Frame (vehicle) facts for kids

A vehicle frame is like the strong skeleton of a car, truck, or bus. It's the main part that holds everything together. Think of it as the backbone! All the other important parts, like the engine, wheels, and even the body, are attached to this frame. This way of building vehicles is sometimes called body-on-frame construction. The frame is a key part of what's known as the chassis.

A Land Rover ladder type frame

Long ago, almost all cars were built with a separate frame. But over time, most cars changed to a different design called "unibody" (we'll talk about that soon!). Today, you'll mostly find these strong frames in big vehicles like trucks and buses.

Different Kinds of Vehicle Frames

The Ladder Frame

The ladder frame is the oldest and simplest type of vehicle frame. It's named because it looks just like a ladder. It has two long beams, or rails, that run along the length of the vehicle. Shorter pieces called crossmembers connect these two main beams.

Most car makers stopped using ladder frames for cars around the 1940s. Now, you will mostly see them on trucks.

The Unibody Frame

A unibody (or unit body) design is different. In this design, the metal body of the vehicle is also the frame. It means the body and frame are built as one piece. This makes the vehicle lighter and often safer in crashes.

Unibody designs first appeared in the 1930s on some Citroën cars. Many modern vehicles use unibody construction. This includes most cars, minivans, and crossover vehicles. Some SUVs also use unibody construction, like the Dodge Durango.

Images for kids

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  Ladder frame pickup truck chassis holds the vehicle's engine, drivetrain, suspension, and wheels

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  The unibody - for unitized body - is also a form of frame. Shown, a Proton Prevé

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  A vehicle's bare ladder frame

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  Pickup truck frame. Notice hat-shaped crossmember in the background, c-shape rails and cross member in center, and a slight arc over the axle.

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  High-performance custom frame, using boxed rails and tube sections

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  Ladder chassis with diagonal cross-bracing and lightening holes

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  Backbone chassis of the 1962 Lotus Elan

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  Rolling X-frame chassis

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  Bertone FW11 prototype with perimeter frame

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  Jaguar C-Type frame

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  The Lamborghini Aventador has a carbon fibre central monocoque, with front and rear steel subframes, mounting the mechanicals