# How the Modern Three-Point Car Seatbelt Works

> The foundational 1959 patent for the three-point seatbelt, which secures both the torso and lap to prevent injury during vehicle collisions.

- **Patent:** US 3043625
- **Original title:** Safety belt
- **Owner:** Volvo AB
- **Granted:** 1962
- **Status:** Public domain (expired)
- **Times cited:** 17
- **Field:** automotive, mechanical

## What it does

This patent describes a restraint system that uses a single continuous strap to form both a lap belt and a diagonal shoulder belt. The system anchors at three specific points: two on the floor and one on the door pillar. By pulling the strap across the chest and hips, it distributes the force of a sudden stop across the strongest parts of the human body, such as the pelvis and ribcage, rather than focusing pressure on the soft abdomen.

## What it does NOT cover

- Does not cover two-point lap-only belts common in early aviation or older cars.
- Does not cover automatic motorized seatbelt systems that move along a track.
- Does not cover airbag deployment systems or their integration with belts.
- Does not cover child-specific restraint systems like five-point harnesses.

## The clever bit

The genius lies in the geometry of the single strap, which allows for a one-handed motion to secure the body while ensuring the belt remains locked in place during deceleration.

## Real-world examples

1. Standard seatbelts in almost every passenger vehicle produced since the 1960s.

## Why it matters

This invention is widely considered one of the most significant safety advancements in automotive history. Volvo famously opened the patent to all competitors for free, prioritizing public safety over exclusive profit, which led to the three-point belt becoming the global standard for vehicle occupant protection.

## Frequently asked questions

### What does How the Modern Three-Point Car Seatbelt Works cover?

The foundational 1959 patent for the three-point seatbelt, which secures both the torso and lap to prevent injury during vehicle collisions.

### Who owns patent US 3043625?

Volvo AB owns this patent, granted in 1962.

### 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 3043625 cited by?

This patent has been cited by 17 later patents that build on its ideas.

### What problem does this patent solve?

This invention is widely considered one of the most significant safety advancements in automotive history. Volvo famously opened the patent to all competitors for free, prioritizing public safety over exclusive profit, which led to the three-point belt becoming the global standard for vehicle occupant protection.

### What does this patent NOT cover?

Does not cover two-point lap-only belts common in early aviation or older cars.

**Full plain-English explainer:** https://patentbrief.org/patent/us/3043625/three-point-seatbelt

**Original patent:** https://patents.google.com/patent/US3043625

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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 Early Vehicle Airbag Safety Systems Work](https://patentbrief.org/patent/us/3552770/automotive-airbag-safety-device) — A 1968 patent describing an early vehicle safety system that uses a rapidly inflating confinement to protect passengers during a collision.
- [How Floyd Smith Designed the Modern Parachute Pack and Harness](https://patentbrief.org/patent/us/1462456/free-fall-parachute-smith-irvin) — A 1923 patent for a parachute system that introduced a reliable pack and harness design for aviators to safely exit aircraft.
- [How Elisha Otis Invented the Modern Safety Elevator](https://patentbrief.org/patent/us/31128/otis-elevator-safety-brake) — An 1861 patent by Elisha Otis describing a mechanism to prevent elevators from falling if their support cables snap.
- [How Garrett Morgan Invented the Three-Position Traffic Signal](https://patentbrief.org/patent/us/1475024/traffic-signal-morgan) — Garrett Morgan's 1923 patent for a T-shaped traffic signal introduced a 'caution' position to manage vehicle flow more safely at busy intersections.
- [How the Revolving Door Was Invented](https://patentbrief.org/patent/us/387571/revolving-door-van-kannel) — The 1888 patent for the revolving door, designed to keep buildings warm while allowing people to enter and exit easily.