Achassis (US:/ˈtʃæsi/,[1]UK:/ˈʃæsi/;[2] pluralchassis/-iz/ from Frenchchâssis[ʃɑsi]) is theload-bearingframework of a manufactured object, which structurally supports the object in its construction and function. An example of a chassis is avehicle frame, the underpart of amotor vehicle, on which the body is mounted; if therunning gear such as wheels and transmission, and sometimes even the driver's seat, are included, then the assembly is described as arolling chassis.
In the case of vehicles, the termrolling chassis means theframe plus the "runninggear" likeengine,transmission,drive shaft,differential, andsuspension. The "rolling chassis" description originated from assembly production when an integrated chassis "rolled on its own tires" just beforetruck 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.
Forcommercial 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 includemotor homes,fire engines,ambulances,box trucks, etc.
In particular applications, such asschool buses, a government agency likeNational Highway Traffic Safety Administration (NHTSA) in the U.S. defines the design standards of chassis and body conversions.[6]
Anarmoured fighting vehicle's hull[7] serves as the chassis and comprises the bottom part of the AFV that includes thetracks, 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 theturret. The hull serves as a basis forplatforms ontanks,armoured personnel carriers,combat engineering vehicles, etc.
In theintermodal trucking industry, achassis is a type of semi-trailer onto which acargo container can be mounted for road transport.
In anelectronic device (such as acomputer), the chassis consists of a frame or other internal supporting structure on which thecircuit boards and other electronics are mounted.[8]
In some designs, such as olderENIAC sets, the chassis is mounted inside a heavy, rigid cabinet, while in other designs such as moderncomputer cases, lightweight covers or panels are attached to the chassis.
The combination of chassis and outer covering is sometimes called anenclosure.
In firearms, the chassis is abedding frame onlong guns such asrifles to replace the traditionally woodenstock, for the purpose of betteraccurizing the gun. The chassis is usually made from hardmetallic material such asaluminium alloy (and less frequentlystainless steel,titanium alloy or recentlymagnesium alloy) due to metals having superiorstiffness andcompressive strength compared with wood or syntheticpolymer, which are commonly used in conventionalrifle stocks.
The chassis essentially functions as a more extensive pillar bedding, providing a metal-on-metalbearing surface that has reduced shifting potential under the stress ofrecoil. Abarreledaction bedded into a metal chassis would theoretically operate more consistently during repeated firing, resulting in betterprecision. With the increasing availability ofCNC 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.) andrail interface systems that provide mounting points for various accessories.
