Train Car

Used for this challenge: http://www.aimlessbits.org/bridge-design-contest

The 'Train' car that we'll use for the bridge competition. The bridge will need to span 5" and support a flat path for this train car to slide through. once in the middle of the bridge we'll suspend weights from the car.

Added Traincar_sm (small), it's 10mm shorter on each side, it will be a better test as it's force applied will be more centered to the bridge