This is another simple concept to make an RC car out of a model, this time it's a siku tractor. I've always wanted to do this ever since I was a child playing with model tractors.
I took a SIKU diescast model tractor and fitted it with an RC receiver, a mobile phone battery, two servo motors and a few lego gears. The model I got was a Massey Ferguson MS 8680 like the one in the picture on the right.
I added sockets to the back of the tractor to allow extra batteries to be hidden in add on parts such as a trailer or a mow bar.
I also added an extra socket on the back to allow for the control of add on parts for example to control a trailer to dump its load.
The steering turned out to be remarkably easy to do, I found that the tractors steering rack was exactly match to a lego gear. I connected the gear to a standard RC servo motor and then attempted to fit it into the tractor. To do this I had to cut the pinion gear and half of the steering shaft off to allow the servo to get down to the steering rack. I then milled out part of the engine and fit the servo in, using the engine to secure it. This meant that the bonnet still lifted up and there was still most of the engine visible which was a bonus.
The drive motor was another servo modified to continuously rotate with a lego worm gear connected to it. The wheels and axle were glued so that they wouldn't spin and a lego gear was glued to the axle so that the servo could spin it. This gave the tractor nice speed control although it is quite slow.
A mobile phone battery was used to power the tractor because it could be hidden under the tractor easily. It connects straight to the RC receiver which is also hidden under the tractor. Extra power lines and an extra control line and wired to sockets at the rear of the tractor. This allows for extra features to be hidden in add on parts such as trailers or other accessories.
If you want more information on building RC tractors you can visit my other site www.rctractors.net. Here you will find information on how to build RC tractors, where to hide batteries and how to build other RC vehicles such as radio controlled excavators or dump trucks.