Motor and Gearbox Tips

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  • #933
    RC Tractor Guy

    I just taught I would share some experiences about choosing a motor and gearbox to drive your homemade RC tractors. When I was working on my first Siku model conversion I initially tried to achieve drive using a small servo with plastic gears modified for continuous rotation. I used lego gears to drive the tractor axle, a worm gear on the servo and a small gear glued to the axle. This worked great for a while however eventually the strain of pushing a heavy diecast model, having nothing to slip if the tractor hit a wall and being too powerful just stall meant that the plastic gears in the servo eventually failed. Tip number one, the small plastic gears in a servo simply wont put up to the stress unless there is something to slip before the gears break or the motor is able to stall before the gears break.

    With that in mind I then decided to use a pulley system with rubber o rings which meant that when the tractor hit a wall the o ring would slip on the pulley wheel without breaking anything. The problem with mine at least, was that the pulley slipped a little too easily which meant that the tractor couldn’t pull up hills or pull heavy loads which isn’t great.

    After this I had pretty much given up and decided I needed a fresh start with a new tractor which is when I bought my second, a Fendt 936. This time I decided to use a SIKU motor and gearbox, I chose the gearbox from the SIKU control 32 Fendt 930. This gearbox has metal gears and a solid connection between the axle and the wheels. This motor will simply stall before it damages the gearbox which is ideal. This method was about five times more expensive and require a lot of filing to the model body to fit it in but it has a very solid mounting in the frame now, much better than the previous attempts. That is why I replaced the pulley system in the Massey with another Fendt 930 motor.


    Hi I have just finished converting a John Deere 8360RT, It looks great it will drive forward and reverse and the lights all work. I am using a Aduino uno with one joystick to control it. I fitted two flip N20, 30 RPM motors but they just do not have the torque to turn the tractor and it will stop at a small bump The battery is fully charged. Any ideas of the problem. I have two more motors on order to try them.

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