A chassis (US: /ˈtʃæsi/,[1]UK: /ˈʃæsi/;[2] plural chassis/-iz/ from French châssis[ʃɑsi]) is the load-bearing framework of a manufactured object, which structurally supports the object in its construction and function. An example of a chassis is a vehicle frame, the underpart of a motor vehicle, on which the body is mounted; if the running gear such as wheels and transmission, and sometimes even the driver's seat, are included, then the assembly is described as a rolling chassis.
In the case of vehicles, the term rolling chassis means the frame plus the "running gear" like engine, transmission, drive shaft, differential, and suspension. The "rolling chassis" description originated from assembly production when an integrated chassis "rolled on its own tires" just before truck bodies were bolted to the frames near the end of the line.[3] An underbody (sometimes referred to as "coachwork"), which is usually not necessary for the 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.[4] A car chassis will be different from one for commercial vehicles because of the heavier loads and constant work use.[5] 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 an electronic device (such as a computer), the chassis consists of a frame or other internal supporting structure on which the circuit boards and other electronics are mounted.[8]
In some designs, such as older ENIAC sets, the chassis is mounted inside a heavy, rigid cabinet, while in other designs such as modern computer cases, lightweight covers or panels are attached to the chassis.
The combination of chassis and outer covering is sometimes called an enclosure.
The chassis essentially functions as a more extensive pillar bedding, providing a metal-on-metal bearing surface that has reduced shifting potential under the stress of recoil. A barreledaction bedded into a metal chassis would theoretically operate more consistently during repeated firing, resulting in better precision. With the increasing availability of CNC machining, chassis have become more affordable and sophisticated as well as gained increasing popularity as these types of chassis can be expanded to accommodate customizable "furniture" (buttstock, pistol grip, etc.) and rail interface systems that provide mounting points for various accessories.
^Association of Licensed Automobile Manufacturers (U.S.) (1922). Official Handbook of Automobiles. National Automobile Association. p. 180. OCLC6360726. Retrieved 10 September 2010.
^Sturmey, Henry (2 April 1908). "The Use of Unsuitable Vehicles". Commercial Motor. Vol. 7, no. 160. pp. 146–147. Retrieved 10 September 2010.