Hi, I'm new to this forum. My name is Sander Fondse and I'm 23 years old. I'm a Electrical Engineering Master Student at the Technical University in Delft. I've been collecting
Lego Technic since I was 9.
I would like to present to you my version of the 8285 tow truck. I bought it in Germany when I was on holiday there in 2007. I think this
model is beautiful, but it lacks a bit in functionality given it's price. When I read the review of the model at this forum I was inspired to
try and improve it to make it a worthy Technic flagship. It was important to me to keep the look of the original model.
The modification started with the installation of an XL-motor that drives the rear axle via a 8:24 reduction, as well as an M-motor for steering.
I first used a wormgear for this, but that didn't work, as there was too much torque on the gear. I replaced the steering by a direct 8-24
clutchgear and the motor was relocated under the cab. I was able to squeeze in a battery box behind the far side panel. This hid it away nicely.
The receiver was lowered into the cab after I removed the wormgear assembly that drove the back support arms.
After this, I had a working RC truck, but I still wanted more. I therefore decided to remove the complete crane assembly and replace it with a
motorized version. With a M-Motor and a clutchgear a 4 way gearbox is operated. The gear-handels are located behind the 2 rear flaps, as were the
hand-knobs of the original. The M-Motor is controlled with a PF-Switch that is located behind the flap on the driver-side. On the far side the
pneumatic valve of the tow arm found it's place again like in the original model. With the 2 gear-handles the following 4 functions can be
operated :
1 - raising and lowering the crane-arm with a linear actuator
2 - extending the crane-arm
3 - operating the winch with a wormgear
4 - pneumatic pump
The pneumatic pump was necessary, because I found the original hand pump a real eyesore. The air-spring for the towing eyes was the next victim.
I hate air-springs, because they always seem to break after a while. I replaced the air spring with a large cylinder. Afterwards I
remembered that I had removed the wormgear for the back supporting arms. With help of a small cylinder and a crank I made this function pneumatic
as well. These are the 3 pneumatic functions.
a - raising and lowering the tow arm (only origional cylinder)
b - raising and lowering the towing eyes
c - raising and lowering the back support arms
The 2 valves for the functions b and c are on the back of the truck on the far side.
I still found some room for further improvement, so I did some small jobs like
- A detailed engine bay with simulated intake and exhaust
- Working headlights by a PF-switch on the roof
- shortened front half-axles like the suggestion for the crane truck 8258
And finally, I found that the truck didn't have enough traction. To solve this, I build in a differential into the second back axle, making
this a driven axle as well.
This was a summary of one of my most worked on models and one of my all-time favourites. I can off course take more pictures ;)