by Gauk
Fri, Oct 21, 2016 1:09 AM

A car chassis may refer to either the frame of a car that holds together its components or to a rolling chassis. 

A rolling chassis consists of the frame, engine and drivetrain. That is, it includes almost all components except the body. Most modern automobiles are not built with a rolling chassis, as unibody construction is more common.

It is common for people to refer to the skeletal frame of a car as the chassis, although in some cases this may not be entirely accurate. For many vehicles made in the early-to-middle 20th century, the chassis was simply the car minus the body. Antique vehicles will generally be constructed this way, making the chassis easily identifiable. Later, a technique called monocoque was developed, in which parts of the body and frame were welded together to form a single unit.

Nearly all cars sold in the U.S. today are assembled by unibody construction. Unibody frames integrate the body and frame of the vehicle, which helps reduce weight, while maintaining a solid unit. With reduced weight, cars benefit from increased fuel economy, because the engine is not working as hard. However, many pickup trucks, vans and SUVs still use a body-on-frame design to maximize towing weight and payload.

The term rolling chassis means the frame plus the "running gear" like engine, transmission, drive shaft, differential, and suspension.

An under body (sometimes referred to as "coachwork"), which is usually not necessary for integrity of the structure, is built on the chassis to complete the vehicle.

For commercial vehicles, a rolling chassis consists of an assembly of all the essential parts of a truck (without the body) to be ready for operation on the road. The design of a pleasure car chassis will be different than one for commercial vehicles because of the heavier loads and constant work use. Commercial vehicle manufacturers sell "chassis only", "cowl and chassis", as well as "chassis cab" versions that can be outfitted with specialized bodies. These include motor homes, fire engines, ambulances, box trucks, etc.

In particular applications, such as school buses, a government agency like National Highway Traffic Safety Administration (NHTSA) in the U.S. defines the design standards of chassis and body conversions.

An armoured fighting vehicle's hull serves as the chassis and comprises the bottom part of the AFV that includes the tracks, engine, driver's seat, and crew compartment. This describes the lower hull, although common usage might include the upper hull to mean the AFV without the turret. The hull serves as a basis for platforms on tanks, armoured personnel carriers, combat engineering vehicles, etc.

published by Gauk