Modelling the Kerr-Stuart Brazil Class 0-4-2ST locomotive in 16mm scale. - Keith Bucklitch
1. Pony Truck Carriage.
The swinging arm is cut out from 1.5 mm mild steel, using a piercing or fret saw. The axle boxes are made from gun-metal. The drawing shows the axle boxes split so that the wheelsets may be removed for a change of gauge. If you intend to maintain a single gauge then the axle bearings may be left as a single piece. The axle boxes are soldered to the swinging arm after drilling the axle holes. After soldering, pass a 1/8" reamer through both holes to ensure they are in alignment. The swinging arm is suspended from the lower rear spacer by an 8 BA steel screw.
2. Pony Truck Wheels
The Pony wheels are made in the same manner as the drivers, according to the dimensions on the drawing. However, if you are intending to change the gauge of the locomotive frequently, it might be worthwhile making two sets of pony wheels and permanently fixing each set to the desired gauge.
If it is intended to make the wheelsets replaceable the axle boxes must be split. Drill 1.4 mm diameter for a depth of 10 mm. Open out to 1.8 mm for 5 mm depth and tap the hole 10 BA. Mark the bearing blocks (L) and (R). Saw carefully along the centre line of the axle holes then fasten the components back together with 9 mm long 10 BA cheesehead screws. Pass a reamer through the axle holes again then fit the wheelset. If this is tight, repeat the reaming until the wheels spin freely. Two silver steel pins screwed into the top of the axleboxes restrain the swinging movement of the pony. These are cut 15 mm long and threaded 8 BA for 5 mm and 2 mm at each end. Secure firmly in the axleboxes with nut lock adhesive. If you wish, you can fit short springs over these pins to supply some spring action to the pony truck. Make sure that this is not excessive though!
The pony truck bears against a spacer which has a curved slot cut in it for the retaining pins. This slot can be either milled on a rotary table or marked out, chain drilled and filed. The position of the bearer can now be found by securing the swinging arm at its front pivot point, passing the pins through the bearer and clamping in between the frames. (Note that if you decide to spring the pony truck, the bearer will need to be placed higher than shown on the drawing.) Spot through the frames, remove, drill and tap 10 BA by 6 mm deep for the fixing screws. Secure the bearer in the frames with hexagon head screws. Check the swing of the truck is free within the confines of the curved slot. If necessary file the slot accordingly. The pony truck can be removed from the chassis for now and placed to one side until later. (It has to be removed to place the fuel sump in position later.)
If you have any questions, or comments or find any errors in these notes please contact me by email. Email Keith Bucklitch.
Copyright © 1998, Keith Bucklitch
Last Edited - November 1998