What is a Chassis?

The term “chassis” refers to a framework, or base, that supports something else. Electronic devices like televisions and computers typically have metal chassis on which the circuit boards and electronic components are mounted. In the automotive industry, the chassis is one of the main, structural design components. In that context, a chassis is essentially the metal “frame” component that is used in body-on-frame construction. The term “rolling chassis” refers to that frame plus the drivetrain, suspension, and other essential non-body components.

The Frame in Body-on-Frame

In automotive design, there are two basic construction techniques that are defined by which component provides the structural integrity of the vehicle. Those two styles are defined as using a “structural frame” or a “structural shell.” Vehicles that use body-on-frame designs have a “structural frame” that is composed of a frame, which itself is the main component of the vehicle’s chassis.

While the terms “frame” and “chassis” aren’t completely interchangeable, they do refer to more or less the same thing: the structural skeleton that the rest of the vehicle is built on. The frame is the actual metal structure that supports the coachwork, powertrain, and suspension, while the chassis is the frame plus any number of non-body components.

Rolling Chassis

The term “rolling chassis” refers to a vehicle frame that has a number of components attached to it. These components typically include the engine, transmission, drivetrain, suspension, wheels, steering linkage, and other non-body components. In fact, a rolling chassis is often a complete vehicle minus the bodywork. These rolling chassis are often delivered to coachbuilders that use them in the production of motorhomes and other vehicles.

In addition to bare, rolling chassis, automakers often provide other types of chassis to coachbuilders. One common configuration is the “chassis cab” that includes the chassis and a van or truck cab, in which case the coachbuilder adds the rest of the body behind the cab. Another variation is the “cowl and chassis” that includes a rolling chassis, the front cowl, and one or more seats.

Glider Chassis

Like a rolling chassis, a glider lacks any bodywork. However, gliders also lack any powertrain components (i.e. engine, transmission, drivetrain). These chassis are typically equipped with suspension components, wheels, etc, so they can be moved but will not move under their own power. Additionally, glider kits often come with a body or cab in addition to the chassis.