor mounting set up so there is no backlash in the gears. Then I use cardboard shims to set the motor/worm wheel height so I get the correct backlash. Not enough and the gears will bind. Too much and the gears will jump teeth under load. Neither is desirable. I cut a square hole in the centre of the cardboard as well to make sure that the armature doesn't rub.

The brass tube in the centre is part of what will eventually hold the side frames in place. The top cover for the motor still has to have the pivot attached. Prototypically the pivot should be only about 2mm forward of the axle centre but I think I shall use a slightly more central position than that. Once the pivots are in place I shall be able to permanently set up the motors.


Now to get on with mounting the pivots and the pickup springs. Oh, and the sideframes. Seems there is still a lot to do.