Third article in a series

Photos by the Author

After finishing the wheels I returned to instructions building sequence to complete the frame and under carriage.

Construction of the under carriage starts with gluing the cab floor pan skins (parts 10 and 10a to 0.5mm card) and adding the engine under details (parts 16-20) to the floor pan. The previously completed frame is then glued to the floor pan assembly. The printed side of cross brace part 11 faces the rear of the frame.

One nice aspect of the construction diagrams is that diagrams 1 and 2, which provide top and side views of the frame and under carriage are actual size. This is very useful in confirming placement of the parts and alignment of the axles and suspension. When using the diagrams to orient parts remember that diagram 1 is a top view.



After assembling the frame and cab floor pan I completed the smaller assemblies, such as the traverse gear box pictured here, front hoist, and drive shafts.



Next I built the front leaf springs and their mounting brackets. The springs consist of parts 28-28i, which are glued together. Part 28a is long strip and you are to roll the ends to form at tube at each end for the spring mounting pins (S??). Since these mounting points will bear the weight of the model it is important to make them strong. I reinforced the rolled ends with CA glue to strengthen them. You may also want to consider making part 28a out of a strip of sheet brass instead of cardstock. The instruction diagrams would have you pierce a hole through the mounting brackets (parts 27-27a) and run the mounting pin through. I did not think I would like the appearance of this. To avoid the pin protruding through the outside of the brackets I glued the outside skin to 0.5mm cardstock leaving a small channel in the middle. I then pierced the inside bracket skin only and bent a piece of wire at 90 degrees placed this in the outer skin channel and glued the inner skin leaving the with protruding through the inner skin only. A small dab of white glue sealed the ends of the channel opening. I could then trim the wire to form a 2-3mm pin. When the springs and brackets were glued together this resulted in a strong mount.



After completing the springs and mounting brackets it is time to assemble the front axle, suspension, and hoist. I used heavy black thread for the winch cable. I wound two turns of thread around the hoist gluing them to the drum and leaving about 50mm excess until the remainder of the front-end details is completed. In the photo the remainder of the front underside has also been completed.



With the front springs completed it is time to move to the rear suspension and chain drive. The drive side panels (parts 40L and 40P) are each printed as one part but I found it easier to cut them into two sides and a center skin. I ran a single wire through the rear differential that will serve as a center spindle for the chain drives. For the rear wheels I decided to have a short wire axle for each tire pair instead of a single wire axle. I decided it would be easier to fit the wheels with this arrangement. I had some problem with the teardrop shaped gearbox on the front of the rear differential (parts 39-39b) and wound up having to turn it slightly off center to get it to fit around the brake cylinders (parts 25-25c).

The instructions would have you assemble the chain drives by backing parts 49 and 49a with 0.5mm card and cutting these out as single units. I had some concern with this as I was not sure I would be able to cut these out accurately as directed. So I only backed parts (49-49c) with 0.2mm card and cut each of the sprocket wheels out separately. In the top photo you can see the paper template I made to mark the center of the sprockets and drive chains. I then glued the sprocket wheels I cut out to the drive chains (parts 49b and 49c). The bottom photo shows the parts for each sprocket assembly and a completed drive chain. The white circles at the top of the photo are spacers I made to adjust for the lighter weight backing card.



One hundred forty parts later the rear suspension and drive is completed and mounted to the frame. The cross braces (parts 47 and 47a) are comprised of an inner and outer skin. However, there is no allowance for the paper thickness. To get the parts to shape correctly I cut the inner skin into separate pieces and trimmed them down until the fit properly into the outer skin.



With the front and rear axles complete the drive train is added. At this point the model is starting to take shape. The remainder of the floor pan undersides (all of parts 12, 14, 62, and 63) is also completed at this point. If you refer back to the photo of the front springs and axles you can see all of those components in place.

While I have not kept exact count I would estimate that the completed tractor frame, suspension, and wheel assemblies have consumed about 600 parts to this point.



With the tractor frame completed the next article will continue with the construction of the tractor cab.

Summary:

Model:	Nr. 189 M25 "Dragon Wagon"
Publisher:	GPM
Scale:	1/25
Difficulty:	Rated 3 on a scale of 3
Number of Parts:	2350
Instructions:	Polish, English, German
Diagrams:	7 pages
Fit:	Very Good
Coloring and Artwork:	Coloring Very Good Artwork Excellent
Printing:	Excellent