Car Design Basics

Learn all about mousetrap vehicle propulsion systems and how to make a mousetrap car move. You cannot build a winning mousetrap racer until you know the basics.

A mousetrap powered car is a vehicle that is powered by the energy of a wound-up mouse trap's spring. The Challenge with all mousetrap vehicles is to turn the stored potential energy from a wound up mouse trap's spring into the kinetic energy of motion. The most basic design for propelling a mousetrap racers is to tie one end of a string to a mouse trap's snapper arm and then attach the other end of the string to a drive axle. By turning the drive axle the string is wound around the drive axle causing the mouse trap's spring to compress and store energy. Once the drive axle and mouse trap are released the string is pulled from the drive axle by the mouse trap and this causes the drive wheels to rotate. Although there are other more complex propusion system such as the Jones Pulley System and the direct drive gearing, the basic propulsion system presented here is by far the most common the simplest mousetrap vehicle propulsion system.

step #1: A string is tied to the end of a mouse trap's lever arm.

step #2: An axle hook is attached and glued to the drive axle. (See how to attach an axle hook)

step #3: A loop knot is tied at the free end of the string. (See how to tie a loop knot)

step #4: The loop knot is "hooked" on the axle hook.

step #5: The string is wound around the drive axle by turning the wheels in the direction opposite to the motion of the vehicle's travel.

step #6: Once the string is fully wound around the drive axle the mousetrap car is placed on the floor and released. Once released, the mouse trap will pull the string from the drive axle causing the wheels to rotate propelling the vehicle.

Winding The String

When winding the string around the drive axle make sure NOT to put any slack in the string. The string should be wound tight as it winds around the drive axle or the mousetrap racer well have a jerky motion as the string unwinds. Always wind the string using the force of the mouse trap, do not help lift the lever arm during the winding process (except maybe at the start of the wind and then only just to get things going.

bonus tip: Never put slack in the string as you wind it around the drive axle. Always wind the string under tension. some times it is necessary to lift the lever arm in order to start winding the string but then put the string back under tension to make sure the string winds under the force of the mouse trap's spring.