TOPIC:

Because I didn't have room for the shift servo and therefore the 3-speed transmission was useless, I used a CVT (Continuously Variable Transmission) here. Not one to just buy something assembled and start using it, I began by disassembling the CVT as much as I was able. You can see the parts carefully arranged here on the table. There are no instructions for this unit so it was important I remember how everything was assembled.
I could not disassemble this rear part of the transmission because it uses tiny hex bolts and although I have a tool which fits them, there was no clearance around the head to actually use the tool. The screws were all installed with thread lock so a good grip is needed to break them loose. The right hand picture shows what I could see of the internals of this rear gearbox.
Here the main housing has been attached to the rear gearbox. There is a lot of fake detail on the outside of the housing representing manifolds, valve covers, and an oil pan. The right hand image shows the hollow interior. The hole at the top will allow a gear to pass through and drive the rear gearbox.
I know that most CVTs work by adjusting the relative position of a belt between an input and output cone, thus changing the ratio. But I wasn't sure what mechanism actually caused the belt to make the adjustment. From what I can surmise from the parts below, the 6 steel balls move radially outward from centrifugal forces as a function of shaft speed. As they roll out, the mating bell housing is pushed away from the plate, thus squeezing the lower cone and forcing the belt up the ramp. That's my theory anyway.

Here is the completed cone and belt assembly. The lower pulley is driven by the motor and the upper pulley is the output. There's a compression spring that pushes the top right cone to the left. The lower cone is shown fully engaged (maximum clamp) which would pull the belt down and open the upper cone against the spring. As you slow down the ball assembly on the lower left would shift to the left, opening the lower pulleys. The upper pulleys would squeeze shut to match, powered by the spring. The right hand picture shows the whole thing assembled with a Holmes Hobbies brushed motor.
The CVT is intended to bolt right into a Tamiya tractor truck chassis, but it is not completely compatible with the crane I added. In particular, the rear transmission mounting brackets interfered with the crane support rails. In the photo on the right you can see the notch I had to cut in the aluminum rails to allow room for the CVT bracket to fit beneath.
The next interference was with one of the outrigger tubes. The outer tube interfered with the rear of the engine housing. I was able to notch the outer tube as shown to clear the transmission housing while still leaving room for the inner telescoping outrigger tubes to slide freely.
The CVT is longer than the original 3-speed transmission which means the original drive shaft no longer fits. I looked through my bin but didn't have a dogbone style shaft of the right length. instead, I was able to cut down a universal shaft from a CC-01 to the right length and I squeezed it in as shown. The drive shaft runs very close to the hydraulic hoses so I have some concern about wearing holes in them.

That's an awesome work. Congrats.

Every Tamiya tractor trucks needs lights, but I needed a new plan since I didn't have room for an MFC. I used a combination of the TLU-01 LED light unit and the TLU-02 to control it. This accepts a maximum of 16 lights on 8 channels, but I was able to extend that to 20 by wiring a couple of them in parallel. I used all 12 light buckets on the front grille and 8 of the 10 available tail lights. On the front this means that on each side I have two headlights, one fog light, one turn signal, one amber marker light and one white marker light. On the rear on each side I have two brake lights, one turn signal, and one reverse light. There aren't any marker lights on the side and the lights in the sun shade above the windshield are not functional.
The picture on the left shows the extensions I had to patch into all the wires for the tail lights. This was a lot of solder joints and it took some time to hide all the wires. I did what I could to make the wires neat under the cabin as shown on the right. There are two ESCs, two receivers, and two light controllers here with all their wiring and the interior still needs to fit above. Not shown is the Y-harness I needed to make so both ESCs could share the same battery.
The tail lights are almost completely hidden by the rear outriggers but there is a bit of light visible around the edges.
Voila! All the lights are installed, the wiring is done, the CVA is working (kind of), and the crane is functional. I think that's enough work for this model.

I am really pleased with how this model turned out. The crane is very functional and integrated very well with the truck, although installation was a seriously large amount of work. The truck looks great with the crane fully extended. Now I just need a flatbed trailer....

That's amazing! And the weight?

stingray-63 wrote:

That's amazing! And the weight?

Took me some time to figure out how to get this my scale since it is far too large. Looks like 7.7 kg (17 lbs) without battery.

Ouch 7,7kg. Big baby.