As promised, its finally here. The lego blue truck off roader V2!
TheFoofinator and I originally modified the blue lego technic off-road truck (set number 8435), with power functions from the bulldozer set, to allow the truck full remote control.
The first version was a good proof of concept, showing us that adding power functions to this set would enhance the model, however the first model had some major drawbacks.
Firstly the steering was poor, as the motor was situated in the back of the truck, meaning that there was a long shaft connecting the motor to the steering. This meant that most of the motors torque was lost in the shaft, making steering near impossible when not on a very smooth surface.
The second problem was the transmission. Instead of redesigned the transmission for power functions, we simply replaced the model engine with the XL motor, so the transmission was the original from the model. THe model not being designed for the motor, it meant that it could not handle the immense torque required when driving off road. Often gears would grind, and often break, when faced with any form of incline.
The priorities for the new version were to shorten the steering shaft distance, and redesign the drive mechanism.
To address the steering problem, we had to move the motor. We found a very elegant solution to this. By slightly rejigging some parts in the steering, we were able to attach the motor directly connect it to the steering column. This meant that there is no loss of torque in transmission. We were also able to maintain the centering steering.
To address the transmission problem we again, needed to shorten the transmission shafts, and remove as many gears as possible. Originally the output of the motor faces forwards. It then went down, back under the motor, and to the wheels. So this is where we started, by mounting the motor the other way around. We had to maintain the gears to move the power down, but as they were now inside the truck, we could add more support, to prevent grinding.
We also changes the positioning of the battery pack, to lower the center of mass. We changed some of the bodywork as well to strengthen the entire truck. It can now safely rollover and fall from quite a height without being damaged.
Overall, we are very happy with this version. It is the first mod that allows this truck to work off road properly.