# 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.

- **Patent:** US 2415012
- **Original title:** Toy and process of use
- **Owner:** James Industries Inc
- **Granted:** 1947
- **Status:** Public domain (expired)
- **Times cited:** 29
- **Field:** mechanical, consumer_electronics

## What it does

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 does NOT 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.

## Real-world examples

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

## Frequently asked questions

### What does How the Slinky Toy Works cover?

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

### Who owns patent US 2415012?

James Industries Inc owns this patent, granted in 1947.

### When does this patent expire?

This patent has expired and is now in the public domain — anyone can use the invention freely.

### What is patent US 2415012 cited by?

This patent has been cited by 29 later patents that build on its ideas.

### What problem does this patent solve?

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.

### What does this patent NOT cover?

Does not cover springs made of materials other than metal, such as plastic coils.

**Full plain-English explainer:** https://patentbrief.org/patent/us/2415012/slinky-toy

**Original patent:** https://patents.google.com/patent/US2415012

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_Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._


## Related patents

Semantically similar inventions in the PatentBrief corpus:

- [How the Hula Hoop Works](https://patentbrief.org/patent/us/3079728/hula-hoop-wham-o) — A 1963 patent for a lightweight, rigid plastic hoop designed to rotate around a human waist through rhythmic body movements.
- [How TinkerToy's Original Wooden Construction Blocks Work](https://patentbrief.org/patent/us/1113371/tinkertoy-pajeau) — A 1914 patent for a modular toy system using wooden sticks and circular hubs with holes to build complex three-dimensional structures.
- [How A.C. Gilbert Designed Early Interlocking Toy Construction Blocks](https://patentbrief.org/patent/us/1066809/erector-set-gilbert) — A 1913 patent by A.C. Gilbert for a system of toy building blocks designed to snap together to create structures.
- [How the Koosh Ball's Design Makes It Easy to Catch](https://patentbrief.org/patent/us/4756529/koosh-ball-stillinger) — A patent for a ball made of hundreds of soft, rubbery strings that collapse on impact to make catching easy for small hands.
- [How a Spring-Loaded Pocket Dispenser Works](https://patentbrief.org/patent/us/2620061/pez-dispenser) — A 1949 mechanical design for a pocket-sized container that uses a spring to push items like pills or candies to the top for easy access.