Vehicle frame

[citation needed] It is made by taking a flat piece of steel (usually ranging in thickness from 1/8" to 3/16", but up to 1/2" or more in some heavy-duty trucks[3][4]) and rolling both sides over to form a C-shaped beam running the length of the vehicle.

Modern techniques, however, use a process similar to making C-rails in that a piece of steel is bent into four sides and then welded where both ends meet.

While appearing at first glance as a simple form made of metal, frames encounter significant stress and are built accordingly.

This is done mainly on trucks to save weight and slightly increase room for the engine since the front of the vehicle does not bear as much load as the back.

It consists of two symmetrical beams, rails, or channels, running the length of the vehicle, connected by several transverse cross-members.

This is the design used for the full-size American models of General Motors in the late 1950s and early 1960s in which the rails from alongside the engine seemed to cross in the passenger compartment, each continuing to the opposite end of the crossmember at the extreme rear of the vehicle.

It was specifically chosen to decrease the overall height of the vehicles regardless of the increase in the size of the transmission and propeller shaft humps since each row had to cover frame rails as well.

This frame type allowed for annual model changes, and lower cars, introduced in the 1950s to increase sales – without costly structural changes.

[1] The fourth to seventh generation Chevrolet Corvette used a perimeter frame integrated with an internal skeleton that serves as a clamshell.

To maximize rigidity and minimize weight, the design frequently makes maximum use of triangles, and all the forces in each strut are either tensile or compressive, never bending, so they can be kept as thin as possible.

[7] The 1951 Jaguar C-Type racing sports car utilized a lightweight, multi-tubular, triangulated frame over which an aerodynamic aluminum body was crafted.

[8] The Italian term Superleggera (meaning 'super-light') was trademarked by Carrozzeria Touring for lightweight sports-car body construction that only resembles a space-frame chassis.

Using a three-dimensional frame that consists of a cage of narrow tubes that, besides being under the body, run up the fenders and over the radiator, cowl, and roof, and under the rear window, it resembles a geodesic structure.

It is defined as:[9] A type of body/frame construction in which the body of the vehicle, its floor pan and chassis form a single structure.

Integral-type bodies for wheeled vehicles are typically manufactured by welding preformed metal panels and other components together, by forming or casting whole sections as one piece, or by combining these techniques.

Although this is sometimes also referred to as a monocoque structure, because the car's outer skin and panels are made load-bearing, there are still ribs, bulkheads, and box sections to reinforce the body, making the description semi-monocoque more appropriate.

[12] Budd supplied pressed-steel bodywork, fitted to separate frames, to automakers Dodge, Ford, Buick, and the French company, Citroën.

[12] To convince a skeptical public of the strength of unibody, both Citroën and Chrysler created advertising films showing cars surviving after being pushed off a cliff.

A larger Kapitän went into production in 1938, although its front longitudinal beams were stamped separately and then attached to the main body.

[17] By 1941, unit construction was no longer a new idea for cars, "but it was unheard of in the [American] low-price field [and] Nash wanted a bigger share of that market.

[21] By 1960, the unitized body design was used by Detroit's Big Three on their compact cars (Ford Falcon, Plymouth Valiant, and Chevrolet Corvair).

[22] Most of the American-manufactured unibody automobiles used torque boxes in their vehicle design to reduce vibrations and chassis flex, except for the Chevy II, which had a bolt-on front apron (erroneously referred to as a subframe).

"[23] This design was also used with the XJC concept developed by American Motors before its absorption by Chrysler, which later became the Jeep Grand Cherokee (ZJ).

Typically attached to a unibody or a monocoque, the rigid subframe can handle great forces from the engine and drive train.