Introduction

This kit contains the components required to build a 40:1 (single-start worm) or 20:1 (two-start worm) gearbox to fit the Taff Vale range of motors.

The gearbox can be constructed using the usual low melt solders used in etched kit instruction.

Note the gearbox etch also has hole spacings for the Mitsumi type 030 motors commonly used in smaller models.

1 x etch

1 x worm gear

1 x worm wheel

1 x long 3/16” bore bearing

1 x 3/16” bore spacer

Note that a 3/16” axle is not included as these are normally supplied with suppliers’ wheel-sets.

Instructions

• Remove gear box etch from fret. Separate the brace for the gearbox etch. Fold up with the half-etch lines innermost to form the corner. Use an engineers’ square or similar to ensure sides are at right angles to the motor plate.
• Solder cross brace across two tabs and ensure that gearbox is still square
• Run a fillet of solder into the half etch fold lines to strengthen structure.
• Complete a trial fit of the mechanical components as follows:
  • With the cross-braced side facing you, insert bearing into the apertures on either side of the etch, the shorter one to the left of the box. Do not solder these in at this stage.
  • Pass axle or 3/16 inch rod through the leftmost bearing.
  • Present worm wheel next with the boss/grub screw facing left.
  • Take the spacing collar and place over axle between worm wheel and rightmost bearing.
• Examine the relationship between components. The worm wheel should be central to the gearbox however it may be slightly off-centre. If this is the case, either adjust thickness of leftmost bearing by careful filing or use the etched shims provided on the etch to both ensure position is correct and to ensure there is no lateral “slop”.
• Once satisfied that all these components line up, remove the worm/wheels/collar/shim components and reinsert bushes.
• Take a piece of 3/16” rod (not supplied) and pass this through the bushes to ensure they are on he same plane. At this point the bushes can be soldered to the etch. Take care to prevent solder from getting into the bore of the bushes.If you have one, a chassis axle alignment tool can be helpful for this task.
• Once soldered, ensure that the rod or axle can rotate freely within the bores.
• Take the motor and install the worm gear.
• To do this, press the worm gear on carefully, using a vice or similar. Take care to ensure the gear is not damaged.
• Present the motor to the gearbox and check the clearance between the worm and the front cross brace. There should be a very slight gap between the worm and the cross brace when the motor shaft is pressed in towards the direction of the brace.
• Once satisfied with the fit, the motor can be attached to the gearbox using the screws supplied with the motor.
• Reinstall the axle, worm wheel, collar and shims. If the gears seem tight, then dismantle and adjust the position of the motor in the gearbox.
• Before applying power to test the gearbox, rotate the shaft of the motor in the gearbox to ensure nothing has tightened or “bound”.
• Apply low power initially to motor and test gearbox. The mechanism should run quietly. Further adjustment can be made at this stage if necessary as per the procedures above.
• Lubricate axle bearings with a “model railway friendly” oil.
• A period of running in will ensure a smooth running box.