Tamiya Fuel Tank Trailer Project

Page 1: Building the trailer

Time to build the trailer. The box for the fuel tanker is much smaller than that for the truck, and of course the trailer is just a dead weight with no motor or control so I figured it would be pretty easy compared to the truck. It ended up being much more complicated than I expected.

At first glance it looks like there isn't much in the box. Just a big metal tube protected with blue film like a new airplane fuselage. Most of the parts are actually packed inside the tube. The second image shows the considerable pile of parts and hardware, not including the metal parts which are elsewhere.

Step 1 is the forward deck which is an aluminum plate with some attached plastic stiffeners.

The side rails are long aluminum L-channels pre-drilled and tapped. To this base the front deck is attached along with some complex extruded aluminum supports for the tank.

Step 3 is the spring loaded support legs or "landing gear" for the front of the trailer. They are quite sturdy even with a heavy trailer load.

Now the legs are attached to the frame in Step 4 along with a bunch of other plates and the kingpin. One thing you can start to notice is that virtually the entire trailer is metal. The only plastic parts are the support legs and the bumper.

The rest of the coupling mechanism is installed in Step 5, and it is pretty slick. When the kingpin engages with the 5th wheel it pushes a rod which triggers the spring loaded support legs to retract. This means you can back up to a trailer and couple all remotely without ever touching the model. You do need to manually disengage the coupler and extend the legs when disconnecting though.

Step 6 is the installation of the cradles and also the long tubes along the edge. These are usually used to hold flexible ribbed hoses for unloading the fuel into underground tanks.

Step 7 is the rear bumper and the mud flaps. Notice that these match the shape and style of those on the truck. I'll also be installing trailer lights here which will plug into the truck MFC and operate accordingly.

Step 8 installs the long chrome fenders. There are also a pair of brackets which support the wheel chocks. The chocks end up being important because you need to secure the trailer from rolling backward when you back the truck into it.

Now we start the suspension. Step 9 builds the leaf springs and installs them onto the frame rails. This should look very familiar. The system and many of the parts are the same as used on the tractor.

Next come the axles. Unlike the tractor axles, these are not driven so there's no differential or pinion gear. The left and right sides are independent axle shafts so they can turn at different speeds. Like with the tractor, I upgraded the metal bushings to ball bearings.

Step 11 installs the radius arms which are plastic. There is actually quite a bit of articulation here: certainly plenty for a trailer. Step 12 doesn't actually build anything, it just explains how the legs operate. Why they chose to put that step here in the middle of the suspension build instead of with the legs I'm not sure.

The final step in the suspension (Step 13) is the construction and attachment of the dampers. I had intended to upgrade to oil dampers here, but they were out of stock and after seeing that I wouldn't really have needed them on the tractor I decided to stick with the stock units. Although the tractor dampers were a pink color, these are neutral silver.

Step 14 attaches the wheels and tires which means the trailer is built enough to try. I attached it to the truck and commenced merriment. I confess that there comes a point in most projects at which I become so excited to finish that I forget to take any more pictures. This is that point. All that is left is attaching the tube and ladder (steps 15-17) and then applying the stickers. You'll have to skip forward to the final photos to see the result. The stickers on the side of the tube were hard because they are very long so it will be very obvious if they are not straight. Additionally, since the tube is so lustrous any bubbles or wrinkles will be quite obvious. I managed to avoid any of those pitfalls but instead tore a couple of the big stickers when removing them from the backing. Not very noticeable though.

Final photos of the completed trailer taken weeks later. The metal main tube is highly polished and hard to keep clean. The wire for the lights has to be run through the inside of the can. The back is nicely detailed with a ladder and some piping. The top rail has some access points for filling. The stickers tie everything together and make it real.

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