Electric Rail Kart Experience

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This is a collection of things I learned from test driving my electric rail kart. It will be updated as I learn new things and make adjustments.

Index

• Mechanical
• Electronics
• Changelog

Mechanical

• I used 5 mm thick steel discs as wheel flanges. They protrude around 50 mm below the top of the rail, while normal rail wheels only protrude around 30 mm. This has both advantages and disadvantages.
  Advantages:
  • The thin discs cut through slight to moderately dense dirt (e.g. on level crossings) relatively easily
  • The vehicle stays on the track even when running over some moderately thick vegetation
  Disadvantages:
  • Because they protrude so deep, on some tracks, they hit bolts, the guide rail on some level crossings (causing the vehicle to roll on the wheel flanges instead of the main wheel surface) or other obstacles as well as causing hard impacts.
    • After removing a bit of material on the lathe to make the wheel flanges smaller, everything works fine.
• One of the screws I used to mount the wheel flanges to the motors got loose and jammed between the aluminium extrusion and the wheel flange. I subsequently put thread locker on all those screws to prevent this from happening again.
  • After I still had issues with protruding screws, I changed to countersunk screws and thread locker. No problems since.
• The 3D-printed protective covers for the motor control boards were not strong enough to withstand an impact with sturdy vegetation. A better cover needs to be designed.
  • Also, if the kart derails, the cover might slam onto the track and break.
• Despite tying down the motor wiring, some leaves and small branches still got stuck between the wires. To prevent the wires from being ripped off, another protective cover might be a good idea.
• The vehicle runs best when the wheel flanges have a lateral distance to the rails of around 3 to 5 mm on each side, which is the maximum I have allowed in my design.
• Dirt might get stuck in the open joysticks, causing them to jam or not return to their default position, which might lead to uncontrollable acceleration. A round protective shield incorporated into the design should prevent that.

Electronics

• I had issues with impacts somehow resulting in fried motor controller boards. Somehow, the impacts must have created a short circuit and blown a mosfet. I solved this by changing the interrupt priorities in the firmware, I have not had any problems like that since, despite some more impacts, even on the same spots as before.

Changelog

• 2022-10-04: Published
• 2024-06-26: Changed wording, added some more points