How the Slinky Toy Works

The original 1947 patent for the Slinky, a helical spring toy designed to walk down stairs through the transfer of energy.

What it covers

The patent describes a helical spring made of a specific gauge of wire that can store and release potential energy. When placed on an incline, such as a set of stairs, the spring moves by shifting its center of gravity. As one end of the spring moves forward, it stretches and then contracts, pulling the rest of the coil along with it in a rhythmic, walking motion.

What it doesn't cover

• —Does not cover springs made of materials other than metal, such as plastic coils.
• —Does not cover non-helical spring designs or shapes.
• —Does not cover the use of the spring for industrial or mechanical dampening purposes.

The clever bit

The innovation lies in the specific ratio of wire diameter to coil diameter, which allows gravity to overcome the friction of the coils, creating a self-sustaining walking motion.

Why it matters

This patent protected the Slinky, which became one of the most iconic toys in American history. It established a new category of kinetic toys that rely on physics rather than batteries or complex gears to function.

Real-world examples

• 1.Original metal Slinky
• 2.Physics classroom demonstrations of wave motion