Bonding Trailing Truck Spring Parts to Rear Frame

The trailing truck rear spring frame attach cross member at right on top of rear frame behind trailing truck wheels and the spring saddles from the rear cross member around the trailing truck journals to the front of the trailing truck wheels and the equalization lever mounting boxes towards the front of the rear frame at angles to the frame were glued in place aligned to the trailing truck.  The truck was attached to the front pivot to provide alignment.

The rear view of the trailing truck spring mounting parts attached to the rear frame above the trailing truck are shown above.

Each trailing truck spring sits on a saddle bar that freely rotates vertically to allow compliance with undulations in the track.  The rear of the spring is pinned to the crossbar at the hole shown at left while the center of the spring sits on the middle of the saddle bearing down on the top of the truck journal and the front of the spring is aligned with the small "U" cutout at the right of the saddle just right of the front of the truck wheel in this photo.  A lever will couple the front of the spring down past the "U" slot to the long equalization lever that will be located just in front of the truck "U" frame that passes under the rear frame.

The long equalization lever pivots are near the front of the rear frame and are angled to position the equalization levers from the spring front down link levers to the rear driver down link levers of the main frame.

Number 3-48 screws will serve as pivots and retainers for the equalization levers.  The inside portion of the lever box severs as a nut for the screw and requires threading.  A 3-48 tap in a hand tap handle is used to do the threading.

Avove the 3-48 threading is completed prior to removal of the tap.  The ABS material is soft and easily threaded by hand.

 After threading the levers are inserted in the boxes and screws inserted and snugged down.  Sufficient clearance inside the box permits free movement of the levers which were drilled out for a 5 mil clearance to the OD of the screws.

 Above pix shows the alignment of the levers which terminate at the small "U" notches on the spring saddles at the upper ends of the levers in the above photo,

After connection of the equalization levers at each end to the down links and insertion of the rear frame into the main frame a completed path of equalization exists from the center of the main frame at the top of the main drivers in the top of above photo, through that spring, downlinks to reversing lever inside main frame, up link to rear driver spring, across rear driver to cross equalization lever at rear of back driver, down links to two trailing truck equalization levers, up links to each trailing truck spring front, across trailing truck journals to trailing truck spring rear cross mount on rear frame.  The combined effect of the overall equalization linkages and springs is to transfer force between drivers and trailing truck to maintain approximately constant spring force on all wheels.  All the moving parts of the equalization system described operated on the model.  Everthing wiggles up and down when a driver or the trailing truck moves up/down.