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Body-on-frame is an automobile
Automobile

An automobile or motor car is a wheeled motor vehicle for transportation passengers, which also carries its own car engine or motor. Most definitions of the term specify that automobiles are designed to run primarily on roads, to have seating for one to eight people, to typically have four wheels, and to be constructed principally f...
 construction technology. Mounting a separate body to a rigid frame which supports the drivetrain was the original method of building automobiles, and its use continues to this day. The original frames were made of wood (commonly ash
Ash tree

Fraxinus is a genus of usually medium to large trees, mostly deciduous though a few subtropical species are evergreen. The leaf are opposite , and mostly pinnately-compound, simple in a few species....
), but steel ladder frames
Frame (vehicle)

A frame is the main structure of an automobile chassis. All other components fasten to it....
 became common in the 1930s.

In the USA the frequent changes in automobile design made it necessary to use a ladder frame rather than monocoque
Monocoque

Monocoque, from Greek language for single and French for shell , is a construction technique that supports structural load by using an object's external skin as opposed to using an internal frame or truss that is then covered with a non-load-bearing skin....
 to make it possible to change the design without having to change the chassis
Chassis

A chassis consists of a Frame that supports an inanimate object, analogous to an animal's skeleton, for example in a motor vehicle or a firearm....
, allowing frequent changes and improvements to the car's bodywork and interior (where they were most noticeable to customers) while leaving the chassis and driveline unchanged, and thus keeping cost down and design time short.






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Body-on-frame is an automobile
Automobile

An automobile or motor car is a wheeled motor vehicle for transportation passengers, which also carries its own car engine or motor. Most definitions of the term specify that automobiles are designed to run primarily on roads, to have seating for one to eight people, to typically have four wheels, and to be constructed principally f...
 construction technology. Mounting a separate body to a rigid frame which supports the drivetrain was the original method of building automobiles, and its use continues to this day. The original frames were made of wood (commonly ash
Ash tree

Fraxinus is a genus of usually medium to large trees, mostly deciduous though a few subtropical species are evergreen. The leaf are opposite , and mostly pinnately-compound, simple in a few species....
), but steel ladder frames
Frame (vehicle)

A frame is the main structure of an automobile chassis. All other components fasten to it....
 became common in the 1930s.

In the USA the frequent changes in automobile design made it necessary to use a ladder frame rather than monocoque
Monocoque

Monocoque, from Greek language for single and French for shell , is a construction technique that supports structural load by using an object's external skin as opposed to using an internal frame or truss that is then covered with a non-load-bearing skin....
 to make it possible to change the design without having to change the chassis
Chassis

A chassis consists of a Frame that supports an inanimate object, analogous to an animal's skeleton, for example in a motor vehicle or a firearm....
, allowing frequent changes and improvements to the car's bodywork and interior (where they were most noticeable to customers) while leaving the chassis and driveline unchanged, and thus keeping cost down and design time short. It was also easy to use the same chassis and driveline for several very different cars. Especially in the days before computer-aided design
Computer-aided design

Computer-Aided Design is the use of computer technology to aid in the design and particularly the drafting of a part or product, including entire buildings....
, this was a big advantage.

Most small passenger vehicles switched to Body Frame Integral
Body Frame Integral

Body frame integral is a methodology for manufacturing within the automotive industry. It has become the main technique for chassis assembly for most vehicles except trucks and large sport utility vehicles, replacing the traditional approach of body-on-frame ....
 construction in the 1960s, leaving just truck
Truck

File:Red truck USA.JPGA truck is a type of motor vehicle commonly used for carrying goods and materials. Some light trucks are relatively small, similar in size to a passenger automobile....
s, some bus manufacturers
Bus manufacturing

Bus manufacturing describes the manufacturing of buses and coach ....
 and large cars using conventional frames
Frame (vehicle)

A frame is the main structure of an automobile chassis. All other components fasten to it....
. The switch continued for several decades - even small SUVs typically use unibody construction today. Body-on-frame remains the preferred construction method for heavy-duty commercial vehicles, especially those which are intended to carry and pull heavy loads, such as trucks.

The Lincoln Town Car
Lincoln Town Car

The Lincoln Town Car is a full-size, rear-wheel drive luxury vehicles sedan sold by Ford Motor Company upscale Lincoln brand. The Town Car features a V8 engine and large exterior and interior dimensions....
 dominates the American limousine market because it is the last American luxury car made with body-on-frame, which makes it easy to "stretch."

Advantages and disadvantages compared to unibody


Advantages


  • Easier to design, build and modify (less of an issue now that CAD is commonplace, but still an advantage for coach-built vehicles).
  • More suited for heavy duty usage and off-roading can be more durable.
  • Easier to repair after accidents.
  • Overall better ride quality for SUVs.


Disadvantages

  • Heavier than unibody - lower performance and/or higher fuel consumption.
  • Less resistant to torsion (flexing of the whole car in corners) - compromising handling and road grip.
  • No crumple zone
    Crumple zone

    The crumple zone of a vehicle such as an automobile is a structural feature designed to compress during an accident to absorb energy from an impact....
     - higher rate of death and serious injury.
  • Higher production costs.


See also

  • Frame (vehicle)
    Frame (vehicle)

    A frame is the main structure of an automobile chassis. All other components fasten to it....
  • Body Frame Integral
    Body Frame Integral

    Body frame integral is a methodology for manufacturing within the automotive industry. It has become the main technique for chassis assembly for most vehicles except trucks and large sport utility vehicles, replacing the traditional approach of body-on-frame ....
  • Coachwork
    Coachwork

    Coachwork is the car body style of a motor vehicle which is built around a chassis, rather than being of monocoque construction. Another word is carrossery ....
  • Monocoque
    Monocoque

    Monocoque, from Greek language for single and French for shell , is a construction technique that supports structural load by using an object's external skin as opposed to using an internal frame or truss that is then covered with a non-load-bearing skin....
  • Spaceframe
  • Subframe
    Subframe

    A subframe is a structural component of a vehicle, such as an automobile or an aircraft, that uses a discrete, separate structure within a larger body-on-frame or monocoque to carry certain components, such as the engine, drivetrain, or suspension ....
  • Superleggera
    Superleggera

    Superleggera is an automobile construction technology used in Italy from the middle of the 20th century. The name means "super light" in Italian language, and was coined in 1937 by the Italian coachbuilder, Carrozzeria Touring....
  • Chassis
    Chassis

    A chassis consists of a Frame that supports an inanimate object, analogous to an animal's skeleton, for example in a motor vehicle or a firearm....
  • Backbone chassis
    Backbone chassis

    Backbone chassis is a type of an automobile construction chassis that is similar to the body-on-frame design. Instead of a two-dimensional ladder type structure, it consists of a strong tubular backbone that connects the front and rear Suspension attachment areas....

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